Another 10000 P-36/40 aircraft?

[wuzak]

The obvious way to get 10,000 more P36/P-40 built is for the British to refuse NAA's offer to design and build a new fighter design in lieu of building P-40s under licence.

So NAA begins production of P-40 models in 1941 instead of the P-51/Mustang I.

 

[Akuma]

The Hawk 75 accounted for more Luftwaffe losses during the Battle of France than any other type, so it wasn't a slouch.
Considering that the Bf109, Hurricane and P-36 were all developed at the same time, there is no reason to dismiss the P-36 as a contender through 1940.

I think that if the engineers at Curtiss were maybe a little more daring and had a little more faith in the improvement of radial engines, the P-36 could have become yet another of the great airplanes of WWII.

 

[Shortround6]

It did.

It became the P-40.


Development of the R-1830 and R-1820 sort of stalled in 1940-41, Yes P & W did get the two stage R-1830 into production but 1040-1100hp at 19,000ft was setting the world on fire in mid 1941 and later. They still had not figured out how to get good exhaust thrust from a radial. At least not without getting Carbon Monoxide into the cockpit.
The 1300-1350hp take off R-1820 doesn't show up for a while and it is a completely different engine than the 1200hp R-1820. Uses the same bore and stroke.

The bigger engines (R-2600 and R-2800) were truly big and probably too big for the airframe.

Propeller technology also rears it's ugly head. For some reason P & W and Hamilton went with very large 3 blade props, The B-26 did use four blade (first US aircraft to do so?) but they were 12 ft 2 in? Yes things got better but when it did was too late.

 

[Jay Flynn]

How much more did the two stage weigh and how much longer was it?

 

[Akuma]

It did.

It became the P-40.


Development of the R-1830 and R-1820 sort of stalled in 1940-41, Yes P & W did get the two stage R-1830 into production but 1040-1100hp at 19,000ft was setting the world on fire in mid 1941 and later. They still had not figured out how to get good exhaust thrust from a radial. At least not without getting Carbon Monoxide into the cockpit.
The 1300-1350hp take off R-1820 doesn't show up for a while and it is a completely different engine than the 1200hp R-1820. Uses the same bore and stroke.

The bigger engines (R-2600 and R-2800) were truly big and probably too big for the airframe.

Propeller technology also rears it's ugly head. For some reason P & W and Hamilton went with very large 3 blade props, The B-26 did use four blade (first US aircraft to do so?) but they were 12 ft 2 in? Yes things got better but when it did was too late.

Of course Curtiss was in business to stay in business and had to come up with designs that the military would want, hence the P-40. I'm thinking that it might have been possible to keep the P-36 on the back burner long enough for the arrival of the R-1820 you've mentioned or something similar. Again, I do not know how the contractors and the military buyers dealt with each other before the war. It may be that Curtiss, to work in that direction, might have needed some form of authorization that the military was unwilling to give.

 

[wuzak]

How much more did the two stage weigh and how much longer was it?

Depending on the model, 2 stage V-1710s weighed between 1,600lb and 1,750lb.

Not seeing how much longer it was at the time. Maybe SR6 can help.

 

[wuzak]

Of course Curtiss was in business to stay in business and had to come up with designs that the military would want, hence the P-40. I'm thinking that it might have been possible to keep the P-36 on the back burner long enough for the arrival of the R-1820 you've mentioned or something similar. Again, I do not know how the contractors and the military buyers dealt with each other before the war. It may be that Curtiss, to work in that direction, might have needed some form of authorization that the military was unwilling to give.

I don't believe that the R-1820 got a 2 stage supercharger, so its altitude performance would be not so great, unless you paired it with a turbo.

It would probably have been better to design a new aircraft around the R-2800 if you want a radial engine Curtiss.

That would probably end up being the XP-60C.

 

[Shortround6]

The XP-40 was the 10th production P-36 taken off the production line and fitted with the Allison engine. It went through several radiator designs/locations and several exhaust systems.

There was no back burner. Production P-40s, P-40Bs, P-40Cs, British Tomahawks were all built in the same factory using the same workers and using the same jigs and fixtures as the P-36 and export Hawk 75s used. Continuing to build a small number of radial engine fighters in a trickle just means fewer P-40s built.
June of 1940 was peak production of the Hawk 75/P-36 with 95 built, Curtiss built 25 P-40s the same month. In August they built 14 radial engine planes and 104 P-40s, next radial engine fighters were built in Dec, 16 of them while 165 P-40s were built.
Please remember that the British and US were ordering the P-40D & E in Sept of 1940. Talks of putting the V-1710-39 engine in the P-40 airframe had started in May of 1940.

A single stage R-1830 was about 65lbs lighter than the two stage but that difference does not include the inter coolers and ducting. The two stage engine made the same power about 4000-4500ft higher. 1000hp in a radial engine P-36/Hawk 75 at 14,000ft was not going to impress many people when the Allison could do just as well and offered exhaust thrust to boot.

P & W was concentrating on the R-2800 engine. The R-1830 got some trickle down technology.
Same for Wright, after squandering millions of dollars and tens of thousands of engineer hours on the Tornado engine they went back to the R-2600 and R-3350, the R-1820 also got trickle down technology. Wright had devise a whole new way of making cylinder fins and cylinders to get the R-1820 up to 1300-1350hp and the R-2600 from 1700hp to 1900hp.

The 1700hp R-2600 may have offered around 1150hp at 19,000ft. which is mighty close to what the P-40F had using the Merlin engine.
By the time you beef up the P-36/Hawk 75 to hold an R-2600 engine and four .50s in the wing with self sealing tanks and armor you are going to have plane very similar in weight to a late model P-40, so it is going to act/handle like a late model P-40.

 

[Akuma]

In looking over these posts I notice that the trend seems to be concentrated on larger, more powerful engines. In the past there is another direction that aircraft engineers took which was simply by increasing the power to weight ratio through the design of a lighter airframe. It's not like the Curtiss engineering department did not already have some experience in that direction.

 

[Shortround6]

increasing the power to weight ratio through the design of a lighter airframe.

Unfortunately that option tends to go out the window when military requirements change.
P-40 fuel system before protection, P-36 is going to be fairly close. 171lbs
P-40B fuel system with early protection. 253.4lbs
P-40C fuel system with later protection. 420lbs. The fuel systems for later P-40s that had three tanks was roughly 420-437lbs but that may be the weight of individual aircraft.
Want to cut 250lbs out of the wing structure to make up for it?

Increased weight of armament affected airframe weight. Increased gross weigh called for beefed up/heavier landing gear. And so on.

the "Airframe" of the 5th P-40 built may have gone about 2950lbs for the wing, tail, fuselage, landing gear and engine section (Engine mounts and cowl), out of an empty weight of 5367lbs. P-40 had two .50 cal guns and two .30 cal guns and went 5625lbs basic (no pilot, fuel, ammo, usable oil)
Where are the cuts to make a lighter airframe going to come from?
The Hawk 75 was lighter. But then the Hawk 75 used a lighter less powerful engine and was configured to have a single .50 cal and a single .30 cal machine guns. Gross weight was calculated at 105 US gallons. The wing was about 150lbs lighter than the P-40 wing and the landing gear was about 80lbs lighter for example.
However the advertising brochure provided here.
http://www.wwiiaircraftperformance.org/P-36/Curtiss_Hawk_75-A_Detail_Specifications.pdf

Where the P & W powered version weighs about 300lbs more than the Wright Cyclone powered version also states that the P & W was version to stressed to 11.5 "G"S while the Cyclone powered version was stressed to 12 "G"s . It also states that the P & W version can be provided Stressed to 12 "G"s (standard load factor) at additional cost and weight.
There is no such thing as a free lunch.

Yes, if you leave out some of the payload/useful load (fuel, weapons, protection) you can build a lighter airframe. Do you really have a better airplane?

 

[Akuma]

Unfortunately that option tends to go out the window when military requirements change.
P-40 fuel system before protection, P-36 is going to be fairly close. 171lbs
P-40B fuel system with early protection. 253.4lbs
P-40C fuel system with later protection. 420lbs. The fuel systems for later P-40s that had three tanks was roughly 420-437lbs but that may be the weight of individual aircraft.
Want to cut 250lbs out of the wing structure to make up for it?

Increased weight of armament affected airframe weight. Increased gross weigh called for beefed up/heavier landing gear. And so on.

the "Airframe" of the 5th P-40 built may have gone about 2950lbs for the wing, tail, fuselage, landing gear and engine section (Engine mounts and cowl), out of an empty weight of 5367lbs. P-40 had two .50 cal guns and two .30 cal guns and went 5625lbs basic (no pilot, fuel, ammo, usable oil)
Where are the cuts to make a lighter airframe going to come from?
The Hawk 75 was lighter. But then the Hawk 75 used a lighter less powerful engine and was configured to have a single .50 cal and a single .30 cal machine guns. Gross weight was calculated at 105 US gallons. The wing was about 150lbs lighter than the P-40 wing and the landing gear was about 80lbs lighter for example.
However the advertising brochure provided here.
http://www.wwiiaircraftperformance.org/P-36/Curtiss_Hawk_75-A_Detail_Specifications.pdf

Where the P & W powered version weighs about 300lbs more than the Wright Cyclone powered version also states that the P & W was version to stressed to 11.5 "G"S while the Cyclone powered version was stressed to 12 "G"s . It also states that the P & W version can be provided Stressed to 12 "G"s (standard load factor) at additional cost and weight.
There is no such thing as a free lunch.

Yes, if you leave out some of the payload/useful load (fuel, weapons, protection) you can build a lighter airframe. Do you really have a better airplane?

Sorry; I was just making a general observation. Your information is right and when it comes to the P-40, I was wondering if there might have been any structural improvements that could have led to a better power to weight ratio.

 

[Shortround6]

the "structure" was around 40% of the gross weight (clean) for a P-40. Perhaps improvements could have been made but even a 10% reduction in structure is only about 300lbs on a P-40. Or about 4-5% of the equipped, fueled fighter (assuming about 7,000lbs just for easy figuring) and then you have to recalculate all the stress figures. And probably redo some of the production tooling.

On the P-40E and later you could make a 300lb change just by yanking two guns and limiting the ammo for the remaining four.
The P-40N saved about 60lbs by changing the wheels (magnesium) and tires, the aluminum radiators saved about 65lbs and pulling the forward fuel tank saved around another 60-65lbs just for the tank weight.
It is worth noting that they didn't save any weight on the "structure" (wings, tail, fuselage, engine section).

For the US and British rather large gains could be had with uprated engines.

 

[Admiral Beez]

The first thought that came into my head was 'why would anyone want an extra 10,000 P40's'

Air Vice Marshal Conway Pulford raises his hand, yes please! I'll take one thousand P40s please.

The obvious way to get 10,000 more P36/P-40 built is for the British to refuse NAA's offer to design and build a new fighter design in lieu of building P-40s under licence.

Even faster on the P-36. Tell CC&F in Canada, CAC in Australia and/or HAL in India to begin license producing the P-36 in 1938. With engine supplies nearby, CC&F can likely churn out Hawks faster than Hurricanes. CC&F was already buying Curtiss-Wright engines and P&W Canada was a well established service and sales office.

 

[Jay Flynn]

Kinda curious about the effect a few hundred two stage P-36s, P-66s and/or Boomerangs would have had in the Pacific in 1941-2

 

[Shortround6]

Tell CC&F in Canada, CAC in Australia and/or HAL in India to begin license producing the P-36 in 1938.

CC&F in Canada in 1938 was an assembly shop. They were supplied complete fuselages, complete wings and tail sections, landing gear assemblies and engines/props.
It took over a year to build 20 Hurricanes. When do you start trying to build the Hawk 75which was a more difficult to manufacture airframe? And using what for an engine?
1938 engines or 1940 engines.

CAC in Australia was building (or tooling up for) tube steel and fabric covered trainers. Trying to build all metal planes with 5 spar wings might have been more difficult? (and who builds the trainers?, learning to fly in Hawk 75s is not going to go well.

HAL in India didn't exist until 1940. You aren't going to tell them anything in 1938. They also got a big head start in Hawk production when a trainload of Ex Chinese Hawk 75 parts kits and assembly tooling showed up when it was evacuated from China, the parts kits had been built by Curtiss in the US.

 

[Admiral Beez]

Kinda curious about the effect a few hundred two stage P-36s, P-66s and/or Boomerangs would have had in the Pacific in 1941-2

RAF Malaya had a total of sixty operational Buffaloes, with another forty or so spare aircraft. Add two hundred P-36 or P-66 and we've more than doubled the RAF fighter force.

 

[Peter Gunn]

The first thought that came into my head was 'why would anyone want an extra 10,000 P40's'

Well, it's better than an extra 10,000 P-39's.

I know I know...

I'll be in the penalty box for the next two minutes...

 

[Thumpalumpacus]

Well, it's better than an extra 10,000 P-39's.

I know I know...
View attachment 628903
I'll be in the penalty box for the next two minutes...

You're messin' with Beetlejuice, bud.

 

[BobB]

India built a handful of P-36's under license before the decision was made to concentrate on repair/overhaul of other aircraft. If they had gone into full scale production, they could have been producing thousands of P-36's by 1944. They also could have taken over Curtiss-Wright technical support with an Indian phone call center.

 

[Glider]

India built a handful of P-36's under license before the decision was made to concentrate on repair/overhaul of other aircraft. If they had gone into full scale production, they could have been producing thousands of P-36's by 1944. They also could have taken over Curtiss-Wright technical support with an Indian phone call center.

If you knew anything about the level of quality control that existed in India at the time you would think twice about that thought