# P-40 what-if



## Clay_Allison (Mar 31, 2009)

I was thinking about the P-40 and the reasons it wa considered a stopgap at best. What if, though, the P-40 had been reengined, not with the Merlin (as in the P-40F) but with the RR Griffon (if it had been turned over to an American comany for development when it was de-prioritized). Would that have worked?


----------



## davebender (Mar 31, 2009)

It would be 1943 before a Griffon powered P-40 entered operational service. By then there are better choices available. Heck you could produce a Griffon powered P-51 during early 1943.


----------



## Clay_Allison (Mar 31, 2009)

The first Griffon engine was run in 1933, I think that it would have been available before Jan 1942 if we had wanted it.


----------



## claidemore (Apr 1, 2009)

Rolls Royce had started developing the R version engine in 1933 (Schnieder Trophy R engine), but that project was shelved. Actual Griffon development started in 1939. 

The first Spitfire with a Griffon (RG 2SM) flew in November 1941, the first operational ones in October 42 (Griffon III).


----------



## davebender (Apr 1, 2009)

There's our benchmark for availability.

The P-51 (a British financed project) was flying during 1941. Why not specify that it should use a Packard built RR Griffon engine rather the the Allison? It also could be operational around October 1942, entering mass production ILO the P-47.


----------



## claidemore (Apr 1, 2009)

davebender said:


> There's our benchmark for availability.
> 
> The P-51 (a British financed project) was flying during 1941. Why not specify that it should use a Packard built RR Griffon engine rather the the Allison? It also could be operational around October 1942, entering mass production ILO the P-47.



Probably because the Allison was available right there in the USA, already operational, and the P51 was doing +400mph with it, which made it the fastest plane at low alt in its class at that time. Kind of a "if it works don't fix it" scenario. 
They only switched the P51 to a Merlin because of the experiment done with it by RAE, which showed such dramatic improvement that it could not be ignored. Had they done a similar experiment with a Griffon, they might have used it instead, except that the Merlin had already been proven in combat and in volume production, while the Griffon was still being put out in low numbers at a low rate of production.


----------



## davebender (Apr 1, 2009)

The same reason it was used in the P-38, P-39 and P-40. But if we're going through the trouble of manufacturing the Griffon engine in the USA then it should power the P-51 rather then the less capable P-40.


----------



## BombTaxi (Apr 1, 2009)

It would not have been worth manufacturing the Griffon in the USA though - as claidemore points out, it was an untried design. The Merlin was a combat-proven design which gave the Mustang best-in-class performance. Why sacrifice that advantage for an engine which offered little at the time but a host of unknowns in terms of life, ease of maintenance and overall impact on performance? From the point of view of the original British purchasing mission that commissioned the Mustang, there were some thousands of technicians in the RAF who were well used to working with the Merlin, and production facilities which could provide considerable operational as well as technical expertise to US plants. The Griffon would throw away those huge advantages.


----------



## Marshall_Stack (Apr 1, 2009)

claidemore said:


> They only switched the P51 to a Merlin because of the experiment done with it by RAE, which showed such dramatic improvement that it could not be ignored.



I have read that the USAAF was also experimenting with the Merlin P-51 at the same time as the British.


Didn't the Griffon have more "room to grow" than the Merlin?


----------



## Colin1 (Apr 1, 2009)

Rolls-Royce
did in fact carry out a design study on a Griffon 61-engined Mustang. For some reason they chose a mid-engined configuration over the proven successful conventional layout.
They arrived at the somewhat obvious conclusion that a major redesign would have been necessary and that this would have required major redesign once again if the engine, in later marks, became longer.
The Griffon Mustang was never built although Mustang AM148 was earmarked for a Griffon installation. They did get as far as a mock-up with the cockpit moved forward and other necessary changes.
A Griffon 57 did eventually see Mustang duty in P-51D N7715C as a racer based in Idaho Falls. It was in the conventional position driving a modified de Havilland 6-bladed contra-prop screw. 

The attachment, though a racer, gives a reasonable idea on how it may have looked in service


----------



## davebender (Apr 1, 2009)

Nobody is going to discontinue the RR Merlin. That would be insane. But you could certainly make an argument for having Allison manufacture the RR Griffon or Merlin ILO their own design.


----------



## MikeGazdik (Apr 1, 2009)

Here is a current Griffon engined Stang, I saw it in 07 in Columbus, Ohio. Well actually I drooled on it.


----------



## Clay_Allison (Apr 1, 2009)

BombTaxi said:


> It would not have been worth manufacturing the Griffon in the USA though - as claidemore points out, it was an untried design. The Merlin was a combat-proven design which gave the Mustang best-in-class performance. Why sacrifice that advantage for an engine which offered little at the time but a host of unknowns in terms of life, ease of maintenance and overall impact on performance? From the point of view of the original British purchasing mission that commissioned the Mustang, there were some thousands of technicians in the RAF who were well used to working with the Merlin, and production facilities which could provide considerable operational as well as technical expertise to US plants. The Griffon would throw away those huge advantages.


For the potential of developing its' many design features and making a leap forward in technology.


----------



## davebender (Apr 2, 2009)

That potential needs to be recognized before someone pours millions into research development. Frankly I'm not convinced the U.S. Army Air Corps knew what a good liquid cooled aircraft engine looked like. Which is strange considering that American air cooled radial engines were cutting edge.


----------



## drgondog (Apr 2, 2009)

BombTaxi said:


> It would not have been worth manufacturing the Griffon in the USA though - as claidemore points out, it was an untried design. The Merlin was a combat-proven design which gave the Mustang best-in-class performance. Why sacrifice that advantage for an engine which offered little at the time but a host of unknowns in terms of life, ease of maintenance and overall impact on performance? From the point of view of the original British purchasing mission that commissioned the Mustang, there were some thousands of technicians in the RAF who were well used to working with the Merlin, and production facilities which could provide considerable operational as well as technical expertise to US plants. The Griffon would throw away those huge advantages.



Pretty good summary - for both sides of the pond for a critical resource.

Another question which I don't have answer to, is what was the specific fuel consumption of Griffon vs the 1650-1, 3 and 7. If it was less, then the truly great advantage of the 51 (extreme range with high perfromance) is somewhat mitigated.


----------



## claidemore (Apr 2, 2009)

According to AFDU the Griffon engined Spitfire Mk XIV used 1 1/4 times as much fuel as the Merlin engined Spitfire Mk IX. (10-15 gallons per hour more than Mk VIII.)

Not sure how that would equate to the P51 airframe, but a guestimate of 20-25% decrease in range would seem reasonable.


----------



## drgondog (Apr 2, 2009)

claidemore said:


> According to AFDU the Griffon engined Spitfire Mk XIV used 1 1/4 times as much fuel as the Merlin engined Spitfire Mk IX. (10-15 gallons per hour more than Mk VIII.)
> 
> Not sure how that would equate to the P51 airframe, but a guestimate of 20-25% decrease in range would seem reasonable.



If the 10-15 gal/hr was at cruise settings it would have a corresponding impact on combat radius - I suspect your 25% number would be about right.

That would have had a huge impact on effectiveness in first half of 1944 going deep to Stettin, Berin, Leipzig and Munich.


----------



## BombTaxi (Apr 2, 2009)

Clay_Allison said:


> For the potential of developing its' many design features and making a leap forward in technology.




Agreed we know now, with the gift of hindsight, that the Griffon had huge potential. But the USAAF didn't know that in 1942, and 20000ft above Germany, in combat with the LW was never going to be the place to try and find out...

Interesting info about the fuel consumption - thanks guys. I hadn't realised just how dramatic the effect of the Griffon could be in that respect.


----------



## davebender (Apr 2, 2009)

> 20000ft above Germany, in combat with the LW was never going to be the place to try and find out...


I agree. However that happens a lot during wartime. Sherman tank crew going into battle for the first time thought they had the best tank on the battlefield. Then they encountered the Panther tank. The P-38 fighter aircraft was realistically tested for the first time at 30,000 feet over Germany. That didn't go over too well either. The Luftwaffe attempted to use the Me-110 fighter-bomber as a long range bomber escort during 1940. The B-17 was such a bad dude that it could bomb Germany during the daytime without a fighter escort. Or so they thought.....


----------



## BombTaxi (Apr 2, 2009)

True, there was much learned in combat, although I personally tend to see much of it coming from mistaken doctrine or lack of foresight (said, of course, with the priceless and inexcusable benefit of hindsight). It was not something anyone would want to do by choice though, when a working solution was already on hand.

Slightly OT, your final comment about the B-17 reminds me of something I read while doing a bit of research for a model of an RAF Fortress I that I hope to build soon. Apparently, the USAAF warned the RAF that the B-17C was not sufficiently armed to operate unescorted over Germany, and that altitude alone would not save it. They were right - the RAF suffered horrible problems with mechanical failures and crew capability issues due to high altitude flight, and the LW got fighters up high enough to intercept and destroy several aircraft. The RAF abandoned the type after less than 50 sorties and concentrated on night bombing instead.

Fast foward a year or so, and the 8th AF arrives with newer, admittedly more heavily armed B-17s and... repeats the folly again, although in a slightly different manner. Strange how some lessons can be unlearned isn't it?


----------



## AMCKen (Apr 2, 2009)

One would have to wonder about the 1930s aerodynamics (radiators, airfoils) of the P-40 as opposed to aircraft like the P-51. At what speed would the P-40 reach compressibility problems? What is the VNE of a P-40 - how fast could it go before the wings just folded back? : )


----------



## Ivan1GFP (Apr 2, 2009)

The Griffon was actually quite inferior to the Merlin at the beginning. Consider that the Spitfire Mk. XII was a Griffon engined Spitfire Mk. V and was not able to beat 400 mph while the Merlin engined Spitfire Mk. IX from the same time period was easily able to exceed 400 mph.

The series production of the Packard Merlin was not quite as easy as it appears. The engines were conceptually the same, but were not parts interchangeable. I believe the RR engine was mostly Metric while the Packard was SAE. There was a great demand for Merlin engines while there wasn't such a demand for Griffons which were not very well developed at the time. Packard Merlins were used in Lancasters as well as other multi-engine aircraft as well as some marks of Spitfire. The difference between the Spitfire Mk. IX and Spitfire Mk. XVI is just the producer of the engine.

Regarding the development potential of the P-40, even Curtiss recognized fairly early that the airframe had very little future, which is why there was development on the P-46. Pity that the P-46 never made it to series production.

I actually happen to like the P-40. I believe the aircraft has a character about it that few others have. I wanted one of my own so built one for Combat Flight Simulator a few years back. 

http://www.ww2aircraft.net/forum/schematics/p-40d-drawing-12109.html

Also, it was a favourite aircraft of Snoopy!

- Ivan.


----------



## billswagger (Apr 2, 2009)

Clay_Allison said:


> I was thinking about the P-40 and the reasons it wa considered a stopgap at best. What if, though, the P-40 had been reengined, not with the Merlin (as in the P-40F) but with the RR Griffon (if it had been turned over to an American comany for development when it was de-prioritized). Would that have worked?



i don't see why it wouldn't have worked.
I'm also not sure how much modification would need to be done to fit the new engine into the relatively small P-40 airframe, but to get the type of performance the engineers were looking into would've also required a super charger. (not sure if the P-40 ever had one)

Aside from performance, the war efforts were concentrating on increased range to escort bombing runs. I'm not sure the P-40 had the fuel capacity to fly such missions even if it could hypothetically achieve the altitudes with the Griffon and a super charger.


----------



## Jabberwocky (Apr 3, 2009)

Ivan1GFP said:


> The Griffon was actually quite inferior to the Merlin at the beginning. Consider that the Spitfire Mk. XII was a Griffon engined Spitfire Mk. V and was not able to beat 400 mph while the Merlin engined Spitfire Mk. IX from the same time period was easily able to exceed 400 mph.




That's the difference between a single speed two stage engine (Griffon III/IV) and a two stage, two speed engine (Merlin 60/66), rather than the difference between the airframes.

Its all about the horsepower available at altitude, not about the total horsepower.

The Spitfire XII was about 10-12 mph faster than the Spitfire XI at sea-level on essentially the same power, but it was about 900 ft/ minute slower in the inital climb, and about 45 seconds slower to 10,000 feet.

Later, when the Spitfire XII got the more powerful Griffon IV, it was about 350 ft/ minute better than the Mk IX in the climb and about 25 seconds faster to 10,000, but still slower to 20,000. It was also about 15-18 mph faster than the Mk IX at sea level. 

The Spitfire XII actually had a cleaner airframe than the Spitfire IX, with more extensive use of welding, flush riveting and fewer panels.


----------



## davebender (Apr 3, 2009)

In the comic strips I have seen Snoopy normally flew a doghouse. Compared to that a P-40 would undoubtedly be an improvement.


----------



## Ivan1GFP (Apr 3, 2009)

Jabberwocky,
Why do you say the Spitfire XII had a better airframe than a Spitfire IX? Both were re-engined Spitfire V's. Are you perhaps thinking of the Spitfire XIV which used a Spitfire VII/VIII airframe? One notable difference is the retractable tail wheel.

The Spitfire XII can be distinguised among the Griffon Spitfires in that it retained the asymmetrical oil cooler / radiator setup of the Spitfire V.

I am sure that a later model Griffon with improved supercharging would provide better performance, but I am just comparing installations of contemporary engines in the SAME airframe.

Hello davebender,
Don't forget that Snoopy flew the Kittyhawk as well as his Camel!

- Ivan.


----------



## Marshall_Stack (Apr 3, 2009)

Why didn't any of the major American auto producers attempt to create an in-line engine? The only one that I know of is Chrysler's prototype hemi engine that was put in the XP-47H. Although it had a lot of horsepower, it was too big and the thunderbolt couldn't do much over 400 mph.


----------



## BombTaxi (Apr 3, 2009)

Marshall_Stack said:


> Why didn't any of the major American auto producers attempt to create an in-line engine? The only one that I know of is Chrysler's prototype hemi engine that was put in the XP-47H. Although it had a lot of horsepower, it was too big and the thunderbolt couldn't do much over 400 mph.



I suspect the reasons to be twofold. Firstly, I would suspect (although I am no engineer), that the tolerance expected in auto engineering of the day were nowhere near those sought in aero engine manufacture, requiring a big step up in quality control and engineering finesse from auto makers. And as you have already hinted, an aero engine needs to be as light as possible - not an easy design criteria to adapt to for guys used to making truck engines!

Secondly, I am sure that the auto manufacturers found themselves swamped with demand for engines for tanks and trucks, leaving little production capacity available for the manufacture of large and complicated aero engines. I suspect the numbers that could have been produced would have been quite small compare to the Wright's and P-W's of this world.


----------



## davebender (Apr 3, 2009)

> Why didn't any of the major American auto producers attempt to create an in-line engine?


Because the USN and U.S. Army Air Corps didn't provide funding for research and development. Designing an aircraft engine is too expensive to pursue the project without Government funding and guaranteed sales.


----------



## red admiral (Apr 3, 2009)

davebender said:


> Because the USN and U.S. Army Air Corps didn't provide funding for research and development. Designing an aircraft engine is too expensive to pursue the project without Government funding and guaranteed sales.



The US spent ridiculous sums on money on the various inline designs for the hyper engine program during the late 1930s and early 1940s and all turned up duds. The greatest problem was the lack of experience with inlines as they'd been largely ignored in the US for the past 15 years. All the engines from the program (IV-1430, IV-2220, H-2600, H-3730) were huge failures despite years of development and millions of investment.


----------



## davebender (Apr 3, 2009)

Britain and Germany produced great water cooled V12s during the late 1930s. Why not swap American radial engine technology for European V12 technology?


----------



## Jabberwocky (Apr 4, 2009)

Ivan1GFP said:


> Jabberwocky,
> Why do you say the Spitfire XII had a better airframe than a Spitfire IX? Both were re-engined Spitfire V's. Are you perhaps thinking of the Spitfire XIV which used a Spitfire VII/VIII airframe? One notable difference is the retractable tail wheel.



Not a better airframe, just a slightly cleaner one aerodynamically.

They both had airframes which were BASED on the Mk V, but their airframes were not exactly identical. 

As I said earlier, the Mk XII used different panneling (in the nose) and was the first Spitfire type to use flush riveting. It also had a revised spinner, new (and improved) removable wing panels and better wing leading edge skinning.

As a result, for the same given power level, the Mk XII was approximately 10-12 mph faster than the Mk IX, despite having slightly more frontal drag.


----------



## Elvis (Apr 5, 2009)

Clay_Allison said:


> I was thinking about the P-40 and the reasons it wa considered a stopgap at best. What if, though, the P-40 had been reengined, not with the Merlin (as in the P-40F) but with the RR Griffon (if it had been turned over to an American comany for development when it was de-prioritized). Would that have worked?


Clay,

It almost sounds as if you're trying to design an "Allied Me-109".

Interesting concept.

I would think testing would prove that the P-40 would require so much modification from the installation of such a large engine, that it might hasten a totally new design.
Possibly "P-40 based", but after all was said and done, a new aircraft.
That was one nice thing about the Allison. It was a light enough alternative powerplant that only a partial redesign of the P-36 was needed to yield the P-40.

Interesting pics of the Griffon-powered 51's, too.
I've never seen those before.




Elvis


----------



## Elvis (Apr 5, 2009)

Jabberwocky said:


> Its all about the horsepower available at altitude, not about the total horsepower.


YES, YES! *FINALLY*, someone put it down succinctly!

Cudo's Jabberwocky!
Well written!






Elvis


----------



## Demetrious (Apr 5, 2009)

Elvis said:


> Clay,
> 
> It almost sounds as if you're trying to design an "Allied Me-109".



Interesting comment...

The P-40E was significantly lighter then the P-51 empty- 6,350lbs for the P-40E to the 7,635 lb of the P-51D- making the P-40 a thousand pounds lighter. A Merlin- or a Griffin- would have given the P-40 a power/weight ratio of 0.23 hp/lbs if equipped with a 1500 hp engine, which is comparable to Bf-109 models of it's era. Maneuverability was also similar.

As for engines- the P-39-D2, produced in 1942, mounted an Allison V-1710-63 that put out 1590 horsepower, quite an impressive number. Now, since this Allison engine was clearly available in 1941, was there anything stopping it from being installed in the P-40 besides logistics? Was the P-40's nose too small to accommodate that engine?

EDIT: Random googling turns up values ranging from 1300 HP to 1500 HP for the V-1710-63, but even the low-range estimates give it a good edge over the Allisons installed in the P-40, which never really topped 1100 HP, from everything I've seen.


----------



## Ivan1GFP (Apr 5, 2009)

Hi Demetrious,
The P-40N series had 1300+ HP. The 1150 HP range really goes with the P-40E.

When comparing weights of aircraft, you really need to look at "Basic Weight" and add in the weight of the pilot. Empty weight leaves out essentials such as radios, guns, bomb racks and just about everything else than can be unbolted from the airframe.

I like the P-40, but I believe there are too many little "Gotchas" that need to be addressed to make it into a really good airframe:
1. The plane needs a new radiator location such as under the aft fuselage. The Radiator up front makes for less plumbing that can get shot up, but causes turbulent airflow for the rest of the fuselage.
2. The main landing gear has too many bumps and too much exposed. It should be inward retracting with doors covering everything.
3. The wing should be rebuilt with a laminar flow airfoil.
4. The rivetting and panels should be cleaned up. There are control rods and little fairings or holes poking out from various places that should not be there.

The end result of doing all these changes is that you basically have something looking like a P-46. I wonder if you can still call it a P-40 at that point?

- Ivan.


----------



## Clay_Allison (Apr 6, 2009)

Elvis said:


> Clay,
> 
> It almost sounds as if you're trying to design an "Allied Me-109".
> 
> ...


Well, yeah. The Me-109 was a mass production capable fighter that was a JAck of All Trades with no clear strengths or weaknesses. Its speciality was that it was competitive under all conditions even though it rarely had pure dominance, it always gave its pilots an even shake.

The more I learn about aircraft and aerodynamics, the more unfortunate the P-40 looks to me. The rebalancing it took to make a pretty sleek and light P-36 into what we got makes it look poorly proportioned. 

I think that in place of the P-40, Curtis should have made a ground-up light interceptor with a 3-speed supercharged Allison, even if said supercharger was a heavy aftermarket add-on rather than truly integral.

If not that, they should have just put more and more powerful engines in the P-36 with more weapons, pilot armor, and self-sealing tanks.


----------



## Demetrious (Apr 6, 2009)

Ivan1GFP said:


> When comparing weights of aircraft, you really need to look at "Basic Weight" and add in the weight of the pilot. Empty weight leaves out essentials such as radios, guns, bomb racks and just about everything else than can be unbolted from the airframe.



I personally go by "empty weight" simply because that's the only hard and fast measure to go on. For example, comparing the "loaded weights" of the P-40 vs. the P-51 would be unfair to the P-51, because it has 8 hours worth of fuel onboard- at least half of which will be burned up when it enters combat. If you want to compare, say, a Spitfire to a P-51, then you should only weight the P-51 in with 25% fuel, because that would be it's "combat weight" if given the same mission as a Spitfire- intercept. 

That's why I go by "empty" weight. It's a rough measure, for sure, but it gives a relative idea of the weights of the aircraft that is somewhat unmarred by variables like those. In my opinion, anyway. 



> I like the P-40, but I believe there are too many little "Gotchas" that need to be addressed to make it into a really good airframe:
> 1. The plane needs a new radiator location such as under the aft fuselage.  The Radiator up front makes for less plumbing that can get shot up, but causes turbulent airflow for the rest of the fuselage.
> 2. The main landing gear has too many bumps and too much exposed. It should be inward retracting with doors covering everything.
> 3. The wing should be rebuilt with a laminar flow airfoil.
> 4. The rivetting and panels should be cleaned up. There are control rods and little fairings or holes poking out from various places that should not be there.



Good points, all. The P-40's airframe had a number of vices, and there's only so many that could have been corrected expediently.


----------



## Elvis (Apr 6, 2009)

Demetrious said:


> As for engines- the P-39-D2, produced in 1942, mounted an Allison V-1710-63 that put out 1590 horsepower, quite an impressive number....EDIT: Random googling turns up values ranging from 1300 HP to 1500 HP for the V-1710-63, but even the low-range estimates give it a good edge over the Allisons installed in the P-40, which never really topped 1100 HP, from everything I've seen.


Demetrious,

That figure is wrong.
I strongly suggest you read (or re-read) my response to you (post #140, 5th down from the top), from this thread - http://www.ww2aircraft.net/forum/aviation/p-40-warhawk-kittyhawk-17083-10.html - and note the link for those performance figures.
They're official USAF documents from 1949.
I can't see verification getting any more definitive than that.
...also, why stop at 1500HP?
The Rolls Griffon eventually made upwards of 2300-2500 HP.
--------------------------------------------------------------------------


Ivan1GFP said:


> I like the P-40, but I believe there are too many little "Gotchas" that need to be addressed to make it into a really good airframe:
> 1. The plane needs a new radiator location such as under the aft fuselage. The Radiator up front makes for less plumbing that can get shot up, but causes turbulent airflow for the rest of the fuselage.
> 2. The main landing gear has too many bumps and too much exposed. It should be inward retracting with doors covering everything.
> 3. The wing should be rebuilt with a laminar flow airfoil.
> 4. The rivetting and panels should be cleaned up. There are control rods and little fairings or holes poking out from various places that should not be there.





Clay_Allison said:


> Well, yeah. The Me-109 was a mass production capable fighter that was a JAck of All Trades with no clear strengths or weaknesses. Its speciality was that it was competitive under all conditions even though it rarely had pure dominance, it always gave its pilots an even shake.
> 
> The more I learn about aircraft and aerodynamics, the more unfortunate the P-40 looks to me. The rebalancing it took to make a pretty sleek and light P-36 into what we got makes it look poorly proportioned.
> 
> ...


Ivan Clay,

Yes, you guys get it.
Modifications would have to be so drastic that you're going to end up with a new plane.
A P-46? Maybe. 
Ivan's suggestions seem to almost suggest a "Curtiss P-51".

...also, I see no mention of modifying the prop.
I would think it would at least be _some_ waste of all that added power, if it were to simply turn the same prop that was used before the modification.
Wider, longer or more blades, but something should definately change with that aspect, as well.
This would give you the most satisfactory results from the installation of the upgraded powerplant.

Also, Clay, the reason I made the connection to the 109 is that both the Griffon and the DB-605 are of similar displacement and configuration (V-12 of approximately 2230 cu.in.).
Add to that, that the 109 is basically a modified 108 with a great big engine hanging off the front, and you can see that your idea of the Griffon powered P-40 is very similar.
However, remember that the Allison, being a lighter weight engine, isn't as stout (or doesn't appear to be, anyway) as the Rolls engines, thus the problems with added stress when dealing with power enhancing "add-ons".
_Triple-speed supercharging_ might be an almost "Rube Goldberg" approach to the idea.
I still think a two-speed, single stage, intercooled supercharger with a larger impeller is the way to go with the Allison.
As Jabberwocky stated earlier, its not so much about total HP, its how much you can retain upstairs.
So, if the Allison made, lets say, 1350-1400HP at take off, but could still be making 1100-1150 HP at 20-30K feet, both the early 51's and the P-40's would've been better performers, overall.
The two-speed single stage, intercooled Allison with the prop used on the 51-D, would've given the P-40 an infinately better climb rate ("lack of bounce" being a detraction I've heard before about that plane) and better performance at the higher altitudes that the 109 liked to fight at.



Elvis


----------



## Demetrious (Apr 6, 2009)

Elvis said:


> Demetrious,
> 
> I strongly suggest you read (or re-read) my response to you (post #140, 5th down from the top), from this thread - http://www.ww2aircraft.net/forum/aviation/p-40-warhawk-kittyhawk-17083-10.html - and note the link for those performance figures.
> --------------------------------------------------------------------------



Thank you _so much_ for the links, and I'm sorry I didn't see that post in the old thread before. The links are excellent, especially the P-40 data archive. The issue of the Allison -63 has been bugging me for days. Forgive me for being tremendously thick and missing your original post.  

Here's the curious thing:



> Actually, it made 1325HP @ 3000 RPM on take-off 1150HP @ the same RPM @ 11800 ft.
> It seems that Curtiss skipped this particular version of that engine and went straight to the "-73", going on to mount the "-81" and finally, the "-99" versions of this engine in successive models of the P-40.
> The "-73" differs from the "-39" in that there is no gun synchonizer installed and it has improved take-off ratings.
> Performance for "-73" is as follows:
> ...



This would explain why it seems the P-40 never received an engine upgrade worth a hoot- apparently all the data I've seen (which puts it consistently at 1100HP) was giving full power at middle altitude, not at it's optimum altitude. 

Of course, this also reinforces what Jabberwocky said- the power at altitude consideration. A 200HP advantage over older models (on full War Emergency Power) isn't enough to be a game-changer (400HP and you're talking,) but it would still make a marked difference in a fighter who's primary failing was low power. But if it disappears at the rather low altitude of 12,000 feet, it may as well not exist. 

I don't think of 12,000 feet as being very high at all, perhaps middle altitude. I would have expected most engines to suffer significant performance drops somewhere around 16 or 17 thousand feet. A fighter that flounders at 20,000 feet but dances at 10,000 is not a bad ride for lots of missions. A fighter that chokes out by 10,000 feet, however, is in serious trouble. And at any altitude in between- say, five or six- the small boost in power is already being nibbled away at until it goes from useful to ineffectual. 

In short, the Allisons in the later model P-40s were game, but it was all useless without a supercharger. 




> Yes, you guys get it.
> Modifications would have to be so drastic that you're going to end up with a new plane.
> 
> A P-46? Maybe.
> Ivan's suggestions seem to almost suggest a "Curtiss P-51".



Exactly, especially with the "laminar flow airfoil." When you replace the airfoil you've essentially moved on to building a new aircraft.


----------



## Clay_Allison (Apr 6, 2009)

Elvis said:


> Demetrious,
> 
> That figure is wrong.
> I strongly suggest you read (or re-read) my response to you (post #140, 5th down from the top), from this thread - http://www.ww2aircraft.net/forum/aviation/p-40-warhawk-kittyhawk-17083-10.html - and note the link for those performance figures.
> ...


I was thinking of three speed so that you could have Low, Medium and High alt settings. Mostly I was thinking it was a way to get around our lack of a two-stage supercharger. Adding an extra speed is just another little gear on the gearbox. The larger Impeller is a must though.


----------



## MikeGazdik (Apr 6, 2009)

Clay, one your done fixing up your P-40, I want to put a Packard Rolls Royce Merlin into a P-39 Airacobra! That would be interesting!!!!!


----------



## Clay_Allison (Apr 7, 2009)

MikeGazdik said:


> Clay, one your done fixing up your P-40, I want to put a Packard Rolls Royce Merlin into a P-39 Airacobra! That would be interesting!!!!!


The P-39 was a tragedy. They could have had the original turbocharger, I think if they replaced the cannon with one that didn't suck (a little more modern, maybe 25mm), it would be impressive.


----------



## Ivan1GFP (Apr 7, 2009)

The bottom line is that with the high drag and lack of refinement of the P-36/P-40 airframe, it isn't worth putting the hottest engine you can find just to prove a point. Just about anything you bolt onto a P-40 would get you better results with a P-51. Consider that the P-51A (F-6B) was able to achieve 410 mph at about 12,000 feet with 1350 hp or so from a V-1710-(81?). The Mustang was just an exceptionally clean plane.

I am also not so sure that the P-40 would need a 4 blade prop to use additional HP. Consider that the P-38 had fairly high power Allison engines but used 3 blade props.

You can't really fault the P-36 / P-40 for being what it was considering the time it was originally designed. It was barely out of the biplane era.

- Ivan.


----------



## Demetrious (Apr 7, 2009)

Ivan1GFP said:


> Just about anything you bolt onto a P-40 would get you better results with a P-51.



That's kind of obvious, isn't it? The real "what-if" concerns if Allison corp. had produced a properly powerful, turbocharged engine to power the P-40, or perhaps if Rolls-Royce Co. had produced enough Merlins to go around. 

Remember, the P-51A came about because the British came to North American aviation asking for them to build more P-40s, because the Curtiss-Wright plant was running at capacity. That's why A-36s and P-40s served side by side in the Desert Air Force- there was a tremendous demand for any fighter available, and the P-40 was more then good enough for the role, even if the early Mustangs were better. 

It came down to an issue of only having enough "good" engines to go around, and obviously they chose to put them in the newer, faster airframe, which was the right choice. The "what-if" is, what would have happened if the domestic American aero-engine industry had been on the ball? Quite likely the P-51 would have rode to victory with an Allison powerplant in the D-model and onwards, and there certainly would have been enough of the supercharged engines to equip the P-40s that were still being pumped out at capacity for most of the war. The consequences of more good engines of course is more good fighters- in this case, the P-40 (though it could have been another ship as well.) So of course, it's an interesting "what-if" that really concerns the war at large. Better P-40s is just the fine point of the spear. 



Clay said:


> The P-39 was a tragedy. They could have had the original turbocharger, I think if they replaced the cannon with one that didn't suck (a little more modern, maybe 25mm), it would be impressive.



The decision to ditch the supercharger on the P-39 hurt it much the same way the P-40 was. The P-39 really was a great performer- an excellent turner, though I think she was a bit slow in a roll. A fairly durable aircraft, as well, and generally nimble. 

The cannon wasn't bad at all, in my opinion- it was typical of mid-war heavy cannon, comparable to the 30mm "melon-launcher" in later Bf-109s. That is to say, a heavy cannon with a low rate of fire and anemic ballistics. The Germans learned how to employ it properly, and so did the Russians. 

Replacing the 37mm doombringer with a single 20mm hispano would have reduced the hitting power but made actually hitting a lot easier, for sure, giving the P-39 a battery roughly akin to the P-38.


----------



## Marshall_Stack (Apr 7, 2009)

Ivan1GFP said:


> I am also not so sure that the P-40 would need a 4 blade prop to use additional HP. Consider that the P-38 had fairly high power Allison engines but used 3 blade props.
> 
> - Ivan.



The XP-40Q had a 4 blade prop.


----------



## Elvis (Apr 7, 2009)

Demetrious said:


> Thank you _so much_ for the links, and I'm sorry I didn't see that post in the old thread before. The links are excellent, especially the P-40 data archive. The issue of the Allison -63 has been bugging me for days. Forgive me for being tremendously thick and missing your original post. ......this also reinforces what Jabberwocky said- the power at altitude consideration. A 200HP advantage over older models (on full War Emergency Power) isn't enough to be a game-changer (400HP and you're talking,) but it would still make a marked difference in a fighter who's primary failing was low power. But if it disappears at the rather low altitude of 12,000 feet, it may as well not exist.......In short, the Allisons in the later model P-40s were game, but it was all useless without a supercharger.


Demetrious,

Glad you finally saw that comment and links from the other thread, and no worries. None of us are "eagle eyed" _all_ of the time. 
You're right about the engine petering out at low altitudes.
I wish I had an answer as to why the USAAF never addressed the low ceiling of the P-40.
Later engines made similar power at slightly higher altitudes, but even 15K feet is a bit low, when everyone else is playing at 20K feet +
BTW, if you look again, you'll see all of those engines were indeed supercharged, there just didn't seem to be enough "blow" to get the plane to perform at a _proper_ altitude.
--------------------------------------------------------------------------



Clay_Allison said:


> I was thinking of three speed so that you could have Low, Medium and High alt settings. Mostly I was thinking it was a way to get around our lack of a two-stage supercharger. Adding an extra speed is just another little gear on the gearbox. The larger Impeller is a must though.


Ok, I think I see what you're getting at now.
The problem I see here is that you're making a part of the airplane more complex than it really needs to be.
If you had a two-speed supercharger, and say the higher speed section used a 50% overdrive, that would effectively spin the impeller twice as fast.
So if your "first gear" is 8.8:1, then the impeller speed @ 3000 RPM is going to be 26,400 RPM.
Once the engine starts "weezing" at around 12-15K feet, the second gear kicks in, changing the effective gear ration to 17.6:1, and that spins the impeller at 52,800 RPM, and that's a whole lotta extra air going into the engine.
I think it would work fine for the remaining 10-15,000 feet you'd still need to climb.
Remember, the plane did fine to about 12-15,000 feet, it was _past_ that altitude that things went "horribly" wrong.
By keeping the gearbox simpler, you make it more reliable. If you can set the gearing and build the box so that it would stand up to that gearing, you've now got a reliable piece of equipment that will do the job you need it to do.
...and who's to say the gear even needed to be that high.
Testing would be needed to see how the engine actually performed at the requred altitude.
Not sure if such a facility existed at that time.
--------------------------------------------------------------------------



Ivan1GFP said:


> The bottom line is that with the high drag and lack of refinement of the P-36/P-40 airframe, it isn't worth putting the hottest engine you can find just to prove a point. Just about anything you bolt onto a P-40 would get you better results with a P-51. Consider that the P-51A (F-6B) was able to achieve 410 mph at about 12,000 feet with 1350 hp or so from a V-1710-(81?). The Mustang was just an exceptionally clean plane.
> 
> I am also not so sure that the P-40 would need a 4 blade prop to use additional HP. Consider that the P-38 had fairly high power Allison engines but used 3 blade props.
> 
> You can't really fault the P-36 / P-40 for being what it was considering the time it was originally designed. It was barely out of the biplane era.


Excellent points, Ivan. 
Thus my suggestion for the supercharging upgrade to the Allison.
I wouldn't want to make it a competitor to the 60/61 series Merlin, since we already had the Merlin.
However, making the Allison a "better" engine at more useful altitudes, using a supercharging system we already had access to (thart used on the Merlin series 20 engine), would be worth the effort at a minimum of cost and testing.
BTW, the 51A used the same engine as the P-40, although this page lists the HP a little higher, @ 1200.


> The P-51A was powered by the Allison V-1710-81 which had automatic boost control and rated at 1,200 horsepower. This Allison had increased performance at altitude over the V-1710-39 used in the P-51. The propeller was a 3-blade, 10 feet 6 inch Curtiss electric. Top speed was 390 mph at 20,000 feet and the service ceiling was 31,500 feet.


I believe that prop is approximately the same size as that used on the P-40, as well (I'll have to verify that, though. Not sure).
What I like about the early 51's is that it _could've_ been a very effective aircraft, at a lighter weight than the Merlin powered version, thus giving it better balance and agility.
As for the prop, you're going to need to "more" as the altitude gets higher, since what is highly effective at sea level to, say, 5,000 feet, is not nearly as effective at 25K or even 15K feet.
You're right, though, it doesn't neccessarily have to be an extra blade. 
The difference might just be a longer blade or a wider blade.
Any way you slice it though, to effectively work at higher altitudes, you're going to need _more_ blade, how ever you attain it, and the fact is, you now have a lot more power to twist those blades with, so why not take advantage of that.
It would seem almost stupid not to.



Elvis


----------



## Marshall_Stack (Apr 7, 2009)

Elvis said:


> Demetrious,
> 
> However, making the Allison a "better" engine at more useful altitudes, using a supercharging system we already had access to (thart used on the Merlin series 20 engine), would be worth the effort at a minimum of cost and testing.
> 
> Elvis



Didn't the Merlin equipped P-40s have the RR Merlin 20 series? If it did, it really didn't make that much of a difference in performance at altitude. Its critical altitude was only a couple of thousand feet higher.


----------



## Elvis (Apr 8, 2009)

Yes, but it still made more power than the Allison, as it was normally equipped in the P-40 (the Allison, that is).
With the Allison's increased displacment over the Merlin, a similar system should yield a better performing engine...at least compared to the one's that were actually fitted to the P-40. 

...and I like your new avatar. Did you design that?




Elvis


----------



## HoHun (Apr 9, 2009)

Hi Marshall,

>Didn't the Merlin equipped P-40s have the RR Merlin 20 series? If it did, it really didn't make that much of a difference in performance at altitude. 

You're right. Here is a diagram showing the various versions of the P-40, supplemented by a hypothetical P-40 with Merlin 61. For the latter, I have looked at the Spitfire V/IX comparison and added 300 kg of weight and 15 % in terms of Cd0 for the Merlin 61 model over the standard Merlin model.

Performance is not all that impressive.

Regards,

Henning (HoHun)


----------



## Elvis (Apr 9, 2009)

HoHun,

Just wondering where you got the figure for climb rate of the P-40N from?
It appears you're giving that version an initial climb rate of 19 m/s, which converts to about 3740 ft/min.

Am I reading that correctly?




Elvis


----------



## claidemore (Apr 9, 2009)

Elvis said:


> ...and I like your new avatar. Did you design that?
> 
> Elvis



Marshalls avatar is the logo of the St. Louis Blues hockey team.


----------



## Elvis (Apr 9, 2009)

Ah. Very nice.
Thanks for the info.



Elvis


----------



## HoHun (Apr 9, 2009)

Hi Elvis,

>Just wondering where you got the figure for climb rate of the P-40N from?
It appears you're giving that version an initial climb rate of 19 m/s, which converts to about 3740 ft/min.

>Am I reading that correctly?

Yes, that's correct. There is no direct source for this climb rate as the analysis is a match of several different, often partially incomplete and sometimes contradictory data sets. However, a good source for P-40 data can be found here: Perils P40 Archive Data (and Peril actually provided tons of data for my analysis).

Note that (as I have occasionally pointed out before) my calculations do not (yet) account for additional drag in the climb case caused by wide-open radiator flaps, which I suspect can give about 1 m/s high results for aircraft with "draggy" flaps.

However, you can find even quicker-climbing P-40N data sets on Peril's site - though I'm not sure they can actually be accurate. My figure is probably the maximum possible for the lightest P-40 model in perfectly clean configuration at the highest historical power setting.

Regards,

Henning (HoHun)


----------



## Elvis (Apr 9, 2009)

Interesting.
So if I'm understanding you correctly, I should regard your graphs as "optimistic".
Ok, will do. Thanks for the heads up.
FWIW, I'm at Peril's site now and found some climb info for the P-40N-1, but they are "time-to-altitude" figures and the best I can come up with is a little over 2600 ft./min., up to 15K feet.
The highest "outright" climb rate I could determine, using that chart, was 3000 ft./min., which I determined by noticing that it only took 1:40 to climb from 5K to 10K.

http://www.raafwarbirds.org.au/targetvraaf/p40_archive/pdfs/P40N-1 RAF Test.pdf



Elvis


----------



## HoHun (Apr 9, 2009)

Hi Elvis,

>Exactly what section of Peril's gave you the 3740 ft./min. figure?

As pointed out above, none 

>I'm at Peril's site now and found some climb info for the P-40N-1, but they are "time-to-altitude" figures and the best I can come up with is a little over 2600 ft./min., up to 15K feet.

The average from a time to altitude is inevitably lower than the peak climbrate near sea level.

It's this comparison that gives even better time to altitude figures than I have calculated:

http://www.raafwarbirds.org.au/targetvraaf/p40_archive/pdfs/P40s compared.pdf

Note that this report provides a weight for the P-40N, while the one you quoted provides theoretically more useful small intervals of time-to-altitude, but lacks the important weight information. It also is at a slightly lower power setting than the one I used for calculation.

Assuming 7400 lbs weight, I get 84 s to 5000 ft, compared to 130 s from the British chart. Doesn't look good! But they also provide a total time of 540 s to 20000 ft, while I calculate 578 s - so suddenly their climb rate is better than mine. But we don't know their flying weight, whether they have corrected the data for standard day conditions so that it is comparable at all, and whether they have normalized the data for a constant weight (while in the climb, the real aircraft gets lighter as it climbs because it consumes fuel, ejecting the gases through the exhausts).

Sorry that I can't give a simple answer - the climb data is calculated from the evaluation of multiple data sets of different P-40 aircraft, none of which was actually tested yielding the exact climb curve I originally posted.

Regards,

Henning (HoHun)


----------



## HoHun (Apr 9, 2009)

Hi Elvis,

>So if I'm understanding you correctly, I should regard your graphs as "optimistic".

Roger that! For the cases in which I had well-documented data to compare to, my calculation often tended to be about 1 m/s on the high side. My best guess is that the additional drag of adjustable cowl flaps in the open position which I have not included in my calculations is causing this difference.

Regards,

Henning (HoHun)


----------



## Elvis (Apr 9, 2009)

Elvis said:


> BTW, the 51A used the same engine as the P-40, although this page lists the HP a little higher, @ 1200.
> *I believe that prop is approximately the same size as that used on the P-40*, as well (I'll have to verify that, though. Not sure).


Ok, checked this out earlier this morning and from what I can see, its highly likely both planes used the same prop.
USAAF document found at Peril's P40 site lists the P-40 prop as a Curtiss Electric 3-blade of 11'0" diameter.
The prop listed for the P-51A, at the MustangsMustangs site shows its also a 3-bladed Curtiss Electric, although the text lists the diameter at 10'6", yet the specs shown at the bottom of the page lists the same prop but with a 10' 9" diameter.
Small differences in size, so I'm _speculating_ that all props mentioned are most likely the same one.
This is a great indication of just how much cleaner the 51A was, compared to the P-40, when you start looking at differences in climb rate and speed @ altitude, since both planes used, essentially, the same engine/prop.



Elvis


----------



## Elvis (Apr 9, 2009)

HoHun said:


> Hi Elvis,
> 
> >So if I'm understanding you correctly, I should regard your graphs as "optimistic".
> 
> ...



Right-0.
Thanks for the clarification.


Elvis


----------



## HoHun (Apr 9, 2009)

Hi Elvis,

>The prop listed for the P-51A, at the MustangsMustangs site shows its also a 3-bladed Curtiss Electric, although the text lists the diameter at 10'6", yet the specs shown at the bottom of the page lists the same prop but with a 10' 9" diameter.
>Small differences in size, so I'm _speculating_ that all props mentioned are most likely the same one.

Might be ... but on the other hand, North American might have deliberately chosen a slightly smaller diameter propeller for the same engine because they built a faster plane, so the propeller tip Mach numbers they'd experience would be higher, decreasing efficiency more seriously than it would happen with the slower P-40.

You're researching an important parameter here! 

Regards,

Henning (HoHun)


----------



## Marshall_Stack (Apr 9, 2009)

claidemore said:


> Marshalls avatar is the logo of the St. Louis Blues hockey team.



It figures that it had to be someone from Canada that had to point this out....

Elvis, the logo is the "blue note" (a musical note). It is based on an old song entitled "The St. Louis Blues".

Sorry for the digression in this thread.


GO BLUES!


----------



## Ivan1GFP (Apr 9, 2009)

I believe Elvis commented that "the early 51's COULD'VE been a very effective aircraft at a lighter weight than the Merlin versions". I believe that it WAS quite effective, just not at the higher altitudes. Seems to me that the lack of engine power was more of an issue than the lack of a good propeller.

With the Allison engine, you have a plane that was faster than the Merlin engined up to 15,000 feet. This fact is hidden somewhat by the typically quoted 390 mph at 20,000 ft. The critical altitude for the P-51A was only about 12,000 ft, and it was certainly lighter, a bit less draggy and carried the same armament. The Allison engined planes also seemed to last longer than the Merlin engined because some F-6 types were still operational at the end of the war.

Although late model P-40's had the same engine and probably a very similar propeller, their propeller efficiency was probably much reduced because of that awfully big radiator. I am not an aerodynamics person, but from reading a few NACA and other reports, it seems that propeller efficiency is reduced by having a large area in the air stream behind the propeller such as on the radial engined planes or the large-mouthed P-40.

Just a little food for thought.
- Ivan.


----------



## Elvis (Apr 12, 2009)

Ivan1GFP said:


> I believe Elvis commented that "the early 51's COULD'VE been a very effective aircraft at a lighter weight than the Merlin versions". I believe that it WAS quite effective, just not at the higher altitudes. Seems to me that the lack of engine power was more of an issue than the lack of a good propeller.


YES!
Thus my point about reconfiguring the blower system.
The Allison's biggest problem was an inability to breathe effectively much beyond 15K feet.
_if one could introduce a system onto the engine to produce better breathing at higher altitude, it would follow that the plane would perform better at a higher altitude_.
However, its a lighter engine, so it won't take the same amount of stress, thus you have to breathe on it a little easier and allow some of that increased power to come from the increased displacement of the Allison (compared to the Merlin).
As I stated earlier, I never meant for my version of the "improved Allison" to be a competitor to the Merlin. but rather, as a _companion_.
What it would lack in power, over later models of the Merlin, it would make up for in a lighter weight aircraft, yielding better balance and manuverability.
It would basically make the "razorback" 51's a better dogfighter at a more _competitive_ altitude.



Elvis


----------



## Elvis (Apr 12, 2009)

HoHun said:


> Hi Elvis,
> 
> >The prop listed for the P-51A, at the MustangsMustangs site shows its also a 3-bladed Curtiss Electric, although the text lists the diameter at 10'6", yet the specs shown at the bottom of the page lists the same prop but with a 10' 9" diameter.
> >Small differences in size, so I'm _speculating_ that all props mentioned are most likely the same one.
> ...


North American could've also mandated that fuzzy pink slippers were manditory footwear for all production staff.
The mach number stays the same. The Speed of sound is the speed of sound.
A smaller diameter prop only allows the engine/propeller to run at a higher rpm before the tips reach transonic.
The smaller prop also creates less thrust, but my point had nothing to do with any of that.
Rather, only that the descrepencies between the figures were close enough that it could be that all of the props mentioned, where infact, the same one.

That's all I was saying.
Sometimes ya' gotta see through all the figures and use a little reasoning.



Elvis


----------



## Elvis (Apr 12, 2009)

Marshall_Stack said:


> It figures that it had to be someone from Canada that had to point this out....
> 
> Elvis, the logo is the "blue note" (a musical note). It is based on an old song entitled "The St. Louis Blues".
> 
> ...


No apologies needed, although I did get a nice chuckle out of the "Canadian" comment. 
I understand the connection between the "blue note" and "St.Louis".
I actually have that 78. Very popular tune for a very long time now.
Thank you for taking the time to explain it, anyway.
Very nice of you to do that.



Elvis


----------



## Ivan1GFP (Apr 13, 2009)

Sometimes a slight difference in propeller diameter makes a serious difference. The F4U-1 Corsairs had two different diameter Propellers in the 13' something" range. The smaller prop was the more efficient. In fact, with the larger prop, the aircraft was actually slower at higher throttle settings presumably because the prop tips went supersonic and were less efficient.

Regarding differences between the Allison and the Merlin, I don't think they are that directly comparable. Yes, the Allison is lighter, but there are MANY more differences than that. Displacement, Compression, modular design, issues with the intake manifold, etc.

Happy Easter everyone!
- Ivan.


----------



## Jeffro (Apr 13, 2009)

Gday All,

Those those dreaming of the P51 with a Griffon,

Also posted somewhere here by desert Fox a few years back.

from CAC CA-15 - Wikipedia, the free encyclopedia

General characteristics

* Crew: one
* Length: 36 ft 6 in (11.05 m)
* Wingspan: 36 ft (10.97 m)
* Height: 12 ft 2 in (3.71 m)
* Empty weight: 7,540 lb (3427 kg)
* Loaded weight: 12,340 lb (5,609 kg)
* Powerplant: 1× Rolls-Royce Griffon supercharged V-12, 2,035 hp (1,517 kW)

Performance

* Maximum speed: 448 mph (721 km/h)
* Range: 2,450 mi (3,920 km)
* Service ceiling: 39,000 ft (12,870 m)
* Rate of climb: 4,900 ft/min (1,531 m/min)

Armament

* 6 x 12.7 mm machine guns (250 rounds each)


----------



## HoHun (Apr 13, 2009)

Hi Elvis,

>A smaller diameter prop only allows the engine/propeller to run at a higher rpm before the tips reach transonic.

You have to consider the total tip speed, which includes forward speed of the aircraft. With less drag, but the same engine, the Allison Mustang will go faster than the Allison P-40 at the same power (and rpm), so a smaller propeller might be better to avoid Mach-induced efficiency loss. At these speeds, the smaller propeller might yield better thrust (though at climb speeds, the larger one will be superior - aviation is a science of compromses 

Regards,

Henning (HoHun)


----------



## davebender (Apr 13, 2009)

> Regarding differences between the Allison and the Merlin, I don't think they are that directly comparable. Yes, the Allison is lighter, but there are MANY more differences than that. Displacement, Compression, modular design, issues with the intake manifold, etc.


I agree. If it had been a simple matter then Allison would have installed a license built copy of the RR Merlin supercharger on their own engine, vastly improving performance of the P-39 and P-40 plus the early model Mustangs.


----------



## Colin1 (Apr 13, 2009)

Jeffro said:


> Those dreaming of the P-51 with a Griffon...


Not seen that before
reminiscent of a Wyvern, superficially. I'd like to see another view of the radiator housing though, the curves look less than compound in that picture.
I'm not sure how you'd validate the statement 'clearly superior to existing single-engine, propeller-driven fighters' when

i. it didn't fly until 1946
ii. didn't see any operational service anyway

at the close of the war, the P-47M, Ta152 and Do335 could all top the CA-15; post-war the late-mark P-51s, MB.5, Spiteful and Sea Fury could too.

Impressive though, 450mph is not to be sniffed at; typical that they scrapped the sole example...


----------



## Elvis (Apr 14, 2009)

HoHun Ivan,

Valid points, I'll give you that. 
However, THEY WERE NOT THE ONE I WAS CONVEYING WHEN I POSTED THOSE REMARKS.
-----------------------------------------

Re: Allison vs. Merlin.

As I stated earlier, I never meant for my idea of the "improved Allison" to be a competitor (or replacement) for the Merlin, but only to compliment it.
Why didn't they do that?
Who knows. Probably because it was quicker and easier to simply license-build the Merlin.

JMHO.


Elvis


----------



## Ivan1GFP (Apr 14, 2009)

This may be a rehash, but the USAAC made some strategic choices pretty early on (way before the war). The high altitude supercharger type they were backing was the turbocharger and not the highly boosted mechanical superchargers.

Seems like the work on turbochargers was fairly successful with installations in the P-38, P-47, B-17 and B-24. Pity there was no solution for "middle altitude" aircraft.

- Ivan.


----------



## V-1710 (Apr 15, 2009)

Take a look at the performance figures for the two starge V-1710-93 installed in the P-63A. I don't know if that particular two-stage design would have been feasable in the P-40 or P-51, as it was quite large. The second stage was actually a separate centrifical blower driven by a hydraulic coupling. It must have worked, the P-63 could reach 20,000' in less than 5 minutes.


----------



## Elvis (Apr 15, 2009)

Ivan,

Just found something, thanks to V-1710's remarks about the "-93" varient.
I'd forgotten about this, but the Allison's were actually _supposed_ to be turbosupercharged units.
However, heavy bomber production mandated that as many turbo's as possible be prioritzed to them, with other Allison powered aricraft coming second.
In the end, only the P-38 retained its turbo and (pretty much) everything else was left with the single-stage mechanical supercharger.
My apologies for not noting that fact before. I'd completely forgotten about it.

...still, the "-93" sounds like it would've been a nice addition to both the P-40 and the early 51's, from a _power output_ aspect, but pretty much loses the weight advantage the other Allison models discussed have over the Merlin.
Seems to have similar performance numbers to the "-99" (final P-40 varient), except more take-off HP and same rating at "altitude", only 5k feet higher with the "-93".
Maybe the "-97" would be even better, considering it features a counterweighted crankshaft and (it seems, anyway), the "-93" does not.
"-93" is listed at 1520 lbs.
"-97" is listed at 1500 lbs.
(info from enginehistory.org)

Comparitivly, the "-99" (the final Allison varient for the P-40) is listed at 1350 lbs. and I've seen the Merlin commonly listed at around 1600 lbs.




Elvis


----------



## V-1710 (Apr 16, 2009)

Elvis said:


> Ivan,..........I'd forgotten about this, but the Allison's were actually _supposed_ to be turbosupercharged units......Elvis



Absolutely true! The Curtiss P-37 and of course the P-38 used the V-1710 as intended- turbocharged with a small centrifical blower for low r.p.m.'s. I may have brought this up before, but anyone with an interest in the V-1710 and its derivitives should read 'Vee's For Victory' by Daniel D. Whitney (Schiffer). It is the most comprehensive study on the V-1710.


----------



## Elvis (Apr 16, 2009)

In addition, doing a quick check of the V-1710 pages from enginehistory.org, it seems the "best-of-both-worlds" would be the "-89A" varient.

1425 HP on take-off, and rated @ 1100HP @ 2600 RPM, but still retaining the full 1425HP when the engine's sped up to 3000 RPM, and all at an altitude of _30,000 feet_ (  ), yet listed weight is only 1350 lbs.

If I were going to install the "ultimate" Allison V-12 for the P-40, of those that actually existed during the war, this is the one I'd give some very serious thought to.

...now the down side. It appears it was used on the P-38, thus the extra power was coming from the turbocharger it was supposed to have in the first place and we all know how that went down.

Too bad really. Could've made the P-40 shine like the sun and the early 51's probably would've never needed the Merlin, using this powerplant, as well.




Elvis


----------



## Elvis (Apr 16, 2009)

P-37






P-40





Man, now THAT'S a pair of beautiful planes.




Elvis


----------



## MikeGazdik (Apr 16, 2009)

Love those photographs! If the XP-37 had a turbo installation like the P-38,at the top of the cowling, that would have made a very good windshield defroster!!!


----------



## red admiral (Apr 17, 2009)

> 1425 HP on take-off, and rated @ 1100HP @ 2600 RPM, but still retaining the full 1425HP when the engine's sped up to 3000 RPM, and all at an altitude of 30,000 feet , yet listed weight is only 1350 lbs.



Unless Allison found a way to massively lighten their engine whilst adding a turbocharger and creating more power, I find it unlikely that the turbocharger and intercooler are included in the engine weight. Those systems should add about another 0.22lb/hp so 320lb or so, bringing the weight up to 1670lb which is still fairly reasonable. Now, the turbocharger also adds a lot of volume - unless you increase the size of the aircraft towards the P-47 scale it doesn't fit satisfactorily.


----------



## Elvis (Apr 22, 2009)

Hey, Clay Allison wants to shove a Griffon into a P-40....and it may just work (although you'd probably end up with a completely different airplane).
If one can make a Griff fit into a P-51 (seen it) or a P-40 (hypothetical) then the extra piping of the turbo-supercharged engine should fit, too....and with much less modification.
Also, if you look at those weight figures at enginehistory.org, over all the models, you'll see where the two stage engines gained a LOT of weight, so the supercharging system, whatever form it took, must be included in the listed weight.


Elvis


----------



## vanir (Apr 27, 2009)

Dear Elvis. You are a God.


Thankyou so very much for the links to that awesome, awesome site on the P-40.

It is now the subject of a new remodelling for il2 by my team. Just sent the emails. Oleg porked it up, now it's gonna be real...


----------



## Elvis (Apr 29, 2009)

Thank you Vanir, that's very nice of you to say, but really its all about _teamwork_.
I myself, was alterted to that site's existence via a thread I participated in here, back when I first joined.
There's a lot very informed people here and the culminative intelligence is a little _staggering_ to handle, at times.



Elvis


----------



## Elvis (Jun 16, 2009)

Clay_Allison said:


> I was thinking about the P-40 and the reasons it wa considered a stopgap at best. What if, though, the P-40 had been reengined, not with the Merlin (as in the P-40F) but with the RR Griffon (if it had been turned over to an American comany for development when it was de-prioritized). Would that have worked?


In regards to my earlier comment of Clay creating a sort of "American Me-109", how about using the Griffon (granted, MAJOR structural redesign), with a larger prop, and also using the "3-guns-in-the-nose" arrangement that the 109 is most famous for using.
However, instead of 2-30's with a cannon firing through the spinner (what would be our equivelent of the German arrangement), just use three 50's.

Wouldn't this allow for a redesign of the wing (and tail surfaces), as well?
Allowing for a thinner wing, maybe even one of "Laminar Flow" design (or "of-that-type" anyway).

I wonder how overall performance would've compared to the actual P-40.



Elvis


----------



## Colin1 (Jun 17, 2009)

Elvis said:


> In regards to my earlier comment of Clay creating a sort of "American Me-109", how about using the Griffon (granted, MAJOR structural redesign), with a larger prop, and also using the "3-guns-in-the-nose" arrangement that the 109 is most famous for using.
> However, instead of 2-30's with a cannon firing through the spinner (what would be our equivelent of the German arrangement), just use three 50's.
> 
> Wouldn't this allow for a redesign of the wing (and tail surfaces), as well?
> ...


I don't see why a Griffon install would require a major re-work, they shoe-horned one into the Merlin Spitfire without too much ado and that's a tighter ship for room than the P-40. The Griffon II was 240lbs (109Kgs) heavier than the V-1710 or 420lbs (191Kgs) for the Griffon 61 if you want the benefits of 2-stage supercharging, so the rear fuselage would need lengthening - meaning the short-fuselage version of the P-40K would never have gotten off the drawing board.
Neither the Merlin nor the Griffon were fitted with engine-mounted armament, this is where you might run into problems, if the thrust-line needs to be lowered to get the guns on the roof then that chin radiator arrangement is going to limit how far you can drop everything.
As for wings and tail surfaces, I don't think there were any technical reasons why Curtiss couldn't do this anyway, I'd throw out the already-mentioned chin radiator arrangement along with a more conventional approach to undercarriage storage. Cut down the rear fuselage a la XP-40Q and you've got a contender. I don't think a laminar flow airfoil would buy you much.
Armament-wise, I'd stick with the conventional approach of batteries of .50 cals in the wings, 6 for the P-40 (3 in each wing), it worked.


----------



## renrich (Jun 17, 2009)

Here is the problem with putting a bigger engine in an air frame, lets say with going from 2000 HP to 2700 HP and expecting a big jump in performance. Look up the F2G. They went from the R2800 to the R3350, I think, and the airplane was little better in performance than F4U4 with more reliability problems.


----------



## Colin1 (Jun 17, 2009)

It depends on where you're jumping from
the P-40 saw benefits with the V-1650-1 install over previous V-1710-engined models of the P-40, a Griffon install would see significant benefits again over the V-1650-1. The P-40 was a pre-war design and would see the benefit of a more powerful engine, though I doubt the same benefits that a later type with a cleaner airframe would experience.

The F2G was far closer to the edge of the envelope of what a piston-engined fighter can accomplish than the P-40 and any benefit margin would be leaner.


----------



## Elvis (Jun 17, 2009)

Fair enough. 
By Colin's logic, a Griffon powered P-40 would probably end up along the lines of the P-37 I posted a picture of earlier and that was turned down during testing for lack of visibiltiy over the long nose.
A better solution would seem to be a more "efficient" version of the V-1710 then, such as the "-89A" version I aluded to earlier, or development of a two-speed single stage after-cooled version of the engine (saving the "-89A" for the P-38 and P-51).
Yeah, I agree. That would've most likely have been the better way to go.
Thanks for your input, guys.


Elvis


----------



## Colin1 (Jun 17, 2009)

Elvis said:


> ...a Griffon powered P-40 would probably end up along the lines of the P-37 I posted a picture of earlier and that was turned down during testing for lack of visibiltiy over the long nose...


I doubt it would be _that_ drastic, remember, they fitted a Griffon in a Mustang racer and the Mustang started out with the V-1710; the P-51/Griffon arrangement certainly looked feasible enough for operational service although curiously, it was only looked at by the British and they only looked at a mid-engined layout a la P-39.

The P-37 had all sorts of problems, the hot-rodded V12 Allison and the GE supercharger arrangement suffered badly with reliability issues.


----------



## Elvis (Jun 20, 2009)

Well as you stated, the 51 was originally designed for a liquid cooled V-12, so changing to a larger V-12 would be a more minimal modification, compared to installing one in a p-40.
Remember, the P-40 was orginally the P-36 and that platform was originally designed for a radial powerplant.
The P-40 is already a fairly modified platform, with the installation of the V-1710, so it would have to be further modified to allow for the larger Griffon powerplant.
I just gotta wonder how much room is left for such changes...something tells me there's not much.

Maybe someone around here, who has some experience with mechanical drawing, could mock up a Griffon-powered P-40, just to show us how much more modification would be needed, or if there is enough room for such mods, without having to make it a completely different airplane.



Elvis


----------



## Colin1 (Jun 21, 2009)

Elvis said:


> ...the 51 was originally designed for a liquid cooled V-12, so changing to a larger V-12 would be a more minimal modification, compared to installing one in a p-40.
> Remember, the P-40 was orginally the P-36 and that platform was originally designed for a radial powerplant.
> The P-40 is already a fairly modified platform, with the installation of the V-1710, so it would have to be further modified to allow for the larger Griffon powerplant


There's more of a common lineage in there than you're seeing:

Allison P-51 to Merlin P-51 to Griffon P-51 (albeit as a one-off racer)
Allison P-40 to Merlin P-40 to Griffon P-40 (the P-40F and L were fitted with the Packard Merlin V-1650-1)

I think the evolution of the P-36 into the P-40 has no real bearing on the potential evolution of the Allison P-40 into a Griffon P-40, it would be a case of replacing an inline with another inline and given the similar config of the Allison-engined P-40 and P-51, I don't see why a Griffon P-40 would be any more problematic than the Griffon install was on the P-51.

If the Germans could get a DB605 into a Spitfire upside down (inverted V) I can't see why it would have posed any real technical headaches to get a Griffon into a P-40 with engineers of a different country from the same period.


----------



## Elvis (Jun 21, 2009)

What I'm saying is the Allison P-40 was already a modified platform, so yourlineage misses a step, that being P-36 - to - P-40.
The Allison P-51 wasn't modified.

Again, I think someone with a mechanical drawing background could really be of help here.

Could you please direct me to some info on the DB605 powered Spit? First I'm hearing of this.



Elvis


----------



## Colin1 (Jun 21, 2009)

Elvis said:


> What I'm saying is the Allison P-40 was already a modified platform, so your lineage misses a step, that being P-36 - to - P-40. The Allison P-51 wasn't modified.
> 
> Could you please direct me to some info on the DB605 powered Spit? First I'm hearing of this


I missed the step deliberately, concentrating instead on the common ground between the two types, I don't think the radial-engined period of the Curtiss fighter's history really counts for much here, I'll be (mildly) surprised if it does

Link to the Daimler-Benz Spitfire

Unreal Aircraft - Hybrid Aircraft - Supermarine/Daimler-Benz Spitfire


----------



## Elvis (Jun 22, 2009)

Colin1 said:


> I missed the step deliberately, concentrating instead on the common ground between the two types, I don't think the radial-engined period of the Curtiss fighter's history really counts for much here, I'll be (mildly) surprised if it does
> 
> Link to the Daimler-Benz Spitfire
> 
> Unreal Aircraft - Hybrid Aircraft - Supermarine/Daimler-Benz Spitfire



Hmmmm...there may be something to this after all, but I wonder how close the relationship between Sptifire/DB605 is to Warhawk/Griffon.
I mean, after all, it is kind of an apples-to-oranges comparison, but I have to agree. This _might_ be more feasable than first anticipated.
Would still like to see some drawings, though.


Elvis


----------



## Colin1 (Jun 23, 2009)

Elvis said:


> ...how close the relationship between Sptifire/DB605 is to Warhawk/Griffon. I mean, after all, it is kind of an apples-to-oranges comparison...


In what sense? 
In one way, it's not close at all; the Spitfire and the DB605 are very clearly NOT the P-40 and V-1710 or Griffon. In another, higher-level sense, there's not a great deal between them, both sets are of the same period, subject to the same constraints design- and technology-wise; while there are some powerplants that will clearly not fit in some weren't-designed-for-this airframes, I think there's a large degree of leeway in most cases.


----------



## Clay_Allison (Jun 30, 2009)

I think that Elvis is underestimating the extent to which the P-40 really was a new design based on a P-36, not a P-36 with the nose chopped off and a new one bolted on. It had certain characteristics in common, but I resist the notion that the P-36 has to be considered R.E. changing to the Griffon engine.


----------



## Elvis (Jul 7, 2009)

Clay,

You're absolutely correct, however, in light of this (heretofore unknown to me) information about the DB605 powered Spitfire, my thinking is being altered - i.e., maybe this Griffon-powered P-40 idea wouldn't be as difficult to exicute as I had first imagined.
-----------------------------------

Colin1,

My question had to do with the ease in which the modification could've been done.
I.e., would the P-40 mod have been any more or less difficult, compared to what was done with the Spit....or would it have been about the same?
Granted, neither mod would likely have be a "drop-in" fit.


Elvis


----------



## Shortround6 (Jul 8, 2009)

A consideration when proposing "engine swaps" of hypothetical aircraft is that the dry weight of the is only part of the power plant weight. Some peaple refer to it as firewall forward but is some cases that doesn't cover it either. 
Larger, higher HP engines can require larger radiators and header tanks filled with more coolant. They can require larger oil tanks and oil coolers. They might or might not require larger starter systems. The might require larger propellors, either larger diameter, more blades or broader blades. Larger cowls and engine mounts,etc. 
The dry weight of an engine might be 1 pound per HP. The "powerplant weight" might be 1.5 -2 pounds per HP. 
In some cases (like shifting to higher power Merlins) the changes might be rather slight from one version to another. In other cases hundreds of pounds might be added and a fair amount of the weight in front of the CG. 
In some cases tails had to be made larger ( or extended, see some P-40 models) to counter torque or larger cowling forward. 
In some cases the larger engines worked quite well, in other cases the performance gain wasn't what was expected.

P-40 protoype was actually a re-engined P-36 airframe. P-36s were reportedly canablized to provide parts for P-40s in the early Pacific fighting including entire (one side anyway) wings. Wouldn't work so well with the a P-40 E.


----------



## fibus (Jul 8, 2009)

The Allison was a superior design but not as tested and developed as the Merlin. It was Rolls that developed the 150 hour reliability test.
The Griffon was a much bigger and heavier engine than the Merlin. To fit a Griffon One had to design virtually new airframe.
Compare the difference in size of the Mark 1 v. the Spit Mark 14.


----------



## claidemore (Jul 9, 2009)

The Mk XIV Spitifre had the same airframe as the Mk VIII Merlin engined Spit. Mk XII Spitfires were either Mk V or Mk VIII airframes. The first Griffon Spit, the Mk IV, was built on a Mk III airframe. 

I would think that if they could mount a Griffon on the Spitfire airframes that were designed for the Merlin, then there wouldn't be much difficulty in mounting one on a P40, since the P40F and L had Merlin engines.


----------



## Colin1 (Jul 9, 2009)

claidemore said:


> The Mk XIV Spitifre had the same airframe as the Mk VIII Merlin engined Spit. Mk XII Spitfires were either Mk V or Mk VIII airframes. The first Griffon Spit, the Mk IV, was built on a Mk III airframe.
> 
> I would think that if they could mount a Griffon on the Spitfire airframes that were designed for the Merlin, then there wouldn't be much difficulty in mounting one on a P40, since the P40F and L had Merlin engines.


Is the correct answer
unless I'm mistaken the Mk III-based Griffon test-bed was put into service itself as a Mk XII once trials were over.

So where did you get this massive re-architecturing of the airframe from, Fibus?

Nice section drawing of the two engines, Claide. I didn't realise there was THAT much difference but hey, they got it in.

Edit: Elvis, sorry, didn't see your post #96 until just now or I would've answered. Think Claidemore pretty much captured it.


----------



## Elvis (Jul 9, 2009)

No worries, Colin. It was a fair comment. You asked, so I tried to clarify.

I think if a P-40 _were_ to be re-engined with a Griffon, I suppose the F and L versions would be the best candidate, since mod's to use the Merlin would already be in place (and I'm thinking mostly about countering the greater weight. The Merlin's about 300-400 lbs. heavier than the Allison).

So lets start throwing some specs around.

Here's some for the Griff 58:

Model: Griffon 58
Original Application: Avro Shackleton reconnaissance plane 
Engine Type: V-12 Piston Aero Engine, 60° "V" (angle between banks) 
Material: Aluminum crankcase, cylinder banks and heads; Alloy pistons; Steel liners, rods, cranks, etc. 
Bore x Stroke: 6.0" x 6.6" 
Compression Ratio: 6.0:1 
Supercharger Type: Two-speed, single-stage centrifugal 13.4" impeller 
Supercharger Ratio: Medium Speed (MS) - 6.615:1, Full Speed (FS) 7.70:1 
Boost Control: Automatic via Rolls-Royce auto boost regulator, w/increased boost when ADI active 
Fuel System: Speed/Density type Fuel Injection (injected into eye of supercharger) 
Weight: 2,000 lbs 
Power: 2,450 HP takeoff at 2,750 RPM at SL with 25 psig boost using 115/145 PN fuel 
Performance: 0.82 lbs/hp, 314 psi BMEP, 0.42 lbs fuel/hp/hr SFC 
Max. Piston Speed: 3,025 ft/min 

...and some interesting historical comments about why the engine came to be:

"_Development of the Griffon Engine began at Derby, England 1939 when Harry Cantrill was assigned to develop a conventional V-12 scaled up from the 1650 cu-in Rolls-Royce Merlin. The engine was intended to produce more than 1,500 HP at low altitudes for naval torpedo bombers. For maximum utility, it was decided to keep the engine as compact as possible so it could replace the Merlin in some applications. The resulting design had approximately the same frontal area as the Merlin and was actually shorter. The bore and stroke was the same as the Rolls-Royce "R" Schneider Cup race engines of 1929 and 1931, which were direct ancestors to the Griffon, resulting in an displacement of 2,240 cubic inches.. The Merlin proportions of the Griffon were partially achieved by moving the camshaft drives and magneto to the front of the engine._"

(quote and engine specs came from here)

Ok, Clay, you got me. 
This is looking like an even easier re-fit than how I was imagining it a few days ago.
Sorry I doubted you.

So, I think I brought this up before, but aren't there any Mechanical Engineers in the house?....even "amatuer" ones?
I'd like to see some mock-up's (on paper is fine) of what one would look like, if you started with either the F or L version of the P-40.




Elvis


----------



## Colin1 (Jul 9, 2009)

Elvis said:


> I think if a P-40 _were_ to be re-engined with a Griffon, I suppose the F and L versions would be the best candidate, since mod's to use the Merlin would already be in place (and I'm thinking mostly about countering the greater weight. The Merlin's about 300-400 lbs. heavier than the Allison)


Hi Elvis
don't know if it would make that much difference from the P-40E onwards. The P-40F was in fact just a re-engined P-40E and the P-40L was a P-40F in everything but name, it could be stripped/configured for different types of ops but I'm uncertain of the merits of this. 
A P-40K was in turn just a P-40F re-re-engined (!) back to the Allison with the cowling, ducting and Allison carburettor intake and scoop shape re-introduced.

The Griffon II is about 240lbs heavier and the Griffon 61 about 400lbs heavier than the Allison, so

Merlin 300-400lbs heavier than the Allison
Griffon 240-400lbs heavier than the Allison

roughly similar problems weight-wise


----------



## Elvis (Jul 9, 2009)

Gee, that's odd. 
If you look at the specs I listed for the Griffon 58, it shows that its about 700 lbs. more than the Allison.
Was that a particularly heavy version?

Noting the rest of your comments, then base it on the "N"!
That was the newest version that was produced and I understand there was some structural re-engineering with that version (possibly the "M", too?).
Essentially, lighter without sacrificing reliability (how I understand it).


Elvis


----------



## MikeGazdik (Jul 11, 2009)

Colin1 said:


> Hi Elvis
> don't know if it would make that much difference from the P-40E onwards. The P-40F was in fact just a re-engined P-40E and the P-40L was a P-40F in everything but name, it could be stripped/configured for different types of ops but I'm uncertain of the merits of this.
> A P-40K was in turn just a P-40F re-re-engined (!) back to the Allison with the cowling, ducting and Allison carburettor intake and scoop shape re-introduced.
> 
> ...



The K-model P-40 had a dorsal fin fillet and a deeper tail fin to aid in lateral stability. That is different than the previous P-40's and certainly something a Griffon would need. But I think you would have to go with both, the longer fuselage ( I think first out with the L model ), and deeper fin and the fillet to counter the torque from the Griffon.

I love hot-rods, and this is going to be one for sure!!!


----------



## Colin1 (Jul 11, 2009)

MikeGazdik said:


> The K-model P-40 had a dorsal fin fillet and a deeper tail fin to aid in lateral stability. That is different than the previous P-40's and certainly something a Griffon would need. But I think you would have to go with both, the longer fuselage ( I think first out with the L model ), and deeper fin and the fillet to counter the torque from the Griffon


Ks were confusing Mike
read my Curtiss P-40 Pictorial History thread - there were long, sleek Ks and there were short, stubby Ks


----------



## Elvis (Jul 11, 2009)

Hey guys, what about the prop?!

With substaintially more engine, _more_ prop would be in order, to maximize the usage of the larger powerplant.

...but which way should we go?

More blades?
Longer blades?
Wider blades?
A combination of the above, or something else entirely?

What say you, people?




Elvis


----------



## Colin1 (Jul 11, 2009)

Elvis said:


> With substantially more engine, _more_ prop would be in order, to maximize the usage of the larger powerplant.
> 
> More blades?
> Longer blades?
> ...


I don't know

the RAF tended to go for more blades
the USAAF seemed to have a blend of add more blades and make them longer
the Luftwaffe seemed to stick with fewer blades from start to finish that just got wider

I'm not sure empirical data would reveal decisive advantages of one over any of the others which may be why the Luftwaffe stuck with 3 blades throughout but just made them wider.

I'd plump for a 4-bladed hydromatic arrangement, it didn't do the P-51D any harm but that flew with the Merlin, not the Griffon. Easy way out would be manufacturer's recommendations, so whatever Rolls-Royce and Rotol/Hamilton Standard/Aeroproducts came up with; one would have to assume that engine power/airscrew config were balanced to get the best out of each other.


----------



## Shortround6 (Jul 11, 2009)

IF you need more propellor blade area you have two basic choices, wider blades or more blades. 

Increasing diameter only works if you have enough clearance which most single engine fighters did not. 

Increasing diameter would mean new, longer landing gear or tricker landing gear that extended in length as it lowered. It also means a steeper ground angle with more vision problems and perhaps lift/drag problems for take off. Extra power helps acceleration but steeper ange of attack creates more drag until tai wheel lifts?


----------



## MikeGazdik (Jul 12, 2009)

I will have to read you stuff on the P-40 Colin, didn't know there were long body ones.

Instead of a Griffon, I think Chrysler was working on an inverted V-12. Maybe that would be an interesting switch. As a matter of fact, years ago I read about this engine and it may have been tried in the P-40, not sure. I think it was fairly large.


----------



## Shortround6 (Jul 12, 2009)

Yes' chrysler was working on an engine but it was an inverted V-16. Before some bright spark gets the idea of cutting out 4 cylinders and turning it into a V -12 please see:

Chrysler IV-2220 - Wikipedia, the free encyclopedia

and

Republic AP-10 XP-47H Thunderbolt


----------



## Elvis (Jul 12, 2009)

There was also the Continental "Hyper" inverted V-12 engine.
1600HP from only 1430 cu.in.
I understand it was overly complicated and rather heavy and thus, never entered production.
However it introduced some rather innovative ideas at the time (1932), including the hemispherical combustion chamber, a centrally located spark plug and sodium filled exhaust valves.
I believe the hemi c.c./piston shape and the sodium filled exhuast valve ideas were eventually incorporated into the V-1710.
-----------------------------------------------------------------------

Colin1,

Would you have any links that alude to the recommeneded prop size for the Griffon V-12?



Elvis


----------



## Colin1 (Jul 12, 2009)

Elvis said:


> Would you have any links that alude to the recommeneded prop size for the Griffon V-12?


I'll certainly have a dig around


----------



## Shortround6 (Jul 12, 2009)

The Army gave Continental about 1/2 million dollars during the thirties to design and develop their version of the 'Hyper" engine. Unfortunatly the Army only dribbled out the money a little at a time so the first complete 12 cylinder version didn't run untill 1939. by which time it was way behind the Allison in timing.

See: Continental I-1430 - Wikipedia, the free encyclopedia

Which isn't too far of the mark, except the " At the time it was an extremely competitive design, offering at least 1,300 hp (970 kW) from a 23 liter displacement; the contemporary Rolls-Royce Merlin offered about 1,000 hp (700 kW) from 27 l displacement,..." part and a few others
At the time the Melin was in squadron service at 1000HP and in 1938 the Merlin was "OFFERED" at the 1938 Paris airshow with a 2 speed super charger at over 1200hp. The Continental may have made it through a 50 hr test at 1000hp (not 1300) in 1939.

The Continental, while it used the features you mention didn't introduce any of them. ALL high powered aircraft engines were using sodium filled exhaust valves by 1939. High powered includes the P&W R-1340 of 600HP. A few low powered engines were using them too, like 6 cylinder Rangers of 175HP. 

All but the smallest (40HP or so) Aircraft engines in the US were required by law to have dual ignition. 2 spark plugs per cylinder.

By the way, it seems rather doubtful that the Continental ever came close to giving it's rated HP in an actual airplane.

SEE> http://home.att.net/~jbaugher1/p49.html

And> http://home.att.net/~jbaugher1/p67.html


----------



## Elvis (Jul 13, 2009)

Shortround6,

I gleaned my information on the Continental engine off something I saw a few years ago on the USAF's NAtional Museum page.

"_The development of the liquid-cooled Continental Hyper high-horsepower engine began in 1932. It featured cylinders with "spherical" combustion chambers and sodium cooled exhaust valves. An upright V-12 engine was planned, but emphasis was later changed to an inverted V-12 engine for pursuit planes. Continental built the inverted V engine in 1938 and successfully tested it in 1939. In 1943 the 1,600-hp IV-1430 engine, later redesignated the XI-1430, was tested extensively in the Lockheed XP-49, a modified version of the P-38 Lightning. In 1944 it was also tested in the McDonnell XP-67. Only 23 I-1430 series engines were delivered. Although more powerful and lighter than the nearest competitor, the engine was not produced because tooling capacity for large scale production was not available. 

TECHNICAL NOTES: 
Model: Continental I-1430 Hyper
Type: 12-cylinder, liquid-cooled, inverted Vee 
Displacement: 1,430 cu.in. 
Horsepower: 1,600 
RPM: 3,200 
Weight (dry): 1,615 lbs._"







I didn't remember anything about it being installed in an actual airplane, but apparently it was.
Also, it seems I wrong about why it was never produced.
My apologies for the incorrect information in my prior post.


Elvis


----------



## Elvis (Jul 13, 2009)

Colin1 said:


> I'll certainly have a dig around



Thanks!
Look forward to reading about your findings.


Elvis


----------



## gumbyk (Jul 13, 2009)

Elvis, it was fitted to the XP-67 "Bat"




Pictures of the McDonnell XP-67 Bat / Moonbat - Aircraft

A nice looking aircraft...


----------



## Colin1 (Jul 13, 2009)

Elvis said:


> Look forward to reading about your findings


Nothing definitive about the Griffon specificallly (yet)
but did find these interesting, various degrees of technical depth:-

Aerospaceweb.org | Ask Us - Number of Aircraft Propeller Blades

Propeller Thrust

Propeller Propulsion

Engine and Propeller Efficiency


----------



## Elvis (Jul 14, 2009)

gumbyk,

Thanks for the info. I'm aware of the "bat" but never knew about its powerplants.
------------------------------------------------------------------

Colin1,

Great detective work! 
Thanks for posting the links. I'll "wade" through those and see what I come up with.



Elvis


----------



## Elvis (Jul 15, 2009)

So, getting back to the initial question about installing an R-R Griffon into a P-40, here's some dimension specs I pulled off of Wikipedia.

R-R Merlin 66
Type: 12-cylinder supercharged liquid-cooled 60° "Vee" piston aircraft engine 
Bore: 5.4 in (137.2 mm) 
Stroke: 6 in (152.4 mm) 
Displacement: 1,648.96 in³ (27.04 L) 
Length: 88.7 in (225.3 cm) 
Width: 30.8 in (78.1 cm) 
Height: 40 in (101.6 cm) 
Dry weight: 1,645 lb (746.5 kg)

Components
Valvetrain: Overhead camshaft-actuated, two intake and two exhaust valves per cylinder, sodium-cooled exhaust valve stems 
Supercharger: Two-speed two-stage, boost pressure automatically linked to the throttle, water-air aftercooler installed between the second stage and the engine. 
Fuel system: Twin-choke updraft carburettor with automatic mixture control 
Fuel type: 100 Octane from mid 1944 100/150 Grade Aviation fuel 
Oil system: Dry sump with one pressure pump and two scavenge pumps. 
Cooling system: 70% water and 30% ethylene glycol coolant mixture, pressurised. 

Performance
Power output: (Note: 100 Octane fuel, +12 lb boost) 
1,315 hp (981 kW) at 3,000 rpm at take-off. 
1,705 hp (1,271 kW) at 3,000 rpm at 5,750 ft (1,753 m) (MS gear) 
1,580 hp (1,178 kW) at 3,000 rpm at 16,000 ft (4,877 m) (FS gear)
(100/150 Grade fuel, +25 lb boost) 
2,000 hp (1,481 kW) at 5,250 ft (1,600 m) (MS gear) (bmep = 320.2psi) 
1,860 hp (1,387 kW) at 11,000 ft (3,353 m) (FS gear) 
Specific power: 0.95 hp/in³ (43.3 kW/L) 
Compression ratio: 6:1 
Power-to-weight ratio: 0.80 hp/lb (1.76 kW/kg) take-off; 1.21 hp/lb (2.69 kW/kg) 100/150 grade fuel/MS gear. 
--------------------------------------------------------------------------------------------------------------------------------

R-R Griffon 65
Type: 12-cylinder supercharged liquid-cooled 60° Vee aircraft piston engine 
Bore: 6 in (152.5 mm) 
Stroke: 6.6 in (167.6 mm) 
Displacement: 2,240 in³ (36.7 L) 
Length: 81 in (2057 mm) 
Width: 30.3 in (770 mm) 
Height: 46 in (1168 mm) 
Dry weight: 1,980 lb (900 kg) 

Components
Valvetrain: Two intake and two exhaust valves per cylinder with sodium-cooled exhaust valve stems, actuated via an overhead camshaft. 
Supercharger: Two-speed, two-stage centrifugal type supercharger, boost pressure automatically linked to the throttle, water-air aftercooler installed between the second stage and the engine 
Fuel system: Triple-choke updraft carburettor with automatic mixture control 
Oil system: Dry sump with one pressure pump and two scavenge pumps 
Cooling system: 70% water and 30% ethylene glycol coolant mixture, pressurised 

Performance
Power output: 2,035 hp (1,520 kW) at 7,000 ft (2,135 m) 1,820 hp (1,360 kW) at 21,000 ft (6,400 m) 
Specific power: 0.91 hp/in³ (41.4 kW/L) 
Compression ratio: 6:1 
Power-to-weight ratio: 1.03 hp/lb (1.69 kW/kg) 
--------------------------------------------------------------------------------------------------------------------------------

Allison V-1710-85
Type: 12-cylinder supercharged liquid-cooled 60° "Vee" piston aircraft engine 
Bore: 5.5 in (140 mm) 
Stroke: 6 in (150 mm) 
Displacement: 1,710.6 cu in (28.032 L) 
Length: 98.53 in (2,503 mm) 
Width: 29.28 in (744 mm) 
Height: 41.18 in (1,046 mm) 
Dry weight: 1,445 lb (655 kg) 

Components
Valvetrain: Two intake and two exhaust valves per cylinder with sodium-cooled exhaust valves, operated by a single gear-driven overhead camshaft per each bank of cylinders. 
Supercharger: Centrifugal-type, single-stage, impeller 10.25 in (260 mm) in diameter with 15 vanes. 
Fuel system: Bendix Stromberg carburetor with automatic mixture control 
Fuel type: 100 octane 
Oil system: Dry sump with one pressure and two scavenge pumps. 
Cooling system: Liquid-cooled with a mixture of 70% water and 30% ethylene glycol, pressurized. 

Performance
Power output: 1,325 hp (988 kW) at 3,000 rpm (bmep=204.5 psi) 
Specific power: 0.77 hp/in³ (35.25 kW/L) 
Compression ratio: 6.65:1 
Power-to-weight ratio: 0.92 hp/lb (1.51 kW/kg)
---------------------------------------------------------------------------------------------------------------------------------

I'm quite surprised by how close in physical dimension all of these engines are, considering the wide range of displacements listed.
The only thing that concerns me here is weight.
The Griffon that is listed is 553 lbs. heavier than the Allison and 353 lbs. lbs. heavier than the Merlin, with the Merlin coming in at 200 lbs. over the Allison.
I suppose one could extend the fuselage and maybe move the pilot back a little, but I wouldn't want to move him far, lest we fall into a "P-37" situation again.
I wonder how much extension (of the fuselage) would be needed to counter that increase in weight?
...maybe if the radiator were moved rearward, ala P-51, then the chin could be shrunk, OR, part of that space could be used to help contain the slight increase in size of the engine and part of it could be used to house the aftercooler.
That _might_ balance things out, right there.
Changes to the tail would in order, as well, to counter the increased torque of the larger engine....hmmm....




Elvis


----------



## Elvis (Jul 15, 2009)

Colin1 said:


> Nothing definitive about the Griffon specificallly (yet)
> but did find these interesting, various degrees of technical depth:-
> 
> Aerospaceweb.org | Ask Us - Number of Aircraft Propeller Blades
> ...



Colin,


Still looking into the links you posted, but a quick check at Wiki says the Griff-powered Spit Mk. IV used a four bladed Rotol prop of 10.5 ft. diameter.
The P-40 was already using an 11' Curtiss-Electric prop, so maybe upping the blade count from 3 to 4 would be all that were needed.......ah, back to the research.



Elvis


----------



## Colin1 (Jul 15, 2009)

Elvis said:


> Colin,
> Still looking into the links you posted, but a quick check at Wiki says the Griff-powered Spit Mk. IV used a four bladed Rotol prop of 10.5 ft. diameter.
> The P-40 was already using an 11' Curtiss-Electric prop, so maybe upping the blade count from 3 to 4 would be all that were needed...


One of the reasons the Griffon adopted the 5-bladed screw was that the 4-bladed screw of the Merlin had already used up all of the ground clearance - there was nowhere for a bigger screw to go so they started down the path of more blades.
If the P-40 has more ground clearance to move into than the Spitfire then options for absorbing the extra power of the Griffon are a little more open for the P-40; a 4-bladed hydromatic unit probably.


----------



## Elvis (Jul 15, 2009)

INTERESTING!

I didn't know that...maybe a 5-bladed screw IS in order (and wouldn't that just be _so_ cool!)


Elvis


----------



## Clay_Allison (Jul 16, 2009)

Colin1 said:


> One of the reasons the Griffon adopted the 5-bladed screw was that the 4-bladed screw of the Merlin had already used up all of the ground clearance - there was nowhere for a bigger screw to go so they started down the path of more blades.
> If the P-40 has more ground clearance to move into than the Spitfire then options for absorbing the extra power of the Griffon are a little more open for the P-40; a 4-bladed hydromatic unit probably.


IIRC, the P-40 had a good deal more ground clearance and easier ground handling than the Spitfire.


----------



## Elvis (Jul 16, 2009)

Clay,

Was that due to the landing gear arrangement?
I agree about ground clearance. The P-40 was already using an 11' prop, so it much have more ground clearance than a Spitfire.
While the idea of the 4-bladed version from the P-51D is a good one, I had the thought last night that 51D was Merlin powered and the Griff is going to generate a good deal more torque, thus it may actually requrire _more_ prop.
Man, imagine it - a P-40 with an 11' 5-bladed prop....that'd be a sight (  ).
I would think it would climb like a freakin' monkey, compared to what was actually used during the war.



Elvis


----------



## Clay_Allison (Jul 20, 2009)

Elvis said:


> Clay,
> 
> Was that due to the landing gear arrangement?
> I agree about ground clearance. The P-40 was already using an 11' prop, so it much have more ground clearance than a Spitfire.
> ...


In answer to your question, yes. The P-40 had wide, inward-folding landing gear, the Spit had almost as narrow a landing gear arrangement as the 190.

The P-40 was a bigger plane than the Spitfire overall, a bit more of an armored warhorse than a racehorse. An 11' five blade would be my guess as to the best prop arrangement. I think it would climb like crazy and could have been a good second-choice plane until the end of the war, particularly for the Brits where it could have completely replaced the Hurricane in the Pacific theatre.


----------



## Elvis (Jul 22, 2009)

Clay_Allison said:


> In answer to your question, yes. The P-40 had wide, inward-folding landing gear, the Spit had almost as narrow a landing gear arrangement as the 190.
> 
> The P-40 was a bigger plane than the Spitfire overall, a bit more of an armored warhorse than a racehorse. An 11' five blade would be my guess as to the best prop arrangement. I think it would climb like crazy and could have been a good second-choice plane until the end of the war, particularly for the Brits where it could have completely replaced the Hurricane in the Pacific theatre.


I actually like the thought that we had indeed given the Brits the P-40, instead of the designing the P-51, and it was during the time that they had the planes, that the idea for the Griffon powered P-40 came into being.
...pretty cool thought.
BTW, the P-40's landing gear did not retract inward, but rather, rearward. The whole assembly also rotated 90 degrees so that the wheels would sit flat with the wing, when retracted.
I'd post a pic, but this computer is super slow.
Just google "P-40" and click "image". You'll see what I mean.
Also, the 190 actually had a fairly wide landing gear arrangement. Now THAT one did fold inwards, from about 1/2 way out on the wing.
The Spit and the 109 both had rather narrowly tracked landing gear, due to how they extended and retracted, although I think the 109 was "tippier" than the Spit, in that regard.

I'm tellin' ya Clay, the more I think about this, the more I like the idea.
I really wish someone here could slap together some drawings, though.
I'd really like to see what one would look like, even if its just an "artists rendering".


Elvis


----------



## Clay_Allison (Jul 22, 2009)

Elvis said:


> I actually like the thought that we had indeed given the Brits the P-40, instead of the designing the P-51, and it was during the time that they had the planes, that the idea for the Griffon powered P-40 came into being.
> ...pretty cool thought.
> BTW, the P-40's landing gear did not retract inward, but rather, rearward. The whole assembly also rotated 90 degrees so that the wheels would sit flat with the wing, when retracted.
> I'd post a pic, but this computer is super slow.
> ...


190 was a typo, I meant 109, both the 109 and the Spit had landing gear as narrow as landing on a bicycle.


----------



## Elvis (Jul 22, 2009)

LOL! Good thing a lot of the German pilots were trained on gliders!





Elvis


----------



## Clay_Allison (Aug 22, 2009)

Just thought of something and thought I'd resurrect this thread to ask about it.

I was just reading about that 4-blade Hamilton standard propeller and what it did for the P-38K (but ultimately wasn't allowed to do)

What about putting the Paddle-Prop on the P-40? It seemed to just have the same "toothpick-three" that the P-38 had originally, and since its' problem was high alt performance, better props tend to improve that. Also since by that point in the war it was a defensive interceptor and fighter-bomber, it should improve climb and takeoff distance to have the bigger prop.


----------



## Shortround6 (Aug 22, 2009)

The guys who designed the propellors did a pretty good job. problems came up with trying to meet production quotas.
There were formulas in some fairly basic aviation books for propellor design. You need a certain amount of blade area (not the same as propellor disc area) to transmit a given amount of power. As the engine guys kept increasing the power of the engines the props need more blade area (wider blades or more of them or both). How ever just putting bigger blades on an existing engine is not magic.
Like everything else that moves through air there is drag on propellor blades. A big, high altitude, wide bladed propellor will have much more drag at low altitudes than one of those " toothpick-three" propellors and might very well hurt low altitude performance. 

When comparing a P-38 to a P-40 you have to keep in mind that while they both used allison engines the actual perforamce could be rather different. Late model P-38s could get 1600hp WEP at 25,000-30,000ft and so could very well use bigger/wider prop blades to transmit the power at those altitudes. 

A P-40 flying at 12,000-15,000ft in air twice as dense doesn't need quite the same prop blade area to transmit the power even if it made 1600hp at WEP. The less power it makes the less it needs the bigger propellor. 

Please not on the P-47 that it's original porpellor was supposed to handle 2000hp. Maybe it was marginal for that, maybe it was OK, maybe it wasn't very good, I won't tell you I know for sure. When the paddle blades came along the engines were giving any where from 2300-2500hp with water injection and at WEP ratings. so the old prop was trying handle 15-25% more power than it was designed for. 
Same with P-38 Props, they went from handling 1100hp to 1425HP even without WEP.


----------



## Clay_Allison (Aug 22, 2009)

Shortround6 said:


> The guys who designed the propellors did a pretty good job. problems came up with trying to meet production quotas.
> There were formulas in some fairly basic aviation books for propellor design. You need a certain amount of blade area (not the same as propellor disc area) to transmit a given amount of power. As the engine guys kept increasing the power of the engines the props need more blade area (wider blades or more of them or both). How ever just putting bigger blades on an existing engine is not magic.
> Like everything else that moves through air there is drag on propellor blades. A big, high altitude, wide bladed propellor will have much more drag at low altitudes than one of those " toothpick-three" propellors and might very well hurt low altitude performance.
> 
> ...


I know from previous arguments with you that you don't think high altitude performance is at all important (neither did the army) and that the P-40 should never have been anything but a fighter-bomber that defended itself reasonably well.

I still think that it's a bad idea to resign yourself to giving up the high ground and think that the P-40 could have been balanced toward a higher critical altitude.

The Warhawk fought best on the climb and dive and it makes it difficult when you don't have a comfortable cruising altitude that allows you to take advantage of your dive speed for long.


----------



## Elvis (Aug 23, 2009)

Click here to read the sad but amazing story of the P-38K.

Hey Clay, 

I have to agree with Shortround6 on this one. You'd need more power to take advantage of the bigger prop....so lets replace the V-1710-39 engine with its two-speed, twp-stage kin, the V-1710-45 engine!
The -45 made a little more power at sea level and matched the -39's power at altitude, but the -45 made that power at a much higher altitude (over 10,000 feet higher up), so I'm thinking it was probably making more power at the -39's rated altitude.
This may be enough of a change to warrent the use of the Hamilton Standard.
Its an impressive looking propeller, to be sure...










Elvis


----------



## Shortround6 (Aug 23, 2009)

Clay_Allison said:


> I know from previous arguments with you that you don't think high altitude performance is at all important (neither did the army) and that the P-40 should never have been anything but a fighter-bomber that defended itself reasonably well.



I don't believe I have said that high altitude performance wasn't important. You are correct in that I don't believe the P-40 was the plane to try and get high altitude performance out of. they are not the same thing. 



Clay_Allison said:


> I still think that it's a bad idea to resign yourself to giving up the high ground and think that the P-40 could have been balanced toward a higher critical altitude.


1. The army hadn't resigned itself to giving up the high ground, that is why they were paying for P-38s and P-47s
2. With out some sort of 2 stage supercharger and some sort of inter/after cooler you just aren't going to get a big increase in critical altitude. You can get a small one by totally redesigning your single stage supercharger and you can get an even smaller increase (depending on your original critical hight) by going to a 2 speed supercharger. 



Clay_Allison said:


> The Warhawk fought best on the climb and dive and it makes it difficult when you don't have a comfortable cruising altitude that allows you to take advantage of your dive speed for long.



Quite true but designing and building a totally new engine installation, High powered, high altitude flight may require larger radiators and oil coolers among other things, may mean NO Warhawks at all in one theater or another for several months.


----------



## vanir (Aug 23, 2009)

I'm all for increasing P-40 performance but keeping it below 18,000ft.
The USAAF tried the Merlin 20-series trimmed for aerial combat in the L variant in North Africa and it was a non-event. You could WEP +18lbs in that type for what...1650hp? But English based units were being transferred retaining their Spits and these were used to fly top cover while the P-40s did low-med altitude interception duties (mostly decimating whatever was left of the Luftwaffe transport force whilst the Spits handled their escorts).

I mean look at the ca.40mph performance improvement of the Schmood design with the same Allison as the P-40M and it's a heavier a/c.
Let's use that as a rule of thumb and put a Merlin 60/70 series with Rotol into the P-40N. Still having troubles breaking 600km/h at altitude. The second stage is a waste imho, keep it under 18,000ft and loaded with bombs.

The great engine combo would've been Merlin 50 and Rotol and something like that really should've entered production at the time of the P-40M, though really the -81 isn't far off the mark at WEP (60" rated) but I agree it's lacking a decent prop by this stage and would've liked to see the Allison of that time cleared for 66".
Then I think you'd have something about as good as an LF MkVc and after all these were still in front line service in 44. I think that would've been super handy in the South Pacific at the start of 43.


----------



## Shortround6 (Aug 23, 2009)

Elvis said:


> Click here to read the sad but amazing story of the P-38K.
> 
> Hey Clay,
> 
> ...



Nice idea, the question is if it will give enough more performance to be worth the trouble.

Using the numbers from the V-1710-93, the first production two stage Allison and not much different than the -45 model we get 1150-1180HP at 22,400ft. 

This compares to the Merlin 61 used in the MK IX Spitfire which offered 1370HP at 24,000ft. 

Now the Allison engine does show a marked improvement over the single stage Allisons. The best of the later ones were rated at 1125Hp at 15,500ft or 17,300ft depending on which source you believe ( or maybe whither or not ram is taken into accout?). The Two stage Allison does keep it's 1325HP take off rating instead of falling to 1200hp like the high altitude geared single stage Allison does. 

However there is a cost. The two stage Allison is about 300lbs heavier than the single stage engine and is over a foot longer. Could you get one in a P-40 airframe? Sure. but it is going to be a lot more complicated than just lengthing the engine mounts and patching some sheet metal into the gap between the cowl and the old fuselage. 

And what have you got when you are done? A Bf 109G with a DB 605 engine operating at 1.3 Ata at 2600rpm was supposed to give just about 1100hp at the same altitude as the 2 stage Allison gave it's 1150-1180hp. except it is in a smaller, lighter airplane. It will improve the P-40s chances but it won't turn it into a plane that can out run or out climb the 109G. 


As far as that impressive looking propeller goes, I sure would like to see a P-40 with landing gear long enough to use one


----------



## Clay_Allison (Aug 23, 2009)

The -45 with the H-S prop looks like the solution. Kurt Tank balanced the Fw-190D by just putting a spacer into the tail. Something like that could be done. If you want to make up the 300 pounds, switch from 6x.50 MG to 2x20mm in armament. That six-gun armament package was heavy. 

Overall, I've learned that there is no one magical drastic solution, but a lot of little changes that could get the P-40 to 1200 horses at 20,000 feet.

No, it couldn't outrun or outclimb the 109 but it could outdive it and it was more resistant to damage.

If you want a plane to fight down low take the P-39. It could dogfight respectably on the deck and the M4 Cannon could take out most targets of opportunity on the ground.


----------



## Elvis (Aug 24, 2009)

Re: H-S prop.

Personally, I'd like to see that prop's diameter lessened to something closer to the C-E prop's diameter.
Sticking with the WWII-era power figures we have available to us, I fugre either the prop gets longer blades, wider blades or more blades, but not a combination of those aspects. I just don't think the ponies were there, at that time.
Wider, ok, but not wider and wider (so to speak). To me, this seems a case of picking only one.
---------------------------------------------------------------------------------------------------------------

Re: Weight

What is the weight of the Merlin XX?
What is the weight of the Allison -45?
---------------------------------------------------------------------------------------------------------------

Re: CG

Quite true, the engine is 22" longer with the extra stage added, but I wonder if we couldn't re-engineer that setup (I know, firghtful words) so that it would keep the length closer to the single stage setup.
While I've never seen a pic of an Allison with the two-stage setup, from what I can tell, I suppose those stages were in-line with the engine, thus the added length.
What if we were to take the two stages and position them to each side of the crankshaft.
This way, they could both drive off a single gear.
Forgive my rather rudimentary representation, but I'm thinking along these lines...

o0o

The smaller "o's" are the stages. The larger "0" is the drive gear that is connected directly to the crankshaft.

You could even place a second gear in there that could move in and out, thus engaging and disengaging the second stage.
This would also allow one of those turbines to rotate in the opposite direction, so the piping could run straight up the vertical centerline of the engine, making the setup even more compact.
Kinda like this:

db

I think that would be a more _balanced_ arrangement than not having that gear, which would yield the manifolding to look more like...

dd

...and you really want to keep all that piping as close to the same length for each stage, as possible.

While this would probably put the length back close to the single stage's 85", I dont' know how it would fit width-wise, especially considering that the nacelle actually narrows towards the bottom rear (remember, its sorta shaped like an upside down egg)....hmmm, maybe if we rotated those stages upwards a little, so they were more inside the wide part of the "V".

Anyway, what do you guys think about setting the stages side-by-side like that, instead of in-line?

Would that work, or am I just Nuckin' Futs?




Elvis


----------



## Shortround6 (Aug 24, 2009)

You are "just Nuckin' Futs?"

No, not really. you would be surprised at some of the stuff that was actually tried, sometimes more than once, that never made it into production. 

For propellors. I think you are correct. Spitfire needed those 5 blades because it more than doubled the engine power. A 20% increase would only require modest increase in blade area. 
However everthing is a trade off. Propellor blades are like wings. Sure, a larger wing(blade) can give you more Lift(thrust) but it also has more drag, weight and may have a twisting motion. 
The extra weight may be minimal. The extra drag may be trumped by the extra thrust at full throotle but it may shift the other way at cruising speeds. 

Weights, The Merlin XX weighed 1450lbs or so depending on source. The -45 (one made) weighed 1515lbs but the first production engine By Allison went 1620lbs. THis is for the P-63 and may include the drive shaft?

Another table gives 175lbs as the weight of the auxilary stage of the -93 model used in the P-63. 

Allison changed the drive set up from the -45 to the later models. THe -45 used a single speed drive while all the later models uses a hydraulic clutch like the German DB series of engines which gave a variable speed drive so the engine only used just enough power to drive the aux stage at low levels and didn't waste power like ALL gear drive superchargers did at low level. Yes there was a shaft that spaced out the second compressor. 
In a test an Allison was fitted with the 2 stage supercharger from a Merlin. THere were bearing problems and it took 3 supercharger assembies to complete the test as each supercharger was appearently destroyed in succession.
You do need to route the output of one compressor from the outside or periphery of the compressor casing to the inlet or hub of the second compressor with a minimum of sharp bends. 

Am I confused or are your diagrams trying to show two superchargers working in parallel rather than series?

Don't be confused by the diamiater of the compressor impellor given in many data sources. The diameter of the casing (diffuser) was much larger than the impellor.

There was a late model Corsair engine that used TWO impellors turned 90 degrees to the crankshaft running in parallel to feed a third impellor running in line with the crankshaft. Please note that this was still a TWO stage system


----------



## Elvis (Aug 24, 2009)

Shortround6,

My diagrams were attempting to show each turbine, with the initial outlet piping that would lead up to the intake manifold.
Maybe I should've "drawn" them as such, instead...
d0b
d0d
Is that a clearer picture?
Without the extra gear, both impellers would rotate in the same direction, thus the piping would come off of the same side of their respective housings.
That is what the second diagram was attempting to show.
Setting up the stages that way would've led to unequal length piping, which (apparently) is a big "no-no" when setting up any kind of forced air induction system (I'd have to consult my book as to why, as I cannot recall, off-hand).

What bearing were destroyed in the test you referred to? Engine bearings or turbine bearings?

AFAIK, the "-45" engine was never used in any plane (my reference shows no application for that particular engine), but the "-47" is only slightly heavier, and that version does show application for the P-63 (or "F-63", as its notated in my resource), so I don't think the extension shaft is included in the listed engine weight.
However, both the "-47" and the later "-93" show a much longer length (217+", IIRC).
Since both of those engines were applied to the P-63, maybe the shaft is included in the dimensions, but not the listed weight?
Seems odd, but we are talking about a division of the United States Government and who knows what those boys are up to, half the time! 
I think, though, you see my point about the weight of those two engines, right?
Only about 65 lbs. and it didn't require any modification to the fuselage when the Merlin was installed in the P-40 (and actually, the weight difference there is more. About 135 lbs., comapred to the "-39" engine that the Merlin replaced).
I'm thinking, though, that setting that additional weight 2' farther out from the center would create a noticiable difference in the CG point, but Curtiss could've simply gotten around that by extending the aft section of the fuselage (I believe F-W did the same thing during the lifespan of the 190).

I believe the "twisting motion" aspect of changing the prop could be countered (at least somewhat) by shortening the diameter back down to 11' (as the pic I posted earlier shows the H-S prop to have a larger diameter, although I don't know by how much).
I would really hate to have to increase wingspan, in order to counter any additional "twist". That plane had a really great roll rate and I'd hate to mess with that aspect.

In your post, you seemed to alude to the fact that both stages are working at all altitudes.
Is that a correct assumption?
My comment concerning the additional gear was so that one stage would be enacted at lower altitudes, then, as altitude continued to increase, the gear would move in and enact the second stage, and _only then_ would both stages work in unison.
This way, one could better tailor each stage to work at the presecribed altitude ranges, more accurately.

Lastly, could you please explain "in series" and "in parallel", please?
I think I know what you're getting at, but those terms, in relation to supercharging, are foreign to me.
I just want to make sure we're both on the same page.

Thanks.



Elvis


----------



## Shortround6 (Aug 24, 2009)

Going in reverse order.

2 impellors/superchargers each with it's own intake and each one feeding one bank of a V-12 engine would be operating in parallel. Or two impellors/superchargers feeding into a common intake manifold. If your compressor's could only achieve a pressure ratio of 2.8 to one then that is your maximum pressure in your manifold. 2.8 times the the airpressure at what ever altitude you are at. 

Having 1 impellor/supercharger's output feed into a second superchargers inlet would be operating in series. Now the first supercharger could raise the pressure by 2.8 times the ambiant pressure and then the second super charger could raise it by 2.8 again giving you an overall pressure rise of 7.84. 

This is in theory, in practice the overall pressure ratio was closer to 5-6 to 1 for a variaty of reasons

On the -45 engine both stages would be turning at all times and both stages would be turning in direct proportion to the engine speed/rpm. The -45 engine also only had a single gear ratio so at low altitude in thick air the supercharger/s would be turning much faster than was needed, wasting power. The later units with the hydraulic drive could "slip" and reduce the speed of the auxliary unit. Since centrifugal superchargers output goes up with the square of impellor speed ( as does their power consumption) large changes in impellor rpm are not needed to make large changes in power consumption or in output. 

The Merlin was set up so that both impellors turned at the same speed and both impellors turned all the time. the Merin did have a two speed gearbox so it could use a slower speed at low altitudes.

R-2800s used by the Navy had a single speed supercharger on the engine, it rotated at a fixed ratio to the crankshaft. The other impellor,which was hidden inside the same large housing on the back of the engine had two speeds plus a neutral. At take off and low altitudes the auxialry stage was in neutral and provided no boost, it also didn't require any power to drive. As the plane climbed the low gear was engaged to provide pressureize air to the engines supercharger. as the plane climbed higher into thinner air the higher gear was selected to again provide sealevel (or slightly higher ) pressure to the inlet of the engine supercharger. SEE: http://www.zenoswarbirdvideos.com/Images/F4U/F4USEC.GIF
for an idea of how this works. 

AS for the propellors I am sorry for any confusion. a larger propellor blade will have a larger twisting motion in relation to itelf. The outer part of the blade will try to twist in relation to the shank or part that goes into the hub. Depending on how much strength is already there it might require heavier construction, it might not. 

AS to what the -45 was used in? as far as I know, nothing. it was developement engine. Only ONE was listed as being built. the -47 was listed as THREE built. used in XP-39Es which was the sort of prototype for the P-63. THe production version was the -93. 

You might be able to work out or visualize the weight problem. how far from the center of gravity of plane was the center of gravity of the existing engine? weight X distance. 
using a heavier engine of nearly the same size means the weigh goes but the distance stays the same.
A lighter engine further forward might balance out the same.
A heavier engine another 1 1/2 feet further out ?

see:More P-40 Stuff from a real Curtiss P-40 Warhhawk pilot's manual

Let us assume the center of the P-40s 1310lb engine is 80 in front of the desired center of gravity.

This gives us 104,800 in lbs of torque try to pull the nose down.
Using a 1500lb engine 100in from the CG gives us 150,000 in lbs of torque.
Now add the weight of the propellor and cowling to the weight moved foward. 
Of course you can move the oil tank and some of the other stuff and move the new engine back a bit. you can also move the radiators and oil coolers back ( which was done on the P-40 Q) 
And you can extend the tail for balance but that can bring in a few problems of it's own. Moving the control surfaces futher from the CG changes their effectivness which might be a good thing or it might be a bad thing.

More later.

Edit>

THE Bearings that were destroyed were in the supecharger, the Merlin had no turbine. Something to do with the supercharger being remote form the engine ( it was a test lash up) and the temperatures not being the same as when the supercharger was attached to the engine fouled up the tolerances. 

Some cars have used two superchargers in parallel but the problem they were trying to solve was a bit different. Car engines operate over a much wider rpm range than aircraft engines and need better throttle response over this wide rpm range. THey were trying to match the volume of flow required at different rpm ranges which is not the same as the pressure variations that aircraft engines have to deal with. Unless you are racing up Pike's peak


----------



## Elvis (Aug 25, 2009)

Shortround6,

That was a nice little exercise you showed, concerning how where the weight is placed, affects the CG, but you forgot that my solution to that problem was to attempt to take the extra 22" of length out of the -45 engine, by setting the stages side-by-side, instead of in-line.

...by the way, you never did state whether you were into that idea or not. So which is it? (CLAY, this means you, too).

As for the history of the -45, I believe I already touched on that, however, whatever you're using for a source is incorrect. 
The -45 engine had two speeds, 8.1:1 and 6.85:1, but used the same size of impeller - 9.5".
My source lists applications for the -47 engine as: XP-39E, XP-63, XP-63A and P-76.
The description I have for that engine states that it was similar to the -45, except: "E" series engine with extension shaft, remote reduction gear and independant internal hydraulic system.
My source for the -93 engine lists its applications as: XA-42, XB-42, F-63A and F-63C.
Its differences from the -47 are that it used a different propeller shaft, some of the power ratings are a little different and it has a longer OAL.
This is all according to Official USAF Documentation.

Lastly, thanks for explaining those SCing terms. My diagrams were showing a system that was in parallel, feeing into a common manifold inlet (i.e., no prescribed banks).
FWIW, I like the "in parallel" system better than the "in series" system. Seems like it would be less hard on the equipment and if one of the stages were to fail (for whatever reason), you'd still be making _some_ power (basically, it would become a single speed, single stage system).



Elvis


----------



## Shortround6 (Aug 25, 2009)

Most of what I am using for a source is "Vee's for Victory, The story of the Allison V-1710 Aircraft engine 1929-1948" by Danial Whitney. 1998.

You are right there were more than three -47s the chart says 3+

The -45 did use two gears. one gear was for the engine supercharger and the other gear was for the auxilary stage supercharger. 

No F-63s were ever built as such. ALL P-series fighters were redesignated as F-___ after the war. 
By the way, no P-76 were ever built.

I am not really in favor of the side by side setup. While it just might fit using a a pair of small superchargers I think it would introduce at least as many problems as it would solve.

A problem with your parallel system is that it won't give the high altitude performance you are after. Centrifugal superchargers are not positive displacement units. If the pressure of the area they are trying to discharge into is too high they just don't flow anymore. I have explained the compund nature of the 2 stage system. Putting two superchargers in parellel not only doesn't get the compund effect, it won't even give you an add effect in regards to pressure. It will in volume but not in pressure.


----------



## vanir (Aug 25, 2009)

If I might jump in on parallel supercharging, one issue is diameter of the casing/impeller. Bear with me as I'm adapting auto industry application to aero.
Bigger diameter raises the altitude regime of best performance, which is great if you want to make a high altitude a/c but loses out on low alt performance (I'll assume this is related to pressure ratio and power wasteage as described by Shortround). The bonus of bigger diameter unit though is higher cfm or passage volume, which means more power output (more in=more out).
The tandem supercharger is designed for this application, where you want more power without raising the throttle heights. You raise the volume without raising the diameter(s) of the casing/impeller.

In other words to get more power you can put a bigger supercharger on, but it raises the throttle heights and reduces performance at low altitude.
Or you can put a tandem supercharger on, which raises the output and won't affect the throttle heights.
Or you can put a series supercharger on, which retains similar low altitude performance but raises the throttle heights and thus gives higher *relative* output in the second stage (if using an intercooler low altitude output will of course be increased for this reason).

Like I said, adapting auto supercharging to aero application (where rpm ranges would substitute throttle heights)

Sound about right Shortround?


----------



## Elvis (Aug 26, 2009)

Well put Vanir.
It would be interesting to read what Shortround6 has to say about that.


Elvis


----------



## Elvis (Aug 26, 2009)

I wanted to throw one more thing into the conversation, and this is in relation to Clay's idea about usage of the H-S prop.

What if one were to build a larger displacement Allison?

I was fooling around with that the other day and found that if the bore were taken out .25" and the stroke lengthened by .5", the resulting displacement would increase to 2025 cu.in.

Now that gets more into the DB601/605 and Griffon territory and may result in enough power increase to make working with the larger, broader propeller more feasible.
You'll loose a little engine speed, but that _could_ be made up with less reduction at the prop (I figured out that a change from 2:1 to 1.8:1 would keep prop speed the same, with the engine operating at 300 RPM less).
That does put more stress in that transmission, though.
Can it handle it? Beats me.

What do you think, Clay? 
Seems this addresses your initial question in this thread a little closer, rather than expounding on mods to the existing V-1710.

Anyway, just an idea, based on looking at the engine power situation from another angle. 
Would still like to expound on the two-stage, two-speed idea (applied to the V-1710), as well.


Elvis


----------



## Elvis (Aug 26, 2009)

Shortround6 said:


> Most of what I am using for a source is "Vee's for Victory, The story of the Allison V-1710 Aircraft engine 1929-1948" by Danial Whitney. 1998....The -45 did use two gears. one gear was for the engine supercharger and the other gear was for the auxilary stage supercharger.


Interesting, but doesn't that make the system two-speed, two-stage?


Shortround6 said:


> No F-63s were ever built as such. ALL P-series fighters were redesignated as F-___ after the war.
> By the way, no P-76 were ever built.


In case you didn't notice, the link has information that dates from 1949.
As you stated, by that time, fighter designation had been changed from "P" to "F".
As it is _official_ government documentation, the applications mentioned, that are fighter planes, would then have to be mentioned with the "F" designation, regardless if the plane was still in the inventory or not.
They're simply saying that those were the applications for that particular version of the engine, phrased in a _modern_ format.


Shortround6 said:


> I am not really in favor of the side by side setup. While it just might fit using a a pair of small superchargers I think it would introduce at least as many problems as it would solve.


Thank you for answering my question, but how does it introduce new problems?
Are you concerned about the strength of the gearing, or the "fit" of the engine, or something else?


Shortround6 said:


> A problem with your parallel system is that it won't give the high altitude performance you are after. Centrifugal superchargers are not positive displacement units. If the pressure of the area they are trying to discharge into is too high they just don't flow anymore. I have explained the compund nature of the 2 stage system. Putting two superchargers in parellel not only doesn't get the compund effect, it won't even give you an add effect in regards to pressure. It will in volume but not in pressure.


According to this page, pressure will increase by the square of the increase in engine speed.
This is where the R&D work comes in.
You need to set the gearing so that you don't exceed that max. pressure.
If this is done correctly, the SC's will always produce more power, as engine speed increases, within the limits of the engine's operating speeds.
If you set the system up so that the engine is only initially running on the primary SC, and it is optimized to work from SL to a certain altitude, _then_ kicks in the aux. SC, only when the initial altitude is exceeded, and optimize that aux. SC so that it helps maintain that amount of power to a much higher altitude, then I don't see how the system doesn't work.
There's also a sort of "safety" built into this type of design.
If you use the primary SC only as a feed to the aux. SC, then if that aux. SC is damaged in such a way that it no longer operates, you've pretty much lost all of your SCing effect, because the aux. SC now acts as an obstruction in the line, rather than a power augmenter.
If setup in the way I just explained, then at least you still see _some_ amount of boost.
Although engine power at the higher altitude will be lost (because you're now basically running a single-stage, single speed SC optimized for low altitude work), it won't be as much of a power loss as running the system in series...and I get the idea you prefer the "in series" setup to the "in parallel" setup, correct?



Elvis


----------



## Clay_Allison (Aug 26, 2009)

Elvis said:


> I wanted to throw one more thing into the conversation, and this is in relation to Clay's idea about usage of the H-S prop.
> 
> What if one were to build a larger displacement Allison?
> 
> ...


I like that. You know they say there's no replacement for displacement.


----------



## Elvis (Aug 27, 2009)

True! 


Elvis


----------



## Shortround6 (Aug 27, 2009)

Elvis said:


> Interesting, but doesn't that make the system two-speed, two-stage?



No, it means the engine supercharger spun at at one fixed speed in relatio to the engine crankshaft while the auxilery supercharger spun at a different fixed speed in relation to the crankshaft. two stage yes but a single speed two stage. 



Elvis said:


> In case you didn't notice, the link has information that dates from 1949.
> As you stated, by that time, fighter designation had been changed from "P" to "F".
> As it is _official_ government documentation, the applications mentioned, that are fighter planes, would then have to be mentioned with the "F" designation, regardless if the plane was still in the inventory or not.
> They're simply saying that those were the applications for that particular version of the engine, phrased in a _modern_ format.



I did notice that well over a year ago when I first ran across that list. 
just noting that there are a number of mistakes, typos, omissions and/or other types of errors in that list. It is very useful but shouldn't be take as the last word.



Elvis said:


> Thank you for answering my question, but how does it introduce new problems?
> Are you concerned about the strength of the gearing, or the "fit" of the engine, or something else?



Yep, plus cost (difficulty of manufacture) , weight, possible vibration problems and more that I haven't thought of.



Elvis said:


> According to this page, pressure will increase by the square of the increase in engine speed.
> This is where the R&D work comes in.
> You need to set the gearing so that you don't exceed that max. pressure.
> If this is done correctly, the SC's will always produce more power, as engine speed increases, within the limits of the engine's operating speeds.
> ...



The whole idea of running the superchargers in series is for high altitude work. 
IF your engine needs, say 45in of boost to makes it rated power at sea level (30in pressure) your supercharger only needs to deliver a pressure ratio of 1.5 to 1 which is very easily done. as the plane climbs if you want to keep your manfold pressure at 45in at just under 11,000feet where the pressure is 20in your supercharger needs a pressure ratio of 2.25 to 1. At 18,000 ft the pressure is just about 15in and you need a supercharger that can deliver a pressure ratio of 3 to1. 
This was the problem in the very late 30s. NOBODY's single stage supercharger could deliver a pressure ratio of 3 to 1 in a useable manner. simply gearing the supercharger to spin faster ment that the power to drive it went up with square of the speed. The air coming out of the supercharger was much hotter and much more likily to cause detonation in the cylinders. 
The "series" setup was already known to need less power to reach a given pressure ratio and cause less charge heating even without an intercooler. 
PLease note that if your engine required less than 45in at sea level the existing supercharges could maintain the sealevel power a little higher up while if your engine required more than 45in it's critical hight would be lower. 

Agiain, please note that the centifugal supercharger is NOT a positive displacement device. There is a lot of room arouond the impellor for air flow if the impellor is stopped. I believe that one of the Navy R-2800s actually sucked through the un driven auxialry stage when operating at take-off and at low altitudes.

THe centifugal water pumps we use at work will rotate just fine with their output blocked, at least until the churning of the water raises the teperature to the boiling point. 

That is the problem with your system. the aircraft system needs TWO things. it needs Pressure and volume. putting two centifugal impellors in parallel actually can solve a volume problem but it doesn't do much for the pressure problem. 
We used to have old fire pumps that actually could be switched from one to the other. Two impellors and piping that would change them from series to parallel. if your situation required lots of water at low (under 150lbs) pressure you pumped in parallel (capacity) if you need higher pressure You pumped in seies (pressure). New fire pumps are driven by much larger engines and they just use one big impellor

If all you want is low altitude just stick a big enough single stage impellor on the engine and get on with it. 

British created low altitude engines by turning down the impellors to smaller diameters and locking the two stage gearboxes in low gear.


----------



## Clay_Allison (Aug 27, 2009)

what effect would intercooling a single stage supercharger have?


----------



## Shortround6 (Aug 27, 2009)

Elvis said:


> I wanted to throw one more thing into the conversation, and this is in relation to Clay's idea about usage of the H-S prop.
> 
> What if one were to build a larger displacement Allison?
> 
> ...



basicly you are working with a whole new engine. Which equels how much development time?

Most aircraft engines were not built with anywhere near the amount of stretch in them that car engines have. 

Aircraft engines are usually built to a much tighter power to weight ratio than car engines so they are not over built to any great extent. And in the 1930s a lot less was known about combustion behavior and other aspects of engine design. There were reasons why Mukulin used just about the same bore and stroke in all his engines and why the bore and stroke didn't change much from their BMW ancestors. Or some other familys of engines.

Trying to splice an extra 1 1/2 inches of bore into a V-12 engine means one of two things. Less water circulating between the cylinders or a new longer crankshaft and crankcase. 
I guess you could try bigger pumps to shove the water through quicker but the faster moving water (OK ethylene-glycol) might not have the same heat transfer rate if it is moving faster. One more series of tests for R&D. 

As a" for instance" when it comes to airplane engines the very late model Allisons that could run at 3200rpm used a crankshaft that weighed 27lb more than the earlier 3000rpm engines. the extra weight was actually in the counterbalances which were needed for the increased vibration at the higher rpm. Although the new crank did exhibit much lower bearing loads than the older crank did even at the higher rpm. 

Remember, walking home after blowing an engine is not really an option in an airplane.


----------



## Shortround6 (Aug 27, 2009)

Clay_Allison said:


> what effect would intercooling a single stage supercharger have?



On the size engines we are talking about here it might be worth around 100hp. At least that is around what the Germans got on some of their Jumo 211s. 

But it is not going to change the critical altitude much. You are still limited by the effective pressure ratio of the supercharger. THings did improve after Hooker got involved and both the Russians and the French were working on higher efficinecy compressors in 1940-41 that used variably sized or angled inlet guides and /or extra axial stages. But compare a series 40 something Merlin (Hooker single stage supercharger) to a 60 series engine for altitude performance. 

And you have to fiind space for the intercooler. ANd it has to work at altitude. It is mass air flow that does the trick. say you want a 40% efficient inter cooler (or after cooler on a single stage engine) . You need just about the same mass of cooling air going through the inter cooler as you do induction air. easy enough at sea level but at 22,000feet you need twice the cubic feet of air as you did at sea level to get the same mass. More airflow will get you even lower charge temperatures but after 40-50% it gets into diminishing returns pretty fast.


----------



## Elvis (Aug 27, 2009)

Shortround6,

Ok, I'll concede to your penchant for running the system in series, as opposed to in parallel.
After your further explanation, that does make sense.
It may be more fragile, in war-time conditions, but nothing is perfect and it achieves the goal of more high altitude performance better than the in parallel idea I mentioned.

...in fact, I think my idea of changing the arrangement of the SC's in the -45 is not a good one to begin with.
It not only does not work as well, but changes the engine and no longer makes it a "-45" varient (duh! c'mon Elvis!)....and then there's the time factor you mentioned.

Same goes for the larger displacement engine idea. Too much R&D time needed.

However, I understand that none of the production WWII era Allisons had intercooling. It seems they were stuck on using water injection only as a way to prevent detonation and that alone, apparently, was not enough to allow the engine to put out the power numbers it needed to be more competitive with Axis aircraft (ok, the 109!).
So maybe augmenting the -45's water injection with some form of intercooling (place it in front of, or behind, the oil cooler?) is the answer to preventing detonation (or at least keeping it to a minimum).

So I guess its the -45 engine, augmented with an intercooler, using the H-S prop that makes the P-40 a high altitude "winner".

So how can we address any CG issues the engine change might incur?




Elvis
P.S. If you wanna call it "coolant", It's ok by me.


----------



## Clay_Allison (Aug 28, 2009)

Elvis said:


> Shortround6,
> 
> Ok, I'll concede to your penchant for running the system in series, as opposed to in parallel.
> After your further explanation, that does make sense.
> ...



Lengthen the tail with a spacer, Kurt Tank style.


----------



## Shortround6 (Aug 28, 2009)

Elvis said:


> However, I understand that none of the production WWII era Allisons had intercooling. It seems they were stuck on using water injection only as a way to prevent detonation and that alone, apparently, was not enough to allow the engine to put out the power numbers it needed to be more competitive with Axis aircraft (ok, the 109!).
> So maybe augmenting the -45's water injection with some form of intercooling (place it in front of, or behind, the oil cooler?) is the answer to preventing detonation (or at least keeping it to a minimum).
> 
> So I guess its the -45 engine, augmented with an intercooler, using the H-S prop that makes the P-40 a high altitude "winner".
> ...



None of the Mechanical drive 2 stage engines used intercoolers but all of the P-38 turbocharged engines did. Allison hoped their more efficient compressor compared to the GE one wouldn't cause as much temperature rise. The other situation that Allison may have faced was that the "target" kept changing. What was the target "goal" for horsepower and manifold pressure may have changed from 1940 to 1942. THe -47 supercharger set up was better for a service aircraft in any case although I am not sure how much delay that entails. The goal of that set up being to use only just enough power to drive the auxilary stage to provide sea level pressure (or just slightly above) to the engine supercharger and thus have more power available at the lower altitudes. 

A 'FUN' program to play with is here: motorgeek.com :: Turbo/Engine Flow Calculations and Maps

But please read the notes.
THe program makes no allowances for increase friction at higher rpms nor does it subtract the power needed to drive a mechanical supercharger. It tells you to try to use the SFC number to "adjust" for those effects.
Still it does give an idea of the effects of intercooling and water injection.
you have to 'add' enough manifold pressure to the 

I would think you would want to give the intercooler it's own supply of air. either using already heated air or trying to feed heated air to the oil cooler doesn't sound like a good idea. besides, you might want to be able to control the cooling of each device independantly.


----------



## Elvis (Aug 28, 2009)

Clay_Allison said:


> Elvis said:
> 
> 
> > So how can we address any CG issues the engine change might incur?
> ...


Quite true, but I'm wondering if there's room between the engine and the cockpit to allow (at least some of) that extra length to fit, as well?
This way, we don't rely _solely_ on lengthing of the aft section of fueslage.

Can someone provide a sectional view of the aircraft?
I tried looking for it last night, but couldn't locate one.



Elvis


----------



## Elvis (Aug 28, 2009)

Shortround6 said:


> THe -47 supercharger set up was better for a service aircraft in any case although I am not sure how much delay that entails.


I thought the only difference between the -45 and the -47/-93 engines was the extension shaft used on the latter engines for usage in the P-63?
You're saying the SC setup is different, as well?
Didn't realize that.


Elvis


----------



## Shortround6 (Aug 28, 2009)

Elvis said:


> I thought the only difference between the -45 and the -47/-93 engines was the extension shaft used on the latter engines for usage in the P-63?
> You're saying the SC setup is different, as well?
> Didn't realize that.
> 
> ...



The -45 used a single speed fixed gear for the auxilary stage. the -47 used a single speed gear with a hydraulic clutch that could be 'slipped' to vary the actual rpm of the inpellor. Much like the drive on the German DB engines. 
Because of Allison 'modular' aproach to engine building the front drive, whether reduction gear or extension shaft, could be bolted to any block so using the power figures from the -47 isn't really much of a stretch. Granted the maximums aren't any different but the engine might require less attention in combat. -45 need attention to throttle settings to avoid over boosting. 

As for a cutaway drawing I found this although it is not very good. 

1941 | 0682 | Flight Archive


----------



## renrich (Aug 29, 2009)

According to dean, "America's Hundred Thousand" the two stage supercharger used in the R1830 and R2800 engines had an air to air intercooler. The second stage blower was placed between an outside air intake and the intercooler. The outside air was used to cool, by close passage of outside air, the charge air compressed by the auxiliary stage blower before it entered the carburetor. In this scheme the main blower compressed a fuel air mixture whereas the auxiliary blower compressed air only. The system had three modes of operation. Neutral blower where the second stage was declutched. Low blower with a low ration clutch and high blower with a high ratio clutch.


----------



## Elvis (Aug 30, 2009)

Shortround6 said:


> The -45 used a single speed fixed gear for the auxilary stage. the -47 used a single speed gear with a hydraulic clutch that could be 'slipped' to vary the actual rpm of the inpellor. Much like the drive on the German DB engines.
> Granted the maximums aren't any different but the engine might require less attention in combat. -45 need attention to throttle settings to avoid over boosting.
> 
> As for a cutaway drawing I found this although it is not very good.
> ...


You know, I found something the other day that stated that the -45 engine also used a hydraulic clutch for the aux. stage.
It even stated its reference source was the same as yours - Vee's for Victory.
I can't seem to find it now, but if I ever do, I'll post the link for you.
As for the picture, thanks.
When you blow it up to like 400%, you'll see its actually fairly well detailed.
That pic, plus the one I found here (note the 3rd plane down from the top), both seem to show a little room behind the engine. I wonder if that space couldn't occupy at least some of the second stage (I'm assuming the extra length is coming from the addtional SC and its plumbing).
This would mean that the nose wouldn't stick out quite so far and adding length to the rear of the fuesalage, as Clay had mentined earlier, would be a less drastic affair.
I wonder how bad it would be to push the cockpit back, maybe 3"-4"?
Would it be that different to fly/taxi?
I'm just thinking about the combined weight of the H=S prop and the -45 engine.



Elvis


----------



## Elvis (Aug 30, 2009)

...forgot to address this part...



Shortround6 said:


> I would think you would want to give the intercooler it's own supply of air. either using already heated air or trying to feed heated air to the oil cooler doesn't sound like a good idea. besides, you might want to be able to control the cooling of each device independantly.


Maybe, but sticking the condenser for an A/C unit in front of an engine radiator has been standard practice in automobiles for many years, with no ill effects...and I don't think that one qualifies for the "apples-to-oranges" argument.
Of course, if you went "IA" (intercoolded and aftercooled) with that setup, then each unit could be smaller and maybe you could fit them to each side of the oil cooler.
This would require a small change to the cowling, of course.
...and there's no law that says you can't place them elsewhere, either.

Also, on "independant controls" for SC radiators and oil cooling:
You're saying less SC cooling at SL and more at higher altitudes?
That seems to be a bit much for the pilot to worry about, while in combat.
I'd think if you're going to cool the charge, just cool it, regardless of altitude.
The whole thing's about density per charge anyway, so whatever condition the engine finds itself in, I would think the cooling of the charge would still prove beneficial...EXCEPT, in extreme cold, like Alaska...but then, those planes would be spec'd differently anyway. Chances are the coolers may not even be present, or only one might be spec'd.



Elvis


----------



## Elvis (Aug 30, 2009)

Shortround6 said:


> Because of Allison 'modular' aproach to engine building the front drive, whether reduction gear or extension shaft, could be bolted to any block...


You know they learned that from Cleaveland, right? 


Elvis


----------



## Shortround6 (Aug 30, 2009)

Elvis said:


> You know, I found something the other day that stated that the -45 engine also used a hydraulic clutch for the aux. stage.
> It even stated its reference source was the same as yours - Vee's for Victory.
> I can't seem to find it now, but if I ever do, I'll post the link for you.
> As for the picture, thanks.
> ...



apparently I was in error. The -45 and -47 engines used both types of drives depending on when in their development we are talking about or exactly which serial number engine

From "Vee's for Victory" pages 345-346. 
"In it's intial form, on the V-1710-45(F7), the drive for the Auxiliary Stage was an all mechanical affair with a friction clutch for vibration damping. 4
What was unique with the developed drive was the method for insulating the supercharger from torsional vibrations inherant in a direct drive from the crankshaft. In 1942 Allison fitted a small hydraulic clutch, much like that used in automatic automobile transmissions, to drive the Auxiliary Stage. This provided another significant benefit in that it could be operated to allow a significant amount of "slip" and thereby providean infinately variable control of the speed of the Auxiliary Stage impellor. The unit speed was as controllable as that of a turbosupercharger. The benefit being that the engine throttle could be efficiently maintained wide open so that manifold pressure and power were controlled by the speed of the Axiliary Stage. This minimized the amount of compression heating in the induction systemwhile at the same time reducing the power required to drive the Auxiliary Stage. Quite a neat set up."
From page 269:
"*F-7R*: As the V-1710-45, this 1940 project was the first V-1710 to use the new Auxiliary Stage Supercharger and thereby become a mechanically driven two-stage V-1710. Contract W535-ac-16146, dated December 2,1940, was issued for one experimental engine. Change No. 1 was issued in July 1942 to cover redesigning to provide a larger Auxiliary Stage Supercharger (12-3/16 inch diameter impellor replaced the earlier 9 1/2 inch unit) driven by a hydraulic coupling instead of the original friction clutch. The delivery date was changed from September 1941 to February 1943. Obviously the effort was considerably behind schedule at this point. A second contract, W535-ac-22957 was issued in December 1941 to purchase an experimental engine with aftercooler for the Classified Project No. MX-69, which was the airplane that became the Cutiss XP-60. This version of the two stage Allison never achieved flight status."

And from page 256:
" *E-9*: This was the first two-stage V-1710 to reach flight status. It incorporated the Allison designed and mechanically driven Auxiliary Stage Supercharger. Development of the two-stage V-1710 components began in 1940 and endured a long development cycle, during which a number of different supercharger ratios, both for the engine stage and the Aux Stage, were tested.
Develpment work on the auxilary stage for this engine dates from 1938, and seven of these engines were purchased on development cointract W535-ac-19859 dated June 1941. This followed seven months after the pioneering contract for the two-stage V-1710-F7R. One engine was for development, with two each for installation in the XP-39E and XP-63 airplanes, with two engines held as spares. The engine went through considerable evolution during it's development, in fact, revisions to Allison specification No.137 were issued through "G", all of which used 7;48 engine stage supercharger gears. As early as February 1942 the engine was running in the Allison ltitude Chamber.27 Without the intercooler the engine weighed 1,525lbs.28
In February 1942 development testing of a hydraulic drive for the auxiliary stage supercharger was begun. In July 1942 it was decided to replace the friction clutch in the drive with the automatic hydraulic coupling on both the F-7R and the E-9.................As early as September 1940 the Allison Specification No. 137 was revised as 137-A to reflect the incorperation of an intercooler. 31 The device never went into the production models of the engines...............Aftercooler development for this engine was terminated in December 1943 in veiw of the poor characteristics of the cooler provided by the Harrison Radiator Division of General Motors and the large amount of mechanical trouble with the set up.33"

there are several more pages of text, charts and tables concerning these engines in the book, Why he says 7 engines in the text and list 3+ in the production table for the -47 I have no Idea. Numbers scattered through the text are the numbers of the footnotes. 

I am not saying that you would have to extend the nose the entire amount of the extra length of the egine but moving back a whole lot might not be easy. for instance the engine mount had sidesway braces that went from the rear of the side tubes to a common mounting point in the middle of the firewall about half way in hight between the upper and lower mounting points. 5 mounting points total. 
The 2 stage engines were put into P-40 airframes, this has been mentioned before. See the P-40Q. 
It just wasn't going to be done simply or quickly or without disrupting production.

The big prop might not be nessassary unless you get the engine a lot closer to 1600-1800hp than the 1150-1325hp the -45-47 were originally rated for.


----------



## Shortround6 (Aug 30, 2009)

Elvis said:


> ...forgot to address this part...
> 
> 
> Maybe, but sticking the condenser for an A/C unit in front of an engine radiator has been standard practice in automobiles for many years, with no ill effects...and I don't think that one qualifies for the "apples-to-oranges" argument.



You might want to tell that to the scores of peaple who over heated their cars in the American southwest while running their air conditioners full blast
things have gotten better with newer (post 60's?) cars but that is because they are putting in bigger radiators to begin with. replacing cooked engines under warranty probably got as espensive as the cost of slightly bigger radiators, not to mention the loss of reputation. 


Elvis said:


> ...Of course, if you went "IA" (intercoolded and aftercooled) with that setup, then each unit could be smaller and maybe you could fit them to each side of the oil cooler.
> This would require a small change to the cowling, of course.
> ...and there's no law that says you can't place them elsewhere, either.



no there isn't but what type are you using? Most american planes used air to air intercoolers which means rather bulky ducts (which have to be kept air tight ) leading too and fro in the aircraft. Navy planes kept the intercoolers (and they did use two of them on the R-2800s) tucked sort of behind the engine next to the superchargers.
Merlin used a liquied cooled inter/aftercooler with the "radiator' next to the oil cooler in one of the under wing ducts/housings. Smaller and harder to hit but a single rifle bullet can take out the intercooler setup entirely rather than just degrade it a bit. 



Elvis said:


> Also, on "independant controls" for SC radiators and oil cooling:
> You're saying less SC cooling at SL and more at higher altitudes?
> That seems to be a bit much for the pilot to worry about, while in combat.
> I'd think if you're going to cool the charge, just cool it, regardless of altitude..



Might work if you flew full throttle all the time......nope won't work then either. 
In a full throttle climb max climb the airspeed is rather low, ussually under 200mph so the air flow through the various cooling systems is much lower than it is in a high speed dash. this is why most climb to altitude tests are conducted with radiator flaps and oil cooler flaps wide open (or cowling flaps on aircooled engines) while the speed tests are conducted with the flaps closed or at least closed to the oppoint of maintaing a certain max temperature. Drag goes up with the square of the speed so the extra drag at the low climb speeds isn't quite as important. 
Cruising speeds present another problem. The engine is making much less power (and heat) than full throttle. in fact the engine can be in danger of being over cooled if run with all flaps wide open.
Part of the P-38s troubles in Europe in the winter of 43-44 as due to too much cooling of the intake charge in cruising flight leading to fuel condensing out of the mixture and puddling in the intake manifolds.
Post war commercial Merlins were actual fitted with intake charge heaters to solve similar problems in cruising flight.


----------



## Elvis (Sep 1, 2009)

Shortround6 said:


> apparently I was in error. The -45 and -47 engines used both types of drives depending on when in their development we are talking about or exactly which serial number engine
> 
> From "Vee's for Victory" pages 345-346.
> "In it's intial form, on the V-1710-45(F7), the drive for the Auxiliary Stage was an all mechanical affair with a friction clutch for vibration damping. 4
> ...


Hey, that was quite interesting to read.
Thanks for posting that.
I had no idea the "two-stage" project went back that far. 
The only thing I could find on production of the -45 was 1943.
Obviously, this concept had been "cooking" for a much longer time.

As for modifying the airframe, I didn't mean a drastic change to the cockpit location. Only about 3 or 4 inches.
This is assuming the pics I saw were accurate in showing a small bit of space at the rear of the engine compartment, which might be utilized to help house the extra length.
If that were, say, a 6" long space, and you push the cockpit back 4", you now have 10" of space to house the extra length in.
So now the front of the engine only sticks 12" past the front of the single stage engine, instead of 22".
This additional length, plus the extra 200 lbs. could be further balanced by an extension of the aft fueselage, but that extension wouldn't be quite as large, as if it had to counterbalance the additional 200 lbs., plus the full 22" of extra engine length.

I still say Clay was on the right path by introducing the idea of the H-S prop. My only stipulation is make it the same diameter and same number of blades as the C-E prop.
As for your HP comments, concerning the H-S prop, remember that the 4-bladed, 11'2" version was used on the P-51D...







...and it's Packard-Merlin engine only made 1490HP.
Therefore, I think a 3 bladed, 11' version will work nicely with 1325HP on tap.

As for your Intercooler question, I was thinking air-to-air, because of the fragility you mentioned with the liquid cooled version (however more effieicient it is), but I'll concede to dampers for the IA. I didn't consider night flying in winter-time conditions.





Elvis


----------



## Shortround6 (Sep 1, 2009)

Thank you for your comments.

As far as the propellors go you might want to check your HP figures. There are all kinds of nominal HP figures floating around for Merlin engines. WER for a -7 Merlin was 1720HP in low gear at 18.25lbs of boost (67in ). using 150 octane fuel they could get even more. If you are talking about an 1942-43 Allison engine then you are rarely going to be reaching anywhere near that power. 

What has to be remembered in looking at Allison was that up until 1940 it was a very small company. Before 1940 they had only delivered 67 V-1710s and then had to deliver hundreds of engines in 1940 followed by thousands in 1941 and 1942. even with their modular aprouch they were working on the P-40 engines, the p-39 engines, P-38 turboed engines, several other proects and the V-3420 project( side by side V1710s driving a common prop) Even with help from General Motors there was only so far their engineers could stretch.

try looking at the dates on the Curtiss P-53 and P-60 projects to see when Cutiss and the Army started thinking about improving the P-40


----------



## Elvis (Sep 1, 2009)

Shortround6 said:


> Thank you for your comments.


You're welcome, but why do I have this odd feeling that...


Shortround6 said:


> As far as the propellors go you might want to check your HP figures.


...YEP, here we go...


Shortround6 said:


> There are all kinds of nominal HP figures floating around for Merlin engines. WER for a -7 Merlin was 1720HP in low gear at 18.25lbs of boost (67in ). using 150 octane fuel they could get even more. If you are talking about an 1942-43 Allison engine then you are rarely going to be reaching anywhere near that power.
> 
> What has to be remembered in looking at Allison was that up until 1940 it was a very small company. Before 1940 they had only delivered 67 V-1710s and then had to deliver hundreds of engines in 1940 followed by thousands in 1941 and 1942. even with their modular aprouch they were working on the P-40 engines, the p-39 engines, P-38 turboed engines, several other proects and the V-3420 project( side by side V1710s driving a common prop) Even with help from General Motors there was only so far their engineers could stretch.
> 
> try looking at the dates on the Curtiss P-53 and P-60 projects to see when Cutiss and the Army started thinking about improving the P-40


Which version of the Allison has been the main point of discussion since Clay resurrected this thread with the H-S prop idea ?
In case you're not following, I was referring to the -45 version, when I quoted the 1325HP figure.
As for the P-M HP rating, I believe that figure is take-off power for the -7 engine, used in the P-51D.
While I've seen a numvber of figures bantered about over the years, this one seems to keep coming up, from various sources.
The 1325HP figure for the -45 is also take-off power (granted, it was never actually installed in an airplane. Still, that is how the figure is listed and thus, how I am using it).
Yes, I'm sure the staff at Allison were VERY busy during those years, as was everyone else, but then....this is the "_What if_ " thread.



Elvis


----------



## Shortround6 (Sep 1, 2009)

Elvis said:


> .
> 
> Which version of the Allison has been the main point of discussion since Clay resurrected this thread with the H-S prop idea ?



THe point is that I don't believe a "magic" propellor will really do anything for a 1942 Allison engine.



Elvis said:


> .In case you're not following, I was referring to the -45 version, when I quoted the 1325HP figure.



Oh, I am following , but could somebody pease explain to me why this magic propellor would increase the performance of the P-40 so much over just using a -73 Allison of 1325HP for takeoff as used in the P-40K? Granted it does tend to top out at around 12,000ft instead of the 21,000ft of the -45.



Elvis said:


> .As for the P-M HP rating, I believe that figure is take-off power for the -7 engine, used in the P-51D.
> While I've seen a numvber of figures bantered about over the years, this one seems to keep coming up, from various sources.


It maybe and it might not be, but the real point is that by the time the -7 Merlin showed up most military engines had a WER rating that was at least several hundred HP above the take off rating. Propellors were being fitted to get the most from this WER rating. The AAF was a little late getting into the WER game and didn't allow over boosting officially until sometime in 1942, WHile it might (or was) done at squadron level it means the AAF wasn't buying propellors fo HP ratings the engines weren't supposed to reach.
Propellors are also designed for the altititude at which they are going to work. Propellors for high altitude work needed more blade area for the same HP than a low altitude propellor would have. Using high altitude porpellors at low altitude might actually reduce performance. larger, heavier propellor has more drag and needs more power to rotate it in the thicker low altitude air.

By the way, the Allisons those trick propellors were going to go on in the P-38K were turbocharged engines rated at not just 1425HP for take off but 1425HP military power at 27,000ft and a WER of 1600hp. A new version of the Turbo (B-14) model was expected to give a service ceiling of 46,000ft. BOth 3 bladed 12' 6" and 4 bladed 12' 0" propellors were considered with the 4 blade version being able to utilze the power better especially as the altittude went up. These engines also used a 2;36 reduction gear to keep prop speed down.
Please note the -45 was good for 1150hp at 21,000ft. 



Elvis said:


> .The 1325HP figure for the -45 is also take-off power (granted, it was never actually installed in an airplane. Still, that is how the figure is listed and thus, how I am using it).


No arguement with that, but I will point out that the Original Merlin in the Spitfire was rated at 1030hp at 16500ft but only 880hp for take off when using 87 octane fuel. So is it an 880HP engine or a 1030HP engine? and which rating at which altitude do you think the designed the propellor for?



Elvis said:


> .Yes, I'm sure the staff at Allison were VERY busy during those years, as was everyone else, but then....this is the "_What if_ " thread.



True, it is what if. But there is the fantasy what if ( what if we had P-80s at Pearl Harbor)

and there is the "we could have done so much better if the generals in charge at the time weren't so stupid" what if's. The first is fun if a bit nonsense, the second sort of requires proving the generals actually were stupid. Or that the suggested "modifications" could actually be done in the suggested time line.
Or if the suggested modifications would actually work.

My self, I am partial to a MK II Westland Whirlwind as a what if but sticking with modified Peregrine engines and not trying to go to Merlins.


----------



## Clay_Allison (Sep 1, 2009)

Shortround6 said:


> THe point is that I don't believe a "magic" propellor will really do anything for a 1942 Allison engine.
> 
> 
> 
> ...


I still don't think you recognize that an American fighter capable of flying top cover would be an incredible asset in 1942. You keep saying that low altitude performance would have suffered, and I have no problem with that. If the P-40 could fight effectively at 20-25k feet, we could use the P-39 at low altitude just like the Russians did (to great effect).

It would not have out-turned the 109 in Africa or out climbed it, even with improved climb, but it could have out-dived it and it was still a far more durable aircraft. Flying in sufficient numbers and using good tactics (stay out of low speed turns, dive-and-zoom) the P-40 could have given excellent account of itself against the best fighters of 1942 at all altitudes.

The P-39 was great flying low altitude missions. The Russians loved it and there were several Russian Aces in it.


----------



## Shortround6 (Sep 1, 2009)

Clay_Allison said:


> I still don't think you recognize that an American fighter capable of flying top cover would be an incredible asset in 1942..



I recognize that an american fighter capable of fly top cover would have been a great asset. I also recognize that it wouldn't have been a P-40 unless you stuck a rocket engine it. or used engines and fuel from 1944. 




Clay_Allison said:


> You keep saying that low altitude performance would have suffered, and I have no problem with that. If the P-40 could fight effectively at 20-25k feet, we could use the P-39 at low altitude just like the Russians did (to great effect).



Some of the modifications propesed would have hurt performance at low altitude and yet NOT given you the hoped for performance at high altitude. Not a very good trade-off in my opinion. Lets see, pull the Merlin -1 from the P-40 F that gives 1120hp at 18,500ft and replace it with a two stage Allison of about the same weight the gives 1150hp at 21,000ft. Yeah, that extra 2,500ft of altitude is going to make all the difference when fighting 109Fs and Gs. except the Allison is longer which requires a longer nose and longer tail to balance things (both weight wise and stability wise) and this is going to add how much weight? 
Are you still planning on using the "magic" propellor? how much more that does that weigh?
of course you can still pull two of the guns to lighten it up but that tends to give up one of the P-40s historical advantages. And while the P-39 might have worked against the Germasn down low It probaly wouldn't have done much better against the Japanese that it did. Of course the Russians did tend to change a good number of their P-39s didn't they? like take the wing guns out. 



Clay_Allison said:


> It would not have out-turned the 109 in Africa or out climbed it, even with improved climb, but it could have out-dived it and it was still a far more durable aircraft. Flying in sufficient numbers and using good tactics (stay out of low speed turns, dive-and-zoom) the P-40 could have given excellent account of itself against the best fighters of 1942 at all altitudes.



Let me see if I really have this right: Can't out turn the 109, can't out climb it, can't out run it in level flight.
It can dive faster 485mph IAS for the P-40 vrs what for the 109s. Not a huge advantage. Far more durable, is that before or after you take out the armour and selfsealing tanks to lighten it up or have you given up on that idea?
What are sufficient numbers? Given Sufficient numbers(like outnumbering the 109s 10 to 1) and using appropriate tactics quite a few aircraft could have given a good acount of themselves. 
Plese refrain from the hyperbole, it does your arguement no good. "...the P-40 could have given excellent account of itself against the best fighters of 1942 at all altitudes"

Really. it is better than Spitfires and FW 190s? and at all altitudes? Or some of these Russian planes like the LA-5s Or better at 30,000ft than a P-38? 



Clay_Allison said:


> The P-39 was great flying low altitude missions. The Russians loved it and there were several Russian Aces in it.


There Russian aces that flew I-16s, There might even have been 1 or 2 that flew I-153s
I am not sure what Russian use of P-39s really has to do with how practical or effective your proposed modifications to the P-40 are.


----------



## Clay_Allison (Sep 1, 2009)

> Some of the modifications propesed would have hurt performance at low altitude and yet NOT given you the hoped for performance at high altitude. Not a very good trade-off in my opinion. Lets see, pull the *Merlin -1* from the P-40 F that gives 1120hp at 18,500ft and replace it with a two stage Allison of about the same weight the gives 1150hp at 21,000ft. Yeah, that extra 2,500ft of altitude is going to make all the difference when fighting 109Fs and Gs. except the Allison is longer which requires a longer nose and longer tail to balance things (both weight wise and stability wise) and this is going to add how much weight?
> Are you still planning on using the "magic" propellor? how much more that does that weigh?
> of course you can still pull two of the guns to lighten it up but that tends to give up one of the P-40s historical advantages. And while the P-39 might have worked against the Germasn down low It probaly wouldn't have done much better against the Japanese that it did. Of course the Russians did tend to change a good number of their P-39s didn't they? like take the wing guns out.



If Merlins were available in sufficient quantity to supply the P-40 I'd have had no need to start this thread or chatter about Allisons with different dash #s. 

I think that with a few small improvements, the P-40F was good enough. 

The Allison -45 or -47 would be instead of the Allison -39. 

Thanks for the idea, I just found a way that enough Merlins could have been made available.



wikipedia said:


> In June 1940, Henry Ford had offered to manufacture 1,000 aircraft a day if the Government would let him do it his way, and during a discussion with Secretary of the Treasury Henry Morgenthau Jr. regarding what the Ford company might produce, Ford's son Edsel tentatively agreed to make 6,000 Rolls-Royce liquid-cooled engines for Great Britain and 3,000 for the U.S.[2] However, at the beginning of July Henry Ford stated that he would manufacture only for Defense, not for Britain, and the entire deal was declared off. Members of the Defense Advisory Commission subsequently began negotiations with other manufacturers in an effort to place the $130,000,000 Rolls-Royce order,[2] and Packard Motor Car Company was eventually chosen because the parent British company was impressed by its attention to high-quality engineering. Agreement was reached in September 1940, and the first Packard-built engine, designated V-1650-1, ran in August 1941.[3]



Play nice with Ford, have Packard build for England and Ford build for the U.S. and we have Merlins a-plenty.


----------



## Shortround6 (Sep 2, 2009)

Part of the deal with Packard was that the US was to get 1/3 of Packards production. 

The order books for Allsion in Oct of 1940 show 4315 engines on ordered under French and British contracts with the Air Corps having another 1050 on order.
Orders at Packard were for 6,000 engines for the British and 3,000 for US. 

By Sept of 1940 the US goverment had given over 14 million to Ford to build a New plant to make R-2800s. Starting from a plot of bare ground Ford deliverd the first production engine in about a year and finished 1941 by delivering 264 engines. Ford went on to build 6403 R-2800s in 1942.
Packard managed to deliver 49 Merlins in 1941 but put out 7251 Merlins in 1942. 
First P-40F was delivered in Jan of 1942. 
I really doubt having ford build Merlins would have gotton that many more engines much sooner and since Ford built over 57,000 R-2800s by the end of the war I think they did their bit. By the way production peaked in July 1944 1944 at 186 engine per day. 
US actually wound up with more Merlins than it knew what to do with which is one reason why the Merlin P-38 idea was brought up three times. 

Could a better P-40 have been made, Probably, but not in time to much good in 1942 and by the end of 1942 the P-40 had had it's day and was being used as a cheap fighter to supply our allies with under lend lease.


----------



## Clay_Allison (Sep 2, 2009)

Shortround6 said:


> Part of the deal with Packard was that the US was to get 1/3 of Packards production.
> 
> The order books for Allsion in Oct of 1940 show 4315 engines on ordered under French and British contracts with the Air Corps having another 1050 on order.
> Orders at Packard were for 6,000 engines for the British and 3,000 for US.
> ...


Ford building R-2800s explains why the R-2800 never seemed to be in short supply.

So, if they negotiated the Packard deal in September 1939 (immediately following the invasion) instead of September 1940, the P-40F would have been available in January 1942. 

It would have been eclipsed by the Mustang even earlier since the availability of Merlin Engines in quantity would possibly have led to the Mustang A being Merlin equipped form the beginning.


----------



## Shortround6 (Sep 2, 2009)

R-2800s were also built by Chevrolet (over 4,200), A special P&W plant in Kansas City (over 8,000) and Nash (just under 17,00).

Your time line might work except for a couple of details. In 1939 the Merlin MK XX (or Merlin 28 or -1) didn't exist as anywhere near a production engine. The MK X did. So you had a choice of either a single speed, single stage Merlin or a single stage two speed Merlin, niether of which showed that much more potential than the Allison. The Single speed Merlin is rated at 880HP for take off compared to 1040 hp for the Allison. 

British sign contract for Mustang on May 29 1940.
"Ford announcement of "1000 planes a day" take place end of May/ Early June and falls through in days. 
A Merlin "pattern engine" is in the US in the middle of June.
Packard is approached June 24, and starts work June 27 using Drawing that originally had been sent to Ford but it is not until Sept 13 1940 that the Formal contracts are completed. This might delay your time line by 2 1/2 months. Intial contract is for 6000 two speed single stage Merlins for the UK and 3,000 engines for th US. 

US 1939-40 contracts for the P-40 were for 524 airplanes on April 26,1939. THe first 134 planes were paid for using FY-39 funds while the remaining aircraft (66 P-40s, 22 P-40Ds, 301 P-40Es) are paid for with FY-40 funds. The D-s and Es aren't delivered until mid/late 1941 becasue of delays in the F series engines. 131 P-40Bs and 193 P-40Cs are purchased using FY-41 funds as an interim measure. These were delivered in early 1941 before the D/E models. Army purchases first 5 -39 Allisons Jan 27 1940. they must have recieved a proposal for the engine sometime before that. 

As a note to US opinion of the time, in May of 1941 the U.S. Office of Production Management told Gen. Echols, Cheif of the Material Division that "the Merlin engine borders so closely on obsolescence that it would not be econimical to spend time and money trying to improve it.... "

Late 1939 through 1941 was a great period of confusion on fuel. British were switching from 87 octane to 100 octane. Americans already used A 100octane fuel. Problem was that British 100 octane wasn't the same as American 100 octane. THe Americans had no requirement for rich mixture performance and specified a different chemical composition of the fuel. THis ment you could not use the same rich mixture maximium manifold pressure using the two different fuels. A real problem trying to develop service engines. It was found that British fuel actualy acted like 120-125 octane (or performance number) depending on batch. At least one batch of American fuel reportedly tested 100 octane lean and under 100 octane under rich conditions. Americans started specifing their fuel to a 100/125 standard while the British went for a 100/130 standard which the Americans later adopted. This took until vary late 1941 if not some time into 1942 to sort out. 

While the Production planners in the US could decide on making R-2800s (or other engines) fairly early on and start planning on factories to make the engines the actual specifications for the engines were a little more in doubt as fuel situation was changing so fast. It was found that the liquid cooled engines would tolerate much higher boost pressures than the aircooled engines would. 

I don't think the P-40F was going to be available much before it was without a lot more happening than just talking to Packard in 1939. While the P-40F was better than the E and early models it still didn't compete very well with the 109. It was just too large and heavy for the available power.


----------



## Clay_Allison (Sep 2, 2009)

What about a hydraulic barometer-controlled supercharger drive like the 109? How difficult would hat have been to get for the Allison? Combined with a slightly larger single stage impeller and air to air inter-cooling should get it up a bit higher. The more efficient drive should partially compensate for the power loss from driving a larger blower. If you don't go to two stage you should only be adding about as much weight as you'd save by switching to 2x20mm cannon over the 6x.50 MG.


----------



## Elvis (Sep 3, 2009)

Sorry to intrude on the current discussion, but I felt that I had to post a retort.
Respond, don't respond, its not important right now. I just feel that the below quote needs to be addressed.

The post in question...



Shortround6 said:


> THe point is that I don't believe a "magic" propellor will really do anything for a 1942 Allison engine.
> 
> 
> 
> ...



My response...

_Shortround6, 

It seems you either completely misread my post or am intentionally responding in a way to sway the discussion in a way it was not intended. I don't know which, but you've done this before, so I'm becoming a little suspect of your actions.
In your response (quoted above) you go on about Merlin engines, but my only purpose for bringing up the Merlin is to show that the -45 Allison engine had enough ponies to use the version of the H-S prop I mentioned.
...and I understand what Clay was getting at, by mentioning the P-39.
The point here is that the P-51 never exists in the first place (or comes along much later than it actually did) because N.A. went ahead and built those P-40's for the British, instead of what really happened.
THUS, the P-39, with its big 37mm gun, becomes the Ground Attack / Bomber interceptor and the P-40 is then further developed into the Fighter interceptor / Bomber escort.
This is why I'm so keen on a combination of the IA version of the -45 engine and that H-S prop.
Because the idea IS to make the P-40 into a better high altitude fighter and the engine dates closest to a time period when that development work was being done (although I'd like it better a year or two earlier). 


Elvis_



Thank you for the space to post it, please continue on with your current discussion.


----------



## Elvis (Sep 3, 2009)

ClayAllison said:


> It would not have out-turned the 109 in Africa...


Actually, not exactly true.
I have some video I copped off the TV about an Aussie pilot named Col Paye who collected and restroed warbirds.
The particular show I have dealt with a P-40 he found buried in Canada.
During the show, they interviewd a WWII Australian fighter pilot name Billy Gibbs, who (IIRC) was on hand when the P-40 was first rolled out and test flown, after the restoration was complete.
Gibbs himself said that the P-40 could out turn both the Spitfire and the 109....and he should know. He logged a bit of time in all 3 of those planes.



Elvis


----------



## Shortround6 (Sep 3, 2009)

Clay_Allison said:


> What about a hydraulic barometer-controlled supercharger drive like the 109? How difficult would hat have been to get for the Allison? Combined with a slightly larger single stage impeller and air to air inter-cooling should get it up a bit higher. The more efficient drive should partially compensate for the power loss from driving a larger blower. If you don't go to two stage you should only be adding about as much weight as you'd save by switching to 2x20mm cannon over the 6x.50 MG.



It won't do a thing for altitude performance. 
a. it isn't more efficient than a gear drive in regards to power transmission. It will use more power to drive than a gear setup.
b. a larger supercharger of the same design will give you more volume of air but not more pressure. 
c. the intercooler will help total power but won't actually change critical altitude much. The Jumo 211 was just about the ONLY engine ever to use an intercooler on a single stage engine. They add weight,bulk and drag and were ussually figured as not worth the actual HP improvement on single engine fighter aircraft. 
d. Allison did use just about the same set up ( hydraulic) to drive the Auxilery stage of all their mechanical two-stage engines. 
e.German engines used either 1.3 ata of pressure to make rated power or 1.42ata. The Merlin MK III used 1.423 ata. the Allison needed 1.48 ata to make 1150hp. The same design (pressure ratio) supercharger will always give the German engine a slightly higher critical altitude. 
f. futzing about with guns will not solve the P-40s problem. The XP-40 prototype weighed 6,260lbs loaded with no armour or self sealing tanks, only 100 US gallons of fuel on board and a pair of .50cal guns with 200rpg. A Bf-109F-4 weighed 6,393lbs according to one source. The 109 is just going to have a better power to weight ratio no matter what is done to the P-40. The P-40C had an empty equiped weight of 5,812lbs. Put in a pilot, 600lbs of fuel (100 US gallons) and ammo and see what happens.


----------



## vikingBerserker (Sep 3, 2009)

I have to disagree 

According to _Combat Aircraft of WWII_ by Bookthrift, the P-40F had a better power/weight ratio then the Me 109G

Lt James E. Reed of the 33rd Fighter Group mentions that he could outurn a Me 109 in his P-40


----------



## Vincenzo (Sep 3, 2009)

vikingBerserker said:


> I have to disagree
> 
> According to _Combat Aircraft of WWII_ by Bookthrift, the P-40F had a better power/weight ratio then the Me 109G
> 
> Lt James E. Reed of the 33rd Fighter Group mentions that he could outurn a Me 109 in his P-40



The engine of P-40F it's less power of that Bf 109 G, The P-40F it's heaviest of 109 G, don't true at all you read


----------



## Shortround6 (Sep 3, 2009)

Elvis said:


> Sorry to intrude on the current discussion, but I felt that I had to post a retort.
> Respond, don't respond, its not important right now. I just feel that the below quote needs to be addressed.
> 
> The post in question...
> ...



I am sorry you feel that way. I admit to having a tendency to ramble. 

The point as to the Merlins was that quoting take-off power, while useful somtimes for identifing the model of the engine, doesn't always relate to the actual design requirements of the propellor. I had hoped that was clearer.

The -45 engine was rated at 1325HP at sea level, 1150hp at 21,000ft. 
The Merlin question (-7) was rated at 1720HP WER at 6,200ft and 1505 HP WER at 19.300ft. roughly 30% more power than the -45 Allison. I can see where it needed an extra blade for more area. 
THe P-38K that used the big prop was rated at 1425Hp at 27,000ft (air about 1/3 as dense as sea level) and 1600hp at WER. I can see where fitting the big prop to those engines would increase performance over a propellor designed for 1300-1100hp at sea level/27000ft. 
what I don't see is how the bigger propellor increases performance on the lower HP engine.

I thought I had gone over that in the original post. Please show me that I am wrong about this if you feel that the H-S prop would over a significant advantage. Can you come up with any performance figures just from a propellor swap and not trying to compare plane with a Paddle bladed prop that has 10-30% more power at the same time to a lower powered plane without the paddle blades.

I am glad you know what Clay was getting at when he brought in the P-39 because I didn't have a clue.
I have no idea of what the russians thought about the P-39 has to do with the altitude performace of the P-40, either real or fantasy. Unless his proposed modifications to the P-40 make it unusable at the lower altitudes something like a MiG-3? Strange that the German 109s didn't have this problem. or the Spitfires or the P-51. Their performance did change with altitude but they didn't REQUIRE a second fighter to cover that part of the sky for them.

You can make the P-40 a better fighter in the 20,000-25,000 ft area than it was. the question is can you make enough better to actually make a big difference.

Edit> lets take a hypothetical situation. Say at a certain altitude the Bf-109 has a climb rate twice that of the P-40 (normal) and due to the proposed modifications you increase the climb rate at that altitude by 50%. That is a considerable increase in performance and yet you are climbing only 75% as fast as the 109 (or the 109 is still 33% better). Has your improvement really altered the relation ship between the two aircraft or changed the tatics that each would use in combating the other?
This is the real question. Can you improve the P-40 ENOUGH to make a substantial difference in performance, ENOUGH to enable P-40 to change how it fights the 109?
If all you have done is reduce the time it takes for a P-40 to dive on a target and past it and then climb back up to attack altitude from say 10 minutes to 6 minutes have you really changed much of anything? THe improvement looks very good on paper (and it is) but if the target just continues to fly straight and level at even 300mph it will be several miles away by the time the P-40 is back at attack altitude. The only advantage you have gained is the ability to get into attack position (the first and maybe only time) a bit quicker. Say your squadron is flying at XXX height and is radioed that attackers are coming in at height YYY from direction ZZZ and are QQ miles out. THe "improved" planes might have the performance to climb to attack position before the attackers pass them when regular P-40s might not.< end edit.


----------



## Clay_Allison (Sep 3, 2009)

> I have no idea of what the russians thought about the P-39 has to do with the altitude performace of the P-40, either real or fantasy.* Unless his proposed modifications to the P-40 make it unusable at the lower altitudes something like a MiG-3? *



That's what I was talking about exactly, if the modifications for higher altitude performance make it less effective at low altitude (like the MiG-3) then the P-39 could fill in the gap lower down.


----------



## Elvis (Sep 5, 2009)

Shortround6 said:


> The point as to the Merlins was that quoting take-off power, while useful somtimes for identifing the model of the engine, doesn't always relate to the actual design requirements of the propellor. I had hoped that was clearer.
> The -45 engine was rated at 1325HP at sea level, 1150hp at 21,000ft.
> The Merlin question (-7) was rated at 1720HP WER at 6,200ft and 1505 HP WER at 19.300ft. roughly 30% more power than the -45 Allison. I can see where it needed an extra blade for more area.
> THe P-38K that used the big prop was rated at 1425Hp at 27,000ft (air about 1/3 as dense as sea level) and 1600hp at WER. I can see where fitting the big prop to those engines would increase performance over a propellor designed for 1300-1100hp at sea level/27000ft.
> what I don't see is how the bigger propellor increases performance on the lower HP engine.


Ok, this is a two-fold question, so let me address the "Horsepower" issue, first.
By quoting the take-off power of both engines, that gives one a better standard to compare them by.
You seem to insist on using the take-off power rating for the -45 Allison, but then quote WEP ratings for the -7 PM engine.
How can one come to any kind of logical conclusion using such different ratings?
Keep the power rating TYPE ("take-off", "[email protected] listed altitude", "War Emergency Power", etc.) the same when comparing the power of different engines.
Otherwise, you are doomed to draw incorrect conclusions.
Now then, lets address your concerns about the prop...
Yes, by quoting take-off power, I'm not addressing the design requirement of the new propeller. They were the only relative HP figures I had on hand, at the time I made my post.
I don't have the HP figures for a V-1650-7 @22400ft., but I should see if I can't locate them. 
That _would_ relate the power figures for those engines closer to the design of the prop.
However, you seem to have forgotten that I was excited, not about the Hamilton Standard prop as you say it existed, but that prop _sized and configured the same as the Curtiss-Electric prop that was already on the airplane_" (i.e., 3 [email protected]' dia., not 4 [email protected]' dia.).
So what difference does that make? It gives the engine a managably sized propeller that is better suited for high altitude work, due to the difference in the design of the blades.
Since the point here is to make the P-40 a _better_ high altitude fighter plane, then switching the C-E prop to the H-S prop would be a step in the right directioin.


Shortround6 said:


> I am glad you know what Clay was getting at when he brought in the P-39 because I didn't have a clue.
> I have no idea of what the russians thought about the P-39 has to do with the altitude performace of the P-40, either real or fantasy. Unless his proposed modifications to the P-40 make it unusable at the lower altitudes something like a MiG-3? Strange that the German 109s didn't have this problem. or the Spitfires or the P-51. Their performance did change with altitude but they didn't REQUIRE a second fighter to cover that part of the sky for them.


Although Clay addressed this point, as well, in a separate post, here's something else to think about...
Why was the USAAF so keen on making the P-40 work at an altitude 1/2 of what most of the more prominent axis fighters were capable of working at?
Doesn't that seem like a fruitless design element?
NOW, ask yourself this question - _What flies in the range of 10,000 to 15,000 feet on such a regular basis, and is considered such a threat, that it is felt that one needs to design an interceptor to counter it?_
Answer that question and you answer your own question about the need for a second interceptor (or "fighter", if you wanna call it that).


Shortround6 said:


> You can make the P-40 a better fighter in the 20,000-25,000 ft area than it was. the question is can you make enough better to actually make a big difference.


  BY GEORGE, I THINK HE'S FINALLY GOT IT!
Considering the performance of the P-40's that existed in the first half of the war, YES, I actually think that utilizing a combination of an IA -45 Allison and a H-S "hi efficiency" prop of the same diameter and configuration of the C-E prop it would replace, will actually make it a better high altitude fighter, AND, by a great margin over the -33 and -39 Allisons that were installed in that plane, in those days.
If I didn't think it would work, I wouldn't have ever brought it up.
Even if it ends up not having superior performance figures (or even ones that match) versus the 109's of the time, _IT WOULD STILL GIVE THE PLANE BETTER HIGH ALTITUDE PERFORMANCE_, compared to how it was configured (and I'm not saying that it _won't_ have superior performance to the 109).
Combine this aspect with the P-40's increased maneuverability over the 109 and now we're fielding a much more "serious" adversary than before.



Elvis


----------



## Elvis (Sep 5, 2009)

Shortround6 said:


> The -45 engine was rated at 1325HP at sea level, *1150hp at 21,000ft.*


Actually, its 1150HP @ 3000RPM @ *22400ft.*.

...you were close, though. 


Elvis


----------



## Clay_Allison (Sep 5, 2009)

> Although Clay addressed this point, as well, in a separate post, here's something else to think about...
> Why was the USAAF so keen on making the P-40 work at an altitude 1/2 of what most of the more prominent axis fighters were capable of working at?
> Doesn't that seem like a fruitless design element?
> NOW, ask yourself this question - What flies in the range of 10,000 to 15,000 feet on such a regular basis, and is considered such a threat, that it is felt that one needs to design an interceptor to counter it?
> Answer that question and you answer your own question about the need for a second interceptor (or "fighter", if you wanna call it that).



Since he's being cryptic, information from the defeat of Poland and the battle of France was portraying the Ju-87 Stuka as a terrifying weapon and the army was horrified by the prospect of precision dive bombers wrecking their ground forces. They thought that turbocharged aircraft would be available to provide top cover but in hindsight that didn't materialize for a year. 

The P-39 proved brutally effective in intercepting Ju-87s for the Russians. It would have been a good "second fighter" in the exact same role (and in escorting our own small bombers like the A-20 B-25).


----------



## Shortround6 (Sep 5, 2009)

Elvis said:


> Ok, this is a two-fold question, so let me address the "Horsepower" issue, first.
> By quoting the take-off power of both engines, that gives one a better standard to compare them by.
> You seem to insist on using the take-off power rating for the -45 Allison, but then quote WEP ratings for the -7 PM engine.
> How can one come to any kind of logical conclusion using such different ratings?.



Except for one little fact.
The -45 Allison never recieved a WEP rating so,
A. I can't quote a rating that never existed.
b. what was the point of fitting a prop for a power rating that didn't exist?




Elvis said:


> Keep the power rating TYPE ("take-off", "[email protected] listed altitude", "War Emergency Power", etc.) the same when comparing the power of different engines.
> Otherwise, you are doomed to draw incorrect conclusions.


 Yes, that is true but you can also draw incorrect conclusions if an engine has a different power limitation than another engine. Merlins often had a lower take-off rating than their Max power rating. 
Many American engines (but not all) Used a take-off rating that was equel to or higher than their altitude ratings. 

I will agree that the lower powered -45 might only need a 3 bladed prop.



Elvis said:


> Now then, lets address your concerns about the prop...
> Yes, by quoting take-off power, I'm not addressing the design requirement of the new propeller. They were the only relative HP figures I had on hand, at the time I made my post.
> I don't have the HP figures for a V-1650-7 @22400ft., but I should see if I can't locate them.
> That _would_ relate the power figures for those engines closer to the design of the prop.
> ...



If you were using the best figures you had available to you when you made your post, you were IMHO, making an honest atempt to present your case and I am sorry if I came across as too arguementative.

But if those figures turned out to give a wrong conclusion becasue they didn't adress the actual problem/situation wouldn't you want to be supplied with better information? 

I will agree that the lower powered -45 might only need a 3 bladed prop.



Elvis said:


> Although Clay addressed this point, as well, in a separate post, here's something else to think about...
> Why was the USAAF so keen on making the P-40 work at an altitude 1/2 of what most of the more prominent axis fighters were capable of working at?
> Doesn't that seem like a fruitless design element?
> NOW, ask yourself this question - _What flies in the range of 10,000 to 15,000 feet on such a regular basis, and is considered such a threat, that it is felt that one needs to design an interceptor to counter it?_
> Answer that question and you answer your own question about the need for a second interceptor (or "fighter", if you wanna call it that).



Was the USAAF really "so keen on making the P-40 work at an altitude 1/2 of what most of the more prominent axis fighters were capable of working at?

Can anybody please point out a reference says the USAAF was TRYING to make the P-40 be LESS capable than it was?
Statements that they took out the turbo or other such nonsense will be ignored. 
The AAF needed modern fighters in 1939. It needed a lot of them and it needed them fast. The turbo wasn't quite ready for operational use and the only 2 stage mechanical supercharger even remotely ready for production aircraft was the P&W one. This supercharger on the R-1830 offered 1200HP for take-off and 1050hp at 17,500ft in one of it's early versions and 1200hp for take off and 1000hp at 19,000 in the later Navy versions. For comparison the R-1830 used in the Early P-43 with it's not quite ready turbo offered 1200 for take-off and 1100hp normal at 20,000ft with 1200hp Military at 20,000ft. later versions raised the HP altitudes to 25,000ft. 
Please note that the HP figures for the P&W 1830 with two stage supercharger aren't really much better than the power figures for Merlin MK X two speed single stage engine announced at the Paris air show in 1938.
SO what REAL choice did the AAF have?
They could have used an Allison with a higher geared supercharger like the Merlin III, and probably have gotton over 1000hp at 17,000ft or so but only at the cost of loosing 100-150hp for take-off which the heavier P-40 couldn't afford as well as the Spitfire.
They could have insisted on a two speed gear box which wuld have solved the take-off power problem but not changed things at over 20,000 ft by very much. 
What else was ready to go in 1939-early 1940? 
If you want aircraft that will be in squadron service over seas in the spring of the 1942 you better have DECIDED on the plane, engine and other bits in the spring of 1940. The P-47B proposal was given to the AAF in June of 1940 as a scale of timing. It took them a few months to actualy decide. in another attempt to "SKEW" the thread I will point out that Republic had a letter of intent for over 900 P-44s in Sept of 1940 so combining that with the P-38 I don't think that the AAF was deliberately ignoring the 20,000ft and up part of the sky. If you think different please post a reference. 



Elvis said:


> idea:  BY GEORGE, I THINK HE'S FINALLY GOT IT!



Please show me where I didn't "have It". What post/s and threads?

Saying that the P-40 couldn't have been improved at all and saying it wouldn't have been worthwhile are not the same thing. 


Elvis said:


> Considering the performance of the P-40's that existed in the first half of the war, YES, I actually think that utilizing a combination of an IA -45 Allison and a H-S "hi efficiency" prop of the same diameter and configuration of the C-E prop it would replace, will actually make it a better high altitude fighter, AND, by a great margin over the -33 and -39 Allisons that were installed in that plane, in those days.
> If I didn't think it would work, I wouldn't have ever brought it up.
> Even if it ends up not having superior performance figures (or even ones that match) versus the 109's of the time, _IT WOULD STILL GIVE THE PLANE BETTER HIGH ALTITUDE PERFORMANCE_, compared to how it was configured (and I'm not saying that it _won't_ have superior performance to the 109).
> Combine this aspect with the P-40's increased maneuverability over the 109 and now we're fielding a much more "serious" adversary than before.



Care to share with us how you come up with these perfomance estimates?

THe flight manuals for the P-40D/E, P-40F/L and P-40N and maybe others are on this web site. 
If you haven't yet perhaps you would like to look them up and see what the climb rates were between some of the models. Try the lighter weight climb charts at 20,000 and 25,000ft but be aware these may have been done at normal or maximum continous power rather than military power, except possiably in the case of the N model. Then compare them to Spitfire MK V time to climbs or fpm climb ratings at various altitudes and also try to get numbers for the 109F and G. 

How much improvement are you going to need to match a Spitfire MK V or a 109 F or G?

A few hundred FPM climb won't cut it. Even 1000fpm of extra climb won't equel those fighters. 

Can you get better performance than a P-40E, undoubtably.
Can you get better performance than a P-40F/L or N? quite probably.
Can you make a P-40 equel to even a MKV Spitfire? Now we are getting doubtful.
Can you make the P-40 equel to a 109 F-4 or G? Not in climb. or top speed.

It odes have advantages though and you might have to give up some of them in your attempt to turn the plane into a 20-25,000ft air superiority fighter.


----------



## Shortround6 (Sep 5, 2009)

Elvis said:


> Actually, its 1150HP @ 3000RPM @ *22400ft.*.
> 
> ...you were close, though.
> 
> ...



Care to identify your source?

And if it is :http://www.enginehistory.org/ModDesig/I2 9.tif

Tell me when I can stop laughing.

If it is something else perhaps we can discuss it and I might be wrong.


----------



## Shortround6 (Sep 5, 2009)

Clay_Allison said:


> Since he's being cryptic, information from the defeat of Poland and the battle of France was portraying the Ju-87 Stuka as a terrifying weapon and the army was horrified by the prospect of precision dive bombers wrecking their ground forces. They thought that turbocharged aircraft would be available to provide top cover but in hindsight that didn't materialize for a year.
> 
> The P-39 proved brutally effective in intercepting Ju-87s for the Russians. It would have been a good "second fighter" in the exact same role (and in escorting our own small bombers like the A-20 B-25).



Thank you Clay. But I am not sure that is right. I am not sure that is is wrong either.
From Information in the "Vee's for Victory" book it is claimed that the AAF ordered 524 P-40s on April 26,1939. These were to be 134 planes to be paid for with FY 39 funds and a further 66 P-40's, 22 P-40D's and 301 P-40E's to be paid for with FY 40 funds. Due to delays in the development of the V-1710-F3R engine (-39) (or the P-40D/E ?) An order was placed for 131 P-40Bs and 193 P-40C 's to be paid for with FY 41 funds to keep production lines open. 
If this information is correct then it means the USAAF was ordering fighters with only the knowledge of the combat results from Spain and not Europe. This information my not be correct in which case you could be right. 
Of Course this information only applies to these first batches of aircraft and not to any follow up batches of P-40 E's or K's ( I would consider the F's an attempt to improve the altitude performance of the P-40) which may very well have been ordered in line with reaon you put forward.


----------



## Clay_Allison (Sep 6, 2009)

Shortround6 said:


> Thank you Clay. But I am not sure that is right. I am not sure that is is wrong either.
> From Information in the "Vee's for Victory" book it is claimed that the AAF ordered 524 P-40s on April 26,1939. These were to be 134 planes to be paid for with FY 39 funds and a further 66 P-40's, 22 P-40D's and 301 P-40E's to be paid for with FY 40 funds. Due to delays in the development of the V-1710-F3R engine (-39) (or the P-40D/E ?) An order was placed for 131 P-40Bs and 193 P-40C 's to be paid for with FY 41 funds to keep production lines open.
> If this information is correct then it means the USAAF was ordering fighters with only the knowledge of the combat results from Spain and not Europe. This information my not be correct in which case you could be right.
> Of Course this information only applies to these first batches of aircraft and not to any follow up batches of P-40 E's or K's ( I would consider the F's an attempt to improve the altitude performance of the P-40) which may very well have been ordered in line with reaon you put forward.


For the orders you are referring to, you are definitely right, but I have read elsewhere that the Army was resistant to changes that could have been added to the D/E (I.E. a Supercharger with a higher critical altitude rating) during that delay. I'm sorry I can't provide source, I was sitting in a bookstore reading a book for free when I read that and I don't remember the title.

I also don't know how much high-altitude fighting happened in Spain. I doubt that 1936 Bf 109s and I-16s were capable of fighting any higher than 15k feet.


----------



## Elvis (Sep 10, 2009)

..._and still, he continues to argue_...

Alright, whatever, Shortround.
Just a couple of things I wanted to address from your last post to me...

1) Apology accepted

2)


Shortround6 said:


> Was the USAAF really "so keen on making the P-40 work at an altitude 1/2 of what most of the more prominent axis fighters were capable of working at?
> Can anybody please point out a reference says the USAAF was TRYING to make the P-40 be LESS capable than it was?


I never stated that the USAAF was trying to make the plane less capable than what it was. 
See? this is what I'm getting at about you "skewing" posts. You state your reply in such a way that makes it _seem_ relative to the post, but actually, all you're doing is fanning the flames of an argument.
If I didn't know better, I'd swear you were a lawyer.
Second of all, YES, the USAAF was _keen_ on making the P-40 work at an altitude 1/2 of what most of the more prominent axis fighters were capable of.
...and if you require a quote and a link, here's what our own "JoeB" has to say on that subject.

From his website...


Joe Baugher's XP-40 page said:


> The P-40 was already obsolete by European standards even before the first prototype flew, and it never did catch up. Its initial inadequacies, in the form of low firepower and lack of self-sealing fuel tanks or armor, *were a reflection of mid-'thirties USAAC requirements. The P-40 had been developed basically as a low-altitude close-support fighter under mid-1930s US tactical concepts which envisaged more need for low-level ground support operations than for high-altitude interceptions.* Low-altitude performance and rugged construction received priority over high-altitude capabilities. The military doctrine of the "ascendancy of bombardment over pursuit" was dominant in 1937 when the P-40 first appeared. This doctrine assumed that the prospect of high-altitude enemy air attack on the USA was extremely remote, with coastal defense and ground attack in the defense of US territory being seen as the main tasks for any future fighter aircraft.



...and I'm sure that won't be good enough for you, so if you need validation on the information, its all listed at the bottom of the page the link goes to.

For the record, I believe the P-40 could have been made into a much more formidible opponent for the Me-109 (and, to some degree, the A6M "Zero") had the plane been fitted with an IA version of the -45 Allison engine, coupled with a "properly sized" version of the Hamilton-Standard "Hi-Efficiency" propeller.
You seem to think otherwise, and that's ok, but this is the premise I am standing behind.



Elvis


----------



## Elvis (Sep 10, 2009)

Shortround6 said:


> Care to identify your source?
> 
> And if it is :http://www.enginehistory.org/ModDesig/I2 9.tif
> 
> ...


Glad I could make your day, although I fail to see the humor.
I did get that information from Engine History's Model Designation page, however, I don't know if your link is exactly the page I found it on.
I'm on dial-up and its pretty slow out here. The link you posted never did load up for me.



Elvis


----------



## Shortround6 (Sep 10, 2009)

Elvis said:


> ..._and still, he continues to argue_...



Yes I will continue to argue with things that I think are wrong. 
Unless somebody can come up with evidence to support their position and prove mine wrong.




Elvis said:


> I never stated that the USAAF was trying to make the plane less capable than what it was.
> 
> Second of all, YES, the USAAF was _keen_ on making the P-40 work at an altitude 1/2 of what most of the more prominent axis fighters were capable of.



Which is it?

Keen-----6. enthusiastic: eager and willing to do something
not very keen on the idea

1. in the late 30s there was ONLY ONE axis fighter that could work at the altitudes you are talking about.
2. From Joe Baugher's XP-40 page ;

"Realizing that the radial-engined P-36A was at the limit of its development, Curtiss designer Donovan Berlin got USAAC permission in July 1937 to install a 1150 hp Allison V-1710-19 liquid-cooled engine with integral supercharging in the 10th P-36A (Serial No 38-10). This project was given the company designation of Model 75P, and the USAAC gave the project a new fighter designation, XP-40." 

isn't July of 1937 the first time a DB engined 109 is revealed to the west? two prototypes at an air meet? Production models don't show up for over another year. Granted this is well ahead of the P-40s time schedule but how much faster could the P-40 have been made?
3. The Allison engine doesn't pass a 150hr type test until April of 1937 and this is at 1000hp. 
4. The version of the Allison chosen to power the P40 uses the highest supercharger drive gear available (8.77 to 1) meaning it gives the highest critical altitude. Later engines did use a 9.60 gear ratio but that required a redesigned supercharger drive using wider gears to handle the increase load. 


or is this skewing the posts? 



Elvis said:


> From his website...
> 
> 
> ...and I'm sure that won't be good enough for you, so if you need validation on the information, its all listed at the bottom of the page the link goes to.:



You are right. it isn't good enough for me. While I don't have all those books I do have some of them.
I do have some questions about this therory that the P-40 was so far behind. 
1. At the time it first flew NOBODY was using armour or self sealing tanks. that they weren't installed on production models isn't quite the same question. 
2. for a "close support fighter" the P-40 was horribly ill equipped. 
even the P-26 Pea Shooter was equipped with bomb racks for 200lbs of bombs.
The P-35 had bomb racks.
Some Hawk 75 (P-36 airframe) models had bomb racks and yet this 'close support fighter' is provided with racks for only six 20lb bombs. About 1/3 of what the P-35 could carry.
THe USAAF already a number of 'Attack' planes that mounted two .30cal MGs in each wing so wing mounted guns isn't a new or untested idea. Sticking with two slow firing .50 cal Mg with only 200rpg (prototype) for a ground straffing aircraft doesn't seem to make sense. 
3. Even if the P-40 couldn't match the 109's altitude in 1938-40 the likelyhood of a 109 reaching America was pretty small. What were the service ceilings of the worlds bombers in 1938-40? Or large flying boats or any other type of plane that might be expected to actually make it to America? Did the P-40 have enough performance to intercept any "likely" target?

If the P-40 can intercept any likely target that could threaten America for the next several years after it is ordered why delay ordering the P-40 while trying to come up with something even better. It is not like the USAAF had a surplus of fighters that could perforem anywhere near as well as the P-40 to tide them over until newer, better P-40s or P-38 showed up in numbers. 




Elvis said:


> For the record, I believe the P-40 could have been made into a much more formidible opponent for the Me-109 (and, to some degree, the A6M "Zero") had the plane been fitted with an IA version of the -45 Allison engine, coupled with a "properly sized" version of the Hamilton-Standard "Hi-Efficiency" propeller.
> You seem to think otherwise, and that's ok, but this is the premise I am standing behind.
> Elvis



I think I got that part. what you haven't explained is why this combination is going to perform so much better than a P-40F. I could be in error here. When I get the time I will try charting the power of the two engines and see how far apart they are in power at a few altitudes. 
I also haven't seen (or did I miss it) how an 1150 HP engine in even a 7500lb plane beats an 1100-1200hp engine in a 6100lb plane (Bf 109F-4 operating several thousand feet above critical altitude with 1/2 tank of fuel).


----------



## Shortround6 (Sep 10, 2009)

Elvis said:


> Glad I could make your day, although I fail to see the humor.
> I did get that information from Engine History's Model Designation page, however, I don't know if your link is exactly the page I found it on.
> I'm on dial-up and its pretty slow out here. The link you posted never did load up for me.
> Elvis



It should be the same.

It has been pointed out before, this document has a number of errors. It is a very useful, quick reference and can certainly point the way for further study but it should not be taken as the 'last word' in an arguement. 
IN additon to the fighter/ pursuit designation thing there are weights that are off, fuel requiements that are way off, altitudes for power ratings that are off by 10,000ft (simple typo, a 2 instead of a 1) extra digits showing up in impellor diameters and many others. 

I am not sure that any one document/book can be taken as the "last word". One does have to use a bit of judgement to see if a number is too far outside the 'norm'.


----------



## renrich (Sep 11, 2009)

I see that the effort to make a silk purse out of a sow's ear is still going on for the members of the P40 Appreciation Society. It makes for and interesting and entertaining debate and I am enjoying. Many thanks.


----------



## Elvis (Sep 11, 2009)

renrich said:


> I see that the effort to make a silk purse out of a sow's ear is still going on for the members of the P40 Appreciation Society. It makes for and interesting and entertaining debate and I am enjoying. Many thanks.


Good thing I wasn't drinking any milk or else I'd have shot it out of my nose and across the room, after reading that.
LOL! That was good Renrich.  
-------------------------------------------------------------------------------------------

Shortround6,

LOL! Whatever you wanna think is cool by me. I've stated my point. Thank you all for reading. The dinner show will start at 7:30. 



Elvis


----------



## vikingBerserker (Sep 11, 2009)

renrich said:


> I see that the effort to make a silk purse out of a sow's ear is still going on for the members of the P40 Appreciation Society. It makes for and interesting and entertaining debate and I am enjoying. Many thanks.



Ok, that was funny as hell!


----------



## renrich (Sep 19, 2009)

I think that what would make for a stimulating discussion would be to get the P40 Appreciation Society and the Brewster Buffalo Appreciation Society to have a joint meeting and decide which aircraft is most underappreciated. The winner gets the Sows Ear into the Silk Purse award.


----------



## Clay_Allison (Sep 20, 2009)

renrich said:


> I think that what would make for a stimulating discussion would be to get the P40 Appreciation Society and the Brewster Buffalo Appreciation Society to have a joint meeting and decide which aircraft is most underappreciated. The winner gets the Sows Ear into the Silk Purse award.


Too bad we didn't give any P-40s to Finland.


----------



## Elvis (Sep 21, 2009)

Clay,

They got the P-36, instead (although not from us)....and they made a winner out of that one, too. 
Would've been interesting, though, in that it seems they used their fighters differently than the Russians did.
...oh well, the Finns ended up with the 109 anyway.
I'm surprised they didn't "borrow" the J-22 from the Swedes.
Of course, that would've been 1943 and the Continuation War was almost over by then.
I think they were actually starting transfer of 109's by then anyway.
---------------------------------------------------------------------------------------------

Renrich,

That was only funny the first time.




Elvis


----------



## Elvis (Sep 22, 2009)

Sorry, just had to make the post count a nice round number.




Elvis


----------



## Clay_Allison (Sep 22, 2009)

Elvis said:


> Clay,
> 
> They got the P-36, instead (although not from us)....and they made a winner out of that one, too.
> Would've been interesting, though, in that it seems they used their fighters differently than the Russians did.
> ...


Funny thing about the J22. Why was SAAB busy building bombers? What is the point of building bombers when you don't have fighters? The fighter is the very first plane you should have except a Trainer. There would be something to be said for a small WWII country having an all-fighter air force if they were capable of producing a front line plane like the Bf-109.

Sweden should have been building the Bf 109 under license anyway, they could make back the cost of the license by building more than they needed and selling the extras to Germany and Finland.


----------



## Marshall_Stack (Sep 22, 2009)

Clay_Allison said:


> Funny thing about the J22. Why was SAAB busy building bombers? What is the point of building bombers when you don't have fighters? The fighter is the very first plane you should have except a Trainer. There would be something to be said for a small WWII country having an all-fighter air force if they were capable of producing a front line plane like the Bf-109.
> 
> Sweden should have been building the Bf 109 under license anyway, they could make back the cost of the license by building more than they needed and selling the extras to Germany and Finland.



Good point. It makes sense to have a defensive weapon ( a fighter) if you are neutral but not an offensive weapon (bomber).


----------



## Clay_Allison (Sep 22, 2009)

Marshall_Stack said:


> Good point. It makes sense to have a defensive weapon ( a fighter) if you are neutral but not an offensive weapon (bomber).


On top of that, we all know what happens to unescorted bombers.


----------



## Elvis (Sep 23, 2009)

You know, Clay, you ask some very good questions.
I never thought about that, but your question prompted some searching on the net and while I never could find a specific reason why Sweden in particular was building bombers at near "max production" levels, when they were a neutral nation, but I have to surmise that they must've been supplying somene(s) with these planes.
However, this is speculation on my part.

Anyway, I don't know if you'll find an answer to your question at this website, but I did find a "J-22 website".
Here ya' go.
...and that's an interesting article on airfoils, especially when I read this statement - "_...the overall drag of the J22 was about 20% less than the P51 Mustang..._". 

(shhhh, don't tell the Mustang freaks. You'll never hear the end of it). 



Elvis


----------



## Elvis (Sep 23, 2009)

Marshall_Stack said:


> Good point. It makes sense to have a defensive weapon ( a fighter) if you are neutral but not an offensive weapon (bomber).


Exactly.
It would make better sense to have the fighters for defense, and a large "_airliner_", that (unbeknownst to the general public) had the capacity built into the design to work equally as well as a bomber with minimal changes, during times of war.


Elvis


----------



## Clay_Allison (Sep 23, 2009)

Elvis said:


> You know, Clay, you ask some very good questions.
> I never thought about that, but your question prompted some searching on the net and while I never could find a specific reason why Sweden in particular was building bombers at near "max production" levels, when they were a neutral nation, but I have to surmise that they must've been supplying somene(s) with these planes.
> However, this is speculation on my part.
> 
> ...


Impressive, but compared to size and wing area, the Mustang was still more efficient.


----------



## Clay_Allison (Sep 23, 2009)

Imagine what the J22 could have done with a Db-605


----------



## Elvis (Sep 24, 2009)

LOL!

Oh man, here we go...AGAIN! 






Elvis


----------



## Colin1 (Sep 24, 2009)

Clay_Allison said:


> Imagine what the J22 could have done with a Db-605


Not necessarily anything spectacular
the J22 was a particularly small fighter and its turn-fight capability and combat acceleration would need to be considered by an enemy pilot; it was in the same class as early Spitfire marks and the A6M series.

It's possible that its diminutive size would be the reason why it would not be so simple as 'strapping a bigger powerplant to it'; there would probably need to be structural changes to the airframe to properly accommodate it and re-balance the fighter for the new weight at the front - strengthening and lengthening which would add to the fighter's empty weight and that's before you've even got it off the ground. Trade-off is an inescapable fact of engineering design in any field and you couldn't expect the J22 to hold on to all of its turn-fighting ability in this case.

Moving from an STWC-3G-powered J22 to a DB 605-powered J22 would move the fighter from one set of flight characteristics that the Allies learned to deal with to another set of flight characteristics that the Allies learned to deal with.

The USN learned to deal with the A6M series and the USAAF learned to deal with the Bf109 series, I don't see why the J22 would have been more difficult than either for the Allies to handle - don't engage the J22 on the J22's terms.


----------



## Clay_Allison (Sep 24, 2009)

Colin1 said:


> Not necessarily anything spectacular
> the J22 was a particularly small fighter and its turn-fight capability and combat acceleration would need to be considered by an enemy pilot; it was in the same class as early Spitfire marks and the A6M series.
> 
> It's possible that its diminutive size would be the reason why it would not be so simple as 'strapping a bigger powerplant to it'; there would probably need to be structural changes to the airframe to properly accommodate it and re-balance the fighter for the new weight at the front - strengthening and lengthening which would add to the fighter's empty weight and that's before you've even got it off the ground. Trade-off is an inescapable fact of engineering design in any field and you couldn't expect the J22 to hold on to all of its turn-fighting ability in this case.
> ...


My fighter plane philosophy has been (for a while) that you take the best powerplant you can build and strap the lightest plane you can to it. My ideas tend to follow that theme. My poiint was that a V engine would reduce the drag even further and more power wouldn't go to waste. Some pretty crazy engine swaps took place throughout the war. I don't think it's as impossible as people say.

As far as fighting the allies goes, I'd say participating in the continuation war and fighting the Russians is all it should have been limited to.


----------



## Colin1 (Sep 24, 2009)

Clay_Allison said:


> My fighter plane philosophy has been (for a while) that you take the best powerplant you can build and strap the lightest plane you can to it. My ideas tend to follow that theme. My poiint was that a V engine would reduce the drag even further and more power wouldn't go to waste. Some pretty crazy engine swaps took place throughout the war. I don't think it's as impossible as people say.
> 
> As far as fighting the allies goes, I'd say participating in the continuation war and fighting the Russians is all it should have been limited to.


The best fighter designs balanced the powerplant and airframe at the drawing board stage, shunting the Griffon into the Spitfire airframe changed the handling characteristics significantly. There are examples where it succeeded beyond expectation and the transition from Allison Mustang to Merlin Mustang is a prime example.

Most of your diatribe previously in the thread compared the J22 with the Mustang, I merely responded along those lines.


----------



## Shortround6 (Sep 24, 2009)

Clay_Allison said:


> My fighter plane philosophy has been (for a while) that you take the best powerplant you can build and strap the lightest plane you can to it. My ideas tend to follow that theme. My poiint was that a V engine would reduce the drag even further and more power wouldn't go to waste. Some pretty crazy engine swaps took place throughout the war. I don't think it's as impossible as people say.



That" philosophy" was used by more than one designer at the time. At times it works quite well. At other times not so well. It depends on what other requirements the user has.
In many books we are told that the Specification "XXX" called for such and such a speed and such and such a climb rate or climb to altitude and sometimes they even give a range or endurance requirement. 
This last one starts to throw complications in from the start. If requirement #1 calls for range YYY but requirement #2 calls for range YYY+50% everything else staying the same can you use the same airframe? 
Hidden requirements are often landing or take-off speeds or take-off/landing runs. A new super fighter doesn't do much good if it can't use existing runways. And in the 1930s that was much more likely to be landing fields, Large patches of rolled grass so the planes could take-off/land in any direction without having to worry about cross winds. 
Granted as WW II went on the airfields/ runways did get larger and construction crews got better at fast construction of runways/airfields but given the usual 2-3 year time from drawing board to actual use trying to predict runway length available is tricky. 
Costomer requirements as airframe strength also varried. I would note that the site for the FFVS J22 claims a Design load factor, limit of 6Gs with an ultimate limit of 10Gs. Many American fighters were designed for a load limit of 8Gs with an ulitimate of 12G with British fighters being somewhere in between. This means that American airframes are going to be heavier for equel size. It does mean that they will probably be more rugged. However it also means they are going to need a bigger wing to meet the landing/take off requirement which means more drag in cruising flight which means more fuel which means more weight which means more.......... 
Using the smallest airframe also means limiting the fuel. See problems the 109 had in the BoB. Or that Spitfires had trying to go on the offensive. Or trying to operate in the Pacific. The best performing fighter in the world doesn't do anygood if it can't get to the fight.
What is the fighter designed for? point defence intercepter, area defence, bomber escort? 
Drop tanks help but a fighter using drop tanks might have more drag than a larger fighter carring the same fuel inside until the the tanks are dropped. 
Armament is another consideration. It is after all one of the primary resons for being for a fighter. A fighter has to get an effective armament into firing position against an opponent/enemy. Too light an armament and they plane is a waste of effort. To heavy an armament and the plane may not be able to get into firing positions and is a waste of effort. The target would tend to drive the armaent selection but this didn't seem to be understood at times during the 1930s. "If 2 rifle caliber MGS were good enough for (insert name of WW I ACE) they should be good enough for you" thinking. Or American six .50s are good enough, of course the Americans never tried shooting down B-29s.
The plane should be designed from the start to have an effective armament, not see what can be crammed in to fit after the prototype flies and hope that is good enough.


----------



## Clay_Allison (Sep 24, 2009)

Shortround6 said:


> That" philosophy" was used by more than one designer at the time. At times it works quite well. At other times not so well. It depends on what other requirements the user has.
> In many books we are told that the Specification "XXX" called for such and such a speed and such and such a climb rate or climb to altitude and sometimes they even give a range or endurance requirement.
> This last one starts to throw complications in from the start. If requirement #1 calls for range YYY but requirement #2 calls for range YYY+50% everything else staying the same can you use the same airframe?
> Hidden requirements are often landing or take-off speeds or take-off/landing runs. A new super fighter doesn't do much good if it can't use existing runways. And in the 1930s that was much more likely to be landing fields, Large patches of rolled grass so the planes could take-off/land in any direction without having to worry about cross winds.
> ...





> Many American fighters were designed for a load limit of 8Gs with an ulitimate of 12G



Explains why the P-40 was so damned heavy for such a relatively smallish fighter. It really doesn't look bigger than a spitfire or a 109, nice to know where the weight came from.


----------



## Colin1 (Sep 24, 2009)

Clay_Allison said:


> It really doesn't look bigger than a spitfire or a 109, nice to know where the weight came from


The P-40 could be more closely approximated with the P-51 or the Hawker Hurricane for general, overall size. It didn't sit tall on the ground but length and span were a good foot over the Spitfire and more again over the Bf109.


----------



## Shortround6 (Sep 24, 2009)

P-40 also carried more fuel than the european fighters as did the P-36. Might have something to do with the size of the United States and even trying to deploy fighters from one area to another.

The designer that can combine ALL the requirements into the smallest airframe is probably going to come out ahead. 
Of course the really smart designers had to walk a fine line between making the plane just a little too small and not leaving any room for growth (the customer is always going to want more of something) and making the plane just a little too large and losing the competion or failing to met the specification AS CURRANTLY WRITTEN.


----------



## Colin1 (Sep 24, 2009)

Shortround6 said:


> P-40 also carried more fuel than the european fighters as did the P-36. Might have something to do with the size of the United States and even trying to deploy fighters from one area to another


That 5-spar wing must have contributed something extra to the empty weight


----------



## Elvis (Sep 24, 2009)

_fine_, I'll throw-ijn, AGAIN...



Clay_Allison said:


> Imagine what the J22 could have done with a Db-605


Forget the DB605, THIS, or possibly swapping for the R-2000, would've been a better way to go.
Less mods, and accomplishes the same objective.

...HOIWEVER...

If we're going to start discussing the J-22, we should really start a new thread.



Elvis


----------



## Clay_Allison (Sep 24, 2009)

Elvis said:


> _fine_, I'll throw-ijn, AGAIN...
> 
> 
> Forget the DB605, THIS, or possibly swapping for the R-2000, would've been a better way to go.
> ...


true. maybe I will start a J-22 thread.


----------



## Shortround6 (Sep 24, 2009)

Colin1 said:


> That 5-spar wing must have contributed something extra to the empty weight



Quite possiably. But no one spar of the 5 is going to be as heavy as the spar/s in a single or 2 spar wing. that is per spar. 

I believe I have also read that some american planes were stessed for a higher g load for landing than some other countries planes. 

All metal (including metal skinned) monoplanes were only a few years (less than 5?) old when the P-36 was designed. Several prototype or racing monoplanes had had wings foldup or come off in the early thirties so designers might have been erring on the cautious side of their calculations.


----------



## Elvis (Sep 25, 2009)

Shortround, 

I believe the first all-metal monoplane fighter in the American arsenal was the P-26, so yeah, that concept wouldve only been a couple of years old, when the P-36 was developed.

Re: wing weight.
Forgive me, but are you saying that the 2 spar wing you mentioned would weigh the same as the 5-spar wing of the P-40, because the spars of the 2-spar wing would be heavier?


Elvis


----------



## Shortround6 (Sep 25, 2009)

The P-26 sounds right, thank you.

Aerodynamic loads increase with the square of the speed so the forces acting on the 300mph P36 would have been about 62% higher than the 235mph P-26. (level speeds not dive

THe two spar wing might be a bit lighter but both wings have to carry the same loads. If built to an ultimate load factor of 12G the wing of a 6000lb fighter is going to have another 66,000lb of sand bags, steel plates,etc placed on it, hung from it in static testing.

The faster a plane goes the more the leading edge of the wing tries to twist up. the wing structure has to resisit this twisting. A 2 spar wing cannot just use 2 spars of the same size/weight/shape as the 5 spar wing unless it uses heavier ribs or spaces them closer together and/or uses heavier wing skinning. 

You aren't going to get something for nothing. THe 5 spar wing may cost more to fabricate and it might be more damage resistant. one spar damaged you 4 others carring the lad. of course with 5 spars the likily hood of one of them getting hiit goes up 

There may be a weight difference, I just dont believe it is going to be as great as some peaple seem to think.


----------



## Elvis (Sep 25, 2009)

LOL!
Leave it Shortround to turn the answer to a simple "Yes-or-No" question into a 5000 word essay.
God bless ya, Shortround.


Its ok, I'll just stay _mystified_.



Elvis


----------



## Clay_Allison (Sep 26, 2009)

Shortround6 said:


> The P-26 sounds right, thank you.
> 
> Aerodynamic loads increase with the square of the speed so the forces acting on the 300mph P36 would have been about 62% higher than the 235mph P-26. (level speeds not dive
> 
> ...


I had always thought that the P-40 was similar in size to the spitfire, since it wasn't (just too big) I think it's worthwhile to adjust the requirements to emphasize speed and power loading over all other concerns.

One thing I think that would be possible is just shrinking the plane. Trimming it but keeping it balanced to the same scale. This would reduce internal fuel capacity but I am a big proponent of drop tanks and the Bf 109 made good use of them throughout the war.

The P-40 was a big sturdy plane, there's no reason not to make it a small sturdy plane with the same horsepower as the big one. It would reduce unassisted range and I'm sure shortround can come up with some other trade-offs that would have to be made, but I think it would be worth it to get a real honest-to-god dogfighter into the war in 1942.

By the way I do agree that these decisions would have to be made pretty early in the process (ca. 1937 when Curtiss was first looking at mating the V-1710 to the P-36 and reports were coming back from Spain about the Bf 109)


----------



## Elvis (Sep 27, 2009)

Clay,

Courtesy of Warbird Alley...



P-40 said:


> Specifications: (P-40N):
> Engine: 1360hp Allison V-1710-81 inline piston engine
> Weight: Empty 6,000 lbs., Max Takeoff 11,400 lbs
> Wing Span: 37ft. 4in.
> ...


]



Spitfire said:


> Specifications (Mk VA):
> Engine: One 1,478-hp Rolls-Royce Merlin 45 V-12 piston engine
> Weight: Empty 4,998 lbs., Max Takeoff 6,417 lbs.
> Wing Span: 36ft. 10in.
> ...





P-51 said:


> Specifications (P-51D):
> Engine: One 1,695-hp Packard Merlin V-1650-7 piston V-12 engine
> Weight: Empty 7,125 lbs., Max Takeoff 12,100 lbs.
> Wing Span: 37ft. 0.5in.
> ...




Now, what you're proposing, by shriinking down the plane, in order to boost performance, is very similar to what Grumman did in the very late stages of the war.
While the F6F was an absolute _Godsend_ to Naval fliers all over the pacific, the fact remains that it was still a large and heavy aircraft.
Someone at Grumman mused about how much performance would increase, if they could design the smallest possible airframe that was still stout enough to handle the R-2800.
The result was the F8F Bearcat. One of the, if not THE, highest performing propeller driven airplane of the entire war (and it did serve during the war, even if only for a very short time).

...and so, again, courtesy of the good people at Warbird Alley, here are the stats comparing those two planes...



Hellcat said:


> Specifications (F6F-5):
> Engine: 2000hp Pratt Whitney R-2800-10W Double Wasp 18-cylinder radial piston engine
> Weight: Empty 9150 lbs., Max Takeoff 15,410 lbs.
> Wing Span: 42ft. 10in.
> ...





Bearcat said:


> Specifications (F8F-1B):
> Engine: 2,100hp Pratt Whitney R-2800-34W Double Wasp 18-cylinder radial piston engine
> Weight: Empty 7,070 lbs., Max Takeoff 12,947 lbs.
> Wing Span: 35ft. 10in.
> ...



Now, would the P-40, altered the same way, show similar increases in performance?
I don't know, but if someone had access to some computer similation programs, it would be interesting to find out.
Seeing how you're setting an early timeline on things this time, maybe the "P-40" (no letter designation) would be the plane to use for testing..



Elvis


----------



## tomo pauk (Sep 27, 2009)

Elvis said:


> ...
> Now, what you're proposing, by shriinking down the plane, in order to boost performance, is very similar to what Grumman did in the very late stages of the war.
> While the F6F was an absolute _Godsend_ to Naval fliers all over the pacific, the fact remains that it was still a large and heavy aircraft.
> Someone at Grumman mused about how much performance would increase, if they could design the smallest possible airframe that was still stout enough to handle the R-2800.
> ...



F8F was a great plane, but: 
a) many planes that really served in war were outperforming it - 6 months, or even a full year before the Bearcat flew in units
b) war service of the plane is equal to zero


----------



## Shortround6 (Sep 27, 2009)

Clay_Allison said:


> One thing I think that would be possible is just shrinking the plane. Trimming it but keeping it balanced to the same scale. This would reduce internal fuel capacity but I am a big proponent of drop tanks and the Bf 109 made good use of them throughout the war.



The Bf 109 did not make good use of them. It turned necessity into a virtue if you can call it that. Needing drop tanks to perform any but the most local/point defence missions might not have meet the requirement of the U.S. Fighting in the Pacific theater with a plane that had the range of a 109 would have been a bit difficult. See Spitfires in the Pacific. Sptifires could also carry larger tanks than 109s, in part because of their larger wing.


Clay_Allison said:


> The P-40 was a big sturdy plane, there's no reason not to make it a small sturdy plane with the same horsepower as the big one. It would reduce unassisted range and I'm sure shortround can come up with some other trade-offs that would have to be made, but I think it would be worth it to get a real honest-to-god dogfighter into the war in 1942.



Since you asked

reducing the wing size, From an old book "The Airpalne and it's Engine" by Chatfield, Taylor and Ober. at least 5 edtions and can be found on E-bay for 10-20 dollars.
"A reduction in wing area of 25 percent would increase the minimum speed by 15 percent but the maximum only about 3 percent. climb is slightly increased. Take-off run is increased."

So for a 350mph airplane you can gain about 10mph top speed for about a 13 mph increase in stalling speed. You are heading for a boom and zoom plane and not a dogfighter. 

A smaller plane might have a more cramped cockpit. Not as much of a problem in a shorter ranged fighter as a long range one. 

There were 2 attepts at "smaller P-40s" the P-46, which was actually a bit schizophrenic in try to cram a bigger war load into a smaller airframe and the Republic P-47A.

This design (never went past mock-up) is usually glossed over in most histories of the P-47 and understandably at is bears no realtionship with the P-47B.

As originally proposed it was to weigh 4,900lbs using the V-1710-39 engine (same as P-40 D/E) and armed with the typical pair of .50 cal guns with 200rpg. The 115 sq ft wing may have posed a few problems though. With no armour or self sealing tanks ( and weight escalation) it was decided that this was not what was wanted and a revison to a 6,150lb design was made. 30ft wing span, 27'6" length and a wing area of 165 sq ft. Multiple .30 cal guns were added to the wings, empty weight was supposed to be 4,790lbs with a speed at 15,000ft of 400mph and climb to that hight in 4.8 minutes. Again climbing weight estimates and combat reports from Europe cast doubts on actual performance and wither this design was what was really wanted. Some details of this design are sketchy and conflicting. 
[/QUOTE]


----------



## renrich (Sep 27, 2009)

The F8F was not an altered F6F any more than the F6F was an altered F4F. The F8F was a completely different design other than the engine which was seriously uprated. As far as other aircraft in the same time period outperforming the Bearcat, that depends on where. The Bearcat was a 440-450 mph airplane at low altitudes and could climb like a homesick angel. I doubt any other contemporaries could do that. That type of performance is why the Bearcat has excelled on the air racing circuit.


----------



## VG-33 (Sep 27, 2009)

Del:


----------



## VG-33 (Sep 27, 2009)

Hello



Shortround6 said:


> Since you asked
> 
> reducing the wing size, From an old book "The Airpalne and it's Engine" by Chatfield, Taylor and Ober. at least 5 edtions and can be found on E-bay for 10-20 dollars.
> "A reduction in wing area of 25 percent would increase the minimum speed by 15 percent but the maximum only about 3 percent. climb is slightly increased. Take-off run is increased."
> ...



Well, after theory let's see on practice what it does to the Yak1M from the serial Yak-1.

Reduction from 17,15 to 14,85 m² ( 15% less) wing aera produced

25 mph speed increase
1-2 mph stall speed increase 
20% gain in climb speed

Of course there was a 250 kg weight reduction. Small increase in wingload and P/W ratio.

The Yakovlev design bureau genious was to reduce the wing size *altogether* with the plane weight.

Regards


----------



## Clay_Allison (Sep 28, 2009)

The figure I'd go for with the P-40 is a power loading of at least 0.20 hp/lb. The Spitfire, Bf 109, and Mustang were all in the .21-.23 range in later models, the Zero had a power loading of .18, the P-40 an unacceptable .14.


----------



## Shortround6 (Sep 28, 2009)

VG-33 said:


> Hello
> 
> 
> 
> ...



Going from therory to practice always has a few problems. 
Given the usual + or - of a few % in both individual aircraft wieght and engine power due to production tolerances comparing the results of just one set of numbers and declaring the therory bad doesn't seem to fair.
Especially considering the Russians seemed to have a fair degree of trouble just getting their production planes to perform up to prototype standards. Just which Yak-1 is being compared?
Were there anyother changes to the plane that might change the drag, like different oil cooler location or ducting, a different propeller and/or spinner or other modifications besides a better fit and finish on the Prototype Yak-1M vrs a series built aircraft?

Doesn't take a lot of genious to replace the wooden longerons with metal ones as the metal became more available later in the war. According to one book this accounts for over the half the weight difference.


----------



## Elvis (Sep 28, 2009)

Shortround6 said:


> reducing the wing size, From an old book "The Airpalne and it's Engine" by Chatfield, Taylor and Ober. at least 5 edtions and can be found on E-bay for 10-20 dollars.
> 
> 
> The Airplane and it's Engine said:
> ...


Shortround6,

Did the section of the book you quoted on the affects of shrinking down a wing mention exactly _how_ the wing was "shrunk", for them to come to those conclusions?
In other words, was the wings proportionally shrunk in all dimensions? was it made shorter? was it made narrower, etc.
I ask, because the only thing the quote states is that the wing area is shrunk by 25%. I don't see anything on _how_ it was shrunk.

Also, did YOU calculate the change in stall characteristics, or did you get that from the book, as well?
I ask because I see nothing quoted about a change in stall speed.

Lastly, isn't the "blueprint" for a purpose built _dogfighter_ a plane that has a high power loading with a low wing loading...or do I have that backwards?

Just curious.



Elvis


----------



## Shortround6 (Sep 28, 2009)

No, the book didn't say how it was shrunk. I would assume shrunk in all dimensions because you do get different results from wings of equel area if they have very different aspect ratios. talking about lift caracteristics in general here. See Spitfires for changes in flying characteristics that can't quite be explained by simple changes in square footage.

I calculated the stall speed myself based on a 90mph stall speed. I may be mistaking minimum speed for stall speed 

"reduction in wing area of 25 percent would increase the minimum speed by 15 percent "

You maybe correct in "built dogfighter a plane that has a high power loading with a low wing loading..."

But if you shrink the wing more than you shrink the weight you get a high power loading with a high wing loading..... or at least a higher wing loading than you started with. Please note the proposed XP-47A with it's 165sq.ft. wing would have had a higher wingloading than a P-40 operating at 8500lbs. 

Minimum speed (or stalling speed, in either case you are no longer flying) changes with altitude. In the thinner air at high altitudes the plane has to fly faster to get the same amount of lift. And if you are trying to turn the minimum speed goes up again. 
You might have a "vertical" dog fighter but not a "horizontal" dogfighter.


----------



## Elvis (Sep 28, 2009)

Thanks. That's all I wanted to know.


Elvis


----------



## Elvis (Sep 28, 2009)

...oh yeah, and y'all knew _someone_ would bring this up...











Elvis


----------



## Clay_Allison (Sep 28, 2009)

Elvis said:


> ...oh yeah, and y'all knew _someone_ would bring this up...
> 
> 
> 
> ...


Terrible concept. the light fighter concept is fine if you mean the lightest possible fighter that can handle your best engine.

That pathetic Bell XP-77 had a proposed power loading of .129, on par with a dive bomber.


----------



## Elvis (Sep 30, 2009)

...tee-hee-hee. 




Elvis


----------



## Colin1 (Sep 30, 2009)

Clay_Allison said:


> Terrible concept. the light fighter concept is fine if you mean the lightest possible fighter that can handle your best engine.
> 
> That pathetic Bell XP-77 had a proposed power loading of .129, on par with a dive bomber.


I like the tricycle undercarriage
I understand that cancelled out propeller torque on take-off - not that that is likely to upset that little bird.
Don't quite understand how the cockpit ended up so far back and what were they going to gun it up with, air rifles?


----------



## Elvis (Sep 30, 2009)

The concept was sort of an "essentials only-type" fighter plane. Guns and that's it.
They wanted to do the smallest package possible, so it was developed from the standpoint of a "formula 1" type of race plane, modded for military use.
It was to be powered by a small V-12, thus the reason for setting the pilot so far back.
They promised "500 cubic inches, 500HP", but that version couldn't be developed in time, so a lower (350) HP version was used for testing instead.
Performance suffered because of this and the plane was passed up for that reason..

..._or so I've heard/read_



Elvis


----------



## Clay_Allison (Sep 30, 2009)

Elvis said:


> The concept was sort of an "essentials only-type" fighter plane. Guns and that's it.
> They wanted to do the smallest package possible, so it was developed from the standpoint of a "formula 1" type of race plane, modded for military use.
> It was to be powered by a small V-12, thus the reason for setting the pilot so far back.
> They promised "500 cubic inches, 500HP", but that version couldn't be developed in time, so a lower (350) HP version was used for testing instead.
> ...


It's hindsight and all, but they did it all backwards. You start with an engine, then you tailor an airframe to it. Even though the Bf-109 was designed around the Jumo 210 and evolved to use the Db-601 it was still an inverted V-12 of the same approximate size.

We can think of quite a few planes that failed to reach production because of engine delays, and a few examples where with a proven powerplant to rely on, planes have jumped from paper to production in weeks or months.

If you rely on an experimental power plant to make your idea work you can often find yourself in possession of a windless kite.

In any case I wouldn't want to go up in a 500 horsepower egg crate to fight against real fighters.


----------



## tomo pauk (Oct 1, 2009)

Very true, Clay. 
Many US planes were 'designed' with experimental engines in mind, only to found out that it was a complete waste of time money. The Germans also relied at the Jumo 222, with pathetic results after all.


----------



## Shortround6 (Oct 1, 2009)

The proper way to do it would be to start with the paylad (weapons) desired and the performance that is wanted. 
As in " we want a 1000lb weapons load to go 350mph at 20,000ft and climb to 20,000ft in 8 minutes. Range to be not less than 500miles at 200mph. Landing and take-off speeds to be compatable with standard existing airfields. Design Structural strength is to be 'X' Gs positive and 1/2 'X' Gs negative with an ultimate strength of 'X'+50% to be equiped with standard instraments and radio YYY, etc."
Designer then tries to figure out what engine and what sized airframe will give the desired performance. Sometimes the lowest price will also enter into it. 
In some cases it took a second engine choice to make the airplane work (both Zero and Hellcat).

It has been said that combining a new airframe with a new engine is a recipe for failure


----------



## Shortround6 (Oct 1, 2009)

Elvis said:


> The concept was sort of an "essentials only-type" fighter plane. Guns and that's it.
> They wanted to do the smallest package possible, so it was developed from the standpoint of a "formula 1" type of race plane, modded for military use.
> It was to be powered by a small V-12, thus the reason for setting the pilot so far back.
> They promised "500 cubic inches, 500HP", but that version couldn't be developed in time, so a lower (350) HP version was used for testing instead.
> ...



Could you please give a source or two for this?

I have developed an interest in this airplane due to a long argument about it on another board (I was against it) and I am rather amazed at the amount of contradictory and/or down right false information about on the web and in some books.


----------



## Clay_Allison (Oct 1, 2009)

Shortround6 said:


> The proper way to do it would be to start with the paylad (weapons) desired and the performance that is wanted.
> As in " we want a 1000lb weapons load to go 350mph at 20,000ft and climb to 20,000ft in 8 minutes. Range to be not less than 500miles at 200mph. Landing and take-off speeds to be compatable with standard existing airfields. Design Structural strength is to be 'X' Gs positive and 1/2 'X' Gs negative with an ultimate strength of 'X'+50% to be equiped with standard instraments and radio YYY, etc."
> Designer then tries to figure out what engine and what sized airframe will give the desired performance. Sometimes the lowest price will also enter into it.
> In some cases it took a second engine choice to make the airplane work (both Zero and Hellcat).
> ...


I know you start with a "requirement" issued from the government, but if you want a plane that can be delivered on time and in quantity, you'd better start your program to FILL that requirement with a power plant that you know will be there.


----------



## Shortround6 (Oct 1, 2009)

Clay_Allison said:


> I know you start with a "requirement" issued from the government, but if you want a plane that can be delivered on time and in quantity, you'd better start your program to FILL that requirement with a power plant that you know will be there.



Like the above mentioned Zero and Hellcat?

Both prototypes used engines that were in production yet didn't deliever the required performance and had to switch to another engine.

Or the FW 190?

Engine it was designed for never made it into production. 

P-39, P-40 and P-38 were designed around an engine that had at least passed a type test even if it wasn't really in "production". 7 engines delivered in 1937 and 14 in in 1938.

Or the Hawker Typhoon/Tornado design started with the Sabre, the Vulture was added early in the design proccess, first flew with the Vulture but we all know how that engine turned out Later proposals include 3 additional engines, one of which was the Bristol Centaurus. THe last made it to hardware stage on the Tornado airframe. Strange that the final fighters produced of this family used the Centaurus.

THis is just fighters somewhat of the top of my head.

Some goverment requirements specified which engine was to be used.


----------



## Clay_Allison (Oct 1, 2009)

Shortround6 said:


> Like the above mentioned Zero and Hellcat?
> 
> Both prototypes used engines that were in production yet didn't deliever the required performance and had to switch to another engine.
> 
> ...


I'm not saying that these things never ever worked out. The M.B. 2-5, the entire hyper-engine project (XP-55, 49, 67), P-75, XP-58 are all designs that suffered at the hands of experimental engines.


----------



## Elvis (Oct 1, 2009)

Clay,

You say you start with an engine and design a plane around it.

Actually, you start with a mission or a mission requirement and then you see if you have anything in the exisiting inventory that will satisfy that requirement/mission.
If you have nothing, then you see if you can't modify something in the existing inventory to satisfy the requirement/mission.
Having failed that, _then_, you compile the specs for filling that requirement/mission and send out the offer to your known manufacturers and _they_ design something they think will fill that requirement/mission (and I'll not travel the path that results from none of your known manufactures having the ability/knowledge to design something to satisfy the requirement/mission. However, that is an additional option).
Then you decide who best fills the requirement, have trials, then you induct the winner into your inventory.

...at which point you start the whole process over again when you find that in the meantime, the mission / mission requirement has changed and the recently inducted design is no longer suitable for anything other than a now obsolete mission / mission requirement.  
-----------------------------------------------------------------------------

Shortround6,

Re: Bell XP-77 info.

No single, quoteable source.
Just info I've gleaned over the years.

Times change and half of what we learned as "fact" in our youth turns out to be "not fact".
Forgive me if I haven't kept up with the latest findings.

Did I read your last post correctly, though?
You state that you've recently gained interest in the plane, due to misinformation you're reading about it on the web?
.....wouldn't "_recently gained interest_" mean you didn't really know anything about it before, mainly due to lack of interest, but am now gaining information on?
In which case, how do you know the information you're reading is incorrect and how do you know the information you're using as a comparitive is correct?




Elvis


----------



## Shortround6 (Oct 1, 2009)

Elvis,
By recently I mean in the last year to year and half. 

Some mistakes can be pretty obvious. Like one book claiming the plane was to be armed with two 20mm cannon and two .50cal MGs. Nobody else makes such a claim and trying to figure out were the guns would go makes it pretty clear that this is a mistake.
Other claims don't fall on a common time line. Like claims the plane did 330 mph while armed with a single 20mm cannon and two .50cal MGs. The requirement for the cannon was dropped to allow for a bomb or drop tank to be carried almost 2 years before the first prototyype even flew. Peaple may argue over wither the prototype actually carried any guns at all but why would it carry the 20mm on test flights almost 2years after it was decided not to install it at all? 
I have also tried to gather as much information as I could about the Ranger engine due to an arguement on another Board about light fighters in general. For sources on this I rely on Several old editions of "Jane's all the world's aircraft", several editions of Wilkinsons "aircraft engines of the World". FAA type cetificates on line and some other old books about airplane engines. By double checking such information one can usually spot misprints like rated altitude being off by 10,000ft or so
In another thread on this board I noted that the climb rates for the XP-77 don't seem to agree with themselves. An Intial climb rate of 3,600fpm and time to 9,000ft of 3.7 minutes just don't fit together. Unless the intial climb was done at a power setting that could only be held for one minute and the remaining time to 9000 ft had to be done at a much lower power setting?
Some accounts say the the design was called the "Tri-4" for "400 hp, 4000 pounds, 400 mph". but even in 1936 the Ranger was rated at 420HP and 1941 it was rated at 520HP at 9,600ft. Where the 400hp comes from is a mystery to me. Most acounts claim the Ranger with a special superchager was supposed to supply either 500 or 520 hp at 27,000ft which doesn't explain the "Tri-4" either. 
If the engine used was supposed to supply 520hp at 12,000ft then why is the max speed given at only 4,000ft in much thicker air? The plane should have gone faster in the less dense air at 12,000ft unless there was a problem with the engine? 

Maybe there are expantions for these questions and I just haven't seen them


----------



## Clay_Allison (Oct 1, 2009)

> Some mistakes can be pretty obvious. Like one book claiming the plane was to be armed with two 20mm cannon and two .50cal MGs. Nobody else makes such a claim and trying to figure out were the guns would go makes it pretty clear that this is a mistake.


 maybe confusion with the vague and mysterious Tucker XP-57?


----------



## Shortround6 (Oct 1, 2009)

Possiable but book devotes half a page of text to the XP-57 and a full page 3 view drawing.
Gives two armament options for the XP-57.
Almost a full page of text to the XP-77, a full page 3 view and 3 photos.


----------



## Clay_Allison (Oct 1, 2009)

Shortround6 said:


> Possiable but book devotes half a page of text to the XP-57 and a full page 3 view drawing.
> Gives two armament options for the XP-57.
> Almost a full page of text to the XP-77, a full page 3 view and 3 photos.


I still say you never go with lesser engines. it's a waste of production capacity. "Cheap" Aero engines are still too expensive and the workers building them need to work on real engines.

Building a light fighter is great, just make it the lightest package you can that has everything you need, like the Zero and the Ki-43.


----------



## Elvis (Oct 2, 2009)

Shortround6,

Thanks for clarifiying your sources.
I see what you're getting at.
Yes, definately some descrepencies.
As for testing an engine rated @ 12K ft, at 4K ft., I've heard many times, from different sources, that the engine that was _supposed_ to go in the XP-77 wasn't available at the time testing was scheduled, so they went with a less powerful version.
The jist I got was that it was _hoped_ that the more powerful engine would be available by the time testing ensued.
That could explain why the plane was tested at the lower altitude, although, that does seem like a really low test altitude.
Weird.
-------------------------------------------


ClayAllison said:


> Building a light fighter is great, just make it the lightest package you can that has everything you need, like the Zero and the Ki-43.


Yep, I think that's the best approach.



Elvis


----------



## Altea (Oct 2, 2009)

> Shortround6 said:
> 
> 
> > Going from therory to practice always has a few problems.
> ...


----------



## Shortround6 (Oct 2, 2009)

Elvis said:


> Shortround6,
> 
> Thanks for clarifiying your sources.
> I see what you're getting at.
> ...



According to most sources the engine they hoped for was supposed to give 500-520hp at 27,000ft.
The engine they fitted was supposed to give 520 at 12,000ft for one minute.
Unless they got a dog. It was a standard Navy engine fitted to the Curtiss SO3C if I have things right.


----------



## Shortround6 (Oct 3, 2009)

Altea said:


> > It worked elsewere, with due reservation of course:
> > 109F/109E.
> > Il-10/Il-2
> > D-550/D-520
> ...


----------



## Elvis (Oct 5, 2009)

Shortround6 said:


> According to most sources the engine they hoped for was supposed to give 500-520hp at 27,000ft.
> The engine they fitted was supposed to give 520 at 12,000ft for one minute.
> Unless they got a dog. It was a standard Navy engine fitted to the Curtiss SO3C if I have things right.


Shortround,

As I stated before, all I've ever heard was that the engine they wanted to use wasn't available by the time testing was to commence.
However, I failed to mention that they used the less powerful version, becuase it was already available.
AFAIK, the engine used wasn't a "dog", it was simply less powerful than the version they had designed the plane for.
At the time, they hoped it was "good enough" to get it through the trials period, however, it wasn't and thus the plane failed to pass because it simply couldn't generate the performance required by the Army Air Force for its mission.
Whether those are the engines you mentioned or not, I don't know.



Elvis


----------



## Clay_Allison (Jan 25, 2010)

How much weight could be saved by stressing the P-40 to only 10 g rather than 12 g ultimate?


----------



## Markus (Jan 25, 2010)

See the idea of installing a V-1710 with an auxillary stage supercharger has been discussed already. 
To save weight I suggest removing two of the six .50 guns. Each gun weighs 70lb, one round 0.3lb. With 235 rounds per gun that saves a total of 280lb. What about laminar flow wings? C&W had designed some for the XP-60.


----------



## Colin1 (Jan 25, 2010)

Markus said:


> What about laminar flow wings?


What effect do you think the undercart arrangement is going to have on this? Or are we re-doing that as well?


----------



## Shortround6 (Jan 25, 2010)

Markus said:


> See the idea of installing a V-1710 with an auxillary stage supercharger has been discussed already.
> To save weight I suggest removing two of the six .50 guns. Each gun weighs 70lb, one round 0.3lb. With 235 rounds per gun that saves a total of 280lb. What about laminar flow wings? C&W had designed some for the XP-60.



The Curtiss company was designing the XP-60 as a P-40 replacement. See:

Factsheets : Curtiss XP-60


----------



## Clay_Allison (Jan 25, 2010)

Markus said:


> See the idea of installing a V-1710 with an auxillary stage supercharger has been discussed already.
> To save weight I suggest removing two of the six .50 guns. Each gun weighs 70lb, one round 0.3lb. With 235 rounds per gun that saves a total of 280lb. What about laminar flow wings? C&W had designed some for the XP-60.



The best thing would be to get serious about the H.S. 20mm cannon and replace the 6 MGs with 2 cannon.


----------



## Markus (Jan 25, 2010)

Colin1 said:


> What effect do you think the undercart arrangement is going to have on this? Or are we re-doing that as well?



What´s one more modification for a P-40 among friends?  Fun aside, they turned her into the XP-40Q eventually. If C&W had decided to cancel the four different XP-60 versions and improve the well selling P-40 they would have had the P-40Q sooner.


----------



## Clay_Allison (Jan 25, 2010)

Markus said:


> What´s one more modification for a P-40 among friends?  Fun aside, they turned her into the XP-40Q eventually. If C&W had decided to cancel the four different XP-60 versions and improve the well selling P-40 they would have had the P-40Q sooner.



That goes for the XP-46 as well.


----------



## Markus (Jan 25, 2010)

Clay_Allison said:


> That goes for the XP-46 as well.



They had the XP-46 soon enough and IIRC the USAAF found nothing wrong with it. It wasn´t put in production because the US had joined the war by this time and disrupting C&W fighter production by switching to a very different plane was not tolerable any more. And this was the reason for the rejection of the cancellation of the P-60. Thus C&W deciding to give No.1 priority to a step by step improvement program for the then all-important P-40.

P-40E->P-40F->P-40K->*P-40L*(early 1943: V-1710+aux. stage SC)->*P-40N*(mid-43: a K with laminar flow wings)


----------



## Shortround6 (Jan 25, 2010)

Markus said:


> They had the XP-46 soon enough and IIRC the USAAF found nothing wrong with it.



Except that it wasn't as fast as a P-40 using the same engine.



Markus said:


> It wasn´t put in production because the US had joined the war by this time and disrupting C&W fighter production by switching to a very different plane was not tolerable any more.



Well, disrupting production in order to make a slower airplane certainly wasn't tolerable.



Markus said:


> And this was the reason for the rejection of the cancellation of the P-60. Thus C&W deciding to give No.1 priority to a step by step improvement program for the then all-important P-40.



Or that the various P-60s didn't seem to offer any improvement over Airplanes that either were already in production or further along in development. Perhaps the Helldiver fiasco was also on peoples minds. 



Markus said:


> P-40E->P-40F->P-40K->*P-40L*(early 1943: V-1710+aux. stage SC)->*P-40N*(mid-43: a K with laminar flow wings)



Since the P-63 with production model Allisons with 2 stage superchargers don't start to be delivered until Oct of 1943 I would think that early 1943 is a bit optimistic. Contracts for the XP-39E and the P-63 were signed in Jan of 1941.


----------



## Clay_Allison (Jan 25, 2010)

Seems like we really only had the resources to make one great V-Engine. It's a shame we thought the Merlin was obsolete. We could have killed the Allison V-1710 in its infancy and gone with a V-1650 from multiple sources. Merlin P-40s, Merlin P-39s, Merlin P-38s, that would have been awesome.


----------



## Shortround6 (Jan 26, 2010)

Clay_Allison said:


> Seems like we really only had the resources to make one great V-Engine. It's a shame we thought the Merlin was obsolete. We could have killed the Allison V-1710 in its infancy and gone with a V-1650 from multiple sources. Merlin P-40s, Merlin P-39s, Merlin P-38s, that would have been awesome.



Problem is that decision would have had to have been made in late 1938 or early 1939. The question is would a 1938 Merlin using American fuel in 1939 have given the performance needed?

At this time American 100 octane fuel was not the same as British 100 octane. The American fuel had a (was required to ) much lower aromatic content which meant a much lower rich mixture octane rating. This means that if you ran a Merlin on American 100 octane fuel you would get better performance than on 87 octane but nowhere near the performance the British got in 1940 using the British spec 100 octane fuel.
using an early Merlin might mean 100 hp less for take-off (or more) than using an Allison in 1939. Given that the American planes were usually heavier this might not be a good thing. it would also affect sea level speed and low level climb. 

There were 2 if not three paper studies of putting Merlins into P-38s at various times during the war. NONE of these studies showed any advantage in using the Merlin and in some case showed very large disadvantages in using the Merlin.

The Merlin was never adapted to turbo charging even though it was tried. differences in engine cooling and cylinder head design as given as problems.


----------



## Colin1 (Jan 26, 2010)

Clay_Allison said:


> ...We could have killed the Allison V-1710 in its infancy and gone with a V-1650 from multiple sources...


It was history that hamstrung the V-1710, not technical deficiencies, at least, not in a sense. The V-1710 was having problems even at the C15 model for the P-40, resulting in it losing it's hp rating until much later that year (I'm guessing hp of 1,140 and a de-rated hp of 860 - I'll check when I get home) when the issues were finally resolved but you need to remember that the V-1710 was company funded and Allison wasn't a big company; the Merlin enjoyed the luxury of government funding.

The other skeleton in US inline history is their lack of appreciation of what was going on in Europe and elsewhere, and the outmoded thinking for air combat that prevailed as a result. In light of paying heed to decent intel from those places, and the subsequent down-filtering of the appropriate USAAC requirements to the manufacturers, Allison could well have remodelled (or modelled differently) their approach to power section application.

So with the USAAC keeping their eye on the right ball and more robust funding filtering through, no reason why the Allison unit couldn't have matched the Rolls-Royce unit from the outset.


----------



## Elvis (Jan 26, 2010)

Clay_Allison said:


> Seems like we really only had the resources to make one great V-Engine. It's a shame we thought the Merlin was obsolete. *We could have killed the Allison V-1710 in its infancy* and gone with a V-1650 from multiple sources. Merlin P-40s, Merlin P-39s, Merlin P-38s, that would have been awesome.


I didn't reasearch this, so maybe you're already aware of something I'm not, but I know the Allison dates back to either 1929 or 1931 (don't recall, off-hand, exactly at the moment). 
Doesn't that make it an older engine than the Merlin?...maybe even the Kestrel?

...also, "_C&W_"? Could I get a definition on that, please?


Elvis


----------



## Clay_Allison (Jan 26, 2010)

Elvis said:


> I didn't reasearch this, so maybe you're already aware of something I'm not, but I know the Allison dates back to either 1929 or 1931 (don't recall, off-hand, exactly at the moment).
> Doesn't that make it an older engine than the Merlin?...maybe even the Kestrel?
> 
> ...also, *"C&W"?* Could I get a definition on that, please?
> ...


Curtis and Wright, IIRC.

Yes, the Allison was older, but as shortround points out often, by 1938 they had delivered less than 100 total engines and were about the size of a racing custom shop.

In 1938 everyone knew war was brewing, that England would get involved, and that AC engines would be needed. A move to adopt the engine of one of the top two fighters on earth and take advantage of shared technological advances wouldn't have been considered that illogical. 

Allison would have certainly received orders for license built V-1650s and could have set up their production lines accordingly. What could the war effort have done with >70,000 more Merlins?

A Merlin powered P-51A alone would have had a staggering impact on the war.


----------



## Elvis (Jan 26, 2010)

Re: company name.
Isn't it "Cutiss-Wirght", with a hyphen, instead of the ""?
Is the name, with the "" an older version of the company's name?
Seeing "C&W" reminds me of the line from The Blues Brothers movie, "_We've got both kinds of music. Country AND Western!_".


Re: Allison vs. Merlin.
I see what you guys are saying now. Didn't realize production was that low up 'til that time.
Also, concerning your comments about a Merlin-powered P-51A...that is exactly what happened, except we called it the P-51B/C. 
Not too much difference between the A and the B/C. Main one was the powerplant!
Check out the performance stats at the Mustangs Mustangs website. 
The B/C was a better "hot rod" than the infamous "D"!
Nice thing about the D (other than the bubble canopy) was I think the high G gun jamming problem was finally solved.



Elvis


----------



## Clay_Allison (Jan 26, 2010)

Elvis said:


> Re: Allison vs. Merlin.
> I see what you guys are saying now. Didn't realize production was that low up 'til that time.
> Also, concerning your comments about a Merlin-powered P-51A...that is exactly what happened, except we called it the P-51B/C.
> Elvis



Yeah, but think of how much earlier a Merlin P-51A would have made an impact. It probably would have been flying top cover in North Africa and vastly complicating the Pacific Theater in early 1942.


----------



## Shortround6 (Jan 26, 2010)

a problem with the Merlin/P-51 dream is timing.

In 1938-39 the Merlin was a single speed-single stage engine that showed little difference in potential from the Allison. A two-speed single stage version was on offer but in it's original form it showed very little difference in altitude performance over the single speed (the most common single speed version being optimized for high altitude work). It is not until Hooker does his bit that things improve for the Merlin and that is about the middle of 1940. The improved single speed engines (40 series) and two speed engines (XX or 20 series) engines are what is first contracted for with Packard. The American versions power the P-40F. Please note introduction dates for the P-40F and then figure performance for a P-51 with that engine and not the later 2 stage engines. 

Work starts on the 2 stage Merlin engine but Allison has started work on a 2 stage engine at the end of 1938!

It takes Rolls-Royce several years to get the two stage engines into production and sharing info with Packard and Packard doesn't deliver any real quantity of 2 stage engines until 1943. These are the -3 and later Packard Merlins.

Allison has development problems with their 2 stage supercharger and development is slower. A good engine once developed it reaches production just a little too late to have any real impact on the war (same could be said of the P&W R4360 on which work started in 1940)


----------



## Colin1 (Jan 26, 2010)

Elvis said:


> ...the Allison dates back to either 1929 or 1931 (don't recall, off-hand, exactly at the moment).
> Doesn't that make it an older engine than the Merlin?...maybe even the Kestrel?


Approximately 10 years of development up until the C15 and still with power and reliability issues, against 4 years for the Merlin. This harks back principally to the issue of funding that I pointed out earlier and just as significantly to the USAAC's late acceptance of supercharging over turbocharging, which by 1938 still wasn't doing what it was supposed to be doing as well as it should have been doing it.

There is the fact that the USAAC were gearing up for a different kind of war than the one the ETO would throw at them but that doesn't explain the long development cycle of the Allison quite so directly.


----------



## Colin1 (Jan 26, 2010)

Colin1 said:


> ...The V-1710 was having problems even at the C15 model for the P-40, resulting in it losing it's hp rating until much later that year (I'm guessing hp of 1,140 and a de-rated hp of 860 - I'll check when I get home) when the issues were finally resolved...


C15 1,040hp: this could not be maintained owing to low mechanical strength, so in mid-1940 the powerplant was de-rated to 900hp. The original rating was not restored until the end of the same year, after further development.


----------



## Markus (Jan 26, 2010)

Shortround6 said:


> Except that it wasn't as fast as a P-40 using the same engine.



My mistake, I overlooked the 350mph were reached without guns and reduced armour.




> Since the P-63 with production model Allisons with 2 stage superchargers don't start to be delivered until Oct of 1943 I would think that early 1943 is a bit optimistic. Contracts for the XP-39E and the P-63 were signed in Jan of 1941.



In April 1942 2,000 two stage Allison engines were ordered. The V-1710-47´s critical altitude was 22,400ft. Early 43 seems doable IF someone make an effort to get the engine ASAP. C&W being afraid to fall behind could have been the one. 




Clay_Allison said:


> Seems like we really only had the resources to make one great V-Engine. It's a shame we thought the Merlin was obsolete. We could have killed the Allison V-1710 in its infancy and gone with a V-1650 from multiple sources. Merlin P-40s, Merlin P-39s, Merlin P-38s, that would have been awesome.



Why do you want to pay RR 6,000 $ per engine if the V-1710 just needs an aux. stage supercharger and an intercooler to be as good? The Allison was stuck with the lesser supercharger not because of technical reasons but because the USAAF did not want a better one. They had 100% faith in the turbocharger and even objected to Allison developing altitude rated engines.


----------



## Markus (Jan 26, 2010)

Colin1 said:


> Approximately 10 years of development up until the C15 and still with power and reliability issues, against 4 years for the Merlin.
> 
> There is the fact that the USAAC were gearing up for a different kind of war than the one the ETO would throw at them but that doesn't explain the long development cycle of the Allison quite so directly.



Strikter US standards. A UK engine had to pass a 100 hour test before being put into production, a US engine had to survive 150 hours. The V-1710 usually failed a few hours short of the 150-mark. Interestingly the first US build V-1650 failed the 150 hour test even worse than any Allison did but was put into production anyway. 

See "Vees for Victory" for more.


----------



## Colin1 (Jan 26, 2010)

Markus said:


> Stricter US standards. A UK engine had to pass a 100 hour test before being put into production, a US engine had to survive 150 hours...


Thank God they didn't ask for Napier Sabres...


----------



## red admiral (Jan 26, 2010)

> A UK engine had to pass a 100 hour test before being put into production, a US engine had to survive 150 hours. The V-1710 usually failed a few hours short of the 150-mark.



The US 150hour type test consisted of 10x1hr periods of full power and all other time at reduced power. It's challenging to compare this to the continuous running in UK tests.


----------



## billswagger (Jan 26, 2010)

Has anyone else heard that the P40 could've out performed this spitfire if it had more horsepower?

Pilots claim that contemporary Spitfires were matched in turn performance of the P-40B, but that the P-40 fell behind in performance when the SpitV came out. This also has to do with the fact that the P-40 was given more pilot armor and since it had better range was to be used as an attack aircraft. 

I really don't see it as a stop gap aircraft, considering every allied nation used it in service. I just think that when the war called for higher and faster, the plane was no longer fit for the war. 

The P-40N was to make up for that but you hear of complaints of how much more maintenance it took because of a removal of parts for weight reduction. Something to consider, but getting more out of the powerplant was probably at the forefront of the original design in 1939, considering that P-43s were to be an alternative to the P-40 in some theaters. I think its reputation for being a tough fighter probably carried it a long way. 


Bill


----------



## drgondog (Jan 26, 2010)

Elvis said:


> Re: Allison vs. Merlin.
> 
> Also, concerning your comments about a Merlin-powered P-51A...that is exactly what happened, except we called it the P-51B/C.
> Not too much difference between the A and the B/C. Main one was the powerplant!
> ...



Elvis - the wing was dropped 7 inches to accomodate an entirely new Cowl from the bulkhead in front of the cockpit all the way to the spinner. New Prop. New radiator and radiator cowl design. It was close to being given an entirely new aircraft designation.

The changes from the B/C to D/K were fewer in substance.

The change to the H was nearly 100%


----------



## Vincenzo (Jan 26, 2010)

billswagger said:


> Pilots claim that contemporary Spitfires were matched in turn performance of the P-40B, but that the P-40 fell behind in performance when the SpitV came out.



Spit V it's the contemporary of P-40B, there is some wrong in the claim

and afaik there was little difference in turn within Spit I and V


----------



## gjs238 (Jan 26, 2010)

Shortround6 said:


> a problem with the Merlin/P-51 dream is timing.
> 
> In 1938-39 the Merlin was a single speed-single stage engine that showed little difference in potential from the Allison. A two-speed single stage version was on offer but in it's original form it showed very little difference in altitude performance over the single speed (the most common single speed version being optimized for high altitude work). It is not until Hooker does his bit that things improve for the Merlin and that is about the middle of 1940. The improved single speed engines (40 series) and two speed engines (XX or 20 series) engines are what is first contracted for with Packard. The American versions power the P-40F. Please note introduction dates for the P-40F and then figure performance for a P-51 with that engine and not the later 2 stage engines.
> 
> ...



How were the Daimler-Benz DB series of engines performing during these times?
If the DB's were performing as well or better, how was that being achieved?


----------



## Shortround6 (Jan 26, 2010)

Markus said:


> In April 1942 2,000 two stage Allison engines were ordered. The V-1710-47´s critical altitude was 22,400ft. Early 43 seems doable IF someone make an effort to get the engine ASAP.



The V-1710-47 turned out not be a production engine. By the time they got it straightened out other improvements had been worked in and a later model number was the first production engine.


----------



## billswagger (Jan 26, 2010)

Vincenzo said:


> Spit V it's the contemporary of P-40B, there is some wrong in the claim
> 
> and afaik there was little difference in turn within Spit I and V



Hmm, not sure of that either. From what i read the P-40 could turn with spits and dive with 109s, it just suffered in climb. 
This changed as fighters got bigger engines and increased in performance, where the P-40 fell behind,
although other comparisons put the P-40 as having better range and offering more protection to the pilot and engine with armor plating. 


Bill


----------



## Shortround6 (Jan 26, 2010)

gjs238 said:


> How were the Daimler-Benz DB series of engines performing during these times?
> If the DB's were performing as well or better, how was that being achieved?



The Early DB engine's superchargers didn't perform any better or worse than the superchargers on the early Merlins and Allisons. The larger displacement, slower turning DB engines didn't need as much boost to make their rated power however. A Merlin using 6lb of boost is running at 1.4 Ato as is an Allison at just 42in. The more boost used to make rated power the lower the ceiling a given pressure ratio supercharger is going to work. Once the British and Americans start going to 12lbs of boost or 50in plus of manifold pressure to make rated power either the altitude performance suffers (or more accurately low altitude performance improves but high high altitude does not) or improved superchargers are needed. 
The Germans with their lower manifold pressure needs can keep up the pressure to higher altitudes using the same basic supercharger. The Germans did improve their superchargers too as the war went on. A better impeller or a different diffuser design or even just a better inlet geometry could give small but useful improvements without any out change in appearance or weight.


----------



## Vincenzo (Jan 26, 2010)

billswagger said:


> Hmm, not sure of that either. From what i read the P-40 could turn with spits and dive with 109s, it just suffered in climb.
> l



not sure of P-40B it's contemporary of V? or that turning performance of V and I are similar?
afaik P-40B can't turn with spit I or also V or best can turn but it's beat to spit, this generally talking, it's every possible that a pilot with a P-40B can turn and win a pilot with spit for many reasons.


----------



## gjs238 (Jan 26, 2010)

Shortround6 said:


> The Early DB engine's superchargers didn't perform any better or worse than the superchargers on the early Merlins and Allisons. The larger displacement, slower turning DB engines didn't need as much boost to make their rated power however. A Merlin using 6lb of boost is running at 1.4 Ato as is an Allison at just 42in. The more boost used to make rated power the lower the ceiling a given pressure ratio supercharger is going to work. Once the British and Americans start going to 12lbs of boost or 50in plus of manifold pressure to make rated power either the altitude performance suffers (or more accurately low altitude performance improves but high high altitude does not) or improved superchargers are needed.
> The Germans with their lower manifold pressure needs can keep up the pressure to higher altitudes using the same basic supercharger. The Germans did improve their superchargers too as the war went on. A better impeller or a different diffuser design or even just a better inlet geometry could give small but useful improvements without any out change in appearance or weight.



So I guess it comes down to the old adage, "there's no replacement for displacement?"
I assume the DB engines were heavier as well?
If so, it sounds like they performed very well despite the weight - while not suffering the supercharger/turbocharger issues.


----------



## Clay_Allison (Jan 26, 2010)

Markus said:


> Why do you want to pay RR 6,000 $ per engine if the V-1710 just needs an aux. stage supercharger and an intercooler to be as good? The Allison was stuck with the lesser supercharger not because of technical reasons but because the USAAF did not want a better one. They had 100% faith in the turbocharger and even objected to Allison developing altitude rated engines.



Pay? Owe. Big difference. Take it out of the lend lease they still haven't paid off. (They haven't screwed us out of it, they make payments very slowly because our rate of inflation is higher than the interest)

The Aux-Stage supercharger only worked so soon on the Merlin because the Vulture Supercharger happened to be the perfect size for the Merlin. Ask Shortround about it. In order to develop the same for the V-1710, it would take much more development time/cost.


----------



## Shortround6 (Jan 27, 2010)

gjs238 said:


> So I guess it comes down to the old adage, "there's no replacement for displacement?"
> I assume the DB engines were heavier as well?
> If so, it sounds like they performed very well despite the weight - while not suffering the supercharger/turbocharger issues.



The early DB engines were quite similar in weight. While engine designers might argue about power per cu. in or liter, the aircraft designer was much more interested in power per pound of engine weight.

DB and Junkers used a different approach. AS did Hispano.

The smaller, high revving engines were actually in the minority.

The DB engines (and Junkers) had critical altitudes several thousand feet higher than the Merlin/Allison but without NO2 systems could not really compete with two-stage-engines in the altitude race.


----------



## Clay_Allison (Jan 27, 2010)

Could the Allison have been bored out to ~2000 CID (similar to the R-1830 becoming the R-2000)? An Allison V-2000 could have had a pretty high critical altitude if it was possible. I know the engine types are different, and I am asking for even more, but could it be done?

Alternately, what if we had bought the patent for the RR Griffon with its huge 36L displacement?


----------



## Colin1 (Jan 27, 2010)

Clay_Allison said:


> Could the Allison have been bored out to ~2000 CID


Re my post #275
regarding low mechanical strength I'd hazard a guess unlikely


----------



## tomo pauk (Jan 27, 2010)

Clay_Allison said:


> ...
> 
> Alternately, what if we had bought the patent for the RR Griffon with its huge 36L displacement?



36L was medium/small displacement for a better part of ww2 - only when compared with Merlin's 27L it looks huge. Griffon was to late for US planes, since R-2800 Merlin already filled the needs perfectly.


----------



## Colin1 (Jan 27, 2010)

tomo pauk said:


> Griffon was to late for US planes, since R-2800 Merlin already filled the needs perfectly


I still think it's a shame NAA didn't consider building a P-51 around it


----------



## Shortround6 (Jan 27, 2010)

Clay_Allison said:


> Could the Allison have been bored out to ~2000 CID (similar to the R-1830 becoming the R-2000)? An Allison V-2000 could have had a pretty high critical altitude if it was possible. I know the engine types are different, and I am asking for even more, but could it be done?
> 
> Alternately, what if we had bought the patent for the RR Griffon with its huge 36L displacement?



If the bore spacing was big enough to allow it, it might have been possible, if the bore spacing wasn't big enough then you are dealing with essentially a new engine. 

As a for instance, many sources say that the R-R Vulture used Kestrel/Peregrine cylinder blocks which used 5in dia. pistons. It didn't, While the Vulture did use 5in dia. pistons it's cylinder blocks were sized to allow the use of 5.4in dia. pistons in a later (never built) version. Using the larger pistons would mean a cylinder block 2in longer between the 1st and last cylinder centers even if the spaces between the cylinders was kept the same compared to the Kestrel/Peregrine. 

The Griffon used the same bore and stroke as the late 20s Buzzard and the racing "R", as well as the overhead cams and 4 valves per cylinder, not sure how much else carried over.

Packard had built aircraft engines of up to 2500 cu in during the 20s and 30s but got little or no sales.


----------



## Colin1 (Jan 27, 2010)

Clay_Allison said:


> Could the Allison have been bored out to ~2000 CID?





Shortround6 said:


> If the bore spacing was big enough to allow it, it might have been possible, if the bore spacing wasn't big enough then you are dealing with essentially a new engine


Umm, well, OK...
assuming that there was some spare diameter, how would this affect the mechanical strength issue?


----------



## Cromwell (Jan 27, 2010)

Shortround6 said:


> The Early DB engine's superchargers didn't perform any better or worse than the superchargers on the early Merlins and Allisons. The larger displacement, slower turning DB engines didn't need as much boost to make their rated power however. A Merlin using 6lb of boost is running at 1.4 Ato as is an Allison at just 42in. The more boost used to make rated power the lower the ceiling a given pressure ratio supercharger is going to work. Once the British and Americans start going to 12lbs of boost or 50in plus of manifold pressure to make rated power either the altitude performance suffers (or more accurately low altitude performance improves but high high altitude does not) or improved superchargers are needed.
> The Germans with their lower manifold pressure needs can keep up the pressure to higher altitudes using the same basic supercharger. The Germans did improve their superchargers too as the war went on. A better impeller or a different diffuser design or even just a better inlet geometry could give small but useful improvements without any out change in appearance or weight.



If you can get a back-copy of 'Aeroplane' from May 2005 (VE Day Special) there is an article called 'Developing Power' all about DB and the 109

From 1934 to 44 power of the DB went from 850 hp to 2,000 hp

A lot of this was due to Water and Methanol - MW50 - and N2O or Nitrous Oxide.

MW50 - This is another way of getting round the Detonation problem - especially without High Octane fuels to hand. It also increases the Fuel/Air Mass that you can cram into a cylinder

N2O - 25% increase in power at Altitude due to releae of Oxygen from the Nitrous Oxide

This is *still* something of a secret held by DB - _even to this day_


----------



## Shortround6 (Jan 27, 2010)

Colin1 said:


> Umm, well, OK...
> assuming that there was some spare diameter, how would this affect the mechanical strength issue?



It sure wouldn't help

Various parts of the Allison were beefed up as production continued and new models came out. Sort of a question of when the bore job was done. With a late model engine it might have been OK.

Larger diameter cylinders are harder to cool however. A higher ratio of volume to surface area. The larger, heavier pistons aren't going to help bearing loads either. Not that these can't be solved but it might not be quite as easy a a new set of pistons and running a boring bar through the cylinder liners.


----------



## Shortround6 (Jan 27, 2010)

Cromwell said:


> If you can get a back-copy of 'Aeroplane' from May 2005 (VE Day Special) there is an article called 'Developing Power' all about DB and the 109
> 
> From 1934 to 44 power of the DB went from 850 hp to 2,000 hp
> 
> ...



Thank you for the suggestion. 

Some other engines went through a similar increase. 

The Water/ Methanol method was used by a number of American planes and offered some real improvement when combined with an inter-cooler. Inter-coolers also allowed for some high speed-high altitude cruise settings without worry over exhausting supply.

For high altitude work the N2O does show a good increase but unless the boost needed is of short duration the installation may compete with turbos and inter-coolers for weight. The longer the endurance needed the better the turbo/intercooler set-up looks.

I am not sure how much of a secret N2O still is given the amount of use it gets in street performance cars.


----------



## Elvis (Jan 28, 2010)

Shortround6 said:


> a problem with the Merlin/P-51 dream is timing.
> 
> In 1938-39 the Merlin was a single speed-single stage engine that showed little difference in potential from the Allison. A two-speed single stage version was on offer but in it's original form it showed very little difference in altitude performance over the single speed (the most common single speed version being optimized for high altitude work). It is not until Hooker does his bit that things improve for the Merlin and that is about the middle of 1940. The improved single speed engines (40 series) and two speed engines (XX or 20 series) engines are what is first contracted for with Packard. The American versions power the P-40F. Please note introduction dates for the P-40F and then figure performance for a P-51 with that engine and not the later 2 stage engines.
> 
> ...


Exactly.
Very Succinctly stated, Shortround.
What's too bad is that an inter/after-cooled "-45" and later varients of the Allison weren't available by, say, late '42. If it had, maybe dependency on the Merlin series 60 wouldn't have been such a large factor.

One last note - In some earlier discussion, it seemed some here were trying to "re-design" the P-40 into, essentialy, a "P-51 type" aircraft.
Why?
If you want the performance factors of a P-51, get a P-51!
This does not say that the P-40 was a "bad" aircraft.
In fact, there are numerous reports (some of which were quoted in some of those earlier posts) of P-40's being able to dogfight with 109's with no problem, as long as the 109 kept within the P-40's altitude range.
One thing a 109 pilot always had in his back-pocket was the ability to jet up to 25-30K feet faster than you!
Going with a two-speed/two-stage engine takes that away from the 109.


Elvis


----------



## Clay_Allison (Jan 28, 2010)

tomo pauk said:


> 36L was medium/small displacement for a better part of ww2 - only when compared with Merlin's 27L it looks huge. Griffon was to late for US planes, since R-2800 Merlin already filled the needs perfectly.



For a V-12 it's huge. Merlin: 27L; Allison: 28L; Hispano 36L; Klimov 35L; DB601 34L.


----------



## Markus (Jan 28, 2010)

Clay_Allison said:


> Pay? Owe. Big difference. Take it out of the lend lease they still haven't paid off. (They haven't screwed us out of it, they make payments very slowly because our rate of inflation is higher than the interest)



I´m afraid pay it will be. LL wasn´t "on" before 1941. You wanted to kill the V-1710 before the war. That means the US manufacturer has to pay RR royalties and since we talk about a contract between two private companies the UK´s LL debt does not even come into play.


----------



## Clay_Allison (Jan 28, 2010)

Markus said:


> I´m afraid pay it will be. LL wasn´t "on" before 1941. You wanted to kill the V-1710 before the war. That means the US manufacturer has to pay RR royalties and since we talk about a contract between two private companies the UK´s LL debt does not even come into play.


Well, if the US govt' wanted Merlins or Griffons, Allison or whomever would have to make Merlins or Griffons. If a slightly higher unit cost were to come from royalties, they can make it up by not having so many planes shot down in North Africa.


----------



## Markus (Jan 28, 2010)

Elvis said:


> One last note - In some earlier discussion, it seemed some here were trying to "re-design" the P-40 into, essentialy, a "P-51 type" aircraft.
> Why?
> If you want the performance factors of a P-51, get a P-51!
> 
> ...



True but the Mustang I entered production in mid-41, the Brits got the idea of putting a Merlin into it a year later and the "result" did not see combat before the end of 1943. IMO a good reason to continue to improve the P-40. Another is that we have the benefit of hindsight, contemporary decision makes could not have been sure about the huge success of the P-51B.


----------



## Markus (Jan 28, 2010)

Clay_Allison said:


> Well, if the US govt' wanted Merlins or Griffons, Allison or whomever would have to make Merlins or Griffons. If a slightly higher unit cost were to come from royalties, they can make it up by not having so many planes shot down in North Africa.



P-40F did quite well in NA as a whole. Very well below 20,000ft, not so well above but for that task enough Spits were around. And regarding the cost, the cheapest sollution is still an earlier effort to make aux-stage SC for the Allison. Something Allison considered necessary as early as 1938.


----------



## Clay_Allison (Jan 28, 2010)

Markus said:


> P-40F did quite well in NA as a whole. Very well below 20,000ft, not so well above but for that task enough Spits were around. And regarding the cost, the cheapest sollution is still an earlier effort to make aux-stage SC for the Allison. Something Allison considered necessary as early as 1938.


If that were possible, yes. Shortround seems to consider that task 150% IMPOSSIBLE.


----------



## Markus (Jan 28, 2010)

Clay_Allison said:


> If that were possible, yes. Shortround seems to consider that task 150% IMPOSSIBLE.



The first Allison with an aux-stage SC actually existed and worked in mid-42. Ok,the critical altitude was not just as good as the Merlin´s but that was fixed with the next version.


----------



## Shortround6 (Jan 28, 2010)

Markus said:


> The first Allison with an aux-stage SC actually existed and worked in mid-42. Ok,the critical altitude was not just as good as the Merlin´s but that was fixed with the next version.




having one engine in flight test (or even 6 engines in flight test) is not the same as as rolling them out door a dozen a day. 

Allison had a few advantages and a number of disadvantages during this period. Back in the late 20s and early 30s they had subcontracted supercharger production for GE, that is they fabricated superchargers to GE designs for deliver to other engine manufacturers. Advantage in manufacturing knowledge but not in design knowledge. GE supercharges weren't particularly good. A number (Both?) of other engine makers abandoned the GE designs and started designing their own as did Allison. Allison was a small company under going enormous expansion in 1939 as were the other major engine makers.

P&W quadrupled their floor space in under two years. Allison built an entire new plant for production and that one only sufficed for war production because so much of the Allison engine was contracted out to other GM divisions. Many of these plants did not have enough engineers to start with and with such rapid expansion getting enough new ones was a problem. 

Allison got caught in several production problems. in Early 1939 the actual number of engines either delivered or on order was very small. Of these engines there were 5 or 6 different models, so in an attempt to squeeze some profit out of what they were making Allison had taken the approach of building a central power section and then adding accessories (gear drives, extension shafts and the like ) to this central, standard section. For people who say this was short sighted it is good to remember that R&D contracts are not like today. Back then the Army only paid for the successful completion of a test, if then. If a test engine blew up on the test stand the company had to supply a replacement at it's own expense. in the spring of 1939 (months after Allison had decided a 2 stage supercharger might be needed) the Army was over 900,000 dollars in arrears to Allison and weaseled out of paying this by getting Allison to forgive the debt in return for allowing Allison to export the V-1710 to France and England.

Allison started by trying to use the same size impeller in the aux stage as on the engine (sharing of parts to save costs?) but had to change to a larger diameter impeller. They also changed the drive system. They went from a single speed drive for the auxiliary stage to a hydraulic variable speed (much like the DB supercharger drive). there were many other changes along the way. the -47 model went through engineering changes A through G. The final supercharger system may have been better than the R-R system in terms of power used at lower altitudes and less power fluctuation with altitude ( smooth curve vrs a saw tooth profile) but didn't force a change in the central power section (engine block) but was not as economical in space/volume and did not incorporate an inter-cooler, not for lack of trying. The subcontractor/s failed to deliver a workable unit in spite of months of time spent. 

As far as just throwing more money, some things just weren't available. At one point Allison had orders from the Government and overseas for several thousand engines and enjoyed an "A1A" priority rating rating and yet was still short around 800 machine tools to fill existing factory space.


----------



## Clay_Allison (Jan 28, 2010)

> As far as just throwing more money, some things just weren't available. At one point Allison had orders from the Government and overseas for several thousand engines and enjoyed an "A1A" priority rating rating and yet was still short around 800 machine tools to fill existing factory space.



What is unknowable is if throwing more money AND TIME at the problem might have been enough. Make AUX supercharging a priority in 1938 and you may have it by Jan 1942.


----------



## Cromwell (Jan 28, 2010)

Shortround6 said:


> Thank you for the suggestion.
> 
> Some other engines went through a similar increase.
> 
> ...



I wondered about that 

- But apparently to this day no-one has quite figured out how DB could get so much power out of their engines with such rough aviation fuel made from coal mostly.

You can read it all in the article I referred to above in Aeroplane.


----------



## Cromwell (Jan 28, 2010)

Cromwell said:


> I wondered about that
> 
> - But apparently to this day no-one has quite figured out how DB could get so much power out of their engines with such rough aviation fuel made from coal mostly.
> 
> You can read it all in the article I referred to above in Aeroplane *.




* Footnote: I refer to that magazine as a reference source not to promote sales in a commercial context.


----------



## Cromwell (Jan 28, 2010)

Clay_Allison said:


> I was thinking about the P-40 and the reasons it wa considered a stopgap at best. What if, though, the P-40 had been reengined, not with the Merlin (as in the P-40F) but with the RR Griffon (if it had been turned over to an American comany for development when it was de-prioritized). Would that have worked?



It is true that engines can make all the difference, even the Bloomin awful 'Beef-alo' responded to the Wright 1820

See the following from Military History Encyclopedia on the Web 

_"F2A-2

This was by far the best version of the Buffalo. It had a more powerful Wright R-1820-40 engine, producing 1,200 hp. This increased its top speed to 344 mph at 16,500 feet, making it quicker than the F4F Wildcat."_

This is as fast or possibly faster than the Hurricane, which was Merlin powered as you know.


----------



## Clay_Allison (Jan 28, 2010)

It's funny but I've come full circle back to the conclusion that a Griffon powered P-40 would have provided the power and altitude performance to make it competitive and keep it competitive as the power plant produced more and more horsepower.


----------



## Cromwell (Jan 28, 2010)

Clay_Allison said:


> It's funny but I've come full circle back to the conclusion that a Griffon powered P-40 would have provided the power and altitude performance to make it competitive and keep it competitive as the power plant produced more and more horsepower.



Personally I am amazed at the complexities (of WW2 engines) that these forums constantly throw up.

There are some highly knowledgable people on here, and the arguments and counter-arguments rage on for weeks sometimes.

For example, I never realised how much Allison struggled to keep up with the game. Really it was a bit of a mess.

But then - It makes you wonder how Packard managed to get their act together so relatively quickly ?


----------



## Colin1 (Jan 28, 2010)

Clay_Allison said:


> It's funny but I've come full circle back to the conclusion that a Griffon powered P-40 would have provided the power and altitude performance to make it competitive and keep it competitive as the powerplant produced more and more horsepower.


An expensive waste of powerplants
the Griffon would be getting the best out of the airframe, the airframe would not be getting the best out of the Griffon. Airframe refinement easily kept pace with powerplant development, allowing the match-up to get the best out of each other; just dropping a cutting-edge powerplant into a mid-30s airframe would put you at a disadvantage to your enemies who've considered the aerodynamic aspects.

The Mustang I with the V-1710-39 was around 30mph faster than the P-40E with the same powerplant.


----------



## Cromwell (Jan 28, 2010)

Colin1 said:


> An expensive waste of powerplants
> the Griffon would be getting the best out of the airframe, the airframe would not be getting the best out of the Griffon. Airframe refinement easily kept pace with powerplant development, allowing the match-up to get the best out of each other; just dropping a cutting-edge powerplant into a mid-30s airframe would put you at a disadvantage to your enemies who've considered the aerodynamic aspects.
> 
> The Mustang I with the V-1710-39 was around 30mph faster than the P-40E with the same powerplant.



For some reason, some airframes just 'max out' and you just have to go an light your fire somewhere else

I think the P40 was as good or as flawed as the Hurricane - best kept for ground attack beyond a certain point as the designs were not going to get much better or give you much more either.

Then run for home and pray you don't get bounced


----------



## Markus (Jan 28, 2010)

Shortround6 said:


> having one engine in flight test (or even 6 engines in flight test) is not the same as as rolling them out door a dozen a day.



Sure, but "Vees for Victory" says 2,000 V-1710-47 were actually ordered in April 1942. That strongly indicates the engine was ready. Even if it was 100% ready, neither was the P-51B. Her production did not begin until a full year later. Plenty of time for Curtiss-Wright to improve the P-40 more than in OTL. 

@Cromwell:

I disagree, the XP-40Q made 422mph at 20,000ft, not 25,000ft thus I´m convinced the Warhawk had a lot of unused potential.


----------



## Colin1 (Jan 28, 2010)

Markus said:


> the XP-40Q made 422mph at 20,000ft... ...the Warhawk had a lot of unused potential


Which would remain unused
the P-51D was available by 1944 and it was flying faster, higher and further. The XP-40Q was pushed as far as it could be pushed by a small team of dedicated Curtiss engineers and USAAF test pilots; Curtiss themselves weren't interested by this stage.


----------



## Markus (Jan 28, 2010)

Colin1 said:


> Which would remain unused
> the P-51D was available by 1944 and it was flying faster, higher and further. The XP-40Q was pushed as far as it could be pushed by a small team of dedicated Curtiss engineers and USAAF test pilots; *Curtiss themselves weren't interested by this stage.*



First, this is a "what if", so we assume C-W was interested. Second, if the plane can make [email protected] it will be faster at a higher altitude iif the engine is rated for a higher altitude. Some Allisons were some were not as the customers prefered max. performace at 20,000ft. Third, IIRC the P-51B was not that available at first. All went to the UK for some time, resulting in complaints from the Med for example.


----------



## Colin1 (Jan 28, 2010)

Markus said:


> First, this is a "what if", so we assume C-W was interested. Second, if the plane can make [email protected] it will be faster at a higher altitude if the engine is rated for a higher altitude


Thank you
if Curtiss hadn't realised by 1944 that the war in the ETO was raging 5,000ft higher than your XP-40Q was capable of flying at then Curtiss's interest is a what-if too far


----------



## Clay_Allison (Jan 29, 2010)

Colin1 said:


> An expensive waste of powerplants
> the Griffon would be getting the best out of the airframe, the airframe would not be getting the best out of the Griffon. Airframe refinement easily kept pace with powerplant development, allowing the match-up to get the best out of each other; just dropping a cutting-edge powerplant into a mid-30s airframe would put you at a disadvantage to your enemies who've considered the aerodynamic aspects.
> 
> The Mustang I with the V-1710-39 was around 30mph faster than the P-40E with the same powerplant.



It does immediately beg the question, if you can have a Griffon engined P-40F, why not a Griffon engined P-51A? Talk about a bat out of hell.


----------



## Shortround6 (Jan 29, 2010)

Markus said:


> Sure, but "Vees for Victory" says 2,000 V-1710-47 were actually ordered in April 1942. That strongly indicates the engine was ready. Even if it was 100% ready, neither was the P-51B. Her production did not begin until a full year later. Plenty of time for Curtiss-Wright to improve the P-40 more than in OTL.
> 
> @Cromwell:
> 
> I disagree, the XP-40Q made 422mph at 20,000ft, not 25,000ft thus I´m convinced the Warhawk had a lot of unused potential.



A lot of engines were ordered before they were really ready. For instance it wasn't until July of 1942, 2-3 months later that Allison decided to replace the single speed aux supercharger drive with the variable hydraulic drive on the -47. The -47 also had an intercooler as part of it's specifications at times ( the specifications were amended a number of times) but no intercooler was fitted to any flying example of the -47 or it's immediate successors.


----------



## Elvis (Jan 29, 2010)

Shortround6 said:


> having one engine in flight test (or even 6 engines in flight test) is not the same as as rolling them out door a dozen a day.


Thank you for stating that. 
After all the conversation that's gone on about the V-1710-45 engine, what you stated MUST be understodd going into the conversation to begin with. 



Shotrround6 said:


> Allison got caught in several production problems. in Early 1939 the actual number of engines either delivered or on order was very small. Of these engines there were 5 or 6 different models, so in an attempt to squeeze some profit out of what they were making Allison had taken the approach of building a central power section and then adding accessories (gear drives, extension shafts and the like ) to this central, standard section.


This sounds very much like the design of the Detroit 2-stroke....and who was paired with them, back when they were owned by GM?...oh yeah, _Allison_.
Co-ink-E-? Maybe. Interesting how that "thought train" seems to transition so smoothly, though...doesn't it?



Shortround6 said:


> For people who say this was short sighted it is good to remember that R&D contracts are not like today. Back then the Army only paid for the successful completion of a test, if then. If a test engine blew up on the test stand the company had to supply a replacement at it's own expense. in the spring of 1939 (months after Allison had decided a 2 stage supercharger might be needed) the Army was over 900,000 dollars in arrears to Allison and weaseled out of paying this by getting Allison to forgive the debt in return for allowing Allison to export the V-1710 to France and England.


I believe the term is "built on spec". This is exactly why there is no longer an Amercian Bantam Company in existence.


Shortround, one other thing I wanted to comment on.
In an earlier post, you touched a little on Packard's experience building large displacement engines and mentioned a 2500 cu.in. V-12 aircraft engine they made back in the 20's.
Was this the same engine as the 2500 cu.in. V-12 _Marine_ engine they made, at around the same time?
I know 3 were included with every PT boat that hit the waves. Also, I believe Gar Wood himself ran an extremely successful boat racing campaign during the mid-late 20's and possibly the early 30's, with the "Miss US", which used a couple of those big Packard Marine V-12's, too.

...oh yes, and before I forget, there was some earlier talk about the DB engines and how/why they made so much power.
I once did a little math concerning this and found out that 2205/1475, pretty much = 1150/1710, and that 1/2" added to 5.5" 6" = 2205, when the revised combination is multiplied by 12.
Just saying.



Elvis


----------



## Elvis (Jan 29, 2010)

Shortround6 said:


> A lot of engines were ordered before they were really ready. For instance it wasn't until July of 1942, 2-3 months later that Allison decided to replace the single speed aux supercharger drive with the variable hydraulic drive on the -47. The -47 also had an intercooler as part of it's specifications at times ( the specifications were amended a number of times) but no intercooler was fitted to any flying example of the -47 or it's immediate successors.


Sorry, seems like I missed this page of the thread.
Shortround, good point, but maybe a better question to ask, is what is Markus going to do with that 8 foot space between the engine and the propeller on the "-47" engine, when he tries to install it in a P-40?
THIS, I gotta see. 




Elvis


----------



## Markus (Jan 29, 2010)

Colin1 said:


> Thank you
> if Curtiss hadn't realised by 1944 that the war in the ETO was raging 5,000ft higher than your XP-40Q was capable of flying at then Curtiss's interest is a what-if too far



Please be so kind to fully quote what I wrote:



> First, this is a "what if", so we assume C-W was interested. Second, if the plane can make [email protected] it will be faster at a higher altitude if the engine is rated for a higher altitude. *Some Allisons were some were not as the customers prefered max. performace at 20,000ft.*



Ever heard of the V-1710-117? 




Elvis said:


> Sorry, seems like I missed this page of the thread.
> Shortround, good point, but maybe a better question to ask, is what is Markus going to do with that 8 foot space between the engine and the propeller on the "-47" engine, when he tries to install it in a P-40?
> THIS, I gotta see.
> 
> Elvis



Playing stupid I see!


----------



## Colin1 (Jan 29, 2010)

Markus said:


> Please be so kind to fully quote what I wrote





Markus said:


> First, this is a "what if", so we assume C-W was interested. Second, if the plane can make [email protected] it will be faster at a higher altitude iif the engine is rated for a higher altitude. Some Allisons were some were not as the customers prefered max. performace at 20,000ft. Third, IIRC the P-51B was not that available at first. All went to the UK for some time, resulting in complaints from the Med for example.



Thank you
if Curtiss hadn't realised by 1944 that the war in the ETO was raging 5,000ft higher than your XP-40Q was capable of flying at then Curtiss's interest is a what-if too far


----------



## Markus (Jan 29, 2010)

Colin1 said:


> Thank you
> if Curtiss hadn't realised by 1944 that the war in the ETO was raging 5,000ft higher than your XP-40Q was capable of flying at then Curtiss's interest is a what-if too far



Ok, I get it you don´t get the concept of a "what if".


----------



## Shortround6 (Jan 29, 2010)

Elvis said:


> I believe the term is "built on spec". This is exactly why there is no longer an Amercian Bantam Company in existence.



I am not sure it is the same thing. My understanding on "built on spec" is that the buyer either puts out a specification and invites proposals/prototypes or a company builds an Item it believes the buyer will want/need even if no specification has been issued. In Allison's case there were signed contracts detailing how much money was to be paid for what item and level of performance. As in engine model "X" will produce 1000hp at 3000rpm for "Y" number of hours. Fail to meet the conditions and the Army didn't have to pay.



Elvis said:


> Shortround, one other thing I wanted to comment on.
> In an earlier post, you touched a little on Packard's experience building large displacement engines and mentioned a 2500 cu.in. V-12 aircraft engine they made back in the 20's.
> Was this the same engine as the 2500 cu.in. V-12 _Marine_ engine they made, at around the same time?
> I know 3 were included with every PT boat that hit the waves. Also, I believe Gar Wood himself ran an extremely successful boat racing campaign during the mid-late 20's and possibly the early 30's, with the "Miss US", which used a couple of those big Packard Marine V-12's, too.



Yes it was the same engine. It differed from the Allison and most other WW II V-12s in that each each cylinder was separate rather than using a common cylinder block for each bank. They were surrounded by a common sheet metal water jacket however so this is not apparent when looking at the engine.


----------



## Colin1 (Jan 29, 2010)

Markus said:


> Ok, I get it you don´t get the concept of a "what if"


Yes, I do
but you stepped outside the bounds of the what-if (which is hardly illegal), furnishing us with some data on the XP-40Q appended with an opinion on the 'hawk fighter as a result of that data:



Markus said:


> I disagree, the XP-40Q made 422mph at 20,000ft, not 25,000ft thus I´m convinced the Warhawk had a lot of unused potential.



There is very likely some credence in your claim to unused potential, I just don't think Curtiss-Wright by that stage were inclined to try that hard to achieve it; to get from 422mph to 437mph (simply to match the P-51D on level flight speed), they would need to do something else to the XP-40Q.

My first port of call (in my uninformed opinion as a non-aerodynamicist) would be to adopt a conventional main undercarriage; I do not believe that getting from 400mph to 422mph is anywhere near as difficult as getting from 422mph to 437mph.

The next best thing to catch a V-1650-equipped P-51 is probably a V-1650-equipped XP-40Q and when we've finally secured one of those and nailed the speed @ altitude issue, we can start working on how we're going to defeat the P-51 on range.

This wasn't going to happen, the high minds at Curtiss-Wright were elsewhere.


----------



## Markus (Jan 29, 2010)

Colin1 said:


> There is very likely some credence in your claim to unused potential, I just don't think Curtiss-Wright by that stage *were* inclined to try that hard to achieve it; to get from 422mph to 437mph (simply to match the P-51D on level flight speed), they would need to do something else to the XP-40Q.
> 
> This wasn't going to happen, the high minds at Curtiss-Wright *were* elsewhere.



True, very true. In OTL C-W concentrated on replacing the P-40 with the XP-53/XP-60 whose prototypes had the following engines: XIV-1430, V-1650-1(two speed), V-1650-3(two-stage), V-1710-75(turbo), XV-2200 and R-2800. Than there were the XP-62 with an R-3350 begun in 1941, the XF14C again with an R-3350 and the XP-55.

But in an ATL C-W *could* have cancelled some of these planes and thus freed engineers to work on the P-40. IMO the XP-55 and -62 would have been logical candidates as they were supposed to be bombers interceptors. And between 1939 and 1942 no such thing as a German B-17 had been seen by anyone. Same goes for the Japanese.


----------



## Clay_Allison (Jan 30, 2010)

Shortround6 said:


> I am not sure it is the same thing. My understanding on "built on spec" is that the buyer either puts out a specification and invites proposals/prototypes or a company builds an Item it believes the buyer will want/need even if no specification has been issued. In Allison's case there were signed contracts detailing how much money was to be paid for what item and level of performance. As in engine model "X" will produce 1000hp at 3000rpm for "Y" number of hours. Fail to meet the conditions and the Army didn't have to pay.
> 
> 
> 
> Yes it was the same engine. It differed from the Allison and most other WW II V-12s in that each each cylinder was separate rather than using a common cylinder block for each bank. They were surrounded by a common sheet metal water jacket however so this is not apparent when looking at the engine.



Spec stands for speculation or more properly "Speculative Investment". The most common example is buying an empty lot in a new suburb and putting a house on it. 

For the purpose of the what if, he's implying that Allison anticipate the need better than the War Department would and spending their own money on development.


----------

