P36 vs Hurricane

[RCAFson]

General feelings are that the P36 was too slow and obsolete to fight in WW2, yet the Hurricane has a loyal following especially up through the Battle of Britain.

Yet, I was looking at the specs on wwiiaircraftperformance and the P36 was 17 mph faster than the Hurricane at 10,000 feet. It was equal in top speed to the Hurricane at 17,000 feet when equipped with the P&W R-1830-23 engine. It could beat the Hurricane in a time to climb to 23,000 feet and it could easily out turn it under any conditions. The Hurricane had 8 .303 machine guns, the P36 either 1 .50 and 5 30's or, I understand the later models had 2 .50's and 4 30's.

So why was the Hurricane ok and the P36 was obsolete? If the P36 had the 1830-23 engine or later, I don't see what the Hurricane had over it at all.

I don't see those numbers showing an advantage for the P-36. IIRC, the P-36 did not have armour and self sealing tanks. Add those and there's no contesting that the Hurricane1 was superior.

 

[FLYBOYJ]

Altitude can be converted to speed. So if Zero has an altitude advantage then P40 might not have a speed advantage when the turning & burning begins.

Not really - the Zero cannot out dive a P-40 and its ailerons become bricks at speeds above 250

 

[pinsog]

Weight gain would have been much higher.

The R-1830 engine/s used in the P-36 were single speed engines. the -17 used a 7.15 supercharger gear and the -23 engine used a 8.0 supercharger gear. More power higher up but it cost 100hp at take-off or low level (1100hp for take-offat 2700rpm) .
-17 engine weighed 1403lbs, -23 engine went 1436lbs. The -33 engine used in the P-66 and early non-turbo B-24s was a two speed engine that went 1480lbs. gear ratios were 7.15 and 8.47. engine would give 1000hp at 14,500ft (no ram) compared to the -23 engine 950hp at 14,300ft, both at 2700rpm.

Only one P-36 was ever fitted with four wing guns in US service.
Tomo is quite correct in the weights for the self sealing tanks for the P-40s. I would also note that the fuel tank behind the pilot was referred to as a ferry tank or overload tank. In other words, much like the rear tank on the Mustang, full combat maneuverability was not AVAILABLE with the rear tank full.
You want four wing .30s? Add 222lbs to the US weight figures for guns and ammo.
You want four .50 cals? rip out the 100lbs of gins in a P-36/A and put in 314lbs worth of guns, 214lb increase. Instead of 83lbs worth of ammo even 200rpg for the four .50s is 200-240lbs

Wildcat engine used a two stage supercharger. it weighed 1550/1560lbs and needed inter-coolers.

The XP-40 was the 10th P-36 pulled off the production line.
Why is it so hard to understand that just about any "improvement" done to the P-36 would track the same sort of improvement done to the P-40 almost pound for pound?
Allison went about 1350lbs with a 290-295lb cooling system.
The P-40 gained around 150lbs of weight in the wing group compared to a Hawk 75. (P-36 weight unknown) Hawk 75 with P&W engine was about 300lbs heavier than a P-36 with both holding 105gals of fuel. P-36s had some trouble with wing skin wrinkling or buckling in the wing root landing gear area.

Using the figures provided in the spec sheet. Use the -23 engine giving 317 mph at 17,000 feet. Remove 3 30 caliber machine guns weighing 44 pounds for both wing guns, 27 for the synchronized gun and 1,500 rounds of ammo at 33 pounds per 500 totals 170 pounds. Add 3 50's back in at 73 pounds per gun and 200 rounds of ammo per gun at 50 pounds per 200 equals 369. 369-170=199 pounds increase.

Add another 100 pound armor plate behind pilot

I don't see those numbers showing an advantage for the P-36. IIRC, the P-36 did not have armour and self sealing tanks. Add those and there's no contesting that the Hurricane1 was superior.

Why? From what I read, all the Hawk75's that went into action had seat armor for the pilot.

Self sealing tanks...do they actually have to work? The last place on the planet I would want to be in 1940 was in a Hurricane that just had the "self sealing fuel tank" in front of me hit by 8mm fire from a 109 or a defensive gunner on a bomber because apparently they were self sealing in name only, from what I have read they tended to drench the pilot in petrol and then ignite. Hurricane pilots were notorious for being burned and if your opened the canopy to bail out, evidently it sucked the flames down through the open canopy like a blast furnace. I'd rather have 2 50's than 8 DRC (deer rifle caliber) machine guns

 

[Greg Boeser]

The Finns loved their Hawk 75s. LLV 32, equipped with Hawk 75s had the third best combat record during the Continuation War behind LV 24 with B-239s and later Bf 109Gs and LLV 34 with Bf 109G (introduced in 1943).
The Finns used a mixed bag of models, 75A-1, -2, -3 and -4 from French stocks and -6 from Norwegian stocks.

 

[FLYBOYJ]

I don't see those numbers showing an advantage for the P-36. IIRC, the P-36 did not have armour and self sealing tanks. Add those and there's no contesting that the Hurricane1 was superior.

And the Hawk H75s supplied to France? I believe the Hawk Hawk 75A-2/3 had armor and self sealing tanks - and again they accounted for a third of the kills during the Battle of France.

 

[pinsog]

Not really - the Zero cannot out dive a P-40 and its ailerons become bricks at speeds above 250

I assume he means the P40 is flying level when the Zero bounces him, not that they were diving together. The Zero in a dive from altitude is faster than a P40 flying flat out straight and level

 

[pinsog]

And the Hawk H75s supplied to France? I believe the Hawk Hawk 75A-2/3 had armor and self sealing tanks - and again they accounted for a third of the kills during the Battle of France.

I didn't realize they had self sealing tanks. I knew they had seat armor. If they had the -23 engine, giving them 317 mph at 17,000 and a pair of synchronized 50's instead of 6 light machine guns they might have done even better. Pilots talked about having to get within 50 yards/meters of a bomber before the light machine guns would have any effect

 

[FLYBOYJ]

I assume he means the P40 is flying level when the Zero bounces him, not that they were diving together. The Zero in a dive from altitude is faster than a P40 flying flat out straight and level

I don't think by much - the Zero was a poor diver - if you can't control an aircraft in a dive, what good is the tactical advantage?

How fast was the Zero?

 

[Greg Boeser]

Another interesting thing about the Hawk in Finnish service is that the highest scoring "Suusu" was a four gun H-75A-6. So more guns doesn't necessarily mean better success. The Finnish aces preferred the four gun models because they were more maneuverable than the heavier six gun models.

 

[pinsog]

I don't think by much - the Zero was a poor diver - if you can't control an aircraft in a dive, what good is the tactical advantage?

How fast was the Zero?

I agree with that, and as I pointed out, the P36/H75 didn't have that problem, it was light on the controls at any speed. Even the Spitfire had stiff controls and trouble rolling at high speed as did the 109. The H75 with a 109 on its tail could do a single 360 and be behind the German.

 

[pinsog]

Another interesting thing about the Hawk in Finnish service is that the highest scoring "Suusu" was a four gun H-75A-6. So more guns doesn't necessarily mean better success. The Finnish aces preferred the four gun models because they were more maneuverable than the heavier six gun models.

What guns was that plane equipped with?

 

[Greg Boeser]

What guns was that plane equipped with?

The H-75A-6 as supplied to Norway was supposed to have 4 x 7.9mm Brownings. I believe that in Finnish service they carried 7.7mm Brownings, though in 1942 Hawks began to replace one or both nose guns with .50 caliber Brownings, or sometimes captured UBSs.
The -6 was also supposed to be powered by the SC1G-3, as were the Hawk 75A-3s from France, but the source I recall - Backwoods Landing Strip - is no longer available. It mentioned the use of the Swedish licensed SC3-G. Did Finns have access to 100 octane fuel?

 

[RCAFson]

I didn't realize they had self sealing tanks. I knew they had seat armor. If they had the -23 engine, giving them 317 mph at 17,000 and a pair of synchronized 50's instead of 6 light machine guns they might have done even better. Pilots talked about having to get within 50 yards/meters of a bomber before the light machine guns would have any effect

They didn't have SS tanks, nor armoured glass and the armour on the pilot's seat was "optional". Here's the detailed specs:

http://www.wwiiaircraftperformance.org/P-36/Curtiss_Hawk_75-A_Detail_Specifications.pdf

strip all of these off the Hurricane and it's performance would increase dramatically. Note that the manufacturers' spec performance falls along way short of actual USAAF and RAF testing:
P-36 Flight Tests


MOHAWK testing at Boscombe down:
Mark/airframe/engine/weight/ time to climb/RofC/ceiling /speed
I AR645 R-1820-G20SA 6,317lb 6.2 min to 15,000ft 2,600fpm @ 8,000ft 33,800 302mph @ 14,000ft Ex French - contract - Model75C
II AR631 R-l830-SC3G 5,962lb 7.3 min to 15000ft 2,260fpm @ 9,600ft 31,200ft 300mph @ 10,000ft Ex Norwegian - 84 gal fuel

 

[FLYBOYJ]

They didn't have SS tanks, nor armoured glass and the armour on the pilot's seat was "optional". Here's the detailed specs:

http://www.wwiiaircraftperformance.org/P-36/Curtiss_Hawk_75-A_Detail_Specifications.pdf

That's a flight manual for a basic 75A - the French aircraft had different equipment, a throttle that was "backwards" and I think the armored seat. Despite what you say I think its evident that it held its own despite its limitations. Maybe the pilots flying it had something to do with it?!?!

 

[GregP]

Somebody's smoking weeds; not saying it is Greyman, either.

The Hurricane was never a 327 mph fighter in combat configuration. Operational examples in the BOB could not even hit 300 mph. Most topped out at 288 - 294 mph, and that was at full throttle, best height. We all know how long full throttle can be used, so most were basically 275 mph airplanes in combat trim, with a little "extra" if badly needed for a short time.

At least they were in the combat reports I have read and the books I have seen. The only 300+ mph Hurricanes I can recall were unarmed prototypes. The 327 mph variant was ONE mark in unarmed fitment, IIRC. The fastest fully armed, large production rtun version I can recall went 31 mph at the company trials. In service they lost a bit of speed and were down to sub-300 mph performance, too.

 

[wuzak]

The fastest fully armed, large production rtun version I can recall went 31 mph at the company trials.

That fast?

 

[wuzak]

Somebody's smoking weeds; not saying it is Greyman, either.

The Hurricane was never a 327 mph fighter in combat configuration. Operational examples in the BOB could not even hit 300 mph. Most topped out at 288 - 294 mph, and that was at full throttle, best height. We all know how long full throttle can be used, so most were basically 275 mph airplanes in combat trim, with a little "extra" if badly needed for a short time.

At least they were in the combat reports I have read and the books I have seen. The only 300+ mph Hurricanes I can recall were unarmed prototypes. The 327 mph variant was ONE mark in unarmed fitment, IIRC. The fastest fully armed, large production rtun version I can recall went 31 mph at the company trials. In service they lost a bit of speed and were down to sub-300 mph performance, too.

You might want to check this out Greg:

Hurricane L-2026 Trials Report

 

[Shortround6]

I believe that 304mph for a Hurricane top speed speed was quoted in a speech about the time of the BoB and repeated quite a bit since. The speed was quoted a bit out of context as that was the average speed of Hurricanes being returned to service after repair. Not new Hurricanes from the factory/s.
High speeds for the P-36 and Hawk 75 follow the same general rules. Full power (2700rpm) was only available for 5 minutes (if that) with 2550 rpm being the "normal" rating and for the most part, planes did not go charging about the sky at 88-90% power ratings either.

Something to note from the USAAC Handbook of operation and flight instruction was that the P-36 had a max gross weight of 5840lbs. This was true for both the P-36A (2 gun) and the P-36C (4 gun) and has the following note.

"The weights given in the normal weight column represent approximate useful military load. When overloads are carried, flight restrictions as specified in Air Corps Circular 60-9 must be observed."

Please note that the P-36C with four guns was within 2lbs of the max gross with 105 US gallons of fuel.
I would also note that the P-36C gained 124lb over the P-36A without guns being installed. And that a P-36A could hit 6017lbs with full fuel,oil and landing flares.
If you want more powerful engines and more guns/ammo, armor/protected tanks something has to give. Either less fuel or you need heavier structure if you are going to keep the same flight safety margins. There is no free lunch.

 

[FLYBOYJ]

If you want more powerful engines and more guns/ammo, armor/protected tanks something has to give. Either less fuel or you need heavier structure if you are going to keep the same flight safety margins. There is no free lunch.

And I believe the last version of the H75 (-4?) had some structural modifications

 

[Lefa]

The Finns apparently used Hawk's 87 octane gasoline.
The bomb racks and light bomb tanks were removed as unnecessary.
Armament changed to 1 or 2 12.7 mm machine guns and two or four 7.7 mm Browning on wings.
Nickname is "Sussu" = Sweet heart, because the machine was easy and pleasant to fly.