Should Grumman have built a fighter for the US Army?

[Shortround6]

I've often wondered why the army didn't at least approach, if not Grumman, then another Naval company and find out how they got such terrific range in their aircraft. I can understand them being hesitant to put the Merlin in the Mustang as it was a different country's product but was there that much animosity between services that they couldn't have worked together on better range?

The Army "KNEW" how the Navy got such great ranges from their aircraft. You can get a P-40F with a 52 gal drop tank to fly 890miles and that is after start, warm up and take-off. No reserves though. You just have to fly at about 160mph at about 5,000ft.

Navy ranges are usually given for a real "max range" speed or ferry range speed and a low altitude which would be near suicidal in a combat zone.

 

[oldcrowcv63]

I would start with the lightest weight in the charts. 7500lbs for the "F"? and then the next higher and average them. The L went about 8000lbs clean (give or take).

The "D" or a light weight "E" isn't going to work at high altitude. Critical height for the engine was under 12,000ft compared to the 18500ft for the F&L. The E was going to be about 140-150hp down at 18500ft compared to an F. There is simply no way to strip out enough weight.

Look the charts in AHT the F is about 20-30mph faster than an E at 20,000ft and above. If the F or L won't work there is no hope for an Allison powered version.

Don't mean to belabor the point, but the B was reputed to have a ceiling of 32,400+ ft. with an earlier engine that is essentially the same as the E (except at low alt) based on graph 24 (AHT Page 232). admitedly the power has fallen off to about 300 hp, and that for an aircraft (P-40B) weighing about 7,600 lbs. So that's the target weight. In order to get it to have a similar ceiling, the weight reduction must be ~ 700#, and deleting two 50's with ammo is only going to get you half way there, which is perhaps why FEAF pilot Brownwell had to dump 4 of his 6 guns to get the performance he sought. But wouldn't you split the difference and get to something less than 32,400 ft but above the favored 8.5 km (27,500 ft) altitude of the IJN raids. The standard heavy P-40E (with drop tank) just barely gets there and typically late, I'd expect its ceiling and climb to be somewhat dependant on tropical environmental considerations. Wouldn't just a 300 pound reduction have given the P-40E some excess in both ceiling and time to climb? We're talking about just pushing it over a performance threshold to be more effective against those high altitude IJN raids.

 

[Shortround6]

Here is a link for the P-40B-C Manual (or parts of it)

http://www.ww2aircraft.net/forum/attachments/other-mechanical-systems-tech/182770d1320921322-p40-tomahawk-p-40b-c-tomahawk.pdf

There are a few differences between the weights of the B/C and the D/E. One way to get the weight down is not fill all three internal fuel tanks. On the Early models (and the P-36) the Fuselage tank was referred to as the "overload" tank yet on the L-M-N light weight versions it was the froward wing tank that was removed???

You also might want to consider the engines 1040hp at 14,300ft vs 1150hp at 10,800ft (?)

The engine in the D/E may have been good for 1060hp at 14,300ft.

Ram works a lot better for high speed flight than for climb.

 

[oldcrowcv63]

Thanks Shortround, I used the tables for the E (and the D) by just varying gross weight. The GW of the P-40D taken to be 8,100# and that of the P-40E: 8,400#. By 25,000 feet, the D is leading the E by about 4 minutes and is carrying an additional 100 fpm climb rate. That's pretty much what I was anticipating. If the P-40D can reach an altitude of 28,000 feet about 5 minutes earlier than the P-40E which was not, or barely, able, to reach that altitude, then, assuming the IJN escort has been distracted or is poorly positioned (a frequent occurrence), the P-40D has a pretty good chance of knocking down or putting a few rounds into a bomber. This level of success was an unusual event during the defense of Java or Darwin and never happened at all during the PI campaign. I believe it lends credence to the idea that the 6 gun fit was a real handicap in the early months of the war (over the PI and over Java and Darwin), when attempting to intercept IJN Raids. I doubt the P-40E's extra 2 guns was much of a handicap when encountering A6Ms at any altitude and assuming they worked may have paid for themselves in the increased lead throw-weight when they worked.

 

[rlgdestroyu]

My first post here so be gentle, but was the main difference in navy and aaf, strategies? It would make sense that the biggest hurdle both had to overcome was range, over such an expansive area like the pacific. But it would seem range may be a bigger hurdle for the aaf, considering their bases were on islands the marines had to clear out. Like was said earlier, both the navy and the aaf could find range, and maybe looking at what the aaf used in the European theatre makes even more sense since if I have a bunch of pilots, ground crew, parts and pieces for certain planes it would be more streamlined to use the same aircraft. Thoughts?

 

[FLYBOYJ]

Folks remember - aircraft manufacturers then and now develop military aircraft based on a government solicitation 99% of the time and most of that time are "invited" to bid a solicitation based on their previous experience supplying aircraft to the government. There was a day when private ventures were submitted (a real gamble) or when companies would offer an unsolicited proposal. Bottom line, aircraft manufacturers don't arbitrarily decide to build planes for one branch of the military "just for the hell of it."