R-1830 vs. Allison V-1710

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you might have had company.

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

or the Lycoming O-1230.

On the other hand betting on the R-1830/R-2000 might not have gotten much further. The number of radial engines that used more than 10-12lbs of boost without using ADI or fuels of higher than 100/130 rating can probably be counted on the fingers of one hand with fingers to spare.
 
1350 on 87 octane IIRC. I don't know how much of a new plane the P-40 was, but since you tend to come down on the side of "It is impossible to change any part of a plane" I assume it must be a very different design to take an inline engine and weigh 3000 pounds more.

I'm glad Lavochkin didn't have you on staff. When I suggest altering a propeller or a radiator you say the plane will blow up or fail to take off. If they had suggested the La-5 to you (replacing a 1200 lb inline with a 1900 lb radial) you'd have probably attacked them with something.

You're telling me that under no conditions could Curtis have IN ANY WAY designed a plane with self sealing tanks, armor, 4 guns and the ability to accept drop tanks to take a two-stage supercharged R-1830 even with the P-36 available to beef up. That might require a longer, rebalanced fuselage (!!!) and we all know that would be totally impossible.
 
No inline for any type of naval aircraft. Although the Seamew was deployed, I do know a lot of navy folk got nervous with the thought of another potentially hazardous liquid (glycol) aboard ship.
 

Have you got a source for the 1350Hp on 87 octane?
Everything I have seen seems to call for 100/130 fuel and a start date of very early 1942.

THe Curtiss model 81 might have been very closely related to the P-36. but without a really good weight break down it is a little hard to tell. The model 87 tends to stray a bit further, the wing weighing about 100lbs more than on the model 81. Beefed up or just modified to mount the six .50 cal guns? I don't know. some other part gained weight and a few lost weight.

So in eary 1942 you take a P-40E, strip out the Allison and replace it with a P&W R-2000 that weighs almost 300lbs more but lets call it a wash since you get rid of the Allisons almost 300lb cooling system. Yes you have 1350-1450 hp for take off but even with a a two speed supercharger what have you got at altitude?

The Allison you took out was rated at 1150 for take off but it would still give you 1150hp at 11,700ft. A Standard R-2000 with a two speed supercharger was good for 1100hp at 16,000ft military power. Better but certainly not a world beater. THe Allison could be over boosted for a WER of 1490HP at 4,300ft which should take care of whatever performance the R-2000 would have. And you have the higher drag of the Radial.
We don't really know what these small radials could do for WER power since they were never rated for it.

Now you want to combine the two stage supercharger from the R-1830 with the R-2000. THe two stage forrm the R-1830 was an improvement but it had problems, surging at high altitudes was one. For some reason the !830 with the two stage supercharger that gave 1200hp at sea level was only good for 1000hp at 19,000ft. Better than the Allison but nowhere near what is needed to compare to Merlin powered Spitfires or DB 601 powered Bf 109Fs in the plane you are proposing unless you can come up with a way to loose a lot of weight.

You can propose anything you want. What I get tired of is peaple who only want to take the advantages of a change and ignore the downsides.
And your comparison of the Lagg 3 to the LA 5 isn't quite fair is it?
Remove a closer to 1300lb engine AND its COOLING system (another 250-300lbs) and replace with the 1900lb radial for a net change of much closer to 400lbs than the 700lbs you are implying. Of course the LA 5 wound up weighing almost 900lbs more empty than the Lagg 3 so the LA 5 picked up some sort of extra weight in the engine swap that isn't accounted for in the bare or dry engine weights.

Curtiss could certaily have designed and built the fighter you propose. The question is would it have actually performed any better or enough better than the existing P-40 to make such a plane worthwhile. Weght oof the two stage super charger is some where between 10-200lbs more than a single stage engine and it makes the engine a bit longer. not a real big problem. The problem sems to be the intercooler. I don't know enough about it. How big was it? was it big enough? did it pose a restriction or cause too much pressure drop? did it actually remove enough heat from the intake charge to allow full boost to be used. THis last was the Problem with the intercooler on the XP-39 and it was also a problem on every single P-38 until the "J" model.
Now just for arguements sake let us assume you get a R-1830 to perform just like an R-2800-8 or -10. The same HP per cu in at the same altitudes as this two stage engine. It means you get 1300hp for take off and sea level. it means you get 1080hp at 15,500ft and 990hp at 22,500ft.
The 990hp at 22,500 doesn't look bad compared to a standard P-40E but then we haven't figured in the drag of the radial and the drag of the intercooler.
Of course comparing this hypothetical engine to the V-1650-1 in the P-40F shows up the problem. THE Merlin was good for 1300hp for take off. 1235 up to 12,000ft and 1120 hp at 19,000ft.
While the radial offers just about the same HP changing to the Merlin doesn't require as much redesign does it?
Or argue that the goverment and Allison should have just put a two speed gear drive on the existing supercharger. Not as easy at is appears but probalby easier than designing half a new airplane.

Something that may be of interest to you is that the weight of an empty P-40C (with no guns) is about 5767lbs including radio.
The weight of an F4F-3 with the the two stage R-1830 engine without guns AND without radio is 5426lbs. A difference of less 300lbs if we include the radio. No folding wing on the F4F-3.
Of further interest might be that the powerplant of the P-40E weighes 2565lbs while the power plant of of the F4F-3 weighs 2510lbs. These weights include the oil system but not the fuel system.
 
Pratt Whitney R-2000 - Wikipedia, the free encyclopedia

There were a number of detail changes from the R-1830, such as front mounted instead of the rear mounted magnetos, plain bearings for the crankshaft rather than roller bearings, and 87-octane fuel. 87 octane was specified because there were fears wartime supplies of 100 octane might fall short, but those fears were groundless. The R-2000 produced 1,300 hp @ 2,700 rpm with 87 octane, 1,350 hp with 100 octane and 1,450 hp @ 2,800 rpm with 100/130-grade fuel.

The R-1830 had a two stage supercharger without much emphasis on developing mechanical superchargers coming from the war department. In previous arguments, you suggested that something would have to be sacrificed to get a two-stage supercharger that worked well fielded in January 1942. I say that if you sacrificed V-1710 development back in 1938 to give more funding to an improved radial fighter you could have that.

I think that focus could result in an R-2000 optimized for use in fighters with higher HP ratings and a two-stage supercharger driving a better F4F and a radial-powered P-40 with good performance at altitude.
 
You have to admit a P-38 with a pair of Turboed R-1830s would be a pretty strange aircraft.

Besides in 1938 the R-1830 is already behind the curve and P&W Knew it. It is already 7 years from start of work and P&W is deciding that the R-2180 twin Hornet isn't going to cut it in the long haul.
They started work on an 18 cylinder R-2600 in 1936 and then when they found out about the Wright R-2600 they changed it to a 2800 cu in engine to beat Wright. THey started on the 2800 version in March of 1937.
the Wright R-2600 is already being fitted to the Boeing clipper flying boats at 1500hp in 1938, Spending big money to wring another couple of hundred HP out of an engine that already increased in power by about 50% since it's introduction doesn't seem like good sense if it still leaves your product behind the competions staring point.
As far as canceling the Allison really getting you anywhere, consider that in 1938 Allison has done most of the developemnt work and is almost ready for production. They deliver all of 14 egines in 1938 Bring total production to just 30 engines since 1932.
By Comparison P&W has delievered 13,500 engines by mid 1938 since the start of the company.
Wright has delivered over 8000 of the Cyclone model alone and is building them at over 1000 per year.
Closing down Allison doesn't realy buy much in the scheme of things.
P&W was also working on 2 if not threee liquied cooled sleeve valve engines at about this time and scrapped then all.
Stopping work on the Allison V-12 engine doesn't free up any supercharger experts even if it does free up a little bit of money. A mighty little bit considering that by early 1939 the Army was almost 1 million dollars in arrears to Allison for work already done.
 
Just one of those quirks of fate on the V1710 had a proper two stage supercharger been developed eariler some US aircraft may have had a little better reputation then they already do and some history rewritten

Just look at a properly supercharged V1710-117/9 in the P51J of course political agendas not with standing the V1650 Packard-Merlin needed to be used as it was.

It was be interesting to put a development time line of the V1710 and V1650 side by side.
I'm in Garmish on vacation right now so I don't have access to my materials.

Zwei beir bitte!!!!
 
The main problem with the V-1710 is as Shortround6 has said; Allison was a very small company, with limited experience in designing engines. By 1940 they'd only built a handful of examples. Realistically it's going to take magic to get a V-1710 designed with a two-stage supercharger in the late 1930s. The US only managed to produce one, large, moderately successful lc inline engine in the period: the V-1710. Why, because the design experience wasn't there following the decision in the early 1920s to concentrate on radials. As a result, a couple of good radials got produced, and lots of lc inlines that were colossal failures.

It's funny that the Brits were ok with having Seafires.
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The Seafires were never properly navalised, but accepting shorter lifetime for higher performance paid off. Otherwise you get the Firebrand. At the same time, lots of the pre-war FAA aircraft were lc inlines and don't seem to have had too many problems.
 

On the other hand, there should be significantly less magic involved in getting an R-1830 with a Two Stage Supercharger with the surging bug worked out.
 
There wasn't really any magic required
Both the USAAC and Allison were to blame for the lack of a two-stage supercharger.
The USAAC were committed to turbochargers way before 1938, unfortunately they still weren't around in any satisfactory shape or form.
Allison's error was to standardise the power section to simplify production lines, you could get a second stage on a powerplant but it would have to be fitted as an external unit.
Allison and Curtiss-Wright jointly coerced the USAAC into buying the V-1710 off the back of the as yet non-availability of the turbocharged powerplants and fuzzy promises of development of the power section but as history has shown, this development never happened.
 
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Clay_Allison said:
On the other hand, there should be significantly less magic involved in getting an R-1830 with a Two Stage Supercharger with the surging bug worked out.
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I am sure the P&W tried to work on the R-1830 a little bit but I will bet most of their effort was going into the the two stage supercharger on the R-2800. And the Turbo R-2800.

And the turbo supercharged R-1830s for the B-24s.

The R-1830 despite being the most produced large aircraft engine in history (if not the most produced aircraft engine of any size) was recognized in the late thirties as NOT being the future of the Company. THe Company was shifting their effort to the R-2800 and by late 1939 or early 1940 was promising the R-4360 28 cylinder engine.

And even if you get the surging bug worked out you are left with an engine that that is several hundred horsepower BELOW what the military wants for their newer planes.

A large part of the problem is lack of experience. Until the 100 octane fuel was available there was no need for high pressure ratio superchargers, the engines and fuel just couldn't use the higher pressure.
A number of experiments had been done using straight Benzene for fuel but even these experiments were at much lower pressures than would be routine even by 1943.

Rolls Royce got lucky in two or three ways. They hired Hooker at just about the right time ( hireing even one year later might have put them behind the currve they did achieve.) And Hooker was able to see the errors in the formulas right away.
They also got lucky in that the supercharger from the Vulture engine turned out to be, quite by accident, to be almost exactly the right size to work as a 1st stage on the Merlin. This saved them months of time in setting up an experimental rig to begin intial testing and, again by luck, was such a close match that they were able to get a lot of testing done without having to fabricate new components. THe final configuration may have changed but there was a considerable time savings.

Depending on, or expecting an American development to have the same amout of luck doesn't seem resonable. Allison certainly didn't have any bits and pieces floating around that could be put to use even if they had a supercharger specialist to guide them.

Edit> I am throwing this out a guess but perhaps the importance of a good intercooler design wasn't well understood at the time. THe US had been fooling around with intercoolers for about as long as they had been working on turbos but perhaps the design that worked at for 400-500hp at 200mph wasn't what was needed at 1500hp and 400mph?
Without a good inter/after cooler the two stage supercharger is never going to give it's best.
 
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And even if you get the surging bug worked out you are left with an engine that that is several hundred horsepower BELOW what the military wants for their newer planes.
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If the P-40 had been designed for the R-1830 instead of the V-1710 the money that would have gone to buy Allison Engines (admittedly only unit cost, the development cost would have been lost like the Hyper-Engine money) could have paid for a little more development on the R-1830. It would have delivered 1200 HP in 1942 (because it did) and I think that a higher performance, higher boost R-2000 might have eventually threatened Hyper-Engine performance (2000 horsepower). We'll never know how successful or unsuccessful stretching that design might have been, but I think it would have delivered more than the Allison ultimately did.
 

I am not sure how your accounting works. If you are not paying the unit cost for the Allison engine for production engines you still have to pay unit costs for the R-1830 production engines to equip the same number of planes. Now maybe the R-1830s are cheaper per engine but I still don't see where this frees up any large of sum of money, Especially in the time it would be needed which is in 1939-1940.

It still doesn't change what is known about superchargers at the time.
Most of these engine programs were planned 3-6years in advance. in 1939 peaple certainly knew about 100 octane fuel. peaple might have expected the fuel to impreve even more but in 1939 nobody really knew when or even how higher performance fuels would come to be. In 1939 Nobody could predict a date when 100/130 would be available, or when 100/150 or 115/145 would be available. And nobody could do more tha give a rough estimate on the perforamnce increase that such a fuel would give until they had the fuel to test because each engine reacted differently (gave different results) to the same fuel.
Making choices about which engine to develop and place into production based on the feuls that might or might not be availabel 2-5 years in the future doesn't seem like a good idea.

Have you looked at the differences between a "B" series R-2800 and a "C" series R-2800 that allowed the "C" series engine to make 2800hp with high boost and ADI? Did you know that design work started on both engines the same day in 1940 but it took several years longer to get the "C" series into production and the first model "C"s were NOT the 2800hp version.

2 hiccups in the 2000hp R-2000 plan. 1, THE ONLY version of the R-2800 to make 2800hp used a turbo to do it. 2. THese are peak, very short duration power levels that require extra maintaince when used. A 2000hp R-2000 will still have a cruising power level several hundred HP below the cruising power level of a 2000hp R-2800. THe R-2800 will use lower grade fuel and go longer periods of time between overhauls. Maybe it's extra weight means it is not as good a canidate for a small high performance fighter but the 2000hp R-2800 is much better choice for bombers, transports, and larger single engine planes.

If P&W could only concetrate on one engine which should it be?
THe small specialized engine that requires fuel that is just around the corner or the larger general purpose engine that will run on the fuel available now? ANd the bigger engine will ony get more powerful as/when the fuel situation improves.

Please note that P&W did market a second R-2180 after the war that used 14 "C" series cylinders. This engine was rated at 1800hp for take off using ADI and 1650HP without ADI. it was a two speed engine not 2 stage and had a take-off rating of 1300hp at up to 16,000ft in high gear. It also weighed 1900lbs. This was done on 100.130 fuel.
 
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Well, for one thing sinking the V-1710 effectively ends the P-38 program. I'm pretty sure that cost a lot of money.

I know the Lightning is a fan favorite, but I'd trade the entire line for an R-1830 with a two-stage supercharger with the surging bug worked out.
 
Hawk 75 with................................................ P-40B...................................... P-40E
P&W Twin Wasp S3C3-G
Wing group………………….835lbs………………………..1022lbs……………………………………..1126lbs
Tail Group…………………….117lbs………………………….125lbs……………………………………….129lbs
Landing gear…………………543lbs………………………….649lbs……………………………………….695lbs
Body group…………………..567lbs………………………….420lbs……………………………………….449lbs
Power plant…………………2170lbs………………………2527lbs^1……………………………….…2565lbs^1
Fixed equipment…………...481lbs………………………..456lbs……………………………………….606lbs

Total empty weight …….4713lb……………………….5615lbs……………………………………...5995lbs^2

Normal Useful Load:
Pilot………………………………...200lbs………………………..200lb…………………………………..…180lbs
Fuel (105 gal)……………………630lbs….………(120 gal)720lbs…………………………(148 Gal)888lbs
Oil……………………………………..75lbs………………………….86lbs……………………………………….97lbs
Fuselage guns*…………………174lbs…………………….….378lbs……………………………………….00lbs
Wing guns**……………………..00lbs………………………..222lbs……………………………………….903lbs
Radio…………………………….…112lbs………………………….71lbs………………………………………...71lb
Oxygen………………………….…15lbs…………………………....0lbs…………………………………………..0lbs
Signal pistol………………………….3lbs…………………………...0lbs…………………………………………..0lbs
Armor………………………………….0lbs………………………....93lbs……………………………………….111lbs

Total useful load………………..1209lbs……………………1770lbs……………………………………..2270lbs

Normal Gross weight………….5922lbs……………………….7385lbs……………………………………8245lbs.

Notes:

^1, these power plant weights DO NOT include the Fuel system. Fuel system includes pumps and lines in addition to the fuel tanks which , being self sealing on these later models are much heavier and might distort things even more than they are.

^2 , Empty weight does include fuel tank for the E model but not radio which is included below.

*Weights include guns and ammo but perhaps not mounts, ammo boxes and other equipment?

** Wing gun weights for the P-40C are for four .30s and for the P-40E six .50s.

A further note is that the body group weight for the Hawk 75 may include the engine cowl and/or the engine mount while the P-40 weights DO NOT.

From this I think we can see where the weight in the P-40 came from compared to the Hawk 75/P-36.

Weights for the Hawk are from: http://www.ww2aircraft.net/forum/at...5d1207509120-curtis-hawk-75a-h75-a_folder.pdf

Weights for the P-40 are from the Book "America's Hundred-Thousand".

The Hawk 75 was stressed for an ultimate load of 12 "G"s with a landing load factor of 7 "G"s when powered by a Cyclone engine at a gross weight of 5692lbs. Changing to the P&W engine increase the Gross to 5922lbs and changed to load factors to 11.5 and 6.8. As the Brochure says " The Airplane can be furnished with standard load factors at an increase in weight and price."
While the Change from 12 to 11.5 might not be significant, changing armament to four .50s, adding armor and self sealing tanks and changing to a more powerful engine (or bigger supercharger) and bigger propeller would almost certainly change the load factors to a point where SOMETHING has to be done. I don't know how much extra weight would be involved but I would think that a Radial engine P-40 isn't going to weigh that much less than an Allison powered one. The power plant weight of an F4F was 2510lbs not including fuel system.
 
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