Packard P40

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Hi SHortround,

You could have a handle on it there. The P-40 WAS slated to wind down ... but the XP-40Q showed real signs of promise. Still, the people who would take over the "shortfall" when the P-40 was phased out might already have been ramping up and the XP-40Q might have been just a bit too late to change the decision despite showing signs of renewed life. At this point we know what happened, but are speculating somewhat on exactly why. In the end, no theories can be substiated or disproved unless and until some actual documentation for the reasons crops up. Might happen at some time and might never happen.

Your speculation above is about as solid as I've heard and I'm not inclined to disagree or speculate further even a little bit; your reasoning fits the facts as we know they played out.
 
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BiffF15 said:
Anyone what to fathom a guess as to how much better a P-40Q would have had to be to warrant production?

Cheers,
Biff
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I imagine it is not just a matter of being superior in some aspect of performance. All belligerents showed a tendency at times to avoid disrupting production lines in favor of quantity over quality to varying degrees. If the P-40Q could be built with minimal disruption, or retooling or spare parts it might have been favored even with slight inferiority compared to the P-51B/C/D. The new bubble canopy might have been just a little too much for instance. I suspect that there would have been changes inclusive of the firewall all the way through the engine and prop. Beyond a certain threshold if there are too many changes you might as well as retool for the P-51 or P-47 or P-80A. Also perhaps the Allison was better used elsewhere: such as the P-38.
 
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The P-38K was not proceeded with because the different reduction gearing changed the thrust line and required re-profiling of the cowling.

The 2 stage Allison was quite a bit longer than the single stage versions, so teh cowling would have needed a bit of work. And the radiators were moved to under the leading edges of the inner wings. So that would have bee a bit of effort.
 
The XP-40Q was about 2 feet longer in the fuselage to accommodate the two stage Allison most if not all forward of the firewall? (Merlin version could be a bit shorter?). Oil coolers or radiators (accounts differ?) moved to the wings in the inner gun bays (which raises the question of where the extra 2 guns go on a production version with 6 guns?), wing clipping is not a big deal. Bubble top will change production fixtures some. Not sure if production version would need larger tail or fuselage extension?





The US suffers from a transportation problem in that any particular fighter airframe (serial number) will take 6-12 weeks from when it rolls out the factory door to when it is available in a combat zone once production has started. fighter has to test flown and accepted then knocked down, engine treated with preservatives, crated and shipped to sea port where it is loaded aboard ship and taken to the war zone, unloaded, re-erected and test flown before being sent to the local supply depot.
IF ordered into production in April or May of 1944 when do production P-40Q's show up in combat theaters? Fall of 1944??

A Merlin version might be available sooner ( the two stage Allison is only in limited production for the P-63 ?) but then Packard don't really hit it's stride with two stage Merlin until the 2nd half of 1944 so every Merlin P-40 X is one less P-51.
 
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Wow this ill-fated super P40, looks like a beautiful love child of a P39/63, P51D and a P40 - another reason why it was let go, was that the Mustang was in production already and, that was concieved as the 40's replacement -even if it was termed so by North American Aviation, that term once attatched, relegated any 40 based bird to the thought of being obsolete or near to being so (in the minds of its prospective buyers/users and their pilots), unless the replacement 40Q was far and away above/better than the 51D/E in a majority of aerial aspects of flights tests.

But boy, that Q does look hot to trot like a firebird...
 
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Simple answer. P-51H contract, based on Performance of XP-51F/G in February 1944, was let in April 1944.

The XP-40Q with four 50's and far less range, far less performance than the P-51H, was Not competing with P-51B/D.

Every comment regarding drag by Shortround and Koopernic, specifically regarding drag rise, was correct. The 'cube rule' does not work well for airspeed/power relationships starting Mach> .6. The Prandtl-Glauert correction for drag is used extensively for the transonic region but good results for 0<M<.8.
 
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Thanks guys, there was a lot of good points made in this thread. I can't think of any better answers than have already been given. The question of how they would perform with the same Merlin was in the discussion. I can't really help with that answer. But, the two aircraft did fly into combat with the same Allison engine. Just for fun I decided to put them side by side to see how they matched up. The P-40 turned tighter and rolled quicker.

P-51A A/C No. 43-6007 report dated 4/2/43 and the (P-40N-1 the following information is from performance points given and calculated points using the performance graph of the V-1710-81 powered P-40N):

Altitude...Speed/Climb
Meters...mph/fpm
S.L......376/3500.(332/3520)
1,000..387/3625.(346/3600)
2,000..400/3750.(360/3680)
3,000..412/3405.(374/3465)
4,000..412/2925.(376/2965)
5,000..410/2455.(373/2480)
6,000..405/2025.(367/2025)
7,000..399/1605.(363/1635)
8,000..389/1160.(354/1265)
9,000..367/..765.(350/..940)

Maximums: 415 mph./10,400 ft. and 3,785 fpm./7,575 ft. (378 mph./10,550 ft. and 3,720 fpm./8,000 ft.

Ceilings
Combat (1000 fpm): 27,650 (28,920) ft.
Operational (500 fpm): 31,675 (33,980) ft.
Service (100 fpm): 35,100 (38,200) ft.

Engine: Allison V-1710-81/3,000 rpm: 1,480 hp@ 56.8"Hg (57"Hg: 1,415 hp./2,960 ft., 1,480 hp./10,550 ft.)

Combat Weight: 8,000 (7,413) lbs.

Wing Loading (@ take-off): 34.33+(38.79+) lbs./sq.ft.

Power Loading (best altitude): 5.405+(5.000) lbs./hp.

Armament: 2 x 0.5in./350 rpg + 2 x 0.5in/280 rpg (4 x 0.5in./235 rpg for test. (Norm: 2 x 0.5in..265 rpg. + 2 x 0.5in./285 rpg.)

Range internal: 750 (750(P-40N-15)) mls.
Range maximum: 2,350 (1,080 (-15)) mls.


Just for fun, Jeff
 
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Hi Jeff,

No surprise the P-51 is faster than a P-40N, but I think a P-40Q with the same engine would be much closer to the P-51. And that was the point.

Had they made it, they would not be using any Merlins for the P-40Q and the performance was quite good is not quite as fast as a P-51. The premise there is a bit off-topic, but valid.

I enjoy your performance threads ... keep 'em going.
 
Thank you Gregg.

drgondog pretty much hit the nail dead square on the head in post #46 about the actual contemporary of the P-40Q. The P-40Q"s story is something like the P-63's. They both were very good aircraft with excellent handling qualities. But the supply and parts lines of the P-47, P-38 and P-51 were already in existence by the time these two were in the air. The USAAF just didn't need fighters that did not have the internal range they were looking for.

Jeff
 
Yah, we know what happened. The XP-40Q was flying in 1943 ... the pilot test I saw was dated 2 Nov 1943 - at ww2aircraftperformance, so we KNOW it was flying before that time. And I have my own opinion of what it would have been competing against.

Just to set the record straight, the very first P-51H-1-NA was flown by Bob Chilton on 3 Feb 1945. I don't think that if Curtiss has been given the go ahead for the P-40Q that was flying in 1943, they'd have wasted over a year waiting around for the P-51H to become a reality before proceeding. Had the P-40Q been ordered into production, it would have been competing squarely with the P-51D. The H was a gleam in someone's eye in 1944 when the P-40Q's could have been in service.

As I stated before, we know they weren't, but hey, at least call the timeframe correctly so you can assess the correct competition.

This is not an attempt to glorify the ZP-40Q, just to set the record and timeframe straight.

Go to the aircraft performance site (WWII Aircraft Performance), scroll down about 1/5 of the way and click on "P-40 performance tests - major update," scroll down all the way and click on "Memorandum Report on P-40Q, AAF No. 429987: Pilot's Comments." Check the date on the report. It's 2 Nov 1943. The plane FLEW well befoire that date.
 
And Greg at that time the Packard-Merlin P-51Bs were on there way to Europe.
 
On October 13, 1942 the first Merlin powered Mustang took to the air. December 1, 1943 they were flying there first combat mission.
All I am saying is, I do not believe Curtiss worked close enough with the USAAF to try to fill their needs. From what I have read they took a stance that they were into building aircraft not improvements. Although I am quite sure many at Curtiss did not feel that way, apparently some of the administration did. I am not a historian in these matters. All I know is what I have read.

Jeff
 
Yes Milosh, so if the P-40Q's got there in early 1944, they would have been direct competition for P-51's, and not the H models. That was my entire point. Glad you made it for me. The P-51H's didn't get into combat until very late ... and never saw an enemy aircraft. And the P-40Q's that COULD have gotten there in time would not have been using Merlins. Actually, they probably would have been assigned elsewhere, assuming they got built in the first place, and would not have really competed against P-51's until later. Altogether an interesting "what if," but it's all conjecture. Never happened.

Hi Jeff,

An interesting "what if," as you say. Alternate history lines are fraught with disagreement, and no two people can seem to agree. I've already stated what I think here and elsewhere in athe XP-40Q thread. As far as THIS thread goes, a 2-stage Merlin-powered P-40was defintely possible, but seems to never have happened, though I have HEARD it did ... with no concrete proof of same.

This is repitition of what has been said earlier.

Everyone in here knows that whether or not a 2-stage Merlin-powered P-40 was ever built or not, it never entered production, and they never bought P-40Q's. The author of this post asked why the 2-stage unit never happened and I don't have a good reason why it didn't except for politics. The technical issues were certainly solvable. If they coiuld salvage the P-75, they could salvage a 2-stage Merlin P-40 ... unless everyone got really stupid all at the same time.

Instead I think the politics caused closure of the P-40 line without investigation into the potential of the XP-40Q though, in truth, I'd probably have closed it sooner myself. As long as there are three people around, politics will likely live.
 
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What would the earliest a P-40Q could get into service?

Early 1944 is optimistic IMO. More realistically it would be mid 1944.

That time line gives the competition as P-51D, P-38L, P-47D (I am not sure on this) and Spitfire XIV.

I don't think the P-40Q has the range of the P-40D, nore the performance. It would possibly be a match for the P-38L and P-47D in terms of range and performance? All three out-gun the P-40Q.

It would out range the Spitfire XIV. But the XIV would be faster, climb better, turn better, and have more firepower.
 
Not a really big "what if," Milosh.

It was built by mid 1943, was tested very quickly and COULD have gone into production without too many major changes to the line. I'd say March 1944 in service was possible ... assuming anyone wanted it to BE there at that time. In the real world, they didn't, but it certainly could have been. Not sure what it might have changed and neither is anyone else.
 

Curtiss sure spent a lot of time on the XP-46, XP-53, XP-55 the whole XP-60 series and the XP-62 (in addition to a bunch of other aircraft) trying to fill the USAAF needs. Now maybe Curtiss spread themselves too thin or they lost any designers with true spark but Curtiss probably had more programs and designs being worked on than any other aircraft company. Granted 4 single engine planes might require less work than a single big 4 engine plane

The main problems with the XP-40Q was that it was both late and a bit like putting lipstick on a pig. Greg is quite correct in that the plane was flying in the fall of 1943, only trouble is that it is NOT the 422mph XP-40Q as the engine that powered the XP-40Q to 422mph isn't built until the beginning of 1944. The engine flying in Nov 1943 has 100hp less for take-off and 200-250 hp less WEP and lot lower full throttle height. Using this engine the XP-40Q might have trouble cracking 400mph at 20-21,000ft.

Now the engine situation is not the fault of Curtiss. They are dependent on Allison, however one does have to wonder just what was in the XP-40Q for equipment during the November test as it was over 700lbs lighter than in the March test with the more powerful engine. Report says it had 160 gallons of fuel. The more powerful engine was supposed to weigh the same. One thing noted in the Nov test seems to be a lack of a battery ( or a big enough one) as starting is by either by hand or other external means. engine cooling while ground running seems marginal (in November in Buffalo New York ?)

Neither Curtiss or the USAAF really expected the P-40 series to be hanging on at the end of 1943 or they wouldn't have been working on things like the XP-62.



420 sq ft of wing, a turbo-charged R-3350 engine, counter rotating propellers, pressure cabin, twelve .50 cal guns. A P-47 with a serious steroid problem.
This is what the USAAF was saying it wanted in 1941-42, for delivery in 1943-44.
 
There's no problem Shortround.

If they had elected to proceed with it, the P-40Q would have done just fine as a fighter. I never made any outrageoud claims ... it's a WHAT IF. If they had built it, it would have done just fine and would have been head and shoulders better than the P-40N.

If you can't wrap your head around that simple fact, then read the flight reports. Nothing whatsoever bad to say. It would not have taken any Merlin engines or Hamilton-Standard props and would not have affected the P-51's in any way. But, it didn't happen.

So ... you can lay camoflague and denigrate it all you want and it doesn't change the fact the the XP-4Q with the Allison V-1710 was a MUCH better airplane than the P-40N. That was my point and it is true in any real alternate history. Doesn't mean it would be better than anything else, only that it was MUCH better than a P-40N.
 
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The P40 might be inferior to the Mustang in speed but this is not clear cut with the Spitfire.
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That is, unless you throw in the Spitfire XIV, which was superior to the XP-40Q in speed and altitude, turn rate, climb etc. Both are contemporaries time line wise. The first Mk.VIII converted to a Griffon first flew in January 1943.

The thing I'm curious about is how much better an aircraft, in this example a P-40Q, would have to be over a P-51 to rate production?
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The other issue is how long would it take to get P-40Qs into production? Merlin engined P-51s began production in 1943 and then squadron service in December that year, so already it has a march on the P-40Q. The USAAF needed more aircraft sooner than what Curtiss could produce a suitable aeroplane to suppliment what was at the front line in Europe and the Pacific. The Merlin engined Mustangs were all produced to USAAF production orders, including the RAF ones, which were supplied on Lend Lease and when the P-51B went into production, the RAF orders were taken over by the USAAF, who received them as first priority over the needs of the British squadrons, whose aircraft went to the USAAF squadrons first. If Curtiss was to produce such an aircraft, then when would it get into service? Late 1944? Early 1945? By then, Lockheed is supplying the first P-80s and the P-47N is about to go into service. One of the big advantages of the P-51 was not just its performance, but that it was available in numbers much sooner than anything that Curtiss could produce that could match it and, as I mentioned above, the British had a superior fighter in the Spitfire XIV. Let's not forget how the P-40Q might go against opposition such as the Fw 190D and Ta 152.

The main problems with the XP-40Q was that it was both late and a bit like putting lipstick on a pig.
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Never wrestle with a pig, you just end up getting dirty and the pig likes it! This is a saying attributed to the RAAF F-111 drivers!
 
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The XO-4Q wasn't a pig, but the F-111 might have been ... depending on who you ask.

Most F-111 pilots at 100 feet AGL, 450 knots, at 1:00am in the morning would disagree with the contention.
 
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