P-40 Warhawk/Kittyhawk

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HoHun,

Forgive me if this sounds like a silly question, but what is the line running through the graph represent?
It doesn't seem to corresspond with the plots.


Elvis
 
Hi Elvis,

>Forgive me if this sounds like a silly question, but what is the line running through the graph represent?
>It doesn't seem to corresspond with the plots.

The line is the performance I calculated for the Hawk 75C powered by the R-1830-17, running at 2700 rpm.

It is calibrated to the coresponding data point from T.O. 01-25CB-1 - as the other data point from that source is for another power setting, that one is not on the line.

The line also runs close to another data point for P-36A and C with the same engine.

The other data points are for differently-engined Hawk variants so they cannot be expected to coincede with the calculated performance line.

Regards,

Henning (HoHun)
 
Ah, I see now.
Thanks for explaining that.

...and since I'm here...

Clay Allison said:
Vultee could have made cheap P-36s under license for lend lease, Brewster could make Buffaloes for lend lease. One used the P&W Twin Wasp, the other used the Wright Cyclone 9, so there was a niche for both.
Click to expand...
I don't know about Vultee, but that's the very reason why Brewster and the US Government ended up on bitter terms.
Brewster kept promising to fill the orders, but could never deliver.
Maybe, if the Government had owned the Buffalo design (like what they did with the Jeep), Vultee could've been brought in to help produce the plane for sale/lease to foreign markets (thus a "Brewster / Vultee Buffalo" would've existed), along with the P-36, but Brewster, as the sole manufacturer, seemed to have a hard time actually producing the design in the numbers the military needed.
This could've eventually led to the two companies coming together, to create one "new" company, who's job would've been to produce planes (and maybe other munitions) for foreign sales / lease.
...and this probably would've included some P-40 manufacture, as well.
Of course, with the demand for "US-use-only" items needed so desperately, I feel that may have been only part of what they would've been doing.

So maybe, "B-V Aviation", or "Brew-Tee", or maybe even, "Vulster" might have a been name that would now be remembered as one of the manufacturers that helped with the war effort during those years...had this actually happened.


Elvis
 
I believe the Willow Run factory was built by Ford to build B24s. GM may have built a factory to build FM2s and TBMs and Goodyear also to build Corsairs.
 
Mike the F4F was the same vintage fighter as the P40 and was flown by pilots in the beginning with no combat experience but acquitted itself well against tough competition.
 
Hi Elvis,

>FWIW, the Merlin that did make it into the P-40's were lower powered versions, making about 1300HP, and they didn't last long in the P-40. I think by the "K", they were back to outfitting them with Allisons.

>Why? I don't know. Probably more "prioritizing".

Have a look at the performance curves here:

http://www.ww2aircraft.net/forum/aviation/p-40-performance-allison-versus-merlin-14118.html

The lower-powered Merlin versions used in the P-40F wasn't so much better than the Allison V-1710, all considered.

It might be that the Allison was in fact more attractive for the P-40 since emphasis in P-40 use had shifted away from fighter missions towards ground attack, where a better take-off performance when loaded and more power at lower altitudes were an advantage. I haven't checked if this matches the powerplant timeline, though.

Regards,

Henning (HoHun)
 
renrich said:
Mike the F4F was the same vintage fighter as the P40 and was flown by pilots in the beginning with no combat experience but acquitted itself well against tough competition.
Click to expand...

You are very right, as I would say too of the P-40. ( one source,article by Corwin Meyer) shows the F4F/ FM kills at 1006, the P-40 at 706 in the Pacific.

Which considering the time in which they fought, far from useless.
 
Took a look at the link. Thanks for posting that.
Its clear that the Merlin was a more stoutly built engine, than the Allison, thus you could "huff it up" a lot more, and push it harder, without fear of breakage, compared to the Allison.
This is clearly evident in the performance improvement that occured between the 20 and the 60 series versions of the Rolls Merlin engine.
The fact that the Allison was built a little lighter was also probably one of the leading reasons why it had less supercharging available to it, thus its performance was more fitting to lower altitude operations.

That being said, I wonder how a single stage, two-speed intercooled version of the Allison, with a larger supercharger (say around 12"-15") would've faired. Especially in one of the "G" engines, which had the better crankshaft in it.
I looked around a little the other night, but could not find mention of such a beast, so I'm assuming it never existed.
That setup would be similar to the Merlin you aluded to, that was used in both the P-40 and the early Merlin-powered 51's.
According to my (rather rudimentary) calculations, an Allison setup in that fashion, and being one of those types, would have a peak HP rating somewhere in the upper 1300 - lower 1400 HP range.
...plus you trim about 300-400 lbs. off the plane, because the Allison is lighter.
I think the Allison could live very nicely setup in that fashion and probably would've had more useable power over a wider altitude range, than most of the versions that did exist during that time.
Now, you combine that with a more efficient propeller and now you've got something.

The combination of engine / prop would probably have improved the P-40's lack of "bounce", in any case.




Elvis
 
Hi Elvis,

>That being said, I wonder how a single stage, two-speed intercooled version of the Allison, with a larger supercharger (say around 12"-15") would've faired.

Qualitatively, increasing the since of the supercharger increases high-level performance at the cost of reduced low level performance. As the two-speed gear allow the operation of the larger supercharger at a reduced speed, this will restore most of the low-level power.

In effect, the setup you're proposing is similar to the Merlin XX, and accordingly, the P-40F can be seen as a good example for the kind of performance one might expect.


(The main problem of the P-40 was its heavy weight ... I think most of its other characteristics were good or at least satisfactory. Weight unfortunately has quite an impact on climb rate and manoeuvrability though, so it was difficult to get around this. The lighter British designs would always get more performance and manoeuvrability out of an equivalent engine.)


>According to my (rather rudimentary) calculations, an Allison setup in that fashion, and being one of those types, would have a peak HP rating somewhere in the upper 1300 - lower 1400 HP range.
...plus you trim about 300-400 lbs. off the plane, because the Allison is lighter.

Hm, how did you calculate that? I'm interested even if it's a "rule of thumb" approach

Regards,

Henning (HoHun)
 
The P40 had good results against the Japanese Army AC in the CBI, not as good against the IJN in the Pacific. My source has the P40 with 741 kills in the CBI and 661 kills in the Pacific. The F4F had 1408 kills in the PTO. My source gives the P40 592 kills in the Med and another source shows the P40 with 67059 sorties with 553 losses in the ETO. Those must have been in the Med which would have included Italy.
 
For what it is worth, I think it is difficult to compare U.S. Navy fighter kills vs the U.S. Air Corps fighter kills in the Pacific. The Navy was usually in a much more target rich environment than the Air Corps. What I am trying to say is the kill numbers don't tell the whole story.

Is there any information to compare kills vs loss on the F4F against the P-40?
 

Something you'll have to explain to me - why is it that I keep seeing comments about the P-40's weight?....or rather, overweight.

I think if you averaged out the weight for all the different models of P-40 that existed, I bet you'd find the plane generally found itself around 8500-10000 lbs.
Does this make the P-51, which was like 12500 lbs. by the time the "D" model came around, obese?
If so, why does that fact never seem to come up whenever the 51 is mentioned?
Comparitively, the P-40 seems like a lightweight and yet I see comments written all the time about the plane being overweight.

As for the power figures I aluded to, I should recheck those, but it was nothing more than a simple HP/Cu.In comparison, then I added in a little, allowing for the higher R's that version of the Allison could operate in.
Not really anykind of "rule of thumb". More like a "ballpark" figure.



Elvis
 
The power loadings tell the tale. At 10000 feet the power loading of the P40F at 8678 lbs GW was 7.11 and at 20000 feet was 8.15. The corresponding for the P51D at 10176 lbs GW were 6.78 and 7.48. The P40 at all altitudes had more weight per HP available and was not nearly as clean so drag not only slowed it down but hampered it's climb significantly.
 
This has nothing to do with P-40's but I take nevertheless the liberty to ask you whether someone of you guys could send thru a picture of the Curtiss A-12 Shrike while servicing in China or this aircraft with chinese (nationalist) markings.
Thanks a lot
carson1934
 
Hi Elvis,

>Something you'll have to explain to me - why is it that I keep seeing comments about the P-40's weight?....or rather, overweight.

Just have a look at the fighters it opposed - they were all lighter than the P-40, or in the case of the Fw 190, had a lot more power to make up for the weight.

>As for the power figures I aluded to, I should recheck those, but it was nothing more than a simple HP/Cu.In comparison, then I added in a little, allowing for the higher R's that version of the Allison could operate in.

Not a bad method, considering that indicated power depended on displacement. The effect of supercharger power being subtracted from indicated power, leaving a reduced brake power value, means it's not perfectly accurate, but I'm still searching for a perfectly accurate method to calculate brake power from the geometric parameters of an engine

Regards,

Henning (HoHun)
 
Elvis, switching from the other thread and discussing a P40 outclimbing a Spit, Bob Johnson in his book, "Thunderbolt" said the early Jug could not stay with a Spit in a steady climb. His tactics in a mock dogfight with a Spit were, with the Spit on his tail, to start rolling one way and then the other, as the Spit did not roll as well as the Jug. Once he had the Spit out of firing position, he would dive(the Spit could not stay with him in a dive) until reaching a very high speed and then zoom climb as the Spit could not zoom climb like a Jug, until far enough above where he could hammerhead stall and drop down on the Spit still laboring to get to his altitude. The P40 rolled well(better than the Jug) and dived well. Perhaps the pilot you quoted meant that he could outclimb a Spit in a zoom climb.
 
Intensifying an engine design, when good quality assurance standards are uninhibited at the manufacturing level, can produce some interesting results. One in particular is the Nakajima HA-45 Homare. It was an 18 cylinder, twin row air cooled short stroke engine with a diameter about 46 inches and HP rating of 1900. This was the engine used in the Ki-84. Had there been 100 octane fuel available to the Japanese Army this engine/airframe combination would (not might) have enjoyed equality with anything the Allies had at the time. But, the engine was a compact powerhouse plagued by quality control problems in its manufacturing.
 
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