P-40Q vs P-60A/D

[wuzak]

If Curtiss was given the go-ahead to manufacture a "new" P-40 replacement for the late war period, which would be better, The P-40Q with its two stage Allison, cleaned up aero and bubble canopy, or the P-60A (turbo V-170) or P-60D (2 stage Merlin) with its laminar flow wing and revised cooling systems?

An alternative may also have been a P-60 with 2 stage Allison (don't think one was ever built).

We can ignore the R-2800 P-60s (P-60C and P-60E) because that would require a lot more rework for production lines).

The XP-60 (Merlin 28 ) was about 20mph faster than the P-40F (V-1650-1/Merlin 28 ).

Which has more long term potential?

 

[rogerwilko]

As I'm biased, i would prefer the Bell product just for it's more modern tricycle landing gear and cannon setup.

 

[rogerwilko]

Sorry. I was too fast with my digits. I thought you meant the P400 Airacobra!!

 

[Shortround6]

If Curtiss was given the go-ahead to manufacture a "new" P-40 replacement for the late war period, which would be better, The P-40Q with its two stage Allison, cleaned up aero and bubble canopy, or the P-60A (turbo V-170) or P-60D (2 stage Merlin) with its laminar flow wing and revised cooling systems?

An alternative may also have been a P-60 with 2 stage Allison (don't think one was ever built).

The XP-60 (Merlin 28 ) was about 20mph faster than the P-40F (V-1650-1/Merlin 28 ).

The P-60 had more "potential" but seems to have been handicapped by the initial requirement for the eight gun armament, which helped lead to that 275 sq ft wing, great when you hung the R-2800 on the nose but not so good with 1300-1500hp engines.
Ideal (or at least better) would have been a wing designed from the start for six guns and about 230-240sq ft with the airfoil used on the P-60. Wing might have been 150-200lbs lighter and had less drag than the big wing allowing for higher performance with the lower powered engines. Please remember the IV-1410 that started this was "supposed" to give 1600hp at 25,000ft with a turbo. Maybe they also wanted the big wing for high (over 30,000ft?) work?

Once you give up on the turbo the P-60 series is stuck with too big a wing for the available power of the engines (unless you use the R-2800) even if the airfoil is better than the P-36/P-40 wing.

Old airfoil on right sized wing vs new airfoil on too big wing, which has more potential?

Which has more long term potential?

 

[Capt. Vick]

P-60 all the way.

 

[nuuumannn]

Can't say I know anything other than what I've read here or on the net about the P-60. To remain competitive in a European environment, the inline engined aircraft would have to be two-speed two-stage engine powered, either V-1650-3 and above or Merlin 60 series. Either the P60D or P-40Q with two-speed two-stage engine.

 

[RpR]

``

 

[RpR]

As P-60s were second thought aircraft from the the death of the P-53 due its engine not being available and as the P-53 and P-60 were simply a modified P-40, the Q, had it not been the least favorite son of Curtiss would have easily been the better.

Better Allison engines existed but were not considered important till too late the in the war but had the Q with the improved Allison been built it was faster than any P-60 with excellent handling.

The was no reason for the P-60 except the mind of Curtiss money crunchers.
Don Berlin left Curtiss in 1941 because of Curtiss cluster-f mentality in wasting money on doa designs rather than simply improving the P-40.

 

[wuzak]

The only performance numbers I have seen for the P-60 was the XP-60 with Merlin 28, which was faster by about 20mph than the P-40F with a similar engine, and the XP-60A with the turbo which may, or may not have, been measured at 420mph (within a couple of the P-40Q).

The P-60D with 2 stage Merlin flew earlier than the P-40Q. I have yet to see any performance figures for that version.

One wonders what a P-60 with the same 2 stage V-1710 could have done in comparison to the P-40Q.

The reason for the P60 was a request from the USAAF for a Packard Merlin airframe with the laminar flow wings.

 

[wuzak]

As P-60s were second thought aircraft from the the death of the P-53 due its engine not being available and as the P-53 and P-60 were simply a modified P-40, the Q, had it not been the least favorite son of Curtiss would have easily been the better.

The Q was 2 or 3 years later than the XP-53 proposal and the XP-60 program. The XP-60 program was basically cancelled before the P-40Q started. It was never a choice between the two.

as the P-53 and P-60 were simply a modified P-40

Don Berlin left Curtiss in 1941 because of Curtiss cluster-f mentality in wasting money on doa designs rather than simply improving the P-40.

If the XP-60 was "simply a modified P-40" then wasn't it an attempt to improve the P-40?

 

[Shortround6]

Perhaps a bit too much blame on the

Curtiss money crunchers

.

How much of the blame can be put on Curtiss or how much goes to the USAAC for the eight .50 cal armament I don't know.

There was quite a craze for laminar flow wings in 1940-43, it is a wonder that the USAAC didn't ask for a modified Stearman with laminar flow wings

It took a while before people realized that the laminar flow wings didn't work in the real world as well as they worked in wind tunnels.

Even if you are a money cruncher, if your main customer is putting out requirements for "NEW" aircraft (like the XP-55) you can either go along and give then new designs, try to argue with them that the old design with a few tweaks will do just as as good a job, or just go out of business anyway as your competitors give the customer what the customer says it wants.

to a 1939/40 request Bell offered;

Speed est: 425mph at 19,500ft.

Vultee got a contract covering engineering data and wind tunnel models on June 22, 1940 that lead to

Curtiss submitted the XP-55 Ascender and later built a full sized low powered test rig at company expense to keep the project alive.

Northrop came up with the

These were ALL in response to the Circular Proposal R-40C, issued November 27, 1939 which called for "a fighter that would be much more effective than any extant--with a top speed, rate of climb, maneuverability, armament, and pilot visibility, all of which would be far superior to those of any existing fighter. In addition, the fighter was required to have a low initial cost and had to be easy and inexpensive to maintain. The Army specifically mentioned in R-40C that they would consider aircraft with unconventional configurations." *

Submitting a slightly modified P-40, even in 1941 when the original engine some of these planes were designed around was canceled and they were scrambling for substitutes was unlikely to find favor with the purchasing agency. They were looking for a major change in performance/capability and not a small increment. Unfortunately the major change was running into some problems with trans-sonic drag and most if not all of the performance estimates were way off.

In this field of prototypes the XP-53/60 was actually somewhat low risk. Take P-40 fuselage and stick on a new wing and engine.

Please note that the original PAPER proposals for all these aircraft were made in 1940 when Curtiss was making long nose P-40s and was just starting work on the P-40D/E.

*From Joe Baughers website.

 

[GregP]

Modifications are usually attempts at improvement. Otherwise, why make the mod?

The only reason is to test a new configuration.

Nice pics, Shortround.

 

[Shortround6]

Army was looking for a major change, not an extra 20-30mph.

Granted it was a question of how much performance could be had when, an extra 20-30mph in 6 months or an extra 75mph in two (or more)years, but even number crunchers are looking for what the company can be producing 2-4 years down the road.

 

[GregP]

I am wondering what sort of "major change" the army was expecting without a major change in engine horsepower. Using basic aerodynamics you can easily calculate the horsepower required for a quantum jump in speed, and about the only thing you can do about it is to lower the coefficient of drag and increase the coefficient of lift. Doing both simultaneously isn't easy.

I haven't ever looked at the specifications (R-40C) that were passed around which generated the planes Shortround shows above, but since they are all pushers and of "interesting" design, I'd bet there was something in there leading them all toward that configuration. The group certainly includes some unusual designs. They all flew, but none were world-beaters. I haven't seen a single good review of the XP-55 or the Northrop, and have yet to see any flight report on the Vultee. I wonder if any of this group was a decent aircraft or could have been turned into one.

Had the same amount of effort been put into a new conventional design, I'd bet the performance might have been slightly better than what was actually produced.

I also wonder if the R-40C spec somehow found it's way to Japan since the Japanese Kyushu J7W1 Shinden looks right at home with the bunch above.

And there is more than one such beast about. Here's an SAI-Ambrosini SS.4.

There was a fascination with the configuration even after the war. This is the Sud-Ouest SO.8000 Narval 6.

All flew, but none made production. There are more such oddities, and it's almost as if everyone thought the other guys were onto something new until they built one for themselves and found out otherwise.

 

[gjs238]

https://en.wikipedia.org/wiki/Saab_21

 

[m37b1]

P-60x was really just an evolution of the P-40, so -


If the early fighters, P-39, P-40 and P-38 (to a lesser extent) were given the same sense of urgency for improvement/evolution, that types like the Spit and Bf109 had, you'd have:

P-63: In USAAF service, Maybe with Merlin power. (Any thoughts on it's performance with a two stage Merlin)?

P-40Q: (or something like it) Again, maybe with Merlin power. Laminar wing added at some point.

P-38x: Merlin power, laminar wing . . . . . Who knows.

All of the above would have been good fighters.

BUT . . . . We had better, more modern designs on the way and fighters were needed NOW.


I guess my answer is P40Q.

 

[wuzak]

I am wondering what sort of "major change" the army was expecting without a major change in engine horsepower.

The three winners of R40C were supposed to be powered by the Pratt Whitney X-1800 (XH-2600) sleeve valve H-24 engine. This was cancelled, so alternatives were substituted - the Lycoming XH-2470 for the XP-54 and the R-2800 for the XP-56. The Xp-55 went back to the V-1710.

 

[GregP]

I recall these facts, Wayne, but am seriously wondering why the projects proceeded when the projected powerplants weren't going to be available. If they anticipated some level of performance with X HP, they should have been able to anticipate the performance with X - Y HP, and should have elected not to spend the money for such performance.

None of them were parcicularly fast with the Vultee P-54 Swoose Goose coming in at 382 mph, the Northrop P-56 coming in at 417 mph, and the Curiss XP-55 coming in at 390 mph. The Douglas XB-42 ws a pusher and went 410 mph with two Allisons, mostly by virtue of being very streamlined and having little in the way of armament projections sticking out. The Saab J-21A-2 of 1943 managed 404 mph on a 1,475 HP DB 605.

So NONE of the pushers of WWII were as fast as a decently-designed conventional aircraft. You'd think someone would have noticed after one or two.

I realize the pushers were destined to be very fast when equipped with overpowered jets, but none of the propeller units was especially much of an advance. I suppose they had to try to find out, but so many of them makes little sense to me. Try a coupe and se what you get. If it pans out, you have your advance. If it doesn't why waste so much money on so many of a configuration that offers so little?

 

[wuzak]

Greg, only the XP-54 was measured at that speed. The XP-56 was flown to a speed about 100mph less than that, NACA estimating top speed at around 360mph. The power of the R-2800 was not dissimilar to that of the X-1800/XH-2600, but it caused a fatter fuselage which caused aerodynamic interference with the props, causing them to become much less efficient.

The problem with the XP-54 was that it was huge - large and very heavy. The reason for this is that was the requirements that the USAAF set for it - using the 37mm cannon and having a tilting nose to help aim it, and a pressurised cabin, etc. The XP-54 did receive an engine of similar performance - the XH-2470. There were also proposals to power it with the V-3420.

The XP-55 was a disaster from the beginning.

 

[GregP]

So we agree the pushers were pretty much duds ...