Packard P40

[GregP]

There were a lot of things going against the G-model V-1710. One of the worst was that everyone knew it was a piston last-gasp (along with all the other military pistons) and so were just biding time waiting for their new jets. Maintenance schedules weren't always followed and the operators then and now weren't running them in accordance with factory prodedures. Add to that the fact that the XP-40Q never had a G-series engine in it ... all three planes had F-series engines with very good reliability.

They still don't always follow recommended procedures today ... the C-17 comes to mind.

Anyway, I would not care to speculate whether or not a production P-40Q would be as fast, faster, or slower. It would be pure speculation and they never made one to lay the question to rest. In my view, at least, it's not a case of "good riddance." But I'm also not making claims for the P-40Q that can't be substantiated.

By the time you add in an auxiliary-stage supercharger, you might just as well have installed a 2-stage Merlin as the thread initially speculated about. I would like to have seen it come in at 8,000 pounds or less, ready to takeoff on a mission but, by the time they installed the -121 engine, it was closer to 9,000 pounds. Service planes don't typically get lighter than prototypes, but any more weight would have been a serious flaw in the case of the P-40Q.

 

[Shortround6]

You weren't going to get a P-40 with a two stage supercharger (either Merlin or Allison) down to 8,000lbs without doing the whole thing over again, ala P-51H.

Weights from "AHT" page 235 for a P-40L (stripper with Merlin engine) are 6485lbs empty, 6840lbs basic ( trapped oil, guns, gunsight) and 8120lbs gross weight clean (180lbs pilot, 98lbs useable oil, 282 lbs ammo {235rpg for 4 guns} 720lbs fuel {120 US gallons}.

Two stage engine is heavier (Packard two stage is about 150lbs heavier than Packard single stage), prop is about 65lbs heavier, cooling system is over 350lbs heavier.
Early P-40Ns did save a bit of weight with aluminium radiators/oil coolers and lighter wheels but most of the other "tricks" were reversed in the Field (like taking out the battery so the plane was either hand started or started from a battery cart. Noted in the first test of the XP-40Q in different words), and yanking the forward fuel tank. The permanent weight reduction measures were closer to 200bs.

Allison two stage may have been a bit lighter as there was no inter-cooler and inter-cooler radiator and coolant.

Now perhaps Curtiss engineers could have gone back and redone the entire airframe to a different stress factor like N.A. did for the P-51H so you have a plane that looks like a P-40 but has next to no interchangeable parts and get it down to 8,000lbs.

 

[GregP]

I was talking about the XP-40Q, not a P-541H or any other P-51. How does the P-51 keep getting drawn into a Packard P-40 thread?

A serious weight reduction program might have done it for the XP-40Q, but they never did it, so we don't really know. That's the thing ... since it wasn't proceeded with, it's all speculation.

 

[Milosh]

I would still like to know what use the P-40Q would have put to USAAF service Greg.

 

[GregP]

Since it was a fighter, I am assuming it would have been used as a fighter aircraft, Milosh, wherever the USAAF wanted to deploy it.

They deployed the regular P-40's all over the world, so I'm assuming the P-40Q would be used to replace older P-40's wherever they were needed. It would have given the P-40 units 40+ mph more speed, twice the climb, and better maneuverability, surely a welcome upgrade for the P-40 units. It also would not have affected deliveries of any other US fighter aircraft.

 

[Milosh]

Except Greg the P-40s were being replaced by more capable overall fighters.

Sure it would have affected other fighter deliveries. Every P-40Q shipped would have displaced another more capable fighter.

 

[Shortround6]

I was talking about the XP-40Q, not a P-541H or any other P-51. How does the P-51 keep getting drawn into a Packard P-40 thread?

A serious weight reduction program might have done it for the XP-40Q, but they never did it, so we don't really know. That's the thing ... since it wasn't proceeded with, it's all speculation.

It got dragged in this time as an example of a drastic weight reduction program. Something that took months to accomplish.

If Curtiss could have done a quick but significant weight reduction without screwing up production they would have done it. As mentioned above there were at least two lightweight P-40 models. The P-40L (the Gypsy Rose Lee model?) and the first 200 P-40Ns. P-40N-1= four guns,aluminium coolers, one fuel tank taken out, magnesium wheels, less ammo, no battery or starter (electric?) and no wing racks. Starter motor and battery were added back into aircraft in service and the fuel tank may have been added to some. Later P-40s added back everything but kept the aluminium coolers and mag wheels.

If weight was easy to get rid of, why did Curtiss propose and build and the USAAF accept, less capable combat aircraft?? most of the weight reduction being done at the expense of combat capability.

There is speculation and there is wishful thinking. We know N.A. did a similar program and how long it took and we know that Curtiss built two groups of "light weight" P-40s to different contracts but done in a retaliative hurry and we know the results of the "rush" modifications.
Do we KNOW with 100% certainty what the results of a 3rd program would be or how long it would take? No, we don't. But waving a hand and saying "they could have done it if they wanted to but they didn't" doesn't bring much to the discussion.

 

[GregP]

I don't believe they were necessarily all more capable, Milosh. Maybe that's where we have a disconnect.

I don't think they tested it enough to determine that was the case. Some feel they did, but the only real test I've seen is a pilot's notes report and one flight test of XP-40Q-2 after it was re-engined with the -121 Allison. That was an F-series engine, too, not a G-series unit. There is nothing saying the plane's bugs were worked out and no real comparative tests were flown against other aircraft. It was sort of a one-test summary report, not the best thing upon which to base an opinion of the aircraft. During the test it was only flown by one pilot.

It might well have been as you say, and I wouldn't claim definitely you were wrong, but I don't see evidence to substantiate it either way, particularly with only one flight test report to go on. You guys who are down on the XP-40Q might be right, but it also might not be the real case. The evidence doesn't support it one way or the other since the program was abandoned. There isn't even one single mock combat report on which to base an opinion.

That's why I keep calling it a "what if" ... we don't really know. Now I'm not crying about it, but I'm also not dismissing the aircraft with a wave of my hand and saying it was "just another P-40." I'd need more actual data to come to that conclusion. If we had that data, then you might be absolutely corect, I can't say.

 

[GregP]

We haven't had a discussion Shortround. You said engines weren't available and I said they delivered engines in P-63's right when the XP-40Q was being flown, so there definitely WERE engines available for the program. The only diffrence between an E-series Allison and an F-series Allison was the nosecase. You don't like the airframe and I haven't seen enough information on it to come to a conclusion other than it handled very well, had a good climb rate, and a good turn of speed relative to other fighters. Exactly how it would fare against competition was never established.

You are trashing the XP-40Q with almost no information on which to base your case other than it is related to the P-40 aircraft line. As I said above, there is ONE pilot notes report and ONE brief flight test where the aircraft was given pretty high praise by one pilot. There were zero mock combat flyoff tests and no comparative testing of any sort ... and you think you have enough information to come to a correct conclusion about the aircraft? Maybe you do.

I don't.

I'm not saying you are wrong. For me, there isn't enough information to reach a valid conclusion. You might be correct on all counts. And you might not be. There might be some valuable information out there we haven't yet seen and it might not exist. If it DOES exist, it should have surfaced by now. And since the program died aborning, that's about as close as we can get to the truth. It's either a dud or there isn't enough data to make a good conclusion.

Since they elected not to proceed, we may never know for sure, and it is getting tiresome to keep saying that after 8 pages of posts, so I won't. If you don't get it by now, you won't.

 

[Milosh]

For every engine that went to P-40Q production meant one less engine for P-63 production.

 

[GregP]

I don't care, the P-63's mostly went to the Soviet Union anyway. It wasn't a big factor in the USAAF. If none had been acquired, the difference would have been zero.

However, since a large number of Allisons were never installed in planes or even made it out of the shipping crates, perhaps the impact would have negligible anyway.

It isn't much if a factor in any case.

 

[Shortround6]

We haven't had a discussion Shortround. You said engines weren't available and I said they delivered engines in P-63's right when the XP-40Q was being flown, so there definitely WERE engines available for the program. The only diffrence between an E-series Allison and an F-series Allison was the nosecase.

You are quite right, this is getting tiresome. I gave you a time line of the relevant P-63 engines but you seem to ignore it. The production two stage Allison for the majority of 1944 offered 1325hp for take-off and not 1425hp and had a FTL quite a bit lower than the engine used in the March 1944 tests of the XP-40Q.

You are trashing the XP-40Q with almost no information on which to base your case other than it is related to the P-40 aircraft line.

Hmmm, related? The XP-40Q-2 (and the -1) were modified P-40K airframes. Wings were clipped, Not changed in airfoil. fuselage was lengthened and the turtle deck cut down and a bubble top put on.

P-40Q bore about the same "relation" to the the P-40 line as this aircraft did to the rest of the Spitfire line.

Or this

BTW another P-40K modified to represent a P-40N (stripper) managed to hit 378mph at 10,550ft on 1480hp. The "Q" did about 10mph slower using 90-100hp less or 28mph (?) faster using 285hp more so it sure doesn't look kike the drag changed all that much.

As I said above, there is ONE pilot notes report and ONE brief flight test where the aircraft was given pretty high praise by one pilot. There were zero mock combat flyoff tests and no comparative testing of any sort ... and you think you have enough information to come to a correct conclusion about the aircraft? Maybe you do.

Maybe I don't have enough information but "best P-40 Yet" doesn't exactly mean the plane is the best USAAF fighter or even in the top 3 does does it?

It might have #1 in a dog fight at altitudes below 20,000ft, I don't know, but it was not what the USAAF was looking for at the time, was it? Granted the test plane seemed to have some trouble in that the engine used in the March test missed its "book" FTL by over 5,000ft so a production version might have actually gone a whole lot faster at higher altitudes.

But that still doesn't solve the armament problem or the range problem. Good short ranged low-mid altitude dog fighter wasn't what the USAAF was looking for ( and if it was they had the P-63).

From a report on the 'Operational SUITABILITY OF P-40N-1 AIRPLANE" June of 1943

"The fire power of four (4) present slow firing .50 caliber machine guns is considered insufficient for the majority of combat missions where heavily armored enemy aircraft are encountered, or for most ground strafing missions."

Now we could argue about if this was in fact true but it speaks to what the USAAF wanted or believed to be true at the time. They might (and did) take planes with four .50 cal guns into service but they were not what was wanted and given a choice they were going to go with heavier armed planes.

From the same report "While the P-40N-1 is the superior in performance of the P-40 series, it is generally inferior to all other current types of fighters tested at this station."

Granted this is in June of 1943 and by March 1944 the XP-40Q is demonstrating much better performance but then so are most of the other US fighters.

And " The P-40N-1 is of a design which is believed to have reached its limit in performance unless major changes in control surface design, wing form, structure and horsepower are made."

The "Q" certainly addressed the horsepower issue but clipping about 1 foot from each wing tip is not really changing the wing form all that much. It does seem that some minor tweaks were done to the control surfaces or that a bit different CG and/or airflow pattern helped a bit.

This report also details a few more of the "tricks" used to get the weight of the N-1 down. Some of the things left out include the "Gyro compass, artificial horizon, climb indicator, suction gauge and carburetor temperature gauge."

Now we can pick and choose quotes from different reports and wonder which were the most "true" but is sure seems like the USAAF was about done with the P-40 in Mid 1943 and it would take a minor miracle to get them to change their minds. The XP-40Q may have been good but by March 1944 it may not have been good enough (and production would have been how far off?) considering their other choices.

Of the 5 major USAAF fighters the P-40Q would have been 4th for range. Doesn't matter how good you can roll or turn if you can't reach the enemy at all.

 

[GregP]

Yeah, you still don't get it, just as I thought. You're doing an aero review of a prototype with nothing but the two reports we've read on it?

Notice I never said it was the best USAAF fighter, and whether or not it was wonderful above 22,000 feet would be irrelevant in the PTO and MTO and CBI. With the P-51's above doing escort work in the ETO, perhaps the P-40Q qould be just what they nbeeded in 1944. Whatever it encountered it would outperform or be very competitive with at under 20,000 feet and most of Germany was below 20,000 feet. That would also see fewer losses of P-51's and P-47's on ground attack opportunities coming home from escort and other missions.

There are any number of possibilities, none of which were pursued.

Unsurprisingly, we disagree yet again. C'est la vie. Made zero difference in the war ... let's move on and agree to disagree.

 

[Shortround6]

Your right, I should have learned by now not to argue religion.

Super P-40s are based on faith and not facts.

 

[Milosh]

I don't care, the P-63's mostly went to the Soviet Union anyway. It wasn't a big factor in the USAAF. If none had been acquired, the difference would have been zero.

However, since a large number of Allisons were never installed in planes or even made it out of the shipping crates, perhaps the impact would have negligible anyway.

It isn't much if a factor in any case.

Large numbers of other a/c engines never made it out of their shipping crates either. You know extra engines that would be installed when the engine in the a/c was removed for maintenance or damaged.

 

[Milosh]

That would also see fewer losses of P-51's and P-47's on ground attack opportunities coming home from escort and other missions.

Except the P-40Q didn't have the range where the strafing was taking place > Germany.

 

[GregP]

Shortround,

I never claimed it was a "Super P-40." For the 4th or more time, I said we dind't have enough information to make an informed choice. Maybe you should re-read that sentence. I also don't disagree that you might be right in the end. I have attempted to stay away from sarcastic replies to posts but it ain't religion ... it's jumping to a conclusion without sufficient information.


Hi Milosh,

If they were operating solely from the UK, you are correct. But very shortly after D-Day they could have been operating from fields in continental Europe that continuously approached Germany. At some point, they would be in range, as they were in the real war. After D-Day, they didn't continue to fly back and forth to the UK for very long ... airfields moved with the general advance. Also, had they made P-40Q's, they might not have been deployed to Europe. They might have gone to the Pacific or CBI. I make no claims as to where they might have been used.


Hey, I don't disagree that some of what you fellows are saying might well be true. Where I disagree is with the notion that one flight test report with no comparative mock combat flights gives us a complete picture of what the capabilities of the plane (any plane, not just a P-40Q) might be. And doing things like changing an airfoil is no big deal. All it takes is different rib templates. We make those anyway when we restore a wing, and they aren't all that difficult to make. I've made a rib template in less than 2 hours from start to using it. I'd bet Joe has, too. It's not rocket science. If you had 10 guys making rib templates, they could knock out an airfoil change in a day.

None of the above has a thing to do with the P-40 exclusively, it true of almost any aircraft production line in WWII. Some changes were quite difficult and some were easy. It depended on what you wanted to change. Moving the wing forward or backward to compensate for a shift in CG would be a time-consuming change. Changing the airfoil shape of a wing rib would not be. It's the same number of ribs in the same locations with the holes going in the same place ... it's just a slightly different airfoil shape. It also might or might not require a slight modification to the wing skins as the total chord may or may not be exactly the same skin width.

 

[m37b1]

Wow! Go away for a week and this happens!

My two cents -

P40 lineage is very much like it's contemporaries mentioned here. The Q would have been a significant change, but very much doable. Somewhat like the revision of the Bf-109E to Bf-109F. Or the single stage Merlin Spit to the two stage Spit.

And as speculated here, the P-40Q would have been very competitive in this field of players.

Had it been PRODUCTION ready in mid to late 1943, or even early 1944, it probably would have received some backing.

In the end, the US didn't have to keep developing existing fighters like its allies or enemies did. The capacity of the US aircraft industry allowed us to develop, test, produce and field brand new fighters using the latest data from the front and the aeronautics lab.

That said, the P-40Q would have been the perfect aircraft to produce for lend-lease to the Soviet Union, along side the P-63.

 

[GregP]

Not a bad notion M37b1, I hadn't considered it as a lend-lease. The biggest problem I have with it is lack of real information when trying to compare the XP-40Q with other planes. It surely LOOKS like a winner. Maybe that information might surface someday.

Shortround could be right in almost everything he said above, I don't disagree with that. But it would be nice to know. It's good when things are black and white, but this one is in shades of gray to me. The XP-40Q looked the part and had some good numbers, but the hard data doesn't address comparative tests against other planes. Saying it handled well isn't the same as saying it out-turned a P-51 at all speeds and altitudes flown ... and I don't claim that is the case here, it's an example only. We KNOW that almost any P-40 would out-roll our other fighters.

I bet there are Heinkel He 100 fans out there thinking the same things about that plane. The He 100D could have been a good one ... and like the XP-40Q, wasn't proceeded with. At the Planes of Fame, we at least have a 100% full scale replica of the He 100D, so we can at least see what it looked like in person. Looks like a winner to me. Wish we had a mockup of the XP-40Q, too.

 

[GregP]

Duplicate post for some reason ...