Packard P40

[GregP]

Don't think it would have been a world beater, either ... but it could have been built. Had I been in charge, it would have been at least tried as early as a 2-stage engine was available, and then probably consigned to the dust bin since it probably would not have justified further development. I can't really say since it wasn't documented as having been tried.

The only real difference we have is that I don't know and speculate that it might have been a decent fighter, but not necessarily as good or better than what we actually developed. I'd have tried it, but others elected not to do so, and it's tough to go back and change it now.

 

[Shortround6]

P-40Q keeps coming back into the discussion as it is a P-40 airframe (mostly) with the installed power closest to the two stage Merlin. It is best comparison starting point. It proves several things.

You could stick a heavier engine/prop on the basic airframe.
You could stick a longer engine in the airframe.

Unfortunately the P-40 airframe was a high drag airframe, or perhaps a medium drag airframe, it was around 25-30mph faster than a Hurricane with the same engine.

It was running into wall around 400mph and needed large amounts of power for small gains in speed.

The Army did screw up ordering the P-53/P-60 series in a way. They thought the P-40 had little future growth in it and the world beating IV-1410 engine deserved a new airframe, or at least a new wing. (sarcasm

Saddling a P-40D/E fuselage with a 41ft 3 3/4in span 275 sq ft wing with planed eight .50cal guns pretty much doomed the project given the available engines. When performance fell below expectations (and proposed engines fell like dominoes) and the gun load was cut to 6 guns an in some cases to four the advantage/s of the new plane shrank in comparison to the old P-40.

The XP-53 project was started in Oct of 1940. First P-40D didn't fly until May of 1941. BTW the company designation for the XP-53 was #88 compared to #87 for the P-40D/E.

Reason for this is in hind sight the basic P-40 had more stretch or growth than they gave it credit for but the P-40 was always an interim fighter to be built until something better could be built.

Once you relax the requirements ( drop from eight guns to four and drop from 420mph to 390-400mph) the P-40 could do a reasonable job if given a high powered engine.
Unfortunately the high powered engines (or high powered at above 20,000ft) don't become available in numbers until the end of 1943 or into 1944. You had Mustang airframes sitting at the factory in the summer of 1943 waiting for engines.

Allison takes most of of 1943 (until Nov/Dec) to sort out the two stage engine used in the P-63 and while a bear of engine at low altitude it is still a bit short above 20,000ft.

Complicating things for a 2 stage Merlin powered P-40 is the fact that the XP-40Q didn't use and intercooler. I am sure one could be fitted somehow but an intercooler causes extra drag so a P-40 airframe using one will be slower than the Allison powered "Q" when operating at the same power. Please remember it was a lousy intercooler installation that killed the turbo P-39.

A two stage P-40 would have been better than P-40N, it just wouldn't have been as good as the other choices available when it was practical to make it.

 

[wuzak]

Complicating things for a 2 stage Merlin powered P-40 is the fact that the XP-40Q didn't use and intercooler. I am sure one could be fitted somehow but an intercooler causes extra drag so a P-40 airframe using one will be slower than the Allison powered "Q" when operating at the same power. Please remember it was a lousy intercooler installation that killed the turbo P-39.

Slightly different in that the Merlin intercooler was a liquid to air intercooler, so it is a bit more flexible in placement and it would be smaller. It may have required a slightly larger radiator area, but nothing as bad as the XP-39's installation.

 

[wuzak]

One of the proposed engines for the P-60 was the IV-2220. Imagine how that would have looked?

 

[GregP]

I wanted to let this go but I can't. I keep hearing about the "high drag" airframe of the XP-40Q and it doesn't wash.

One of the best of the German fighters was the Fw 190D-9. It had a Junkers Jumo 213 of 1,726 HP normally and 2,140 HP with water-methanol injection. It's top speed with MW50 was 426 mph, which is a whopping 4 mph faster than the XP-40Q's demonstrated top speed. I don't see you guys trashing that crate in this forum for being an obsolete, high-drag airframe. If they started side by side with a 4 mph difference and if 2000 feet is "out of range" then the vaunted Fw 190D-9 could be out of range in only 8.3 minutes in a straight line, assuming it could reach 426 mph. Surely any competent pilot can shoot something fleeing in a straight line down in that amount of time!

Production of this very good "high-drag" German airframe started in August 1944 and it didn't get into service until September 1944, about 10 months before the P-51H did. Maybe the rest of the world simply didn't realize how outdated the Fw 190D-9's performance was?

No, I think the P-40Q could have competed very nicely and it's top speed was just fine if the Fw 190D-9 is any measure of the importance of high speeds. Seems like a case of bias against the P-40 monicker to me. Your opinion may vary. Now I didn't make the claim that the XP-40Q was an Fw 190D-9 beater, I said it would have competed just fine, and there is no evidence at all that it couldn't have done so, at least to me. They didn't test it long enough or thoroughly enough to make a determination.

For several pages of posts now I have heard how slow the XP-40Q was compared with the competition, but it seems the 1944 competition was right there, particularly the competition from Focke-Wulf. Fw 190D-9's were still in the fray when VE Day happened. All the Japanese planes were slower except for their jets, of which none or virtually none got into combat. The 1944 Bf 109's were faster but we unmaneuverable in the extreme when they were going that fast. Their top speeds were used almost exclusively to run away from a fight or run to a fight. If they were to compete in a dogfight, it was at speeds the XP-40Q could easily manage.

And the XP-40Q rolled better than the Messerschmitt and was closer to the Fw 190D-9's roll capabilities than any deployed American fighter. We might recall that the P-40 was more agile than either the Bf 109 or the P-51 ... it was just slower and didn't have the altitude or climb performance. The XP-40Q would have gone a long way toward removing the altitude, speed, and climb differences, making it a very good candidate for an effective fighter in any theater. It's initial climb rate was better than 4,000 feet per minute, certainly better than any Focke-Wulf.

All of this doesn't change the fact that it wasn't procured, but it sure makes ME wonder.

 

[Koopernic]

I have a very high regard for the P-40: It speed on the same power as the Spitfire was equal unfortunately it never received an engine equal to that of its contemporaries. Perhaps it was a bit heavier and therefore lacking in climb but it also carried far more fuel.

The two stage intercooled Merlin was supposedly designed with the Spitfire according to one of its designers in mind (though some narratives have it as an engine for the pressurised Wellington) and to this end it used a water cooled intercooler. The increased thermal 'waste heat' from the engines great power density and the intercooler was dealt with by adding a second radiator under the wing where once only the oil cooler was.

It occurs to me that fitting the Merlin 61 or 66 to the P-40 may have been too much for the nose radiator and required re-engineering to the chin/belly position. The Spitfire IX entered service in Mid 1942 so one might reasonably expect a Merlin 61 P-40 to lag only 6 months. (which would still put it one year ahead of the P-51B)

Apart from that I see no great difficulty: the heavier longer Merlin two stage would likely require a little tail ballast or simply equipment such as radios, oxygen bottles moved further aft.

German/Luftwaffe/Procurement sometimes come in for criticism in their failure to get a reliable 2500hp Jumo 222 running on 87 octane engine in production in 1942 but its worth considering that the mightiest industrial power on earth at the time, the USA, struggled to not only get its own hyper engines in production but could not get resources allocated to GM/Alison to produce a two speed let alone a two stage integral supercharger or investigate other improvements. Lycoming XH-2470, XH-3130, Wright R-2160, Continental IV-1430-3, Pratt Whitney X-1800-A3G, Pratt Whitney X-1800-A4G. The IV-1430s failure to mature to its promise doomed the C46/C53/C60 series while work on these engines might even have distracted from V-1710 development. V-3420 development was essential as it was backup to Matterhorn's R-3350 (B-29 the Manhattan a-bomb carrier)

The improvements the Germans made to the Jumo 211 show what might have been done to the Allison without going to two stages and the heavy thermal loads it imposes: they included a pressurised cooling circuit (which the V-1710 already had), a two speed mechanical supercharger giving 1350hp and a two speed single stage intercooled engine the Jumo 211J with 1420hp on 87 octane.

Putting effort into the P-40 after early 1943 seems to have been of academic interest only as the P-47 and P-38 were finally giving good service.

Also below 10000ft P-40 speed was competitive.

It's worth considering the kinds of aircraft the Germans were planning for when the P-40Q could enter service in 1944.

May 1944 the 1700hp High Altitude Water Methanol engines for the Me 109 are in service. Shortly thereafter, before June, the Fw 190 is getting new boost approvals as well. By the end of 1944 Me 109K's can speed at 440 mph. The USAAF was looking towards the P-40M/N and P-51H/K by 1944.

The Luftwaffe had hoped to have the 488mph Fw 190D13/R25 with the Jumo 213EB engine in service by late 1944 and although it ran into problems it was only a matter of time before it did enter service. The Weaker Fw 190D13 with the less powerfull Jumo 213F with a speed of 452 mph did see service though the Fw 190D9 derived radiator was a little too small.

The P-40Q would have been competitive for only 6-9 months with German designs. It probably needed a 2200hp Griffon engine to stay competitive, not just a Merlin 66 or a two stage Allison.

Simple opportunities to help the P-40 were missed by 1941/42.

 

[Shortround6]

I wanted to let this go but I can't. I keep hearing about the "high drag" airframe of the XP-40Q and it doesn't wash.

It actually does wash. Try comparing the power used at the altitude the speeds were done at, not take-off power. The Allison two stage system worked very well as the 1750hp take-off/WEP (wet)rating only fell to 1700hp at 20,400ft according to the performance charts in the test report. Allison spec sheet/chart claims 1700hp at 26,000ft which means Max speed should have been at a higher altitude.

Power chart for the Jumo 213A shows 2100PS for take-off but power drops with altitude. Only 1550-1600PS at 6,000 meters?

http://www.wwiiaircraftperformance.org/fw190/Jumo_213A_power_graph.jpg

Slightly faster using less power=less drag. BTW most speed charts for the Fw 190 have it fitted with the drop tank/bomb rack, Was the XP-40Q fitted with a rack?

As for drag vs contemporary (1944) aircraft. Try looking at a Hawker Tempest V which could manage a bit over 420mph at 20,000ft or so on 1700-1750hp. A rather larger aircraft.

We are also back to when can Allison supply the -121 as a production engine and not a prototype as it took until Nov 1943 to clear the -93 engine for full use, the -117 engine (which actually preceded the -109 engine) took until Dec of 1944. The -109 engine took until the spring of 1945. The -109 and -121 seem to have identical ratings.
The lower than expected altitude performance of the XP-40Q-2 might be due to it's engine not being a full -121 but might have been a -101 engine fitted with the supercharger drive gears of the -121 without any other minor modifications.
With a full -121 the "Q" might have been even faster higher up.

 

[wuzak]

I have a very high regard for the P-40: It speed on the same power as the Spitfire was equal unfortunately it never received an engine equal to that of its contemporaries. Perhaps it was a bit heavier and therefore lacking in climb but it also carried far more fuel.

The P-40F (V-1650-1 Merlin 20-series) was within a few mph of the Spitfire V (Merlin 45).

Bear in mind that the Spitfire had the 2 x 20mm cannon, which sapped some performance but gave much greater firepower.

Also, the V was an interim model. The III with Merlin XX was a bit faster.

 

[wuzak]

The two stage intercooled Merlin was supposedly designed with the Spitfire according to one of its designers in mind (though some narratives have it as an engine for the pressurised Wellington) and to this end it used a water cooled intercooler. The increased thermal 'waste heat' from the engines great power density and the intercooler was dealt with by adding a second radiator under the wing where once only the oil cooler was.

The Merlin 60 was designed for high altitude bombers. It was Lord Hives (head of Rolls-Royce) that came up with the idea of fitting one to the Spitfire.

It occurs to me that fitting the Merlin 61 or 66 to the P-40 may have been too much for the nose radiator and required re-engineering to the chin/belly position.

It would have required an additional radiator for the intercooler, that is for sure. It woudl also have required extra area for the engine radiator to cope with the extra power. This would also be true for the 2 stage V-1710.

The Spitfire IX entered service in Mid 1942 so one might reasonably expect a Merlin 61 P-40 to lag only 6 months. (which would still put it one year ahead of the P-51B)

And where, pray tell, would the two stage Merlins be sourced?

I doubt the British would be willing to sacfrifice Spitfire IXs to send a few 2 stage Merlins to the US for P-40 production.

The first P-40Fs with the Packard Merlin (V-1650-1) were delivered in January 1942. The V-1650-3 will not be delivered in time to get a Merlin 61 P-40 a year ahead of the P-51B.

Apart from that I see no great difficulty: the heavier longer Merlin two stage would likely require a little tail ballast or simply equipment such as radios, oxygen bottles moved further aft.

Later production P-40s had lengthened rear fuselages to help with stability. This may have been repeated for a 2 stage Merlin P-40.

The IV-1430s failure to mature to its promise doomed the C46/C53/C60 series while work on these engines might even have distracted from V-1710 development.

Only the XP-53 was to be IV-1430 powered. The XP-60 was the XP-53 airframe with an engine change (the V-1650-1), while the XP-46 was always designed around the V-1710.

I can't see how Continental's mucking about with the IV-1430 had anything to do with V-1710 development, apart from some government money.

V-3420 development was essential as it was backup to Matterhorn's R-3350 (B-29 the Manhattan a-bomb carrier)

The V-3420 project was about as old as the R-3350, and maybe older (as the X-4320). The V-3420 was on-again, off-again, and was reinstated as a backup when it was clear the R-3350 was in trouble.

The P-40Q would have been competitive for only 6-9 months with German designs. It probably needed a 2200hp Griffon engine to stay competitive, not just a Merlin 66 or a two stage Allison.

2 stage Griffons were thin on the ground.

There were only some 8000-9000 Griffons of all types built.

 

[Koopernic]

The P-40F (V-1650-1 Merlin 20-series) was within a few mph of the Spitfire V (Merlin 45).

I've tended to be leery of the comparison. Spitfire V with a two speed Merlin supposedly like the Mk.III capable of 400mph, with what armament suit I don't know. As we know this engine was reserved to make the aging Hurricane competitive as possible. I suppose a valid comparison should be possible at an altitude both engine powers are similar if we have speed curves of at least one.

In regards to the Fw 190 versus P-40Q comparison. Fw 190A series HAD moved on to BMW801 production engines with potential for field boost improvements to 2200hp and potentially advanced versions to 2400 2600hp. The Fw 190D9 with a 2100 (or so and with 2240hp likely on the way) Jumo 213A had only a single stage supercharger and itself was in the process of upgrading to the Jumo 213F (two stage) which had about the same power level but of course much higher altitude capability due to a two stage three speed supercharger. The Jumo 213EB engine added further mechanical refinements to valve train and an intercooler. No doubt an Allison V-1710-121Q engine or Merlin 66 engine P-40Q would also see improvements in the 1944 time frame but its clear the Germans weren't standing still. The Fw 190 had made the jump to a fundamentally larger and more powerful engine with great growth potential.

The Fw 190, like the P-40Q, lacked the laminar flow wing technology of the P-51 or the Tempest V but it seems that with shear brut power the problem could be overcome, at least to the point that other factors such as propeller efficiency so dominate that airframe and wing inefficiencies fade to low significance. One sees that with the Griffon engine Spitfire XIV/F21 which were able to match the speed of the elegant technology of the P-51D/P-51H. My point, apart from taking the brazen opportunity of talking about the Fw 190, is that the P-40 needed to be moving on to a Griffon class engine, which admittedly was as you point out, in limited production. As drgndog suggested, the planners may have been looking at development potential for which the P-51D and P-51H offered more.

In many ways Curtiss's saga with the P-40/P-53/P-60 parallel Messerschmitt's with the Me 309 and Me 209.

My view is that had the P-51 not been developed by North American out of serendipity then the P-40 could have done the job adaquetly and perhaps more timorously than the P-51 and would have received the support it needed from Allison or Packard.

The development of the Mustang by North American using British Purchasing Commissioning must represent one of the greatest examples of salesmanship, foresight, trust and faith and engineering in the history of aviation.

 

[GregP]

That's bogus Shortround. What you said may be technically correct, but the speed difference is zero for all practical purposes and so it doesn't wash at all.

As I stated, the XP-40Q had a superior rate of climb to the Fw 190D-9, the roll was the best or near the best of Allied fighters, and it is upposed to have been as maneuverable as a regular P-40 in turn. I just don't see at all why it should be judged as uncompetitive.

Looks to me as if were very competitive. Just wasn't selected for production. I suppose we can look at the same data and see diffferent things, which is OK.

 

[Milosh]

Where would the P-40Q be used in Europe?

 

[GregP]

Hi Milosh,

I never said anything about deployment and haven't really considered it. I'd leave that to the military planners of the time. What I said was it would have been competitive if produced and could have been produced with little or no impact to production of other US-made aircraft. The guys at the time could deploy them anywhere they wanted to and they P-40Q would have been an asset.

In real life, we know they didn't get produced ... they were a last gasp of the P-40 series that might-have-been, but weren't. All I'm really saying is the performance shown in test tells me it could have done well had it been selected. But, nobody can win a "what if."

I also wasn't knocking the Fw 190D-9. It surely was a good one. But the XP-40Q was as fast, climbed better, and had a good turn performance. To me, the paper performance of the Fw 190D-9 doesn't look better than the paper performance of the XP-40Q. That's all I was saying. Heck, 4 mph is within the error of the airspeed indicator.

I have made and am making no great claims about the XP-40Q other than the fact that the paper performance is quite good in comparison with the competition of the time. Certainly ir was as fast or faster than the Japanese planes and cimbed better. As fast as the Fw 190D-9 and climbed better. Slightly slower than the Bf 109, but at low altitudes the P-40 already outmaneuvered the Bf 109 and now could come very close to climbing with it at both lower and higher altitudes while retaining the ability of the P-40 to out-maneuver a Bf 109 and being very close in speed.

So, in my book, it stood a decent chance of being very competitive had it been produced. Others don't see it, and that's OK. We've had areas before where we didn't agree with one another. In the relative scheme of things, 3 airplane more or less (the XP-40Q-1, -2, and -3) don't really mean anything to the overall war effort.

It's a very good-looking footnote to the built-but not-produced aircraft list of WWII.

 

[CORSNING]

Hi guys,
You all are doing a way better job at discussing this thread than I was when I tried to put my 2-cents-worth-in. So I am just going to sit over here in the corner and continue to eat popcorn, drink beer and enjoy the conversation. However, I looked up a few items and thought I'd put the info out there for the discussion before I go back to my corner.

The Fw-190D-9 mechanical shortcummings had been ironed out by about October 1944. I figure that would have been about the time the P-40Q would have become fully operational. Even if I am totally full of crap, I'll continue on. Over on Mike's site (Awesome by the way) I found the following information from two reports on the P-40Q-2 aircraft No.42-9987:

1. Army Air Forces, Materiel Command, Report Serial No. Eng-47-1660-A dated 2 November 1943. The test weight: 8,203 lbs. Internal fuel: 160 gallons. Engine: Allison V-1710-101-F-27R. Under heading B. Factual Data, sub-heading 2. Cockpit Layout: "The pilot's seat is non-adjustible and the inertia starter has to be energized by hand or other external means." Under sub-heading 5. Stability and Gerneral Flying Characteristics: " The handling characteristics are excellent and the airplane is very maneuverable. Control forces, although slightly heavy, are well coordinated and highly effective from the stall up to the present limiting I.A.S. of 400 M.P.H. An exceptionally short radius of turn and fast rate of roll are characteristic of this airplane."

2. Engineering Division Memorandum, Report Serial No. Eng-47-1728-A dated 5 April 1944. Flight tests were conducted from March 8 to 24, 1944. Under heading IV Flight Characteristics, sub-heading F. Maneuverability: "The maneuverability of this airplane over previous P-40 model airplanes has been greatly increased due to the squared or clipped wing tips." Under heading VIII Conclusion part A: "The airplane is a decided improvement over previous models of the P-40 series. In theaters where P-40's are being used the airplane could be a very good replacement since P-40 parts and trained mechanics would be available immediately. Major assemblies and small parts are interchangeable with older models." Under same heading part E.: "Flight characteristics of the airplane are very good, all requirements for the fighter being filled adequately. Trim, balance, and effectiveness of the control have been infinitely improved over previous p-40 models."

The following information is taken from the graphs of that report for the XP-40Q. Information for the ( Fw-190D-9 ) is in parinthesis and is from graphs contained in Deitmar Hermann's "Longnose".
In his book he states that the performance was typical of the Fw-190D-9 using B4 fuel, 1.8 ata. boost and MW-50 injection.

Altitude...Speed/Climb
meters...mph/fpm
S.L.......370/4360(376/4428)four,four,two,eight
.1,000..381/4400(388/4388)four,three,eight,eight
.2,000..392/4410(400/4124)
.3,000..403/4310(406/4103)
.4,000..414/4343(416/3985)
.5,000..419/3960(427/3493)
.6,000..418/3470(427/2991)
.7,000..420/2910(421/2499)
.8,000..414/2310(413/1987)
.9,000..410/1690(403/1485)
10,000.401/1040(391/.984)
11,000.387/.550(N.G./.482)
12,000.314/...30(N.G./N.G.)
Feet......mph/fpm/minutes to altitude.
.5,000..386/4410/-1.1
10,000.403/4280/-2.3
15,000.420/4000/-3.4
20,000.418/3420/-4.8
25,000.419/2540/-6.5
30,000.409/1600/-8.9
35,000.393/.700/13.7

Maximums: 422 mph.@ 20,500 ft. and 4,410 fpm.@ 5,000 ft. (430 mph.@ 17,450 ft. and 4,428 fpm.@ S.L.)

Ceilings
Combat (1000 fpm): 33,000 (32,695) ft.
Operational (500 fpm): 36,400 (35,960) ft.
Service (100 fpm): 39,000 ft. (38,580) ft.

Engine: Allison V-1710-121/75"Hg/1,800 hp./S.L. (Jumo 213A/1.8 ata/2,071 hp.)

Combat Weight (at take-off): 9,000 (9,591.75) lbs.

Wing Loading (at take-off): 38.79+(48.69+) lbs./sq.ft.

Power Loading (at best rated altitudes): 5.000 (4.631) lbs./hp.

Armament: 4 x 0.5in./235 rpg. (2 x 13mm/475 rpg + 2 x 20mm/250 rpg.)

I'll add more information here as I find it......OK, I'm done. Proceed now, Jeff.

 

[Shortround6]

That's bogus Shortround. What you said may be technically correct, but the speed difference is zero for all practical purposes and so it doesn't wash at all.

Why is it bogus? because you don't like it?

The D-9 may not have a lot less drag but was somewhat lower or it wouldn't have gone about 1% faster on 6% less power, not counting the drop tank-rack which was good for 4-6mph speed loss or another 1% in speed. The D-9s wing was also bit old by 1944, dating from 1938/39. Newer than the P-36 wing but perhaps not quite up to recent developments?

As I stated, the XP-40Q had a superior rate of climb to the Fw 190D-9, the roll was the best or near the best of Allied fighters, and it is upposed to have been as maneuverable as a regular P-40 in turn. I just don't see at all why it should be judged as uncompetitive.

We have several things going on here with the "Q". The Prototype may have climbed faster than the D-9 (D-9 climb rates are all over the place as the engine was up-rated several times without any real change in designation) production version vs D-9 depends on which Allison the "Q" was using when vs which D-9 and When.

The bit about "to have been as maneuverable as a regular P-40 in turn" needs a bit of explaining as the "Q" weighed about 600-900lbs more than older P-40s. depending on model and had a slightly smaller wing. Perhaps they were close but " as maneuverable as"?

We also have the question of armament. Four .50 cal guns with 235rpg. Not exactly first class in 1944. P-51s with Four .50s at least carried 250rpg for inboard guns and 350rpg for the outers and"D"s could carry 500rpg for 4 guns.
Production P-40Qs were supposed to have six .50s or four 20mm guns. No mention is ever made of what effects this would have on performance.

BTW the D-9 had two 13mm guns with 475rpg and two 20mm cannon with 250rpg. A much great weight of installed armament.

Granted a few seconds is all you need for ONE kill but the "Q" seems a bit lacking in combat duration, of course this is not a big problem because it is also lacking in fuel capacity and range so it is not likely to get too deep into enemy territory. One fuel tank under the fuselage is not going to be enough even if the internal fuel (160 gallons?) was enough for the missions required. A bit of problem in the Pacific in 1944/45, doesn't really matter if you can outfight the Japanese fighters if you can't reach them from the majority of you land bases. Granted you could probably plum the wing racks for fuel tanks if it wasn't done on the last of the P-40Ns already.

SO lets see where we are as far as fast introduction goes, bearing mind that the first P-51D rolled out the factory door in Jan 1944 and sizable numbers only showed up in England in June ( 4 month minimum from Jan 31s to June 1st).

Need a production Allison with two stage supercharger. 1325hp for take-off or 1425hp for take-off? the 1325hp versions offered over 1800hp at sea level with water injection but performance at altitude sucked Relatively speaking, they were down to 1500hp by 6,000ft and 1150hp at 22,400ft.

Need to do a bit of work on the wing? Q used the inner gun bays for radiators and/or oil coolers (accounts differ) so going to six guns means moving the cooling equipment or adding gun bays outboard of the existing ones, I wouldn't say impossible but adds to work needed. Changing to 20mm guns may also be quite possible but again needs new drawings and fixtures. The hit to performance could be substantial, both weight and drag of the gun barrels.

Needs more fuel. Mustang not only carries more fuel inside it can carry 1000lbs under each wing which usually meant 75 or 110 gallon drop tanks for combat operations (corrections welcome) Perhaps a P-40 with plumbed wings could carry a 75 gallon under each wing? Late P-40s did carry a 500lb bomb under each wing and earlier versions were often field modified to carry much more than the "book" 100lb bomb under each wing. I tend to doubt you could fit more than the 52 gallon tank under the fuselage due to ground clearance problems. 202 max external fuel?

Please remember that P-47Ds with the bigger fuselage tank begin to roll out the doors in April of 1944 so work to extend the range of the P-47 was being done in the fall/winter of 1943/44. The bigger fuselage tank extended the "book" radius by 100 miles without drop tanks and by 175 miles when carrying a pair of 150 gallon drop tanks.
The USAAF was not looking for short range fighters in the winter of 1943/44.

Not a lot of engineering work but some, so production examples are NOT going to be rolling out the door in April or May of 1944 even IF you can get the engines.

Looks to me as if were very competitive. Just wasn't selected for production. I suppose we can look at the same data and see diffferent things, which is OK

.

The "Q" might have been competitive for certain limited roles. However the US wasn't really interested in limited use fighters unless there was something really extraordinary about their performance (P-47M ?)

The US didn't even want the P-63, which using the same engine/s (or close) was faster and carried a heavier armament. Had shorter range than even the P-40Q though which explains a lot about why the US didn't want it.

 

[GregP]

No Shortround,

Alcually I don't either like or dislike it. It's bogus because you've been putting down the XP-40Q as an obsolete, high-drag airframe and the Fw 109D-9, one of the best German fighters of WWII is only 4 mph faster, putting them both in the same top speed class. The Fw 190D-9 had better armament but the P-40 was definitely a better-handling option. The regular P-40 already handled better than a P-51 within it's speed and altitude range and the XP-40Q is said to be the best-handling P-40 yet. That means, if nothing else, that it certainhly didn't lose any agility at worst and acquired some more agility at best.

As for the drag, there is ONE fighter aircraft out there with the lowest drag. I don't have all the drag data in front of me but I would theorize it might be the P-51. So there are something like 600 or more other fighter variants out there with more drag. While drag is important, I don't subscribe to the notion that all the more draggy airframes were inferior due to the vast preimminant importance of drag. The P-47 had more drag and the result of it's ground attack effort provided a very good push to the war effort while the P-51's were escorting bombers. I don't know which comtributed more, but when WWII was fought, the effort on the ground is what won the war ... airpower had yet to win a single war on its own.

So, I don't see anything like evidence to suggest the XP-40Q would have been other than a decent mount for a fighter of it's time. The test data and reports I have seen do nothing to convince me that it would have been other than an quantum improvement over it's stable mates. This makes me wonder how it might have fared in combat, if given the opportunity. There is NOTHING to suggest an outcome either way to that question, at least to me.

I think I've said that several times now, and it's a dead horse. We're talking about 3 airplanes. Let it go, we aren't going to agree or convince each other of anything. And I'm not trying to convince YOU of anything. I'm stating my own opinion, which you obviously don't share. Since the XP-40Q wasn't proceeded with, neither of us can be shown to be either correct or mistaken.



Hi Jeff,

I believe your numbers for the XP-40Q above are for WER power with the 422 mph coming at WER power with water injection, 3200 rpm, and 75.0" MAP. The numbers at Military power are less, but then again, so are the normal numbers for the Focke-Wulf Fw 190D-9. In fact, whenver we see almost any test data that reults in the best numbers for an airframe, the engines are at whatever full power thay can produce. So there's nothing with comparing maximum values.

I tend to think that whenever these planes met, 95+% of the time it was a Military or less pwoer, with WER being reserved for self-preservation escape or occasional attack if over home territory and the potential target is ALMOST withing range but not quite. This belief comes from talk with the people who were there flying the planes in the war. There are combat reports of WER use out there, but speaking with the pilot tells me that was the exception, not the common choice. If we we to add up all the fighter sorties flown and all the combat reports where WER was used, the percent of total would not be very high. But that's what I think ... I've never seen it broken out anywhere and doubt very seriously if the data exist.

 

[CORSNING]

Hi Gregg,

Combat (WEP) is what I used to show the maximum available speeds and climb. In Report No. Eng-47-1728-A, under heading IV Flight Characteristics, sub-heading I. Diving Characteristics states: "This airplane has very good diving characteristics as only slight aileron trim and moderate rudder trim are required. No buffeting of airplane or controls have been detected to speeds up to 425 IAS and the controls are moderate in force and very effective." I believe that means that this aircraft was capable of a very high combat speed (speeds at which full maneuvering is still effective).

Cheers (sips beer and gets another bag of popcorn), Jeff

 

[nuuumannn]

Reason: I spilled my bag of popcorn.

 

[GregP]

Hope you enjoy the popcorn, Jeff, and your contributions have always been good. I have eaten some popcorn while reading your posts, too.

Never touched a beer, of course ... and if you belive that one, I have a piece of oceanfront property in Arizona I'll sell you.

 

[rinkol]

Hi Milosh,

I never said anything about deployment and haven't really considered it. I'd leave that to the military planners of the time. What I said was it would have been competitive if produced and could have been produced with little or no impact to production of other US-made aircraft. The guys at the time could deploy them anywhere they wanted to and they P-40Q would have been an asset.

In real life, we know they didn't get produced ... they were a last gasp of the P-40 series that might-have-been, but weren't. All I'm really saying is the performance shown in test tells me it could have done well had it been selected. But, nobody can win a "what if."

I also wasn't knocking the Fw 190D-9. It surely was a good one. But the XP-40Q was as fast, climbed better, and had a good turn performance. To me, the paper performance of the Fw 190D-9 doesn't look better than the paper performance of the XP-40Q. That's all I was saying. Heck, 4 mph is within the error of the airspeed indicator.

I have made and am making no great claims about the XP-40Q other than the fact that the paper performance is quite good in comparison with the competition of the time. Certainly ir was as fast or faster than the Japanese planes and climbed better. As fast as the Fw 190D-9 and climbed better. Slightly slower than the Bf 109, but at low altitudes the P-40 already outmaneuvered the Bf 109 and now could come very close to climbing with it at both lower and higher altitudes while retaining the ability of the P-40 to out-maneuver a Bf 109 and being very close in speed.

So, in my book, it stood a decent chance of being very competitive had it been produced. Others don't see it, and that's OK. We've had areas before where we didn't agree with one another. In the relative scheme of things, 3 airplane more or less (the XP-40Q-1, -2, and -3) don't really mean anything to the overall war effort.

It's a very good-looking footnote to the built-but not-produced aircraft list of WWII.

I would add that the last high powered versions of the V-1710, at least as installed in the P-82, don't seem to have been reliable. Also, it would not be unusual if this was another case where a prototype turned out to be significantly faster than a production version.