Qualities that made for a great aircraft that don't show up in performance stats.

[Schweik]

My great-Uncle, who missed making history because his P-36 had no ammunition that morning, insisted that he would have happily flown the P-36 into battle instead of the P-39 (which he hated with a passion) or his P-38.
He and other pilots liked the P-36's handling and performance - it's only shortcomings were it's light armament and lack of armor and self sealing tanks.
Bottom line, is that it was a magnificent fighter for it's time, but that time had come and gone, as with most things.

I agree, I am a fan of the P-36. It's excellent maneuverability plus good high speed handling (and high terminal dive speed) made it an unusually good fighter for it's time. These traits came over to some extent to the P-40 of course, which is why that plane did so well in spite of some serious flaws. And why it was so often liked by (many, if not all) pilots even when disliked by higher ranking officers and war-planners.

I do also think that we need to consider aircraft within their own times. The A6M was an excellent fighter in 1941 and 1942, it was dated by 1943 and obsolescent in 1944 or 1945. But that doesn't make it a bad fighter.

For that most WW2 fighters were shoved down a notch with the appearance of Jet fighters in some numbers in 1944, even with all of their flaws and limitations. That doesn't make the P-51 or Spitfire or Fw 190 bad planes - even if they had built 10,000 Me 262s instead of just 1400.

 

[Shortround6]

The US had quite a few "types" that carried their own designations even though the airframe essentially remained the same, just different engines, armament or other modifications.
The P-36 is a classic case of this: YP-37, P-40 and XP-42.
P-38: XP-49.
P-39: XFL, P-400, P-63.
P-40: XP-46, XP-53, XP-60A/B/D and YP-60E.
B-17: XB-38, YB-40 and C-108.
B-24: XB-41.
B-29: XB-39, XB-44 and B-50.

There's more, but you get the idea...

nice list but the P-39: XFL, P-400, P-63.
is bit mixed up. The P-39 and P-400 are the same airplane. The XFL is sort of a sibling, same fuselage but larger wing and tail wheel landing gear which required a different cooling system. P-63 just looks the same, no interchangeable parts much bigger than fasteners. A cousin? different wing span, different area and most important, different airfoil and different construction in the wing (different location of spars and other stuff)

P-40: XP-46, XP-53, XP-60A/B/D and YP-60E.

this gets a bit weird. The XP-46 was a plane/design all on it's own. Smaller than the P-36/P-40. the XP-53 kept the P-40 fuselage but used a larger (almost 40 sq ft) laminar flow wing and as it progressed though a number of engine changes the tail/rear fuselage diverted further and the further from the P-40 and finally even the cockpit area changed.

 

[GrauGeist]

Thanks for catching those - I was going off the top of my head and intended to ammend the list when I got home (as usual, I forgot about it).

Although in the case of the XFL, it does hold in keeping with the conversation, as it was essentially a P-39 converted to a Tail-dragger with an arresting hook added and renegotiated engine cooling.

View attachment 514749

 

[Shortround6]

The Hawk hit a wall in terms of it's speed and carrying capacity in the 1930s. It couldn't have done what the Tomahawk and Kittyhawk did. Like the Hurricane the P-36 could survive in 1940 but would suffer in 1941 or 1942 in the same kind of areas, let alone 1943. You wouldn't be flying fighter sweeps or escort missions over enemy airfields in P-36s in 1943 I'll put it that way. They were certainly of the same DNA and very closely related, but I stand by my claim that the P-40 was a different aircraft. If we really have to I can start enumerating the specific features and design elements (Shortound already pointed out some of the changes to the wing) but ultimately it's a subjective opinion so I know some people will never change their minds on it. I doubt I will either as I've done enough research on the type to be pretty confident of my opinion on this. But I'm willing to be surprised by new evidence I hadn't considered.

There were probably more changes between the Kittyhawk and the Tomahawk than between the Tomahawk and the Mohawk.

The Hawk had not hit a wall in terms of it's speed and carrying capacity in the 1930s, or the Tomahawk could not have done what it did.
You may be confusing cause and effect. The radial engine Hawk had a (compared to later aircraft) crappy engine installation, both P & W and Wright that was high drag and made little or no use of exhaust thrust. Neither radial made quite as much crankshaft HP at 13-14,000ft as the Allison V-1710-33.
The company Brochure for the Hawk 75 lists possible bomb loads of 800-850lbs. a 500lb under the fuselage and various loads like six 50lb bombs or ten 30 bombs under the wings.
The P-36G (30 Norwegian Hawk 75s taken over by the US on the fall of Norway and later given to Peru)) was armed with a pair of .50 cal guns in the cowl and four .30 cal guns in the wings.
Engineering had already been done, customers may not have taken up the offer/s.

The Hawker Hurricane had hit the wall in terms of speed due to it's thick wing, not it's engine installation. As seen when the same Merlin engine fitted to the Hawk airframe/wing was over 20mph faster. (and that is the eight gun Hurricane II) despite being well over 1000lbs heavier.

It took until Summer/early fall of 1942 but P & W got a early P-40 (no letter) airframe (no armor, self sealing tanks or guns) up to 382-386mph at around 22,000ft using a version of the engine used in the F4F-4 Wildcat. One source claims only 8% more drag than a P-40 (type not specified) so again it does not look like it was the Hawk 75/P-36 airframe/wing holding the
performance back in 1938/39/40.

 

[Kevin J]

There were probably more changes between the Kittyhawk and the Tomahawk than between the Tomahawk and the Mohawk.

The Hawk had not hit a wall in terms of it's speed and carrying capacity in the 1930s, or the Tomahawk could not have done what it did.
You may be confusing cause and effect. The radial engine Hawk had a (compared to later aircraft) crappy engine installation, both P & W and Wright that was high drag and made little or no use of exhaust thrust. Neither radial made quite as much crankshaft HP at 13-14,000ft as the Allison V-1710-33.
The company Brochure for the Hawk 75 lists possible bomb loads of 800-850lbs. a 500lb under the fuselage and various loads like six 50lb bombs or ten 30 bombs under the wings.
The P-36G (30 Norwegian Hawk 75s taken over by the US on the fall of Norway and later given to Peru)) was armed with a pair of .50 cal guns in the cowl and four .30 cal guns in the wings.
Engineering had already been done, customers may not have taken up the offer/s.

The Hawker Hurricane had hit the wall in terms of speed due to it's thick wing, not it's engine installation. As seen when the same Merlin engine fitted to the Hawk airframe/wing was over 20mph faster. (and that is the eight gun Hurricane II) despite being well over 1000lbs heavier.

It took until Summer/early fall of 1942 but P & W got a early P-40 (no letter) airframe (no armor, self sealing tanks or guns) up to 382-386mph at around 22,000ft using a version of the engine used in the F4F-4 Wildcat. One source claims only 8% more drag than a P-40 (type not specified) so again it does not look like it was the Hawk 75/P-36 airframe/wing holding the
performance back in 1938/39/40.

382 to 386 mph sounds good, but putting back in armour, self sealing tanks, guns and ammunition no doubt resulted in a 20 mph loss of speed, then you probably want a belly tank shackle and sway brace, rear view mirror, maybe snow guard or in the desert dust filters so at least another 10 mph. It all adds up to the P-40F/L Warhawk with the Merlin engine being a much better plane. Then there's the P-40K with overboost, my guess would be the same speed as an A-36A Apache since it didn't have the wing pylons and dive brakes to spoil its streamlining.

 

[GregP]

Hi Schweik,

Regarding post # 241, you say 1,400 like you think they USED 1,400 Me 262s during the war. You don't think that, do you? According to Adolph Galland, who should have known for sure, they never had more than about 150 operational at any one time. They did pretty well, considering the low numbers of flying jets.

It's like the Ta 152 in many ways. They actually built about 150 Ta 152 total airframes. But only about 43 can be confirmed as being delivered to actual units. Of these, there were never more than about 20 flying at any single point in time, and there were no spare parts at all.

 

[pbehn]

Hi Schweik,

Regarding post # 241, you say 1,400 like you think they USED 1,400 Me 262s during the war. You don't think that, do you? According to Adolph Galland, who should have known for sure, they never had more than about 150 operational at any one time. They did pretty well, considering the low numbers of flying jets.

It's like the Ta 152 in many ways. They actually built about 150 Ta 152 total airframes. But only about 43 can be confirmed as being delivered to actual units. Of these, there were never more than about 20 flying at any single point in time, and there were no spare parts at all.

Pretty much par for the course in that era. When war was declared the RAF had circa 130 Spitfires but Supermarine had produced 300. Through the BoB single engine fighters were being produced at upto 1000 per month but front line strength only rose from 500 to 700.

 

[Kevin J]

Pretty much par for the course in that era. When war was declared the RAF had circa 130 Spitfires but Supermarine had produced 300. Through the BoB single engine fighters were being produced at upto 1000 per month but front line strength only rose from 500 to 700.

Correction, about 300 Hurricanes and 150 Spitfires pcm in the BoB. At the start the numbers in service were almost one to one with only slightly more Hurricanes, by the end it was almost 2 Hurricanes to every 1 Spitfire.The problem was the pilot supply so having all those Poles on board that just wanted to kill Germans saved us all.

 

[pbehn]

Correction, about 300 Hurricanes and 150 Spitfires pcm in the BoB. At the start the numbers in service were almost one to one with only slightly more Hurricanes, by the end it was almost 2 Hurricanes to every 1 Spitfire.

At the start numbers were about equal because no Spitfires were sent to France, the higher number of Hurricanes reflects it being easier to produce.
Document-42: Aircraft production during the Battle of Britain

 

[Kevin J]

Correction, about 300 Hurricanes and 150 Spitfires pcm in the BoB. At the start the numbers in service were almost one to one with only slightly more Hurricanes, by the end it was almost 2 Hurricanes to every 1 Spitfire.

At the start numbers were about equal because no Spitfires were sent to France, the higher number of Hurricanes reflects it being easier to produce.
Document-42: Aircraft production during the Battle of Britain

I think your 1000 pcm includes damaged, fixed and returned to service. LOL.

 

[Shortround6]

382 to 386 mph sounds good, but putting back in armour, self sealing tanks, guns and ammunition no doubt resulted in a 20 mph loss of speed, then you probably want a belly tank shackle and sway brace, rear view mirror, maybe snow guard or in the desert dust filters so at least another 10 mph. It all adds up to the P-40F/L Warhawk with the Merlin engine being a much better plane. Then there's the P-40K with overboost, my guess would be the same speed as an A-36A Apache since it didn't have the wing pylons and dive brakes to spoil its streamlining.

You are quite right, a combat ready version would probably have been 20mph slower, just pointing out that the basic airframe had not topped out at just over 300mph in the late 30s'

And it is considerably faster than the F4F Wildcat which may be damning with faint praise against the 109F.

However I wouldn't put much stock in a P-40K being as fast as an A-36 if the A-36 was running at a similar power level. The engine in the A-36A could make 1500hp at 5200ft using 52in of boost.

The P-40Q experiments showed that the Hawk had reached it's limits but that limit was over 400mph. It needed much more power than the Merlin P-51s to go the same speed.
It was also the first Hawk to change the wing and that was merely a short clip of each wing tip.
However one of the XP-60s, using the same engine as the P-40F was faster than the P-40Feven with a 275sq ft wing due to the new airfoil showing that the Hawk airframe/wing was reaching it's limit.

 

[pbehn]

I think your 1000 pcm includes damaged, fixed and returned to service. LOL.

It does, but the point is still the same. Despite the thousands of Spitfires produced the RAF rarely had more than 1000 in front line service. Same for most other air forces.

 

[Kevin J]

You are quite right, a combat ready version would probably have been 20mph slower, just pointing out that the basic airframe had not topped out at just over 300mph in the late 30s'
View attachment 514885
And it is considerably faster than the F4F Wildcat which may be damning with faint praise against the 109F.

However I wouldn't put much stock in a P-40K being as fast as an A-36 if the A-36 was running at a similar power level. The engine in the A-36A could make 1500hp at 5200ft using 52in of boost.

The P-40Q experiments showed that the Hawk had reached it's limits but that limit was over 400mph. It needed much more power than the Merlin P-51s to go the same speed.
It was also the first Hawk to change the wing and that was merely a short clip of each wing tip.
However one of the XP-60s, using the same engine as the P-40F was faster than the P-40Feven with a 275sq ft wing due to the new airfoil showing that the Hawk airframe/wing was reaching it's limit.

I think you'll find that putting 8 British rockets under a Mustang knocked about 80 mph off its speed. It was quite substantial. Maybe the Apache would have been slightly faster, but not by much.

 

[Schweik]

Apaches - and the British Mustang I & II were pretty fast, that was their role, they couldn't do very much else since the ailerons didn't work very well, but they could keep up a high speed down very low. One of the few aircraft that could fly those complex Northern European day-intruder missions planned out by the RAF and survive.

But aside from that, Kevin I think you are spot on.

I have no doubt that given enough time they could have figured out a way to make a radial engined P-36 fly faster, and I'll admit, I don't fully understand why they hit that wall, but they clearly did. They needed at least 350 mph with combat equipment. At the time they were trying to develop that fighter they tried multiple (radial) aircraft engines, between 4 and 10 versions depending on how you differentiate them, with HP ranging from 900 to 1200, and they really couldn't improve the speed sufficiently for 1940's service in an Allied Air Force in Europe or the Med. If it had self sealing tanks and armor it probably would have been Ok at that ~310 mph speed a little longer in the Pacific, but I don't think they made any variants that did (I could be wrong on that). Aircraft development in wartime was always a matter of getting things done under a brutal time limit, and they clearly weren't going to get there in time with the original P-36 design.

If you start out with an 8% drag deficit between the P-36 and the P-40, that right correlates roughly to about 25 mph potentially with knock on effects on acceleration and speed retention. And the inline engine clearly had a lot more room for rapid improvement in terms of cleaning up obstructions and streamlining, when you compare a P-36 hawk to an early 1941 P-40 to a mid 1942 one you can see the difference. I suspect the drag difference between a P-36 and a P-40L is a bit more than 8%.

The pace, the speed , and the intensity of the war just increased very rapidly, particularly in Europe. The aircraft that were fighting the Germans were a whole different beast and had to maintain a much higher combat speed to survive. The P-36 was competitive in the Battle of France in 1940, but by the battle of Britain a few months later (partly due to the nature of the fighting at higher altitude) it was no longer considered viable for the battlefield, even sufficiently to be sent to North Africa and the Middle East. Luckily for the Allies the shift to the inline engine had already got them past the wall and enabled a series of other changes that kept the new P-40 Tomahawk and Kittyhawk design in the game 3 years after the decline of the original Hawk and it's relegation to Tertiary Theaters.

 

[Schweik]

Helpful side by side comparison of two beautiful Warbirds. You can see both the similarities and the differences. 310 mph vs. 370 mph

 

[Shortround6]

Apaches - and the British Mustang I & II were pretty fast, that was their role, they couldn't do very much else since the ailerons didn't work very well, but they could keep up a high speed down very low. One of the few aircraft that could fly those complex Northern European day-intruder missions planned out by the RAF and survive.

The Apache was not a Mustang I, the British got few, if any, A-36s.

If you start out with an 8% drag deficit between the P-36 and the P-40, that right there is about 25 mph potentially. And the inline engine clearly had a lot more room for rapid improvement in terms of cleaning up obstructions and streamlining, when you compare a P-36 hawk to an early 1941 P-40 to a mid 1942 one you can see the difference. I suspect the drag difference between a P-36 and a P-40L is a bit more than 8%.

You don't have suspect, it was more than 8%, as has already been mentioned it was 22% between the P-36A (much like the Mohawk in your first photo and the early P-40 like in the 2nd photo. But that difference had nothing to do with the wings or from the firewall back and everything to do with the engine installation. There may be some confusion as to amount of exhaust thrust was counted or not counted in each plane. But nobodies radial engine installations were very good in 1938-39-40. A lot of work was being done and the Germans were first with a significant change with the fw 190. P & W got the difference down to 8% with that P-40 test hack. From then on many radials got much closer to the liquid cooled engines in terms of drag.

The pace, the speed , and the intensity of the war just increased very rapidly, particularly in Europe. The aircraft that were fighting the Germans were a whole different beast and had to maintain a much higher combat speed to survive. The P-36 was competitive in the Battle of France in 1940, but by the battle of Britain a few months later (partly due to the nature of the fighting at higher altitude) it was no longer considered viable for the battlefield, even sufficiently to be sent to North Africa and the Middle East. The shift to the inline engine enabled a series of other changes that kept the new P-40 Tomahawk and Kittyhawk design 3 years after the original Hawk had already hit that wall.

Even sticking a V-12 on the nose of the P-36 wasn't enough to keep it competitive in Europe as the available V-12 didn't have enough power at altitude for the weight of the P-40.
Please note that in the fall of 1940 the DB 601 didn't offer much more power, it just had a much lighter airplane to haul around, you could have swapped engines and gotten pretty much the same results.

Curtiss was in the business of building airplanes. The more planes you could build to the same basic design the more profit you could make. Many designs were adapted to take different engines to suit the customers preference.

XP-31 as originally built and as modified.

note full span leading edge slats.
Curtiss could also go the other way, A-8 Shrike

A-12 Shrike

Some earlier Curtiss biplane fighters were sometimes fitted with radials for overseas customers instead of the water cooled V-12 engines.

This was done by a lot more companies than Curtiss. Hawker in England built both V-12 powered Fury biplanes and radial engined versions as well as Hart light bombers and variants with both types of engine.

Boeing tried the B-9 bomber with both types of engine.Changing engines doesn't change the design of the airframe.

 

[Schweik]

I'm well aware of the differences great and small between the A-36, P-51A and Mustang I & II, and which were deployed where. We discussed this at length in another thread here and I own a couple of books on this plane. In this case though despite the different designations and some different equipment (like dive brakes on the A-36) I do think they were fundamentally the same aircraft.

Changing engines doesn't have to change the design of the airframe but especially later on in the war it often did. I'm well aware some aircraft were made with both inline and radial engines, including some production aircraft during the war (Beaufighter F. II, D4Y -1 vs D4Y-3 and so on). Each aircraft is different and engines weren't plug and play replaceable parts necessarily. In several cases, including a few already mentioned (like the LaGG-3 / La 5), the difference was dramatic, either in outcome or necessary engineering or (typically) both.

The P-36 was just a different aircraft than the P-40 in both respects. .

 

[GrauGeist]

If we go by that definition of "different", than the P-51/P-51A was different than the P-51B/C and the P-51B/C was different than the P-51D/K.
Same goes for the P-40A/B/C/D being different than the P-40F/L, then...

 

[Schweik]

Like I said, there is some subjectivity in this which is why we will probably never agree. And yes I do think an aircraft is actually a new design sometimes within a specific aircraft model type. Personally (as I said already) I'd say Fw 190D is different from the A for example, or the Spit I from the Spit XXI, and the Allison Mustang from the Merlin ones, but I wouldn't insist on it.

I guess I would draw the line when it's both substantially different in terms of capabilities and performance, and has a different official designation. Admittedly somewhat arbitrary.

Defining exactly what makes a truly different aircraft when they are clearly of the same development lineage is tricky and I don't think there is any "official" criteria we would all necessarily agree on. I would argue it was usually a combination of factors, some dramatic (new type of engine, changes in the number of crew or a substantially changed wing), some more incremental like changes in armament, pilot or fuel system protection, fuel capacity, landing gear, modified control surfaces, and so on.

In the case of the P-36 / P-40 it's the combination of substantially increased performance (esp. top speed and dive acceleration) and overall carrying capacity. At the risk of repeating myself I believe the P-36 hit a wall in the 30's.

 

[Shortround6]

Then tell us how the P-40 and P-36 differed.

Different wing construction, airfoil, shape/size?
Different size/shape of tail surfaces?
Different fuselage construction?
Different length of fuselage (aside from what was needed to mount the engine/s)
Different armament possibilities? And remember that export Hawks had 4 gun wings before the P-40B did.
Different fuel capacities? We know the P-36 and export Hawks could carry 162 gallons (give or take a gallon) in three tanks laid out just like the P-40 tanks) they were not self sealing but changing from unprotected tanks to protected was common at this time and was hardly a "new" aircraft.
Different strength requirements? For the export Hawks with Cyclone engines the ultimate load factor was 12 while the Twin Wasp had an ultimate load factor of 11.5 but could be brought up to the 12 rating with an increase in weight and price.

If you are not aware of it an online version of the sales brochure for the Hawk 75 can be found here.
http://www.wwiiaircraftperformance.org/P-36/Curtiss_Hawk_75-A_Detail_Specifications.pdf