Curtiss P-40Q
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Curtiss P-40Q

Prior to the final termination of P-40 development, some effort was expended in combining aerodynamic refinement with increased power to produce a higher-performance model. A P-40K airframe was fitted with an Allison V-1710-121 engine rated at 1,425hp for take-off and 1,100hp at 7620m. Semi-flush low-drag radiators were incorporated in the wing centre section and a four-bladed propeller was fitted, the designation XP-40Q being assigned. A second, similarly re-engined P-40K for the P-40Q programme reintroduced the nose radiator scoop, but featured an all-round vision bubble-type canopy (previously tested on a P-40N). The definitive XP-40Q (converted from a P-40N-25 airframe) had clipped wing tips, the cut-down aft fuselage with bubble canopy and coolant radiators faired into the wing leading edges. Four 12.7mm guns were carried but proposed production models were to have carried, either six 12.7mm or four 20mm weapons. No production was undertaken.

Curtiss P-40QA three-view drawing (1280 x 988)

    Wingspan10.75 m35 ft 3 in
    Length10.16 m33 ft 4 in
    Max. speed679 km/h422 mph

Comments1-20 21-40 41-60
Boris, 03.01.2016

Also the Oscar and more so the zero could not turn right worth beans at full power at any speed. This was easily compensated for at low speeds but at over 250 mph they were at full or nearly full power.

As far as I know no version of the P-40 had flight control boost. Flight control boost was a rare thing in piston engine fighters.

Ed Foster, 20.12.2015

The P-40 was the only Allied fighter that could out turn the Zero or Oscar at speeds above about 280 m.p.h. The lack of hydraulic boost on Japanese aircraft controls meant their maneuverability suffered at speeds near or above 300 m.p.h. Saburo Sakai would order his pilots to break off rather than engage Australian or New Zealand P-40's in high speed turning matches.

TORBJÍRN KAMPE, 08.03.2015

P-40 war the United States ever airplanes that are worthy of the name fighters. It was as long in the air like me-109 and FW-190, spitfirer and hurrkan.
P-40Q is not fun that it had to be with WW2, but was RENO aircraft. Boring.
Everyone talks about the P-51 Mustang, the beginning of WW2, was the only one attack aircraft named A-36 Aptche. US only real jack plane, the P-40.

Boris, 14.11.2013

oh yes, I had forgotten, Kermitt Weeks is restoring a Fury V powered by a 2,400 hp Sabre. The aircraft will be fully airworthy and have a (maybe at this point) running Sabre. Kermitt admitts it will never fly though we may get to see and hear a running Sabre for the first time in half a century. Reason for not chancing a flight? The legendary "reliability" of Napier's masterpiece!


Boris, 13.11.2013

P-51 and that "lousy Allison"?
The P-51A and A-36 were powered by an up-rated V-1710-81
that gave better performance and speed rose to 408mph@15,000'.
Some say 390 mph, but I tend to believe the USAAC/USAAF
numbers at 408.
To put that in perspective the A model was the best performing
version of the P-51 under 10,000' till the H model came around.
Above 10,000' the two stage Merlin ruled.


Sven, 04.11.2013

I think Boris just about
Nailed it.A different
engine doesn't make a
different aeroplane.
Before anyone says P51.
Exeptions are there for all to see but as rare
as rocking horse manure

Boris, 03.11.2013

Napier's 3,500HP Sabre was a running but still born project.
Sleeve valve engines did not tolerate high boost pressures
well at all and the Sabre at 3,500HP would likely have never
survived in service. In any event the advent of 100+ PN (octane)
fuels made poppet valve engines a more viable option. As much
as I admire the British Sleeve valve en gines they were extremely
costly to build and operate. Roughly twice the operating and
purchase price of equivalent poppet valve engines. If you want
to talk one off fantasy piston engines there were dozens
of candidates from the P&W 4200 hp R-4360 VDT to the previously
mentioned Allison Turbo compounded engines.
Curtiss Wright built the awesome R-3350 TCW series of radials
that made between 3,250 and 3,800 HP! In service to boot.
Mass produced and used in everyday service....
Sabres are cool, but utterly unreliable at any power setting.
When WWII ended so did the Sabre, as far as i know there are
NO running Sabres static or otherwise, and for good reason.

The highest power output for a Sabre in regular service was the Sabre V at around 2,500-2,600 HP.

Weight was decidedly piggish at over 2,350 lbs for the
power unit only.

Allison weight was about 1,400 lbs depending on model.
As a result Sabre installation in a P-40 would have been
an impossability.

Steve Round, 03.11.2013

Ever heard of the Napier Sabre IV 24 cylinder sleeve valve 3500 horsepower no more frontal area than a Merlin and barely 8 ft long the Napier would have made this kite go some

juan, 30.03.2012

Fue una hermosa maquina de limpia arquitectura americana
Literalmente una joya de la mecanica

Klaatu83, 22.12.2011

The P-40Q was the best of the P-40 series, but it was a case of too little, too late. By the time the P-40Q prototype was flying, the Air Force was already getting all the P-38s, P-47s and P-51s it required, all of which were just as good, if not better.

Boris, 03.10.2011

After pouring over everything I have I have found no reference
to a two stage Merlin ever being installed in any P-40.

I would love to read about that, got a reference?

The XP-60 started life as a P-40N and got a British built Merlin 28.
That's a two stage Merlin similar to the Packard V-1650-7 used in the P-51D.
The P-60 was a non performer despite having a laminar flow wing.
Other engines were tried and also failed to impress before the project was cancled.

The Allison V-1710-127 was a turbo compounded engine that was static
tested to 2,800hp and may have been capable of more.
Exhaust temps were high and corrected and a quick fix was
to ingect water into the exhaust stream to drop the temps
to the level the turbo could survive.

No P-40 ever flew with a 2 stage Merlin. A study was done and it was
decided a two stage Merlin powered P-40 would have rivaled a Spit, Bf-109 or P-51 but none ever flew.

The P-60 proved the concept to be a fantasy.



a.machiaverna, 25.09.2011

Curtiss cheif designer, Don Berlin, tested a p-40N with a 1,695 h.p. Merlin V1650 as used in the P51D, and results showed a better airplane than both the ME-109 and Spitfire. The Merlin powered production P-40s used a 1,395 h.p. Merlin V1650. The ultimate Allison V1710 was the E27 variant capable of 3,000 h.p. and was slated to be installed in the P-63 Kingcobra. Extremely high exhaust temperatures prevented further development as it came late in the war.

Boris, 30.08.2011

P-40F and P-40L, which both featured Packard V-1650 Merlin engine in place of the normal Allison. Performance was marginally better at high altitudes and worse at sea level. The Allison V-1710 in it's most developed versions was far better than most know today.

Robert Hill, 27.08.2011

Imagine if this had been available to the AVG.
Part P-40, part P-51 and Part Spitfire!
Now imagine if it had a Merlin!

mwnuk, 09.08.2011

the mustang, lightning, corsair and hellcat were all great aircraft, but you have to keep in mind the us turned the tide in the pacific using the p-400 (bell airacobra), the grumman wildcat and the p-40. for political reasons the airacobra gets little credit (the soviets used it more effectively than we did and since it was an american product the soviets played down its role as well as that of the p-40.) there was good reason that the p-40 stayed in production throughout the war, it was a great fighter aircraft in all its versions!

GLF, 07.06.2011

It's not the aircraft, it's what it's used for.
The Soviets had great low level service from the P39 and P40. The US tried to cover too many bases and ended up covering none. A lesson for today perhaps?

Boris, 13.04.2011

actually the P-40Q had the most advanced version of the Allison,
It had a two stage constant boost supercharger on a variable speed drive.
Performance at all altitudes was excellent.
Problem is as you noted, it was too late.
The P-51 and P-47 did the job better and had far greater range.
Also they were already in the fight.


a.machiaverna, 09.04.2011

The Allison was a fine engine, proved itself in the P-38. Not turbosupercharged in the P-39 and P-40, this US Army decision doomed both machines to mediocrity. If the P-40Q had the right engine ( a turbosupercharged Allison V1710 ), it could have been one of the greatest fighters of World War 2. Too bad Curtiss didn't start the P-40 "clean-up" program sooner. A rugged machine , capable of very high dive rates and more manueverable than the P-51, the P-40 if fully developed sooner would have been a very feared airplane in the skies over the Pacific and in Europe. On hand when needed early on in the war, the P-40 in the hands of a good pilot proved to be a formidable weapon despite its lack of level flight high speed especially at high altitude.

Jim Farry, 27.12.2010

The P40 and C46 were built in Cheektowaga, a suburb of Buffalo, New York. My father was Chief Maintenace Man for all three plants. We did not see much of him during that time. I remember touring the plant on a Sunday in 1943 and being allowed to enter a C46 and peer into the cockpit of a P40. I was 9 years old.

Boris, 09.09.2010

At the time of the US entry into WWII
the P-40 was better than any Japanese
fighter if used properly.
Few if any monoplane fighters could turn
with an Oscar or zero.
I know of none that could combine the turn,
speed and climb of a Zero or Oscar under 5,000'
But the P-40 was faster at all altitudes than
either Japanese plane.
It also posessed a far higher terminal speed
in a dive. The P-40B's climb was not far behind either
Japanese fighter.
Add self sealing tanks and pilots armour and shatter
proof glass then the P-40 don't look all that bad!
The obvious was not that obvious in 1941.
The obvious being hit and run tactics.
Dive, hit em at 400+ MPH and zoom up out of range.
Re-group and hit em again.

A P-40B or C could easily survive a 500mph dive.
It's doubtful a Zero or Oscar could survive more than 400.

Add to the above the P-40 turned rather well and gave
excellent stall warning.

The issues of the P-40, and for that matter the P-39
were mostly speed and range.

We Americans hate to take casualties when a simple matter
of money spent and brain power can give a better weapon.
Speed is life in any fighter.
Range became mission critical!
That is why the P-38, P-51 and P-47 got more kills and
better press.

Oh yes, the P-40 lacking a two stage supercharger still
gave better high altitude performance than any Japanese
fighter of 1941!


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