P-40 what-if

[vanir]

Dear Elvis. You are a God.


Thankyou so very much for the links to that awesome, awesome site on the P-40.

It is now the subject of a new remodelling for il2 by my team. Just sent the emails. Oleg porked it up, now it's gonna be real...

 

[Elvis]

Thank you Vanir, that's very nice of you to say, but really its all about teamwork.
I myself, was alterted to that site's existence via a thread I participated in here, back when I first joined.
There's a lot very informed people here and the culminative intelligence is a little staggering to handle, at times.



Elvis

 

[Elvis]

I was thinking about the P-40 and the reasons it wa considered a stopgap at best. What if, though, the P-40 had been reengined, not with the Merlin (as in the P-40F) but with the RR Griffon (if it had been turned over to an American comany for development when it was de-prioritized). Would that have worked?

In regards to my earlier comment of Clay creating a sort of "American Me-109", how about using the Griffon (granted, MAJOR structural redesign), with a larger prop, and also using the "3-guns-in-the-nose" arrangement that the 109 is most famous for using.
However, instead of 2-30's with a cannon firing through the spinner (what would be our equivelent of the German arrangement), just use three 50's.

Wouldn't this allow for a redesign of the wing (and tail surfaces), as well?
Allowing for a thinner wing, maybe even one of "Laminar Flow" design (or "of-that-type" anyway).

I wonder how overall performance would've compared to the actual P-40.



Elvis

 

[Colin1]

In regards to my earlier comment of Clay creating a sort of "American Me-109", how about using the Griffon (granted, MAJOR structural redesign), with a larger prop, and also using the "3-guns-in-the-nose" arrangement that the 109 is most famous for using.
However, instead of 2-30's with a cannon firing through the spinner (what would be our equivelent of the German arrangement), just use three 50's.

Wouldn't this allow for a redesign of the wing (and tail surfaces), as well?
Allowing for a thinner wing, maybe even one of "Laminar Flow" design (or "of-that-type" anyway).

I wonder how overall performance would've compared to the actual P-40

I don't see why a Griffon install would require a major re-work, they shoe-horned one into the Merlin Spitfire without too much ado and that's a tighter ship for room than the P-40. The Griffon II was 240lbs (109Kgs) heavier than the V-1710 or 420lbs (191Kgs) for the Griffon 61 if you want the benefits of 2-stage supercharging, so the rear fuselage would need lengthening - meaning the short-fuselage version of the P-40K would never have gotten off the drawing board.
Neither the Merlin nor the Griffon were fitted with engine-mounted armament, this is where you might run into problems, if the thrust-line needs to be lowered to get the guns on the roof then that chin radiator arrangement is going to limit how far you can drop everything.
As for wings and tail surfaces, I don't think there were any technical reasons why Curtiss couldn't do this anyway, I'd throw out the already-mentioned chin radiator arrangement along with a more conventional approach to undercarriage storage. Cut down the rear fuselage a la XP-40Q and you've got a contender. I don't think a laminar flow airfoil would buy you much.
Armament-wise, I'd stick with the conventional approach of batteries of .50 cals in the wings, 6 for the P-40 (3 in each wing), it worked.

 

[renrich]

Here is the problem with putting a bigger engine in an air frame, lets say with going from 2000 HP to 2700 HP and expecting a big jump in performance. Look up the F2G. They went from the R2800 to the R3350, I think, and the airplane was little better in performance than F4U4 with more reliability problems.

 

[Colin1]

It depends on where you're jumping from
the P-40 saw benefits with the V-1650-1 install over previous V-1710-engined models of the P-40, a Griffon install would see significant benefits again over the V-1650-1. The P-40 was a pre-war design and would see the benefit of a more powerful engine, though I doubt the same benefits that a later type with a cleaner airframe would experience.

The F2G was far closer to the edge of the envelope of what a piston-engined fighter can accomplish than the P-40 and any benefit margin would be leaner.

 

[Elvis]

Fair enough.
By Colin's logic, a Griffon powered P-40 would probably end up along the lines of the P-37 I posted a picture of earlier and that was turned down during testing for lack of visibiltiy over the long nose.
A better solution would seem to be a more "efficient" version of the V-1710 then, such as the "-89A" version I aluded to earlier, or development of a two-speed single stage after-cooled version of the engine (saving the "-89A" for the P-38 and P-51).
Yeah, I agree. That would've most likely have been the better way to go.
Thanks for your input, guys.


Elvis

 

[Colin1]

...a Griffon powered P-40 would probably end up along the lines of the P-37 I posted a picture of earlier and that was turned down during testing for lack of visibiltiy over the long nose...

I doubt it would be that drastic, remember, they fitted a Griffon in a Mustang racer and the Mustang started out with the V-1710; the P-51/Griffon arrangement certainly looked feasible enough for operational service although curiously, it was only looked at by the British and they only looked at a mid-engined layout a la P-39.

The P-37 had all sorts of problems, the hot-rodded V12 Allison and the GE supercharger arrangement suffered badly with reliability issues.

 

[Elvis]

Well as you stated, the 51 was originally designed for a liquid cooled V-12, so changing to a larger V-12 would be a more minimal modification, compared to installing one in a p-40.
Remember, the P-40 was orginally the P-36 and that platform was originally designed for a radial powerplant.
The P-40 is already a fairly modified platform, with the installation of the V-1710, so it would have to be further modified to allow for the larger Griffon powerplant.
I just gotta wonder how much room is left for such changes...something tells me there's not much.

Maybe someone around here, who has some experience with mechanical drawing, could mock up a Griffon-powered P-40, just to show us how much more modification would be needed, or if there is enough room for such mods, without having to make it a completely different airplane.



Elvis

 

[Colin1]

...the 51 was originally designed for a liquid cooled V-12, so changing to a larger V-12 would be a more minimal modification, compared to installing one in a p-40.
Remember, the P-40 was orginally the P-36 and that platform was originally designed for a radial powerplant.
The P-40 is already a fairly modified platform, with the installation of the V-1710, so it would have to be further modified to allow for the larger Griffon powerplant

There's more of a common lineage in there than you're seeing:

Allison P-51 to Merlin P-51 to Griffon P-51 (albeit as a one-off racer)
Allison P-40 to Merlin P-40 to Griffon P-40 (the P-40F and L were fitted with the Packard Merlin V-1650-1)

I think the evolution of the P-36 into the P-40 has no real bearing on the potential evolution of the Allison P-40 into a Griffon P-40, it would be a case of replacing an inline with another inline and given the similar config of the Allison-engined P-40 and P-51, I don't see why a Griffon P-40 would be any more problematic than the Griffon install was on the P-51.

If the Germans could get a DB605 into a Spitfire upside down (inverted V) I can't see why it would have posed any real technical headaches to get a Griffon into a P-40 with engineers of a different country from the same period.

 

[Elvis]

What I'm saying is the Allison P-40 was already a modified platform, so yourlineage misses a step, that being P-36 - to - P-40.
The Allison P-51 wasn't modified.

Again, I think someone with a mechanical drawing background could really be of help here.

Could you please direct me to some info on the DB605 powered Spit? First I'm hearing of this.



Elvis

 

[Colin1]

What I'm saying is the Allison P-40 was already a modified platform, so your lineage misses a step, that being P-36 - to - P-40. The Allison P-51 wasn't modified.

Could you please direct me to some info on the DB605 powered Spit? First I'm hearing of this

I missed the step deliberately, concentrating instead on the common ground between the two types, I don't think the radial-engined period of the Curtiss fighter's history really counts for much here, I'll be (mildly) surprised if it does

Link to the Daimler-Benz Spitfire

Unreal Aircraft - Hybrid Aircraft - Supermarine/Daimler-Benz Spitfire

 

[Elvis]

I missed the step deliberately, concentrating instead on the common ground between the two types, I don't think the radial-engined period of the Curtiss fighter's history really counts for much here, I'll be (mildly) surprised if it does

Link to the Daimler-Benz Spitfire

Unreal Aircraft - Hybrid Aircraft - Supermarine/Daimler-Benz Spitfire

Hmmmm...there may be something to this after all, but I wonder how close the relationship between Sptifire/DB605 is to Warhawk/Griffon.
I mean, after all, it is kind of an apples-to-oranges comparison, but I have to agree. This might be more feasable than first anticipated.
Would still like to see some drawings, though.


Elvis

 

[Colin1]

...how close the relationship between Sptifire/DB605 is to Warhawk/Griffon. I mean, after all, it is kind of an apples-to-oranges comparison...

In what sense?
In one way, it's not close at all; the Spitfire and the DB605 are very clearly NOT the P-40 and V-1710 or Griffon. In another, higher-level sense, there's not a great deal between them, both sets are of the same period, subject to the same constraints design- and technology-wise; while there are some powerplants that will clearly not fit in some weren't-designed-for-this airframes, I think there's a large degree of leeway in most cases.

 

[Clay_Allison]

I think that Elvis is underestimating the extent to which the P-40 really was a new design based on a P-36, not a P-36 with the nose chopped off and a new one bolted on. It had certain characteristics in common, but I resist the notion that the P-36 has to be considered R.E. changing to the Griffon engine.

 

[Elvis]

Clay,

You're absolutely correct, however, in light of this (heretofore unknown to me) information about the DB605 powered Spitfire, my thinking is being altered - i.e., maybe this Griffon-powered P-40 idea wouldn't be as difficult to exicute as I had first imagined.
-----------------------------------

Colin1,

My question had to do with the ease in which the modification could've been done.
I.e., would the P-40 mod have been any more or less difficult, compared to what was done with the Spit....or would it have been about the same?
Granted, neither mod would likely have be a "drop-in" fit.


Elvis

 

[Shortround6]

A consideration when proposing "engine swaps" of hypothetical aircraft is that the dry weight of the is only part of the power plant weight. Some peaple refer to it as firewall forward but is some cases that doesn't cover it either.
Larger, higher HP engines can require larger radiators and header tanks filled with more coolant. They can require larger oil tanks and oil coolers. They might or might not require larger starter systems. The might require larger propellors, either larger diameter, more blades or broader blades. Larger cowls and engine mounts,etc.
The dry weight of an engine might be 1 pound per HP. The "powerplant weight" might be 1.5 -2 pounds per HP.
In some cases (like shifting to higher power Merlins) the changes might be rather slight from one version to another. In other cases hundreds of pounds might be added and a fair amount of the weight in front of the CG.
In some cases tails had to be made larger ( or extended, see some P-40 models) to counter torque or larger cowling forward.
In some cases the larger engines worked quite well, in other cases the performance gain wasn't what was expected.

P-40 protoype was actually a re-engined P-36 airframe. P-36s were reportedly canablized to provide parts for P-40s in the early Pacific fighting including entire (one side anyway) wings. Wouldn't work so well with the a P-40 E.

 

[fibus]

The Allison was a superior design but not as tested and developed as the Merlin. It was Rolls that developed the 150 hour reliability test.
The Griffon was a much bigger and heavier engine than the Merlin. To fit a Griffon One had to design virtually new airframe.
Compare the difference in size of the Mark 1 v. the Spit Mark 14.

 

[claidemore]

The Mk XIV Spitifre had the same airframe as the Mk VIII Merlin engined Spit. Mk XII Spitfires were either Mk V or Mk VIII airframes. The first Griffon Spit, the Mk IV, was built on a Mk III airframe.

I would think that if they could mount a Griffon on the Spitfire airframes that were designed for the Merlin, then there wouldn't be much difficulty in mounting one on a P40, since the P40F and L had Merlin engines.

 

[Colin1]

The Mk XIV Spitifre had the same airframe as the Mk VIII Merlin engined Spit. Mk XII Spitfires were either Mk V or Mk VIII airframes. The first Griffon Spit, the Mk IV, was built on a Mk III airframe.

I would think that if they could mount a Griffon on the Spitfire airframes that were designed for the Merlin, then there wouldn't be much difficulty in mounting one on a P40, since the P40F and L had Merlin engines.

Is the correct answer
unless I'm mistaken the Mk III-based Griffon test-bed was put into service itself as a Mk XII once trials were over.

So where did you get this massive re-architecturing of the airframe from, Fibus?

Nice section drawing of the two engines, Claide. I didn't realise there was THAT much difference but hey, they got it in.

Edit: Elvis, sorry, didn't see your post #96 until just now or I would've answered. Think Claidemore pretty much captured it.