Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained) (1 Viewer)

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If memory serves, that was also the debut of the Allison Mustang, (in RAF service), when Hollister shot down at least one FW-190. It was a pretty big day.
 
glennasher said:
If memory serves, that was also the debut of the Allison Mustang, (in RAF service), when Hollister shot down at least one FW-190. It was a pretty big day.
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In all sorts of ways, those Spitfires were escorting US manned B-17s, the Mustang MkI also had its first loss. As I understand it it was the first time combat was "joined " with the Mustang Mk I, they had been on operations before that. Quote "After the arrival of the initial aircraft in the UK in October 1941, the first Mustang Mk Is entered service in January 1942, the first unit being 26 Squadron RAF. Due to poor high-altitude performance, the Mustangs were used by Army Co-operation Command, rather than Fighter Command, and were used for tactical reconnaissance and ground-attack duties. On 10 May 1942, Mustangs first flew over France, near Berck-sur-Mer. On 27 July 1942, 16 RAF Mustangs undertook their first long-range reconnaissance mission over Germany. During the amphibious Dieppe Raid on the French coast (19 August 1942), four British and Canadian Mustang squadrons, including 26 Squadron, saw action covering the assault on the ground. " from The History Hangar - Mustang I
 
P-39 Expert said:
Of course unloading the wing guns (and nose armor plate) would have helped the N also, but it already climbed well at normal gross weight.
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I think you've been shown on more than one occasion that if you remove the nose armor plate you will go outside the rear C/G limit if you use all your cannon ammo and get down to 1/4 fuel.

 
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Regarding post #183 Schweik, I have the following:



Looks like the P-40F had about 10 mph on the P-40E, which isn't very much. Still, an advantage IS an advantage. The P-40F had about a 6% climb advantage. Again, not a game changer. The P-40F had about 5,400 feet ceiling advantage. That is more significant than the speed or climb, but in actual fighter performance, the P-40 E started dropping off at about 15,000 feet and the P-40F started dropping off at about 19,000 feet. So, it had a medium advantage, though the P-40E was in combat a full 5 months earlier than the P-40F.

Then we get to the P-40L and P-40N. They only entered combat two months apart, with the P-40L getting there first. The Allison-powered P-40N (interceptor version) was about 6 mph faster, climbed 880 fpm better than the P-40L, and had a 2,200 foot service ceiling advantage. The P-40N's climb was 33% better than the P-40L. The N had a very slight speed advantage, not enough to matter, and the N had about a 6% service ceiling advantage.

So, the P-40F had a slight advantage for about 2 years early in the war and the P-40N had about the same advantage for 2 years later in the war except for climb, where it had a much more significant advantage.

I'll stick with the Allison, myself, overall. In a perfect world where choice was an option, I'd have an Allison P-40 up until Dec 41, right about Pearl Harbor time. Then I'd fly a P-40F until Mar 43, at which time, I'd opt for a P-40N. I'd WISH for a P-40Q that would never show up.

The weights above are for normal combat loadout, not maximum takeoff weight.

I just do not see the P-40F as having a very significant advantage over the P-40E though it DID, in fact, have one. The P-40N DID have a pretty good climb advantage over the P-40L. All in all, they weren't all that much different from one another. Sort of "incremental improvements."
 

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Right. But those numbers are a bit off. They are basically the 'brochure numbers'. The real top speed of the P-40E was a bit over 345 mph at about 13,000 ft. See also here. The real top speed of the P-40F was 370 mph. at 20,000 ft. Note from that same link that the P-40F is down to 347 mph at 30,000 ft, and that is because of reduced power. They did not fight at that altitude normally. And they certainly weren't operating at 34,000 ft any more than a P-40E was hunting at 29.000. The ratios are about right but the real fighting altitudes were much lower.

All of those ceilings are way, way high. Again, brochure numbers. Performance on the Allison P-40s was badly reduced at 12-16,000 ft (depending on the gear ratio of the specific Allison engine subvariant) and really did not permit safe combat operations much over 20,000. They managed to pull off some interceptions a bit over 22,000 ft over Darwin by taking a pair of guns out and removing some other stuff, and they could only make one pass at the Japanese bombers before needing to dive away before a fighter got near them. It wasn't considered safe to fight above the performance ceiling. As you can see on this chart - level speed for the P-40E is down to 330 mph at 20,000 ft. That's compared to a Bf 109F doing ~ 380 mph. Not safe. Rate of climb for a P-40E is down to 1,000 feet per minute at 20k ft at max boost, and declining rapidly.

The difference in speed is largely down to the altitude. Assuming we are talking about one of the strengthened V-1710-39s for the P-40E, speed was probably about equivalent or maybe a bit better down low for the Allison engined version. It was definitely better for the P-40K.

Those climb numbers for the F reflect overload conditions, actual numbers for the 'lightened' (and four gun) F and L are about the same as the 'lightened' (four gun) N, i.e. about 3,300 fpm initially, but the F / L get another boost to climb rate when their second gear kicks in at around 14,000 ', right when the Allison is starting to gasp. However fewer of the 'lightened' N seem to have been used, and none in the MTO as far as I've been able to determine.


As for which one would be better- for air superiority operations against the disciplined fighting style of the Germans, there is no doubt the P-40F/L was better. Against the Japanese, where a lot of fighting occurred down low for a variety of reasons, the Allison was probably better. Also for fighter-bombing operations down low in either Theater, again the Allison is better because it gives very good power below 5,000 ft.
 
P-39 Expert said:
And I have stated more than once that the IFF radio in the tail cone could be moved up under the rear canopy above the engine or removed altogether for balance.
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Have you ever done a proper weight and balance with all the changes you make? I don't remember any being posted.
 

Spitfires at Darwin didn't have it exclusively their own way in 1942, so I would not hold much of hope for P-39s doing better (or the same), even with weight reduction.
Escort of B-25s for ranges they were capable for was out of question - the B-25 combat radius was almost as good as range of P-39.

[/QUOTE]P-47 could only escort about 350mi radius in 1943 and then only after drop tanks introduced in August. I have a range chart but can't seem to make it attach. [/QUOTE]

Two drop tanks under the wing, as used by P-47s for ferrying in August of 1943 from USA to UK via Iceland. Or use a proper metalic flat tank of 200 gals under the belly, as used on P-47s in Pacific from August 1943.

[/QUOTE]A larger engine will make more power.
I'm not talking about an 8900lb P-39E. I'm saying put the -93 engine in a standard P-39, offset the weight of the auxiliary stage with a larger four blade propeller. The -03 engine would fit into a standard P-39, I've shown the drawings on here many times. Whole thing would have weighed about 7900lbs.
[/QUOTE]

NI see no point to discuss that anymore.
 
P-39 Expert said:
And I have stated more than once that the IFF radio in the tail cone could be moved up under the rear canopy above the engine or removed altogether for balance.
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1. It won't make a difference, 2. You're trying to argue about something that doesn't exist. 3. Do you have Bell engineering drawings to show this installation in any area you mention? If you don't it doesn't exist! Stop with the hypothetical BS to support your arguments, it's getting old.
 
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