# Fighters Made in USA, for mid 1943: how would you do it?



## tomo pauk (Apr 1, 2011)

It's Dec 8th 1941. As a man responsible for production of fighters, you are tasked to develop a good-sized production of world-class fighters. Only US-produced ingredients allowed; you'd be able to use those Packard Merlins finally. 
Please look beyond P-51/F4U combo (those are still main contenders); the production lines for P-47 are already established, and good usage/development of P-39/40 is encouraged, since your allies would've used them too. Only single engined types, for sake of simplicity - P-38 can soldier on as it did historically.


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## tomo pauk (Apr 4, 2011)

I agree with most of the proposals 

My 1st proposal is the venerable P-40. 
The main plus is that we have it in production service, holding the line 'till better performers arrive. Some modifications are due, though.
No Merlins for P-40.
The next variant going to production (second half of 1942) will have oil cooler relocated in one wing root, akin to XP-60Q, enabling a shallower chin. 4 x HMG standard, provisions for 2 additional ones. Light alloy radiators when possible. Wings tips clipped. Possibility for stripped variant ( fuselage tank with with half of volume, cca 30 gal), reduced armor.
In the mean time Curtiss starts preparations to produce wings of P-51, in order to mate them with hull of P-40. With later single-stage V-1710s we can possibly touch 390 mph in mid 1943 service planes?
Curtiss will not build any P-47s. 

(for 1944 the two-stage V-1710s, hopefully with intercooler in front of a wing)


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## davebender (Apr 4, 2011)

Immediate needs.
.....P40 short range fighter.
.....P38 long range fighter.
Drop the P39 in favor of more P-40s.
Increase U.S. Merlin engine production. Let Allison know this engine will be replacing their V-1710 V12 if performance of the American designed engine doesn't improve. Commercial competition is a good thing.

The P-47 prototype is becoming very heavy and expensive. Merlin engines and Mustang airframes are readily available. Compare the performance of this combination with the XP47. The U.S. Army should set aside dislike of the USN and compare the F4U prototype also.

Assign someone competent to manage the U.S. 20mm cannon program, if that's possible.


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## tomo pauk (Apr 5, 2011)

I agree about P-38.
What quantity of fighers is assigned to combat units till Bell converts to P-40 production? If we want Bell to produce something else, P-51 is better choice anyway.
Agree about Merlin production; installing them (single-stage V-1610s) into P-40 is bad thing if you can install them in P-51.
Competition is good thing. Expecting that US public and GM would've seat idly is unlikely to happen, aside the thing that we need Allisons for 3 major fighters now. P-51A (with Allison engine in production by early 1943) has performance comparable with Spit IX and contemporary German opposition; the single stage Merlin on P-51 (the one available in quantity by early '43) won't beat that. 
P-47 (historically, almost to 1945) has it's drawbacks, I agree. Combat range, performance under 25K. In the availabilty of engines it has an edge vs. Merlin Mustang, and we need plenty of fighters. 
F4U is good choice, I agree. 
Ditto for 20mm program.


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## Glider (Apr 5, 2011)

tomo pauk said:


> I agree about P-38.
> Competition is good thing. Expecting that US public and GM would've seat idly is unlikely to happen, aside the thing that we need Allisons for 3 major fighters now. P-51A (with Allison engine in production by early 1943) has performance comparable with Spit IX and contemporary German opposition; the single stage Merlin on P-51 (the one available in quantity by early '43) won't beat that.


I was looking at a book on the 309th Fighter Squadron last week. They flew Spit IX and converted to the P51B. When this started the CO was away and the pilots checked out on the P51 and all of them wanted to kjeep the Spit IX, they appreciated the range but for a fight there was only one choice. When the CO returned he took up a P51 wrung it out and made a point of saying how much better the P51 was. The pilots thought that he must have banged his head, until it was pointed out that he was the CO and what did they expect him to say. 

Which is a long way of saying that the P51A unquestionably fast at low altitude but overall the Spit IX was clearly a better aircraft.


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## tomo pauk (Apr 5, 2011)

(not trying to bash Spit, nor to start P-51 vs. debate - we have plenty of threads about their merits)

Perhaps we are both wrong, I for stating P-51A as comparable performer, and you for stating Spit IX as overall better? 
Spit is clearly a better climber, plus it's slightly faster at altitude. P-51A is somewhat faster at lower alt. So I'll agree that Spit was better performer.
As for being overall better, the major disparity lies in combat ferry range. P-51A has clear edge here.

Bringing us at RAF/Allied missed opportunity for troubling Luftwaffe in 1943, Spit VIII, (un)used in ETO. Ditto for P-51A - sent in India China by mid 1943.


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## tomo pauk (Apr 5, 2011)

P-40s, reworked real ones:


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## tomo pauk (Apr 5, 2011)

Next is P-39. 
Two main shortcomings are low performance above 12-15K and combat range. Lack of fuel carried further hampers interception of planes flying at 20K and above, more so if proper early warning is lacking. So we need to have that turbo working, while relocating coolers in wings leaves space for fuel tanks. 
Oil coolers go in one wing. Glycol cooler in another; wing bulge is due here because of bigger bulk. 
Turbo version gets two under-wing drop tanks, since we'll need space for inter cooler just aft nose wheel well.
Armament is either 5 x .50 cals (3 in hull, 2 in wings), or cannon (20 or 37mm) plus 2 HMG in hull. 
Non-turbo version is built 'till turboed one is produced in quantity. With 1325 HP @ 25K, 400 mph looks achievable in second half of 1942. 
Stripped version (3 HMG, reduced armor) to catch Japanese high flyers.

Picture from a pdf about P-39, available on our site IIRC:


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## tango35 (Apr 5, 2011)

To have a fine fighter at the fontline, i would take the P-40; but i would also kick my scientists to develop the Lockheed L 133 !

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## Shortround6 (Apr 5, 2011)

tomo pauk said:


> I agree about P-38.
> What quantity of fighers is assigned to combat units till Bell converts to P-40 production? If we want Bell to produce something else, P-51 is better choice anyway.
> Agree about Merlin production; installing them (single-stage V-1610s) into P-40 is bad thing if you can install them in P-51.
> Competition is good thing. Expecting that US public and GM would've seat idly is unlikely to happen, aside the thing that we need Allisons for 3 major fighters now. P-51A (with Allison engine in production by early 1943) has performance comparable with Spit IX and contemporary German opposition; the single stage Merlin on P-51 (the one available in quantity by early '43) won't beat that.
> ...



People have to get over the idea that the US aircraft manufacturing was a "free" market in 1940-41. They also have to realize that production of large numbers of planes and engines took a long time to implement and production schedules could not be changed on a whim.
Allocation of machine tools and raw materials was already in place in 1940. Maybe if your companies bid is enough cheaper you can get the controlling authorities to change allocations. Trying to go out and buy the raw materials or machine tools in a "side deal" is going to get you arrested for black marketeering and your supplier charged with war profiteering. 
you can't " build it and they will come".

First P-40 With a Merlin engine flew on June 30 1941. While the first production plane doesn't roll out the door until Feb 1942 all the production tooling was ordered and most built before Dec 8th 1941. Allocations of aluminium and steel had been made to Allison and Packard during those months. If there were different radiators or oil coolers needed ( and the two engines did get rid of different amounts of heat through both oil and coolant from each other) then radiator and oil cooler odres had to have been place weeks or months before production starts. 
Just getting steel beams for a factory addition required Govt. approval. 

If you change Bell from P-39 production to P-51 production how many hundreds of P-39s don't get built? 
In the first 3 months of 1942 there were 343 P-38s built, 433 P-39s, 960 P-40s, 5 P-47s 220 P-51s and 234 F4Fs. 
Now consider it could take one to three months to get a plane from the factory door to a combat theater. 

also consider that there seems to be a 5 month gap Oct 42 to Feb 1943 when NO P-51s were delivered. first production P-51B comes out the door in May of 1943. There is a major shortage of two stage Merlins and airframes pile up at the factory waiting on engines. 
Despite Packard building over 800 single stage engines a month since July of 1942 production of Merlins falls to 608 in April 1943 and while production skyrockets in may it is not until July that two stage production exceeds 100 engines a month and not until Jan 1944 does production of two stage engines exceeds single stage engines.


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## tomo pauk (Apr 5, 2011)

Shortround6 said:


> People have to get over the idea that the US aircraft manufacturing was a "free" market in 1940-41. They also have to realize that production of large numbers of planes and engines took a long time to implement and production schedules could not be changed on a whim.
> Allocation of machine tools and raw materials was already in place in 1940. Maybe if your companies bid is enough cheaper you can get the controlling authorities to change allocations. Trying to go out and buy the raw materials or machine tools in a "side deal" is going to get you arrested for black marketeering and your supplier charged with war profiteering.
> you can't " build it and they will come".



That's fine with me 



> First P-40 With a Merlin engine flew on June 30 1941. While the first production plane doesn't roll out the door until Feb 1942 all the production tooling was ordered and most built before Dec 8th 1941.



Production tooling for P-40 with Allison Merlin differs about 5% or less, so no major issues here.



> Allocations of aluminium and steel had been made to Allison and Packard during those months. If there were different radiators or oil coolers needed ( and the two engines did get rid of different amounts of heat through both oil and coolant from each other) then radiator and oil cooler odres had to have been place weeks or months before production starts.
> Just getting steel beams for a factory addition required Govt. approval.



Both engines get produced as historicallly. If possible, in larger quantity, if not, historical quantity is fine with me.



> If you change Bell from P-39 production to P-51 production how many hundreds of P-39s don't get built?
> In the first 3 months of 1942 there were 343 P-38s built, 433 P-39s, 960 P-40s, 5 P-47s 220 P-51s and 234 F4Fs.
> Now consider it could take one to three months to get a plane from the factory door to a combat theater.



To quote myself:
_What quantity of fighers is assigned to combat units till Bell converts to P-40 production?_ 
That applies for Bell converting to building P-51s, obviously.



> also consider that there seems to be a 5 month gap Oct 42 to Feb 1943 when NO P-51s were delivered. first production P-51B comes out the door in May of 1943. There is a major shortage of two stage Merlins and airframes pile up at the factory waiting on engines.
> 
> Despite Packard building over 800 single stage engines a month since July of 1942 production of Merlins falls to 608 in April 1943 and while production skyrockets in may it is not until July that two stage production exceeds 100 engines a month and not until Jan 1944 does production of two stage engines exceeds single stage engines.



They waited for two stage Merlins.
Tough luck for Allies the P-40 ('stead of P-51s) received single stage Merlins, and that it was only 310 P-51As built. And mostly went to Asia.
P-51 is not yet covered by yours truly in this what-if...


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## Shortround6 (Apr 5, 2011)

I think you are missing the point, the decision to put the Merlin in the P-40 may have been made before the first production (initial British contract) ever flew. The Contract for the first 9000 Merlins from Packard called for 6000 to the British and 3000 to the Americans. Contract was signed in Sept of 1940, Just what are the Americans supposed to put those Merlins in besides P-40s in late 1940? Again you are allocating resources a year or more ahead of actual use and up to two years before combat use. Mustang prototype doesn't fly until Oct 26 1940, it crashes on 9th test flight Nov 20 1940. Next Mustang flight is May 25th 1941, just 35 days before first P-40 flight with Merlin. When do you decide the P-51 should get the Merlins and the Merlin P-40s go back to Allisons?


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## tomo pauk (Apr 5, 2011)

Indeed, you are right about Merlin allocation. 
The Merlins for P-51 will be then allocated on our start date, Dec 8th 1941; that leaves perhaps 500-700 Merlins for P-40 depending on how fast NAA can adapt the P-51 production line, or build new ones.


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## tomo pauk (Apr 7, 2011)

200 gal for P-39.
Ammo for wing gun is aft CoG, partially canceling out expanded-ammo issues caused by hull guns. Other wing is left mostly unchanged here (edit: for sake of comparison with historic P-39 wing):


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## Jugman (Apr 7, 2011)

Shortround6 said:


> also consider that there seems to be a 5 month gap Oct 42 to Feb 1943 when NO P-51s were delivered. first production P-51B comes out the door in May of 1943. There is a major shortage of two stage Merlins and airframes pile up at the factory waiting on engines.


 
The five month "gap" was do to A-36 production.


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## Shortround6 (Apr 8, 2011)

Jugman said:


> The five month "gap" was do to A-36 production.


 
Thank you for the correction.


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## drgondog (Apr 9, 2011)

Shortround - you may recall the A-36 'camel's nose under the tent' was because USAAF did not have dicretionary funds for more P-51s (fighters in general) - and NAA proposed a dive bomber where there were funds to be allocated were still avaialable - and USAAF wasn't in mood to buy more A-25 (SB2C) or A-24 (SBD). The situation arose before the P-51 line had to stop and the design changes for the dive flap were incorporated as a block CID (IIRC) but I will look it up.


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## CPWN (Apr 9, 2011)

Some other choices:

XP-47 with Allison engine
http://warbirdsforum.com/showthread.php?t=584

P-66 Vanguard
Vultee P-66 Vanguard - Wikipedia, the free encyclopedia

Curtiss P-60
Curtiss P-60 - Wikipedia, the free encyclopedia


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## tomo pauk (Apr 10, 2011)

I'll venture to say that P-47C is better bet for our time frame than XP-47, P-66 has some tough competition in P-39/40, while P-60 was offering nothing when comapred with what was already produced.


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## tomo pauk (Apr 11, 2011)

A few ideas about P-47, developed for our time frame (provided it doesn't get phased out after F4U gets introduced).
The main shortcomings noted by it's users were low rate of climb under 25K, combat range and cockpit visibility. The 'firm' solution for some performance issues can be introduction of water injection ( provided 2300 HP for historic P-47 in early 1944), along with paddle blade prop. The doc about Mr. Frank Walker states that water injection experiments were just started in early '43, so I won't add that here.
The introduction of the paddle blade prop seem like more doable affair for 'my' P-47C. The R/C of real P-47C was cca 2300 f.p.s. at SL (using 2000 HP - MIL power), declining slowly to 2000 f.p.s. @ 20K, while P-47D, paddle blade prop, 2000 HP (MIL), was capable to almost 2500 f.p.s. at SL, despite weighting 1000 lbs more. Dunno, perhaps additional 200 f.p.s. @ SL for my P-47 with new prop - keep the plane high, boys :\


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## tomo pauk (Apr 12, 2011)

The concept drawing for P-40 high-altitude, developed perhaps after the -C version. Complete installation is in chin, coolers relocated in wings. That, along with loss of hull MGs would've, at least partially, cancel out the shift of CoG after turbo is mounted.


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## Shortround6 (Apr 12, 2011)

a few problems. 
1. The turbo appears to be upside down.





the large pipe exiting to the right is the waste gate. Adding pipe to it to get it out side the airplane isn't that big a deal. All those blades/buckets is where the exhaust comes out when the turbo is actually working. You appear to have it pointed up at the crankcase of the engine. Not good for both cooling the exhaust turbine and cooling the engine itself. There is a reason most US turbo installations had that part of the turbo exposed to the outside air.

2. you are back to the short exhaust pipes to the turbo. Allison found in the turbo compound experiments, with the turbo behind the engine that exhaust gas temperature could exceed 1750 degrees F in the inlet to the turbo. 

3. The cowl .50 cal guns actually stuck through the upper corners of the instrument panel just a tiny bit. They were actually pretty much on the CG to begin with. Weight savings yes, CG shift no.


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## timshatz (Apr 12, 2011)

There really isn't much to do beyond putting the P40 up. If the P51/F4U are out of the picture, the P47 is already up and P38 is moving along, only the Packard engined P40 is left. Maybe the P63 but that was a fighter from a time gone by (local defense) and all the action was in the attack end of the world. 

If the P40 can make the trip from England into France, it might work. But it is an older design. Curtiss's P40 replacement might be a better call.


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## tomo pauk (Apr 12, 2011)

As already said, a concept drawing 

Now to the points:
1) the turbos for B-17 -24 were upside down, when compared with P-38 and worked fine (I know not same types/engines). Or we can move turbo slightly down, and top-down, so the duct inlets are above. That way we can make place for exhaust manifolds to be longer, applying a kind of more elaborate S shape for manifolds in same time. That also solves the issue #2.
3) Oil glycol coolers, radio, hydraulic tank pump, oxygen bottle - all can get relocated further aft. Plus the tail can get longer, as in later P-40s. The hull tank can grow slightly.


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## tomo pauk (Apr 12, 2011)

timshatz said:


> There really isn't much to do beyond putting the P40 up. If the P51/F4U are out of the picture, the P47 is already up and P38 is moving along, only the Packard engined P40 is left. Maybe the P63 but that was a fighter from a time gone by (local defense) and all the action was in the attack end of the world.
> 
> If the P40 can make the trip from England into France, it might work. But it is an older design. Curtiss's P40 replacement might be a better call.



I don't look at such a P-40 as some world beater, more a kind of back-up if some of new fighters have trouble to perform as advertised. 
Think all this sqetches are getting better of me 

I've taken a look only at 39, 40 and 47 so far


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## tomo pauk (Apr 12, 2011)

P-47 with some legs.
Two new fuel tanks for some 150-200 gals (520-570 internal total for 1943). Ideally, we can move the pilot back and put a bigger main tank in front, since all of this fuel would've disturbed CoG. All while praying that water injection is ready for summer of 1943


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## timshatz (Apr 12, 2011)

tomo pauk said:


> I don't look at such a P-40 as some world beater, more a kind of back-up if some of new fighters have trouble to perform as advertised.
> Think all this sqetches are getting better of me
> 
> I've taken a look only at 39, 40 and 47 so far



I agree with you. P40 has the main advantage of being available. But in the form of the late 30s/early 40s airframe, the old P36 version, it really wasn't a second gen aircraft. Needs a bit of reworking. But, as they say, the perfect is the enemy of the good enough. In the early war period, it was good enough. By 43, there were other birds out there that were better.


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## Shortround6 (Apr 13, 2011)

tomo pauk said:


> As already said, a concept drawing
> 
> Now to the points:
> 1) the turbos for B-17 -24 were upside down, when compared with P-38 and worked fine (I know not same types/engines). Or we can move turbo slightly down, and top-down, so the duct inlets are above.



The Turbo actually doesn't care if it is turbine up, turbine down, turbine left or right or turned so turbine/compressor shaft is parallel the engine crankshaft. What is important, both for the turbo turbine and for the rest of the engine, is getting rid of the exhaust gas in way that doesn't add heat to the engine compartment or any thing else you are trying to keep cool. And also provides a flow of cooling air over the turbine blades/buckets to keep them cool. The simplest way was to mount the turbo in such fashion as to have the exhaust from the turbine dump directly to the outside air. Here is a B-17 turbo.






You can see the wastegate open in the pipe. you can also see the amount of sheet metal 'cut away' in both this picture and the P-38 picture to provide cooling for the turbine section despite the drag penalty. You can hide the turbo inside the fuselage for better streamlining but you have to duct the exhaust out (both wastegate and turbine) and duct cooling air for the turbine into and out of the turbo "compartment".
I was in error on the earlier post, while Allison did go to 1725 degrees on the turbo compound experiments (not 1750) normal turbo operation for GE turbos was to keep turbine inlet temperatures to 1600 degrees max. 
You need adaquate sized exhausts to handle the flow and while an "S" bend snaky pipe may help the exhaust cooling it adds bulk and drag if outside the cowl, it doesn't cool as well if inside the cowl and the more restriction you put in the exhaust "system" the higher the back pressure at the exhaust ports which lowers power and hinders cooling of the exhaust valves which shortens their life. Allisons might be better at this last than some other engines. 

here is a Picture of the Curtiss XP-60A using an Allison V-1710-75 engine with planned turbo charger.

http://upload.wikimedia.org/wikipedia/commons/7/71/Curtiss_XP-60A_061024-F-1234P-016.jpg

This what the Curtiss engineers thought it would take to put a 1425hp turbo charged Allison into a single engined airframe BEFORE Pearl Harbor.


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## tomo pauk (Apr 13, 2011)

Don't see the pic of B-17 turbo 

The data about tha XP-60A is rare as hen's teeth. Care to add some? 
Judging at the pictures, XP-60A featured turbocharger behind/under pilot, unlike my proposal.

Here is another take on the turbo installation. Red 'tubes' depicts exhaust manifold, ducted to turbine (only one side deoicted), then exhaust over board, green 'tubes' show air inlet to compressor, then to inter-cooler and finally to carb, blue are cooling ducts (to i.-cooler and out). Note that exhaust tubing is curved at angles above 135deg:


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## tyrodtom (Apr 13, 2011)

I wonder how much the intercooler placed where you have could cool the intake charge ?
The intercooler is in between the exhaust pipe from each side of the engine, only a little back from the turbo itself, plus the cooling air for the intercooler passes right over the turbo unit, which would heat the cooling air even before it gets to the intercooler. Very compact, but probably not very efficent.

In addition placing the turbo directly below the engine, just separated by the intercooler cooling duct, which would carry some of that heat away ( into the intercooler), just doesn't seem too safe. Anything that leaks from the engine will end up in the bottom of the cowling, touch that very hot turbo, and instantly ignite.


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## tomo pauk (Apr 14, 2011)

Then we'll put a aluminum sheet under the engine, or maybe between turbo and i.-cooler intakes 

The cooler part of the turbo is near i.-cooler intakes anyway, so that shouldn't be that much an issue. P-38 had issues re. i.coolers, but it was able to pull 1325 1425 from deck to high alt, in 1942 and 1943 respectively.


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## tomo pauk (Apr 14, 2011)

My take on P-51:
All Packard Merlins allocated for the USAAC go there, once we have airframes (some time late 1942). As a back-up, if in 1943 airframe production surpasses that of engines, V-1710 geared for 15kft+ critical altitude. Adapt the airframe to carry 6 HMGs.
No A-36s; P-40 gets dive brakes if we lack funds for fighters. Start adjusting the airframe to two-stage Merlin, with Packard establishing new production lines for that engine, so we could field it in spring of 1943. Add hull fuel tank of size that doesn't hamper handling and performance too much. Perhaps having 21 (single stage PM : two stage PM : Allison) ratio between P-51 types at hand in mid 1943.


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## Shortround6 (Apr 14, 2011)

tomo pauk said:


> Don't see the pic of B-17 turbo



My appoligies, I am not very good at getting pictures to appear in the posts, sometimes they do and sometimes they don't. 


tomo pauk said:


> The data about tha XP-60A is rare as hen's teeth. Care to add some?



Data is a bit scarce and sometimes confusing. Most performance data is based on Curtiss "estimates" of performance because of the limited flight testing done. 
It also has some aspects that don't make sense to me. Like a service ceiling of 35,200ft for a turbocharged airplane?
Estimated speed was 420mph at 25,000ft and 324mph at sea level. Test flights were undertaken without the turbo after a small fire in ground running/taxi tests. Low altitude speed and climb (where the turbo doesn't add anything anyway) were described as disappointing. The Merlin powered XP-60 which used the same wing but a fuselage much closer to the P-40 was found to have it's wing not manufactured to the tolerances needed to gain any benefit from the laminar flow. Similar problem for the XP-60A? could it be fixed? 
Empty weight is given at 7,806lbs and normal gross as 9,616lbs which doesn't leave a lot of useful load. While there was tankage for 200 US gallons it seems this gross weight only included 116 US gals and ammo was only 200rpg. Climb seems in the 2500ft/min range. 



tomo pauk said:


> Judging at the pictures, XP-60A featured turbocharger behind/under pilot, unlike my proposal.


I believe it was. However the Curtiss company/engineers had built planes with the turbo under the engine, they were called YP-37s. 

http://www.aviastar.org/pictures/usa/curtiss_p-37.gif

Please note that these planes used the old "C" series engines with the longer gear case that positioned the prop 6 in lower than the -39 engine in the P-40E. Also that the turbo is located under the rear half of the engine, intercooler and radiators are located inside the fuselage over the wing leading edge. Area were the cockpit normally is has oil tanks, coolant header tanks and extra fuel tank normally behind pilot on P-36/40. Considering that this plane was built before the P-40 the Curtiss engineers may have had an idea of what they wanted to go were and why. Taking out the inboard guns in the wing and using the space for the radiators may help but anyway you look at it stuffing a turbo into a P-40 airframe is going to be a tight fit. difficult to maintain fighters (hanger queens) may not be what the USSAF needs in 1943


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## tyrodtom (Apr 14, 2011)

I think it would take more than a little aluminum sheet to isolate the heat from the turbo.

I've seen the exhaust portion of modern turbos get red hot under dyno pulls. WW2 era turbos probably operated at lower temps, but most installations i've seen locate them away from parts of the system that needs to be cool. You've surrounded that intercooler with every heat producing part a engine has.


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## tomo pauk (Apr 14, 2011)

Designing a plane around the turbo is always better than attacking a turbo installation at an existing plane type; F4U being an exception perhaps, since it appears it's turboed one-off was a good bird.
OTOH, having 500 of planes that do 1400 HP is better than having 100 ones with 1600, if one is fighting the war.


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## tomo pauk (Apr 14, 2011)

Thanks for the info, SR6 

Sticking a turbo into a SE plane, while not adding the bulk, produces either the low performance type, or the one with low fuel/ammo/armament contents, or a 'hangar queen'*, or a combination of those. At least that's what I've read about historical types. I've tried to use the bulky chin of P-40 to 'produce' not a world beater, but a good performer @ hi alt and hopefully easier to maintain than P-38.
If we add the bulk, we can go Republic's way


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## Shortround6 (Apr 14, 2011)

tyrodtom said:


> I think it would take more than a little aluminum sheet to isolate the heat from the turbo.
> 
> I've seen the exhaust portion of modern turbos get red hot under dyno pulls. WW2 era turbos probably operated at lower temps, but most installations i've seen locate them away from parts of the system that needs to be cool. You've surrounded that intercooler with every heat producing part a engine has.



Max exhaust gas inlet temperature for the WW II Turbos was 1600 degrees F, they glowed quite nicely at night


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## Shortround6 (Apr 14, 2011)

tomo pauk said:


> Thanks for the info, SR6
> 
> Sticking a turbo into a SE plane, while not adding the bulk, produces either the low performance type, or the one with low fuel/ammo/armament contents, or a 'hangar queen'*, or a combination of those. At least that's what I've read about historical types. I've tried to use the bulky chin of P-40 to 'produce' not a world beater, but a good performer @ hi alt and hopefully easier to maintain than P-38.



While a single engine plane will require less maintenance than a twin, if the twin has the parts spread out and decent access it may not be that much worse than a single with restricted access. I once had a car in which the simplest way to get the oil filter out was to disconnect a fuel line. When it was changed from right hand drive to left hand they ran the steering column through the area next to the oil filter


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## billswagger (Apr 18, 2011)

For the sake of using aircraft in a strictly fighter roll I would delegate P-40/39s to the front line and point defense positions and use P-51s and P-39s as interceptor and long range attack runs as well as escort fighters. I know the P-47 was still under developed and saw limited service by 1942, however it was still the only "fighter" plane that could fly higher than enemy aircraft and be a competitive performer in that roll and for that reason i would still delegate a significant portion of P-47s for top cover over combat areas. It wouldn't be til the Merlin 1650-9s were introduced where the P-51s could replace the P-47 in that roll.


bill


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## tomo pauk (Apr 20, 2011)

That would've been roughly my idea, too (the P-*38* instead of P-39 as interceptor/LR fighter - typo?).
The USAAC F4U would've been neat, I agree with opinions of many fellow members. The machine proved itself in Marine hands, so Army would've been just fine with it. Esp. with a dedicated land plane version, saving perhaps 300-500 lbs by deleting arrester gear and having non-foldable wings. The lower hull would've been also built lighter hopefully, since it wouldn't have to endure rough landings. Of course, birdcage needs replacement ASAP. The plane have had generous wings, so perhaps some wing cropping would've been good, now the plane is lighter, to extract some speed.
The main issue is where to produce it. With so many fighter types in production, perhaps having Vultee to build it would've been good? The plane can double as a dive bomber, too.


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## tomo pauk (Apr 25, 2011)

A glance at 'fresh air' ducting tunnel of the P-47 shows it takes plenty of space. So let's install a belly scoop to feed the turbo inter-cooler, and a new fuel tank is located now between exhaust ducts, instead of fresh air tunnel. The another fuel tank is between pilot's seat inter-cooler. With another 200-250 gals of fuel, belly drop tank is superfluous.


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## gjs238 (Apr 26, 2011)

Nice P-47 drawing.
What happens if you swap a V-1710 for the R-2800?
How much smaller/streamlined/lighter can the plane become?


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## tomo pauk (Apr 26, 2011)

We end up at something US-built Fairey Firefly - big plane with not enough power 
Okay, perhaps some 700-1000lbs can be shaved out, or only some 5-8% of take-off weight; 10% at best (ie. TO weight reduced at 90-95%). Some drag also.
In the same time, power is reduced at 71% (MIL), or 80% (WEP - a shortest time power setting), and that's for 1943; in 1944 P-47 develops extra 300 HP. Not that good for V-1710 

P-43 was perhaps the best airframe for turboed V-1710, but it never happened.


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## gjs238 (Apr 26, 2011)

That's what I was thinking.
Not literally swapping the V-1710 for the R-2800, but if the plane had evolved/developed with the V-1710.
Could be interesting.


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## tomo pauk (Apr 27, 2011)

Republic was offering (X)P-47A, basically what you propose; it was re-modelled to the (X)P-47B - Thunderbolt as we know it. Curtiss was offering the XP-60, in one of variants it sported turboed V-1710 - it was not accepted for mass production in any sort.

Such a plane, if properly designed, would've offered circa 400mph at altitude in early 1943 (1425 HP @ MIL; even more if/when 1600 HP @ WEP becomes available), with better mileage than P-47C. Perhaps just 6 x .50 cals - enough for the duty.


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## gjs238 (Apr 27, 2011)

A feasible, single-engine, V-1710 based, turbocharged aircraft seems to be elusive.


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## tomo pauk (Apr 27, 2011)

It was certainly feasible, but USAAC decided to pursue R-2800/Merlin/two-stage V-1710s path for the high-performance single-engined fighters.


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## gjs238 (Apr 27, 2011)

But that shouldn't stop you from designing one for us now


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## tomo pauk (Apr 27, 2011)

A sketch from one of previous threads, P-43 with V-1710 'stead of R-1830:


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## tomo pauk (Apr 27, 2011)

Rough schematics of 51 with turbo. Coolers in, now, deeper chin, exhaust ducted mostly externally towards turbo (fresh air ducting not shown), the compressed air goes to inter cooler, and then to carb.
Same idea applicable for P-40.


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## HBBates (May 7, 2011)

I would like to see a development of the P36/P40 as a cleaned up/lighter version of the P42 along the lines of the Fw190 La5/7 (copy that tight Fw190 cowl/power egg, jet exhaust stacks setup like ever one did)... make it an all Curtiss product using the 14 cyl R2600 that about matches up( and has some common history) with the BMW801 and Ash82 

Again think Fw190 La5/7 (I much perfer aircooled engines for combat aircraft because of ease of survice and they can take battle damage)


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## tomo pauk (May 8, 2011)

The P-40 (or P-36) R-2600 combo is discussed in some threads @ this sub forum; I've learned a lot there


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## P-39 Expert (Apr 11, 2018)

All that was needed for the P-39 was just remove the rifle caliber wing guns and probably the nose armor plate. Leave the rest of the armor plate and glass. The remaining guns (37mm cannon and twin .50s) were considered devastating by the Russians. The weight saved would have done wonders for climb and added a little speed, maybe 10mph.

Then take the Allison upgrade to 9.6 supercharger gears in late '42 and push hard for the mechanical two stage Allison that was in production in March '43. Keep the weight down (no .30 cal wing guns) and performance was good.

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## wuzak (Apr 11, 2018)

All they needed to do to the P-39 was to move the pilot forward a bit, move the prop to the rear, enlarge the fuel tank, add power, use a Y-tail (see Bugatti 100P to see what I mean), ditch the nose wheel, ditch all the piddly little machine guns (yes 0.50"s, that mean s you too) and the boat anchor (the 37mm cannon) and install 4 20mm canon, 2 on either side of the nose. Enlarge the wing if need be, and the radiator to cope with the extra power.

Still, probably, none of the western allies would want them.

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## Shortround6 (Apr 11, 2018)

P-39 Expert said:


> All that was needed for the P-39 was just remove the rifle caliber wing guns and probably the nose armor plate. Leave the rest of the armor plate and glass. The remaining guns (37mm cannon and twin .50s) were considered devastating by the Russians. The weight saved would have done wonders for climb and added a little speed, maybe 10mph.
> 
> Then take the Allison upgrade to 9.6 supercharger gears in late '42 and push hard for the mechanical two stage Allison that was in production in March '43. Keep the weight down (no .30 cal wing guns) and performance was good.




Hmmm, still doesn't solve the range problem.
Look at Russian fighters to get an idea of what they considered "devastating" Mig-3 one 12.7mm gun and two 7.62s. Early Laggs and Yaks, one 20mm and two 7.62mm. Some Yaks got one 20mm and one 12.7mm. La-5 had two 20mm guns, synchronised. 

You are expecting "wonders" from the removal of 200lbs worth of guns and ammo and under 100lbs or armor. 

Most other aircraft, while they did better with such a reduction in weight, did not move into the "wonder" catagory. 
You could take a MK V Spit and strap a 90 imp gallon tank under it (790lbs) and only loose around 500fpm of climb and in fact climb to 20,000ft changed from 8 minutes to 10 minutes. 
Taking out 300lbs from a 7600lb plane was not going to turn it into wonder plane

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## P-39 Expert (Apr 11, 2018)

For it to be a real benefit the weight would need to be around 7100#. A P-39F in production right around Pearl Harbor would do it. 
5409 empty
200 pilot with chute
70 oil
720 120gal fuel
580 37mm (300#), 2x.50 (275#) gunsight (5#)
130 armor plate and glass (not incl. 100# nose armor)
7109 Total gross wt.
The P-39C grossed 7075# and would climb at 3720fpm at 10000' which was 1000fpm better than a standard weight P-39K.

Regarding range, the P-39 held more internal gas than the Spitfire, Yak and Me109. Compared to a P-38F/G, after deducting the reserve for takeoff and climb to 5000' (25gal for P-38 and 16gal for P-39) the P-39 held only 21gal less fuel per engine.


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## pbehn (Apr 11, 2018)

Try removing the 200lb pilot and putting him in something else.

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## Shortround6 (Apr 11, 2018)

P-39 Expert said:


> For it to be a real benefit the weight would need to be around 7100#. A P-39F in production right around Pearl Harbor would do it.
> 5409 empty
> 200 pilot with chute
> 70 oil
> ...


The climb figures were for a plane grossing *6689 lbs.
*
You want to use a the numbers from WWII Aircraft Performance
Use them but don't twist them. 



> Regarding range, the P-39 held more internal gas than the Spitfire, Yak and Me109. Compared to a P-38F/G, after deducting the reserve for takeoff and climb to 5000' (25gal for P-38 and 16gal for P-39) the P-39 held only 21gal less fuel per engine.



Of course we will totally disregard the _FACT _that the P-38 did NOT have TWICE the drag of the P-39 and therefore did not need TWICE the fuel to fo the same distance????


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## P-39 Expert (Apr 11, 2018)

Shortround6 said:


> The climb figures were for a plane grossing *6689 lbs.
> *
> You want to use a the numbers from WWII Aircraft Performance
> Use them but don't twist them.
> ...


The 6689# is average fuel for the flight as I have explained before. I imagine the P-38 did have twice the drag as a P-39 and weighed 2.2x as much as this P-39. Fuel quoted was per engine on P-38.

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## Shortround6 (Apr 11, 2018)

P-39 Expert said:


> The 6689# is average fuel for the flight as I have explained before. I imagine the P-38 did have twice the drag as a P-39 and weighed 2.2x as much as this P-39. Fuel quoted was per engine on P-38.




Unless you can come up with a document or statement that *says* they were using average fuel weight for tests I am not buying it. 
We have given you the fuel consumption figures for the P-38 but since you don't like the results you choose to *imagine *that is has twice the drag_. _
weight is not drag as proved by the P-51 Allison Mustang 
1130hp at 12,650ft for a 8824lb plane was 390mph. WIththis gun installation




strangely with only two cannon installed and no armor(?) it weighed 8114lbs the engine gave 20more HP and the plane picked up a whopping 6mph. Due to lighter weight or less drag? 
http://www.wwiiaircraftperformance.org/mustang/P-51_41-37320_PHQ-M-19-1415-A.pdf

A P-38F clean at 15,000ft gets 5.7mpg at 190IAS/240 true.
..........................................3.57mpg at 225IAS/275 true.
...........................................3.0mpg at 255IAS/305 true.
as per the manual. 

Care to tell use what the P-39 got at comparable speeds/altitudes?

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## KiwiBiggles (Apr 11, 2018)

P-39 Expert said:


> The 6689# is average fuel for the flight as I have explained before. I imagine the P-38 did have twice the drag as a P-39 and weighed 2.2x as much as this P-39. Fuel quoted was per engine on P-38.


Oh God, it's started again.

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## pbehn (Apr 11, 2018)

KiwiBiggles said:


> Oh God, it's started again.


The same BS posted on any thread that can be in any way linked to a P-39.


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## P-39 Expert (Apr 11, 2018)

Shortround6 said:


> Unless you can come up with a document or statement that *says* they were using average fuel weight for tests I am not buying it.
> We have given you the fuel consumption figures for the P-38 but since you don't like the results you choose to *imagine *that is has twice the drag_. _
> weight is not drag as proved by the P-51 Allison Mustang
> 1130hp at 12,650ft for a 8824lb plane was 390mph. WIththis gun installation
> ...


Sure. P-39Q with gondola wing guns at 15000' gets 6.8mpg at 204IAS/265 TAS
5.5mpg at 219IAS/285TAS
4.2mpg at 247IAS/321TAS
Mine's bigger. What exactly are we trying to prove? 

By the way, do you have a P-38F/G manual? Would you mind sharing the Flight Operation Instruction Chart pages (clean and w/drop tanks)? Thanks in advance.


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## Glider (Apr 11, 2018)

Shortround6 said:


> Hmmm, still doesn't solve the range problem.
> Look at Russian fighters to get an idea of what they considered "devastating" Mig-3 one 12.7mm gun and two 7.62s. Early Laggs and Yaks, one 20mm and two 7.62mm. Some Yaks got one 20mm and one 12.7mm. La-5 had two 20mm guns, synchronised.
> 
> You are expecting "wonders" from the removal of 200lbs worth of guns and ammo and under 100lbs or armor.
> ...


Should Also note that the cog would Be Impacted and sorting That out will add weight


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## fubar57 (Apr 11, 2018)



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## Shortround6 (Apr 11, 2018)

P-39 Expert said:


> Sure. P-39Q with gondola wing guns at 15000' gets 6.8mpg at 204IAS/265 TAS
> 5.5mpg at 219IAS/285TAS
> 4.2mpg at 247IAS/321TAS
> Mine's bigger. What exactly are we trying to prove?


 You are trying to prove that the P-38 used twice the amount of gas per mile so that it's mere 30 gallons of fuel more per engine doesn't really give it much greater range.
But the fuel isn't figured at fuel per engine in this case. The P-38s fuel consumption is for the airplane/both engines so
P-39's 219 IAS/285 true is 5.5 mpg and that is not twice the 3.57mpg of the P-38 at 225IAS/275 true.

please note the difference between the IAS and true speeds. True speeds are from the P-38 manual chart and not a calculator. Perhaps the chart is wrong but that only makes the P-38 number better.

P-39's 247/321 true is 4.2 and that is not double the P-38s manual 255IAS/305 true of 3.0 mpg.

Please note if I use an online TAS calculator for 255IAS I get 331.5 true for a mileage of 3.28miles per gallon.

So no, the P-38 does not use twice as much fuel per mile just because it has twin engines and weighs twice as much.

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## tomo pauk (Apr 11, 2018)

P-39 Expert said:


> ...
> By the way, do you have a P-38F/G manual? Would you mind sharing the Flight Operation Instruction Chart pages (clean and w/drop tanks)? Thanks in advance.



Here: link.


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## P-39 Expert (Apr 11, 2018)

tomo pauk said:


> Here: link.


Thank you.


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## P-39 Expert (Apr 11, 2018)

Shortround6 said:


> You are trying to prove that the P-38 used twice the amount of gas per mile so that it's mere 30 gallons of fuel more per engine doesn't really give it much greater range.
> But the fuel isn't figured at fuel per engine in this case. The P-38s fuel consumption is for the airplane/both engines so
> P-39's 219 IAS/285 true is 5.5 mpg and that is not twice the 3.57mpg of the P-38 at 225IAS/275 true.
> 
> ...


Not trying to prove anything, you asked and I replied. All I said was the P-38 only had 21 more usable gallons of internal fuel per engine than a P-39. Then you went all numbers on me. If plane A gets 4MPG and plane B gets 3MPG then then plane A will go farther on the same amount of gas (or the same distance on fewer gallons of gas).


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## fubar57 (Apr 11, 2018)

Facts do try to get in the way of things

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## pbehn (Apr 11, 2018)

fubar57 said:


> Facts do try to get in the way of things


Its that deja vu all over again.


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## fubar57 (Apr 11, 2018)

Yep


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## fubar57 (Apr 11, 2018)

LMAO 
S
 ssnider

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## Shortround6 (Apr 11, 2018)

P-39 Expert said:


> Not trying to prove anything, you asked and I replied. All I said was the P-38 only had 21 more usable gallons of internal fuel per engine than a P-39. Then you went all numbers on me. If plane A gets 4MPG and plane B gets 3MPG then then plane A will go farther on the same amount of gas (or the same distance on fewer gallons of gas).



True but then what happens when plane B has 260 gallons of usable gas and plane a has 100 gallons of usable gas? 
3 times 260 is 780 miles. 
4 times 100 is 400 miles. 

Doesn't matter a rat's fart in a Hurricane that plane B only has _21 more gallons per engine_. 

You wanted facts, you got them. Then you complain I went all numbers. Too bad the facts/numbers don't back up your imagination. 

Try using real numbers and facts and not some half assed assumption like plane A weighs twice what plane B does therefore plane B _ must _get twice the fuel milage.


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## wlewisiii (Apr 11, 2018)

And I thought I could get silly for the P-40. 

Still I try to stick to what I've read people actually doing with them; that's more interesting for me than what ifs...


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## DerAdlerIstGelandet (Apr 11, 2018)

P-39 Deja vu...


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## J.A.W. (Apr 11, 2018)

C'mon guys, give him a break, he's an expert..

www.wired.com/2001/12/aqtest/

Funny thing is, ( & anyone close to the British National Archive in Kew - can confirm it) that in 1941/2,
& on the basis of actual service test results such as this:
( So its no wonder the RAF didn't want the P-39)

http://www.wwiiaircraftperformance.org/typhoon/Typhoon_AFDU_Tactical_Trials.pdf

Bell were in negotiations with the Brits to licence-built Typhoons, with Chrysler to build Sabre engines & GE, turbos - to fit to 'em.

( Hawker project drawings showing this turbo set-up are still on file in the archives too, as noted above)

In the event, 'Uncle Joe' found a useful niche for the P-39, & Chrysler were priority directed to mass-produce
Wright R-3350 mills for the B-29 program ( while fiddle-faddling with their own 'Hemi' V16), so the USAAF
didn't operate the Typhoon, 'cept for dilatory tests at Wright Field, & thus its a hypothetical/what-if deal..

( & that actual test Typhoon is the sole original unit - still extant as a whole aircraft!)


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## P-39 Expert (Apr 12, 2018)

Shortround6 said:


> The climb figures were for a plane grossing *6689 lbs.
> *
> You want to use a the numbers from WWII Aircraft Performance
> Use them but don't twist them.
> ...


I updated my little handmade chart for you. The P-40E weight was updated from 8400# to 8280# from the Wm. Green book. It's still light when tested. The P-38, P-39, P-40 and P-47 were all lighter in official tests than published weights. If you discount the P-39 numbers then you should discount all the other planes numbers too.


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## DarrenW (Apr 12, 2018)

P-39 Expert said:


> I imagine the P-38 did have twice the drag as a P-39



I actually can't believe that I'm saying this but the expert may have a point here, but only if we choose to believe that equivalent flat plate area (f) is truly indicative of an aircraft's aerodynamic cleanliness (I for one am not sold on it yet). In Table 96 of _America's Hundred-Thousand_, Dean lists the P-39N at 4.63 and the P-38J at 8.84 square feet respectively. He also states that the airplane with the lowest figure in this regard will require less engine power to attain a given speed. While this may be true, I don't see what wing area has to do with overall cleanliness, because with it a Sopwith Camel can be considered more aerodynamically refined than a Concorde jet!


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## P-39 Expert (Apr 12, 2018)

DarrenW said:


> I actually can't believe that I'm saying this but the expert may have a point here, but only if we choose to believe that equivalent flat plate area (f) is truly indicative of an aircraft's aerodynamic cleanliness (I for one am not sold on it yet). In Table 96 of _America's Hundred-Thousand_, Dean lists the P-39N at 4.63 and the P-38J at 8.84 square feet respectively. He also states that the airplane with the lowest figure in this regard will require less engine power to attain a given speed. While this may be true, I don't see what wing area has to do with overall cleanliness, because with it a Sopwith Camel can be considered more aerodynamically refined than a Concorde jet!


Twice the horsepower at the same speed means twice the drag.


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## Shortround6 (Apr 12, 2018)

P-39 Expert said:


> Twice the horsepower at the same speed means twice the drag.




at that speed _and altitude. 
_
All airframes did not show the same drag rise as speeds went up however. Especially as some airframes had local airflows much higher than the planes speed through the air.

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## DarrenW (Apr 12, 2018)

P-39 Expert said:


> Twice the horsepower at the same speed means twice the drag.



Total drag maybe but your equation, if I could call it that, tells us nothing about the aerodynamic refinement of an airplane. But in the case of the Airacobra and Lightning this point it probably moot, as both would be considered aerodynamically advanced for their generation.


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## pbehn (Apr 12, 2018)

DarrenW said:


> Total drag maybe but your equation, if I could call it that, tells us nothing about the aerodynamic refinement of an airplane. But in the case of the Airacobra and Lightning this point it probably moot, as both would be considered aerodynamically advanced for their generation.


A P-38 has twice the number of engines, but the same number of pilots. I don't think you can multiply values just based on the number of engines, in fact I am sure you cant, a mosquito was faster than a spitfire with the same engine.

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## DarrenW (Apr 12, 2018)

Shortround6 said:


> All airframes did not show the same drag rise as speeds went up however. Especially as some airframes had local airflows much higher than the planes speed through the air.



Good point Shortround6, I wasn't thinking about that ever changing variable.

I wonder what drgondog would have to say on the subject?


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## pbehn (Apr 12, 2018)

DarrenW said:


> Good point Shortround6, I wasn't thinking about that ever changing variable.
> 
> I wonder what drgondog would have to say on the subject?


I will warm up google just in case

Every long post he makes has me looking up a new "term", interesting stuff.

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## DarrenW (Apr 12, 2018)

pbehn said:


> I will warm up google just in case
> 
> Every long post he makes has me looking up a new "term", interesting stuff.



And I thought I was the only one!

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## DarrenW (Apr 12, 2018)

pbehn said:


> A P-38 has twice the number of engines, but the same number of pilots. I don't think you can multiply values just based on the number of engines, in fact I am sure you cant, a mosquito was faster than a spitfire with the same engine.



Agreed. And although having two engines increases the possibility of more parasitic drag, it's a testament to the engineering skill at Lockheed that they kept the drag coefficient numbers as low as they did.


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## Peter Gunn (Apr 12, 2018)

DarrenW said:


> And I thought I was the only one!



Oh no, far from it...

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