P40 Vs all other fighters in Europe

[Shortround6]

In a chart on page 124 in "Vees for Victory" they have a chart for the V-1710-33 The chart is dated 12-5-39.
the chart is something like this one.

EXCEPT, it shows the graph going all the way to sea level. It is also in finer detail and has standard latitude and temperature along the bottom.

The engine is shown as making 1090hp/3000rpm at 13,200ft using 38.9in. in notes similar to the ones in the chart using as the illustration.
The chart shows that the engine will make 1040hp at 14,200ft.
The engine will also make 1150hp at around 11,500ft. using 42in?
The engine will also make just under 1700hp at sea level using 61in map.

There was considerable argument about the C-33 between Allison and the Air Corp. Allison wanted the 1040hp rating and the Air Corp wanted the 1090hp rating. The Air Corp got the 1090hp rating but they broke of lot engines and Allison had to rebuild 277 engines and the engines still flying were derated to 2770rpm and 950hp at 8,000ft. The modified engines were rated at 1090hp.

Now please note that the 1040hp rating does show up in quite a few books/sources about the P-40.

BTW the chart shows the C-33 engine was good for about 1480hp at 42-4300ft using 54in and 1580hp at 2500ft using 58in which is not too bad considering changes in manifolds, backfire screens and a few other minor differences.

These are test results and are NOT useable for service use


Now even climbing or putzing along at 180mph there is going to be some RAM effect.
Ram effect in theory goes up with the square of the speed. However RAN effect in the engine charts also take into account any limitations in the intake duct duct or problems with the intake.
Also note that P-40s and P-39s (and perhaps Allison P-51) had to have their exhaust pipes modified to get the full effect of the WER performance. The Exhaust pipes were too small and were choking the engine, the exhaust outlets had to be opened up.

Corrected 1580hp at 2500ft in C033 chart

 

[Schweik]

Interesting about the exhaust pipes, I hadn't heard that. I know they eventually changed to fishtail stacks on the P-40s (but I thought that was a bit later, late 42?) and the Mustangs went through various changes.

Do you have a larger / higher-res version of that chart? I can't read it.

 

[Shortround6]

That chart is from the IL-2 Sturmovik forum.

It shows some of the information that the the Chart in "Vees for Victory" shows but not all.

There are several charts for Allison's of different models in the book but there is at least one misprint with a wrong chart showing up next to a caption.


I believe the exhaust stacks were were cut a different angle in order to increase the exhaust opening. After all, if you are trying to shove 28% more fuel/air (1490hp vs 1150hp) into the engine you need to let the exhaust out. This could actually be done with a hacksaw. It also screws things up slightly for high altitude work as at 15,000 to 20,000ft (and above) you are not getting quite same exhaust gas velocity as the would for the unmodified exhaust. Your exhaust thrust is mass X veleocity.

 

[Schweik]

Gotcha

 

[tomo pauk]

In a chart on page 124 in "Vees for Victory" they have a chart for the V-1710-33 The chart is dated 12-5-39.
the chart is something like this one.

EXCEPT, it shows the graph going all the way to sea level. It is also in finer detail and has standard latitude and temperature along the bottom.

Do you have a larger / higher-res version of that chart? I can't read it.

That chart was taken from the manual for Mustang I, showing the V-1710-39 engine. Big pic, not edited (click for hi-res):

 

[Shortround6]

The book may have a chart for the Allison used in the A-36 as well the Allison using the 9.60 gears.

Some of the figures for the WEP ratings don't agree with the charts.

The WEP power for the A-36 engine (-87) is barley attainable with NO RAM at sea level (1500hp) let alone 5,400ft unless you are using a lot of RAM or are over speeding the engine (3200rpm?). Granted the chart is labeled "estimated Altitude performance" but again, RAM covers a variety of conditions. An Allison powered Mustang could do around 340-350mph at sea level using military power. However at max rate of climb it was around 170mph (or under) so your engine chart for RAM is going to show no RAM (unrealistic) and RAM for maxim speed(?) or some comprise?

 

[Admiral Beez]

What was lacking in the P-40 that made the Allies decide not to upgrade it with a Merlin Engine.?
Or maybe it was done and the P-40 proved wanting in some area(s).?
Thank You

I expect if in 1941 you'd asked the VVS if they'd swap all their Yak-1, MiG-3 and LaGG-3 fighters with Curtiss P-40s they'd have jumped at the opportunity. Nothing wrong with the P-40 in the early war years.

As for not sticking a Merlin on it, that wasn't an idea until the British got hold of the Allison-powered Mustang, but which time the P-40 was less competitive. Why stick your limited Merlins onto the P-40 when they can go on the Mustang?

 

[Schweik]

Yes the Soviets did fairly well with the P-40s and considered them good up to the end of 1943, though they much preferred the P-39. They seem to have had more engine trouble with the P-40s (both due to cold weather and dust / dirt)

 

[tomo pauk]

The book may have a chart for the Allison used in the A-36 as well the Allison using the 9.60 gears.

Power chart for the V-1710-81 engine, IIRC from the Perli's P-40s website.
(my comment - this represents the best-case scenario, ie. engine is without backfire screens since it had the 'Madam Queen' venturis in the intake? note that chart gives rated altitude of 15500 ft for mil power [1150 HP], while the two available tables give 14500 ft for the same thing)

 

[Schweik]

Unless I'm reading that wrong it looks like power tops out at less than 1300 hp? But they aren't indicating any WEP / WER...

 

[Shortround6]

I expect if in 1941 you'd asked the VVS if they'd swap all their Yak-1, MiG-3 and LaGG-3 fighters with Curtiss P-40s they'd have jumped at the opportunity. Nothing wrong with the P-40 in the early war years.

As for not sticking a Merlin on it, that wasn't an idea until the British got hold of the Allison-powered Mustang, but which time the P-40 was less competitive. Why stick your limited Merlins onto the P-40 when they can go on the Mustang?

Well, at least they would have radios,

The was a lot wrong with the P-40s in 1941, But then there was a lot wrong with the Russian fighters.

Allison doesn't build with Allison that could withstand until WEP (even unofficially) until about Dec of 1941. That to when the change over to the "new" crankshaft and crankcase occurred (as opposed to the change over from the original crankshaft and crankcase of 1940 and the sort of new crankshaft and crankcase that used from late 1940 through most of 1941.
You could use a lot of boost in the early Allisons, you just didn't know when they were going to quit on you.

The Lagg-3 was overweight but so was the P-40. You are going to need to find climb performance and turn numbers. The P-40 had a big wing and it was fast (better build quality) but there wasn't much you could do about the climb unless you tried hacking some weight out of it. (don't fill the fuel tanks, yank some of the guns out, don't carry full ammo, etc)

 

[Schweik]

There is an article "P-40 in Soviet Service" which goes through their early experience with the Tomhawk / P-40B/C (which IIRC they got by Sept 1941) and then later Kittyhawk types. I'm sure you are familiar with it. It seems from that article to have come in quite handy, and they felt it could handle the 109s they were facing, even though they had a lot of trouble with keeping the engines running. They considered it superior to the LaGG-3, the Hurricane and MiG but not the Yak 1 or 7.

Excerpt:

"Despite these problems, active combat continued. In January some 198 aircraft sorties were flown (334 flying hours) and 11 aerial engagements were conducted, in which 5 Bf-109s, 1 Ju-88, and 1 He-111 were shot down [6]. These statistics reveal a surprising fact – it turns out that the Tomahawk was fully capable of successful air combat with a Bf-109. The reports of pilots about the circumstances of the engagements confirm this fact. On 18 January 1942, Lieutenants S. V. Levin and I. P. Levsha (in pair) fought an engagement with 7 Bf-109s and shot down two of them without loss. On 22 January a flight of three aircraft led by Lieutenant E. E. Lozov engaged 13 enemy aircraft and shot down two Bf-109Es, again without loss. Altogether in January two Tomahawks were lost-one shot down by German antiaircraft artillery and only one by Messerschmitts.

However, the Tomahawk was a frequent target of friendly fire – an unfamiliar aircraft engaged in the heat of battle by both Soviet fighters and antiaircraft artillery. This normally resulted in scores of bullet holes and apologies, but around New Years Day Soviet PVO outdid itself: five I-16s, and later antiaircraft gunners, attacked the Tomahawk AN507 of Junior Lieutenant P. G. Maz. He made a forced landing, resulting in heavy damage to the engine, and the aircraft was sent off for repairs.

But the primary source of losses was mechanical failures. Practically not a single combat sortie was flown without some kind of problem. It was a common practice to land with a dead engine. Not all of these flights were completed successfully. On 17 February 1942, one of the best pilots of the regiment, HSU Senior Lieutenant S. G. Ridnyy (Tomahawk AK325) suffered an engine failure on takeoff and was killed in crash. Despite this abundance of accidents and incidents, the general impression of the pilots of 126th IAP regarding this aircraft remained good. The Tomahawk had qualities that were lacking in aircraft of Soviet production."

Kittyhawks were even more useful especially the K model. They had at least a couple dozen pilots who made Ace flying Kittyhawks, and three or four triple or quadruple aces and HSU. I've quoted some of Nikolai Golodnikov's comments on the type which I know you've seen. They played a significant role at Leningrad and were also in action at Moscow.

Here is a link to the interview somebody posted on a War Thunder forum.

Brief excerpt:

"How would you rate the speed, climb rate, acceleration dynamics, maneuverability of P-40? Did you like it?

- Again, the P-40 was much superior and the "Hurricane", and I-16, was much higher.

Strictly speaking, with all types of "Messers" P-40 fought on an equal level, almost to the end of 1943. If we take the whole complex of performance, then the P-40 Tomahawk was equal to Me-109F, and the Kittyhawk is slightly better. Speed, vertical and horizontal maneuverability were good, with enemy aircrafts quite comparable. On the dynamics of acceleration, the P-40 was a bit heavy, but when you adjust to the engine, it's normal.

When later types of Me-109G and FW-190 went, the P-40 "Kittyhawk" began to yield a little, but not much. An experienced pilot fought with them equal. At P-40, I spent 10-12 air battles and a total of about 50 sorties. Then the regiment once again changed to the P-39 "Aerocobra"."

Most of the P-40 units in the VVS became Guards units. Most eventually switched to P-39, La 5 series or Yak 9.

 

[Schweik]

Golodnikov mentions they flew at higher RPMs and removed some guns from their fighters to lighten them, to get the performance up sufficiently to deal with 109s. He also says engines were burning out after ~ 50 hours. Compared to the life span of an I-16 or LaGG-3 it may make sense.

But they gradually figured out how to deal with Allison (and Merlin) engines better as time went on.

 

[BiffF15]

Golodnikov mentions they flew at higher RPMs and removed some guns from their fighters to lighten them, to get the performance up sufficiently to deal with 109s. He also says engines were burning out after ~ 50 hours. Compared to the life span of an I-16 or LaGG-3 it may make sense.

But they gradually figured out how to deal with Allison (and Merlin) engines better as time went on.

Sounds like they were pushing the engines beyond the book if they were consistently getting 50 hours out of them, and losing so many a/c for mechanical problems. And with that they thought it was a better plane than the indigenous stuff.

 

[tomo pauk]

Unless I'm reading that wrong it looks like power tops out at less than 1300 hp? But they aren't indicating any WEP / WER...

I'm shocked. How dare they?

 

[SaparotRob]

Sounds like they were pushing the engines beyond the book if they were consistently getting 50 hours out of them, and losing so many a/c for mechanical problems. And with that they thought it was a better plane than the indigenous stuff.

What were the VVS paying for the P-40?

 

[Thumpalumpacus]

What were the VVS paying for the P-40?

I've done some hurt on a Hertz, too. Ain't my engine.

 

[wuzak]

BTW the chart shows the C-33 engine was good for about 1480hp at 42-4300ft using 54in and 5800hp at 2500ft using 58in which is not too bad considering changes in manifolds, backfire screens and a few other minor differences.

Wow. Why didn't the P-39 get that engine? It would have been a world beater with that power!

 

[Shortround6]

Wow. Why didn't the P-39 get that engine? It would have been a world beater with that power!

it wouldn't fit because the nose armor got in the way.

 

[wuzak]

Right, and that certainly makes sense. Generally I think this is the wisest approach. Sometimes those Boscombe Downe tests erred on the conservative side a bit, as in using very low boost levels and high weight, especially for foreign planes. But I still think it's the wisest way to do the testing.

I do believe that Boscombe Down performed performance tests and tactical trials of production aircraft using representative weights and ran them according to the operating manuals.

They also checked performance gains when additional boost was cleared for an engine type.

One other counterpoint is, quite often planes were eventually 'souped up' (used at higher boost ratings etc.), including Spitfires. The higher speed under 'best conditions' including sanding, higher boost and all the rest, gave them an idea of the potential of the airframe when certain changes were made... changes which might be out of reach at first but became attainable later. This was incorporated for example in the Spitfire when they put the bulletproof window inside, fared over the rearview mirror and so on. Sometimes small changes could be made to reduce drag and improve performance. With regard to the Merlin P-40, they made about a 20 mph difference by the field stripping and 'cleaning up' they did in the field in North Africa. And that did make a difference, apparently, or they wouldn't have been flying any of those aircraft with four guns.

They tested aircraft at higher engine ratings when the higher engine ratings were cleared for use. And for that the engines had to go through separate testing.

The internal armour screen was not an example of a "souped up" aircraft, but a reflection of production changes.