Most Overrated aircraft of WWII.....?

[Shortround6]

In some case the P-37/H-75 does have an advantage in range/endurance over the Hurricane and Spitfire but not in all and in very few cases, if any, does it have a range/endurance advantage over the P-40. A P-40B could "cruise"at 286mph at 15,000ft using 600 hp. A P-36 at 15,000ft needed 600hp to do 265mph. P-40 has a 10% speed advantage on nearly the same fuel burn.
However part of the point was that many advocates of the P-36/Hawk 75 want all the benefits and none of the penalties. And then they want to modify it using parts made out of anti-gravitium.

Adding weight to the nose or lengthening the nose has nowhere near the same effect as adding weight to the wing tips. Pitch change happens much less rapidly than rolling. most fighters could roll 360 degrees in 4-5 seconds. A few, at optimum speed, could roll 360 degrees in 2.5 seconds.
Nobody was performing a loop or a 360 turn in under 10 seconds, you would break the plane due the "G" forces which brings us to your anecdote.
"(I read somewhere an H75 could be on the tail of a Spitfire in 1 360 degree turn)" I have no doubt you read it but think about. Where was the H75 starting from? A Spitfire could do a 360 turn in about 20 seconds just off the stall and pulling a little under 3 "G"S (any harder and it lost altitude)
WHat kind of turn is the H75 doing to go from in front of the Spit to behind it in 20-25 seconds?

It was possible for a Spitfire to do a 360 turn in under 13 seconds but the speed has to be just right and the altitude has to be just right and the plane lost thousands of feet of altitude doing the turn.

The longer heavier engine may affect how fast the plane starts to change pitch but pitch response has to be slower than roll response. Part of the H75 advantage in some of these early tests was that the Spitfire elevators were too light/sensitive and pilots used them with too much caution. This was changed later with either spring or bob weight?

Comparing the H75 (powered by either engine) to the Martlet II also doesn't tell us much. The Martlet II used the the two speed P&W engine, had armor and self sealing tanks, four .50 cal guns with 300rpg ( 360lbs of ammo) a fatter fuselage and 24sqft more wing area (10%). weighed around 1250lbs more than the Hawk (?) and could bounce around on carrier decks.
No surprise it was slower.

 

[pbehn]

The longer heavier engine may affect how fast the plane starts to change pitch but pitch response has to be slower than roll response. Part of the H75 advantage in some of these early tests was that the Spitfire elevators were too light/sensitive and pilots used them with too much caution. This was changed later with either spring or bob weight? .

This is what I see as important to the test. In 1939 the British were at war but their two front line fighters had not been tested apart from against each other. It seems completely logical to concentrate on areas where the Hawk was superior to the Spitfire and figure out if anything could be done about it. They had no real idea how a Bf109 performed but it was clear if France used Hawks one would fall into enemy hands.

 

[swampyankee]

I am at a loss in this discussion, the RAF received 225 Hawks and considered them obsolete.

I think one thing that's happening is that, 3/4 of a century after the fact, we're looking at a small subset that is part of a large amount of data, scattered over tens to thousand of reports, memoranda, in-person conversations, and phone calls, with no permanent record kept of the last two.

The RAF knew that the Hurricane was inferior to the Bf109 in many flight regimes, and, while the Spitfire was better, it wasn't enough better to have a comfortable margin of superiority. Here's a foreign aircraft, which shows some areas of superiority to the Spitfire, possibly mostly in the horizontal plane, but which can't demonstrate the sort of superiority that the RAF feels it needs to deal with the Bf109 or, most importantly, the partner the Bf109 is likely to have soon. It's also possible the RAF felt an immediate prejudice against that round motor in front: real fighters had V-12s, and that was considered a major point against the P-36. At this time, they couldn't yet know that fighters with round motors -- from Focke Wulf, Grumman, Vought, Lavochkin, Mitsubishi, and others -- would demonstrate that real fighters did have round motors.

As for the longitudinal weight distribution, it's not going to affect steady-state turns, just the pitch acceleration. It will become a serious problem later, with jet aircraft, where the relation longitudinal and lateral mass distribution can have critical repercussions, as occurred on the F-100.

 

[pinsog]

I'm going to retract the "P36 can get on Spitfire tail in 1 360 degree turn", I can't back that up and I think I am confusing another test.

On the other hand, I know the improved P36/H75 would gain a bit of weight. But, I think they could have built an improved P36 at around 6,600 pounds. 2 50's, 4 30's, 2 speed 2 stage engine, self sealing tanks. 1,000 hp at 21,000 feet rather than 600 and 860 hp at 25,000 vs 515 should improve performance dramatically. A 6,600 pound P36 should retain much more turning ability than an 8,000 pound P40. Even the Wildcat at the same weight beat the P40 in every category above 22,000

All the speed in the world matters little when Zeros and Betty's just fly above your ceiling.

 

[pbehn]

I think one thing that's happening is that, 3/4 of a century after the fact, we're looking at a small subset that is part of a large amount of data, scattered over tens to thousand of reports, memoranda, in-person conversations, and phone calls, with no permanent record kept of the last two.

The RAF knew that the Hurricane was inferior to the Bf109 in many flight regimes, and, while the Spitfire was better, it wasn't enough better to have a comfortable margin of superiority. Here's a foreign aircraft, which shows some areas of superiority to the Spitfire, possibly mostly in the horizontal plane, but which can't demonstrate the sort of superiority that the RAF feels it needs to deal with the Bf109 or, most importantly, the partner the Bf109 is likely to have soon. It's also possible the RAF felt an immediate prejudice against that round motor in front: real fighters had V-12s, and that was considered a major point against the P-36. At this time, they couldn't yet know that fighters with round motors -- from Focke Wulf, Grumman, Vought, Lavochkin, Mitsubishi, and others -- would demonstrate that real fighters did have round motors.

As for the longitudinal weight distribution, it's not going to affect steady-state turns, just the pitch acceleration. It will become a serious problem later, with jet aircraft, where the relation longitudinal and lateral mass distribution can have critical repercussions, as occurred on the F-100.

I see it a little differently, the tests were in November 1939, by the time the Hawk arrived diverted from French orders everything had already changed a lot, especially regarding props and fuels. As for V 12s being superior in the eyes of the RAF, they quite clearly were at that time, any radial engine plane had to beat what the RAF already had. The Spitfire in the test quoted was clearly much faster, so it wasn't even discussed. If such a prejudice existed it must have been well covered up, the Sea Fury had an air cooled radial engine that did not just appear from thin air. Long before any radial engine out performed the Spitfire the British had H and X type water cooled engines being developed in addition to air cooled radials. It is a simple fact that the Spitfire remained a top class front line fighter until the end of the war and the P-51 in a different role did too.

 

[buffnut453]

I'm not convinced by the whole "RAF prejudice against radial engines" concept. After all, most of the pre-war RAF biplane fighters had radial engines: Bulldog, Gauntlet, Gladiator etc. Indeed, the ONLY pre-war RAF biplane fighter with an inline engine was the Fury. I suspect, in reality, the RAF would have accepted a rubber-band engine if it delivered the required level of performance.

While the P-36/H-75 may have had some performance advantages over the Spitfire in the horizontal plane, the latter could effectively disengage at will courtesy of its higher speed and better acceleration. Successful fighter pilots maximize the strengths of their own aircraft and strive to minimize the advantages of their adversary's machine. Thus a Spitfire pilot would be foolish to get into a turning fight with the P-36/H-75 and even more foolish to stick with a turning fight instead of using his aircraft's better speed to break off and re-engage at a tactical advantage.

 

[pinsog]

At low altitude the P36/H75 also outclimbed the Spitfire until the low altitude rated engine ran out of wind. I wonder, along with others, how well a continuing development of the P36/H75 would have done. 1000 hp instead of 600 at 21,000 feet, 860 instead of 515 at 25,000. Probably push the P36/H75 up closer to 340 mph. That might be close enough to be competitive.

 

[parsifal]

The improved P-36 being theorised about sounds remarkably similar to the Amee De l' Air's Hawk 75A-3.

http://www.wardrawings.be/WW2/Files/2-Airplanes/Allies/4-France/01-Fighters/Curtiss-Hawk75/Curtiss-Hawk75A-3.htm

It had a top speed of 323mph, a nominal ceiling of 31850 feet. It had 2 x HMG and 2 LMG offensive weapons, and some armour.

Generally it outflew the bf109, when flown by the exceptionally experienced FAF pilots. Theres the difference. FAF had been flying the H-75 since well before the war. The units flying this type were elite units of the FAF, fully worked up with exceptional commanders. They basically flew rings around the Luftwaffe.

None of that makes the H-75 A-3 subtype superior to the Bf109 and not superior to the Spitfire. It wasn't even superior to the Hurricane in my opinion. It was just a ready design in 1940.

RAF and RIN units flew a few H-75 (I think A-3s) over Burma with not much success against JAAF units. In 1942, the type finally began pre-production, but with just 4 produced. The reason for its dis-continuance was that it just wasn't competitive against the JAAF. RAF and RIN units continued to receive, and preferred, Hurricanes over this type almost to the end of the war, albeit as flying artillery.

I'm at a loss to understand what all the fuss is about to be honest

 

[pbehn]

At low altitude the P36/H75 also outclimbed the Spitfire until the low altitude rated engine ran out of wind. I wonder, along with others, how well a continuing development of the P36/H75 would have done. 1000 hp instead of 600 at 21,000 feet, 860 instead of 515 at 25,000. Probably push the P36/H75 up closer to 340 mph. That might be close enough to be competitive.

This is becoming a circular argument, an additional 400HP at 21,000 ft is not in Curtiss domain, the USA was gearing up for 2000HP radials but officially war was not declared. The Wildcat was not a competitive fighter with RAF and LW land based fighters in 1940 neither was the P36.

 

[buffnut453]

The key question is where that extra 400hp is going to come from...and what changes does that force on the design? Bigger, more powerful engines typically weigh more and are thirstier, both in fuel and oil. All of that pushes the weight upwards before we consider armour plating or armament. If we increase weight without increasing wing area, we increase wing loading which impacts rate of climb, landing speed and, crucially, turn performance. There's no such thing as a free lunch. If the P-36 could be improved to the extent you identify, I'd imagine it would have happened in preference to the P-40.

I'd be interested to learn whether the P-36 could still outclimb the Spitfire once the MkV started entering service with constant-speed propellers. Bear in mind that at the time of the quoted test, the Spit was barely being delivered with 2-speed props and still had the some of the earliest variant Merlins. Could the P-36 be updated in time to beat the Spit MkV into service? I suspect not given the extent of the modifications required.

 

[pbehn]

The key question is where that extra 400hp is going to come from...and what changes does that force on the design? Bigger, more powerful engines typically weigh more and are thirstier, both in fuel and oil. All of that pushes the weight upwards before we consider armour plating or armament. If we increase weight without increasing wing area, we increase wing loading which impacts rate of climb, landing speed and, crucially, turn performance. There's no such thing as a free lunch. If the P-36 could be improved to the extent you identify, I'd imagine it would have happened in preference to the P-40.

I'd be interested to learn whether the P-36 could still outclimb the Spitfire once the MkV started entering service with constant-speed propellers. Bear in mind that at the time of the quoted test, the Spit was barely being delivered with 2-speed props and still had the some of the earliest variant Merlins. Could the P-36 be updated in time to beat the Spit MkV into service? I suspect not given the extent of the modifications required.

And (cough cough) 100 octane fuel.

 

[tomo pauk]

I'm going to retract the "P36 can get on Spitfire tail in 1 360 degree turn", I can't back that up and I think I am confusing another test.

On the other hand, I know the improved P36/H75 would gain a bit of weight. But, I think they could have built an improved P36 at around 6,600 pounds. 2 50's, 4 30's, 2 speed 2 stage engine, self sealing tanks. 1,000 hp at 21,000 feet rather than 600 and 860 hp at 25,000 vs 515 should improve performance dramatically. A 6,600 pound P36 should retain much more turning ability than an 8,000 pound P40. Even the Wildcat at the same weight beat the P40 in every category above 22,000

All the speed in the world matters little when Zeros and Betty's just fly above your ceiling.

The SAC for the F4F engine (2-stage, 2-speed R-1830) gives 1040 HP at 18400 ft, that works to 1000 HP at ~19000 ft, or 900 HP at 21000 ft (nor ram effect).
The P-40B has the same armament as stated for the proposed 'P-36 plus', it also features 93lbs of armor. Weights 6833 lbs equipped, ready for take off, with 120 gals of fuel. Good for 347+ mph at 15000 ft. Best cruise at 8.4 mi/gal, vs. 6.5 mi/gal for the P-36 that weighted 5800 lbs, and was good for 317 mph at 10000 ft. Granted, the 2-stage engine will make the P-36 going faster, while sticking the V-1650-1 on the P-40B airframe will make that one going even faster.
The P-40B needs 12 min to reach 25000 ft. That means it can climb on the 20000 ft altitude very fast. Zeros and Betties were flying well under the ceiling of any Allied A/C.

 

[pinsog]

For the 1000 hp at 21,000, I was using the graph for the F4F-3 on wwiiaircraft performance, it must include ram to reach that figure. Same graph drops to 860 at 25,000. The single P36B shows 317 mph at 17,000 on 950 hp so there was obviously improvement left in the P36.

Looks like the P40B would have been a welcome addition to Darwin when the Japanese were coming in above the P40's ceiling, hence he need for Spitfires. They also said the Japanese fighters and bombers came in above the P40's ceiling in the Philippine invasion. At Guadalcanal only the Wildcats were capable of intercepting the high altitude, well above what the P39's could climb to

How, in your opinion does the P40B stack up against the Spitfire II and early Me109?

 

[wuzak]

How, in your opinion does the P40B stack up against the Spitfire II and early Me109?

Since the P-41B first flew in March 1941, the question should be how did the P-40B stack up against the Spitfire V and Bf 109F? The answer, most likely, is very poorly.

 

[wuzak]

I'd be interested to learn whether the P-36 could still outclimb the Spitfire once the MkV started entering service with constant-speed propellers. Bear in mind that at the time of the quoted test, the Spit was barely being delivered with 2-speed props and still had the some of the earliest variant Merlins. Could the P-36 be updated in time to beat the Spit MkV into service? I suspect not given the extent of the modifications required.

Surely the Spitfire Mk II has CS propellers, and Mk Is had them retrofitted at some stage. In 1940.

 

[wuzak]

At low altitude the P36/H75 also outclimbed the Spitfire until the low altitude rated engine ran out of wind. I wonder, along with others, how well a continuing development of the P36/H75 would have done. 1000 hp instead of 600 at 21,000 feet, 860 instead of 515 at 25,000. Probably push the P36/H75 up closer to 340 mph. That might be close enough to be competitive.

The Spiftires high altitude rated engine also lacked at power at low altitude. If it had a 2 speed engine that would have been fixed.

 

[wuzak]

The H75 the brits flew in 1939 test had armour, 6 light machineguns and weighed 6025 pounds during the test where it had no trouble out turning the Spitfire. (I read somewhere an H75 could be on the tail of a Spitfire in 1 360 degree turn) If the H75 jumped the Spitfire, the H75 stayed on him until the Spitfire could outrun him.

No doubt a Gloster Gladiator could out-turn the Spitfire. Perhaps the RAF should have stayed with them?

The Hurricane could also turn tighter than a Spitfire. Perhaps the RAF should have developed them more.

 

[Shortround6]

We have several "ceilings" service ceiling is pretty much useless except as a relative indicator between different designs.
they generally figured you needed about 500fpm of climb in hand just for a small formation to stay in formation as it flew.
In order to actually fight at an altitude (and not just dive down from a certain altitude) you need 1000fpm of climb.

This brings the combat altitude of the P-36C down to somewhere under 25,000ft, perhaps 24,000ft?
A MK I Spitfire using 6 1/2 lbs of boost and mere 2600rpm could climb at 1000fpm at 27,000ft.

We have no tests in which they used the 5 minute combat rating for climb.
This is also the problem when comparing US tests of aircraft to British tests.
The US used the 5 minute rating of the engine for the 5 minutes from sea level and then cut back to the max continuous power for the rest of the climb.
The British used a 30 minute rating for the entire climb and in the case of the Hurricane and Spitfire the 30 minute rating was changed from 2600 rpm and 6 1/2 lbs boost to 2850rpm and 6 1/2 lbs boost. SO climb improved at all altitudes even without going to the 5 minute rating let alone using the 12lb boost limit.

Yes the P-36 and the Wildcat could both do a bit better if you used 2700rpm instead of 2550 rpm for climbing at high altitudes but obviously having an extra 400rpm beats the heck out of an extra 150rpm.

As for a "light weight" Hawk using the two stage engine out of an F4F-3, it wasn't going to happen. Adding up the figures from AHT the powerplant of of a long nose P-40 went about 2440-2450lbs, cowl, mounts, engine, prop, accessories, starter and so on I do not include fuel system. the Power plant for the F4F-3 went 2560lbs, 10-15lbs out of 2550 is actually too close to call as you might have that much difference between two of the same plane on the production line.

Now a P-36C, empty (but with radio) went 4628lbs.
An export hawk with P&W engine went 4713lbs empty with a powerplant weight of 2170lbs (I don't have the list of equipment in the powerplant). An increase of roughly 400lbs in powerplant weight is going to call for some changes in other places.
Now add some of the "extras" that creep in. Export Hawk allowed for 112lbs worth of radio instead of the 62lbs in the P-36 handbook. Ealy P-40s show 71lbs for communications but later ones go to around 130lbs and some P-40Ns go over 200lbs.
Fuel tanks on a P-40 without protection went 171lbs, P-40B went 253lbs and the P-40C went 420lbs where the weight pretty much stayed unless they yanked out the forward tank like on the P-40L and N. Even leaving the rear tank unprotected is going add over 100lbs.
Once you add hundreds of pounds you need to beef up the wing, and the fuselage to keep the 12 G ultimate load rating and you may need to beef up the landing gear (or at least fit bigger tires)

Now in addition to the technical details you have two production problems and a major timing problem. Unless you can magic up a brand new factory, with tooling and a work force every super P-36 you build will be one less P-40, Want 300 super P-36s in 1941? then you have 300 fewer P-40s. Unless you also drastically change P&W's development schedule and production schedule for late 1940 and 1941 you will also have 300 fewer F4F-3s with two stage engines.
And that brings us to the timing problem, Comparing the Super P-36 with two stage engine to Spitfire Is or long nose P-40s is a false comparison. By the time you get two stage P&W R-1830s in quantity (mid to late 1941) the Spitfire to beat is the MK V and the P-40E is in production and the P-40F with Merlin prototype has flown. Hurricanes have Merlin XX engines and twelve .303 guns.

At which point what do you do with the Super P-36? it is useless in Europe vs Bf 109Fs, It's usefulness in the Dessert is doubtful, No subtititution of aircraft or an additional couple of squadrons are going to save the Philippines or Singapore.

 

[wuzak]

Now in addition to the technical details you have two production problems and a major timing problem. Unless you can magic up a brand new factory, with tooling and a work force every super P-36 you build will be one less P-40, Want 300 super P-36s in 1941? then you have 300 fewer P-40s. Unless you also drastically change P&W's development schedule and production schedule for late 1940 and 1941 you will also have 300 fewer F4F-3s with two stage engines.

You could change the F4Fs to the R-1820, but what does that do for B-17 production? A small impact in overall production, but much bigger at a time when B-17 production was ramping up?

 

[Shortround6]

Some Hawks were built with the R-1820 but in two speed supercharger versions at best, no turbo, no two stage mechanical.
P & W was building 10 single stage R-1830s for every two stage R-1830 in 1941 which is where the shortage of two stage R-1830s comes from.

The export F4Fs with Cyclone engines didn't exactly set the world on fire. See Martlet I and IV. The IV gained over 700lbs in empty weight over the Martlet I
http://www.wwiiaircraftperformance.org/f4f/martlet-I-ads.jpg

Can you say "sitting ducks" against Zeros?