P36 vs Hurricane

[GrauGeist]

And, obviously, the sample of any combat over the Pacific was tiny compared to the air battles that occurred around England, Germany and Russia.

Some of the air battles that occurred in the Pacific would have dwarfed aerial engagements in the ETO both on savagery and sheer scale.

Especially when the Japanese still had the manpower and resources to bring a fight to the Allies.

 

[Shortround6]

Hey Fastmongrell,

Thanks for tghe table. His table is deeply flawed.

Follow his example. He says the first row shell has 5% Hei, so he multiplies by 1.5. But that SHOULD be 1.05, not 1.5.

105% is 1.05 and 150% is 1.5. So his numbers are WAY off.

" For projectiles with a chemical content, we increase this by the weight fraction of explosive or incendiary material, times ten. This chosen ratio is based on a study of many practical examples of gun and ammunition testing, and we will see below that it at least approximately corresponds with the known results of ammunition testing." from the paragraph 2 above the the one which details out the .303 calcualtion.

5% X 10 is 50% by my math.

There may be some mistakes in the tables, I certainly believe there are some in table III

 

[tomo pauk]

...
Best guess on cyclic rate for Dauntless 50's? P39 50's?
...

IIRC the cyclic rate for the synchronised .50 BMG was 550 rpm.

But then, if we settle for a pair of .50s as a viable weapon in 1942 for the US fighters, the P-40 and especially P-39 will be far better performers with just a pair of .50s - talk 360+ and 370+ mph, respectively? With a boost to the rate of climb, rate of roll and general maneuverability.

 

[fastmongrel]

IIRC the cyclic rate for the synchronised .50 BMG was 550 rpm.

The synchronised rate for a .50 BMG in 1939 when this plane would be built was about 400 to 450rpm. When the BMG was sped up from 600 to 800rpm in iirc 1941 the synchronised rate went to approx 550 to 600rpm. Synchronised rate varies between planes from the same batch, how many revs the prop is doing and how many blades the prop has. Certain engine and prop combinations worked better with the synchro gear, 3 blades was the maximum no one seemed to get a 4 blade synchro to work and fixed pitch props were better than constant speed props for some reason.

Whatever gun, prop and engine combination was used the synchronised rpm was about 3/4 of the max rpm. It could be sped up by cutting the safety margin but then you have the risk that a slight hangfire means you just shot one of your prop blades off. Which always ruins your day

 

[tomo pauk]

The synchronised rate of fire was approaching 90% or the 'free' RoF in case electically fired ammo was used - basically, we talk about German guns, like MG 131 and 151.

 

[fastmongrel]

The synchronised rate of fire was approaching 90% or the 'free' RoF in case electically fired ammo was used - basically, we talk about German guns, like MG 131 and 151.

Good luck getting a midwar German gun fitted into a 1939 US plane

 

[Shortround6]

P-40 at 360mph at what altitude

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.

Getting back to the Original question.
There was ONE P&W R-1830-23 engine made, it was converted BACK to a P&W R-1830-17 at the end of the test/s. It gave up 100 hp at take-off for the better performance at high altitude.
The P-36B had ONE .50 cal gun and ONE .30 cal gun. The P-36D (one built and and placed in service after tests) had ONE .50 and FIVE .30s but we have no performance data on the P-36D. P-36G had TWO .50s and FOUR .30s but used a Wright Cyclone ( and we have little or no performance data aside from top speed)
We have Performance data for the P-36C with ONE .50 and THREE ,30s.

The P-36 performed pretty good at low altitude, the problem came at high altitudes. once you get to about 15,000 the Hurricane can outcimb the P-36. And that is an equipped Hurricane.
Just adding 150lb to the P-36 (and the large shell boxes) not only dropped the speed by a rather insignificant 2mph but lengthened take-off run and distance to 50ft by 50 and 100ft and added 12 seconds to climb to 15,000ft. It cut climb by 100ftper minute at low altitudes and 50fpm at higher altitudes and cut about 1000ft from the ceiling. Adding armor, self-sealing tanks and more guns is just going to affect things more. The P-40 lost 3000ft worth of service ceiling go from the no letter version to the "C" version as operational equipment and 2 extra .30 cal guns were added.
The P-36C had a ceiling 750 ft lower than the P-40 no letter and 500-1000ft lower than a Hurricane I with Rotol prop (depending on Hurricane weight.
Switching to a 2 speed R-1830 engine gets you 1050hp at 13100ft no ram in hi gear and the engine is a bit late.

 

[Juha2]

Hello Grayman
thanks alot for the graphs!
According to Lionel Persyn's Curtiss Hawk H-75 in French Service (2010) the plane used in the French test (N 1 of the Adl'A's H-75s tested in the USA between Nov 1938 and Jan 1939) was unarmed and not painted. The results match with your graph, 412 km/h at s/l and 502 km/h at 4400 m [256 mph at s/l, 312 mph at 14 436 ft]

Juha

 

[Juha2]

H-75A4 or H-751 as the French called it had Wright Cyclone G-205A engine with a 2-speed supercharger. French got 81 of them before the surrender.

 

[Juha2]

The Russians were basically using 2 .50 Brownings against the Germans when they used the P39. They removed all the wing guns and I would imagine the 37mm was useless against a maneuvering 109 or 190 and only good for relatively non maneuvering bombers, so that leaves 2 50s...

According to some Russian pilots LW 190 pilots had liked head-on attacks with their sturdy fighter against fairly lightly armed Russian fighters but learned fast not to try that against P-39. Also Finnish fighter pilots noted the 37 mm muzzle flash .

 

[Juha2]

A couple clips from the RAE Curtiss H-75 handling tests and comp aileron tests H-75, Spitfire and Gloster F.5/34 based on the RAE Report No BA 1583 AVIA 6/2338

 

[Juha2]

 

[Old Wizard]

 

[tomo pauk]

Thank you very much.
BTW - is there the 2nd page of the report around?

 

[Juha2]

Hello Tomo

the RAE Report No BA 1583 has over 50 pages plus 14 pages of Figures and that Reports and Memoranda No 2379 from which the 2 clips are has 43 pages.

The page 2 of the RAE Report No BA 1583 attached.


Juha

 

[stona]

No mention of altitude?

One could have an aircraft performing superbly at 17,000ft which would be next to useless as an interceptor in the Battle of Britain if it couldn't do something at least similar at 25,000ft +.

Cheers

Steve

 

[tomo pauk]

Hello Tomo

the RAE Report No BA 1583 has over 50 pages plus 14 pages of Figures and that Reports and Memoranda No 2379 from which the 2 clips are has 43 pages.

The page 2 of the RAE Report No BA 1583 attached.


Juha

Thank you again.
Is it possible to download the documents mentioned ( my google-fu seems weak today)?

 

[Juha2]

Hello Steve

I read the reports over a decade ago and fast skimming through them, no time to more thorough checking, didn't reveal altitude, but the plane was a late H-75A-2 with SC3-G engine, a French test (painted and fully equipped, 4 guns) gave following results, no time to conversion to mls/ft, 2540rpm, 412.5 km/h at 1000 m, 482 km/h at 4000m, 491 km/h at 5000m and 449.5 km/h at 8000 m (over 26,000 ft I think).

HTH
Juha

Hello Tomo
no time at least now

Sorry
Juha

 

[wuzak]

Hello Steve

I read the reports over a decade ago and fast skimming through them, no time to more thorough checking, didn't reveal altitude, but the plane was a late H-75A-2 with SC3-G engine, a French test (painted and fully equipped, 4 guns) gave following results, no time to conversion to mls/ft, 2540rpm, 412.5 km/h at 1000 m, 482 km/h at 4000m, 491 km/h at 5000m and 449.5 km/h at 8000 m (over 26,000 ft I think).

256mph @ 3,281ft
300mph @ 13,123ft
305mph @ 16,404ft
279mph @ 26,247ft

 

[stona]

I take it those are TAS. I'm surprised how much slower that is than for a Spitfire I. No wonder the Spitfire pilot in the tests could break off the engagement at will. The same would go for a Bf 109 E pilot too.
Cheers
Steve