P-40 with Merlin

[Marshall_Stack]

Was the P-40 with the Merlin any better than the Allison? I thought I read somewhere that the Merlin supplied for the P-40 was a low altitude version and only slightly better. P-40s started with Allisons, went to Merlins, then back to Allisons. What was the reason and did the Merlin have a different supercharger than what the Spits and P-51s had?

[V-1710]

Comparing the Allison powered P-40E with the Merlin powered P-40F reveals that below 15,000 ft. they perform pretty much the same. The F had a higher service ceiling (34,400 ft. vs. 29,000 ft.) and a better rate of climb, but that's about it. The F used the two-stage supercharged Packard built V-1650-1. Since the U.S.A.A.F. considered the P-40 primarily a low altitude fighter/bomber, and the Merlin was needed for the Mustang, most subsequent P-40's went back to the Allison. And, many of the Merlin powered P-40F and L models when removed from front line service were re-engined with V-1710's and used were as advanced trainers designated the P-40R.

[Twitch]

I agree. The Allison was more than ample for the role the P-40 was used in. I never figured there'd be any advantage to sticking a Merlin in.

[Hop]

The F used the two-stage supercharged Packard built V-1650-1.

The V-1650-1 was a US built Merlin XX series, and was a single stage, two speed engine. The two stage engines were the 60 series and above, the major Packard versions of those were the V-1650-3 and -7

AFAIK, the P-40 never got two stage Merlins, which had much better high altitude performance than the single stage engines, even the two speed ones.

[V-1710]

I think that is correct, the book I found that information in doesn't seem to recognize the difference between a 2 stage and a 2 speed supercharger. There probably wasn't enough room in the P-40's fuselage for a 2 stage supercharger.

[Marshall_Stack]

Originally Posted by V-1710

There probably wasn't enough room in the P-40's fuselage for a 2 stage supercharger.

If it could fit inthe P-51, couldn't it fit in the P-40? The P-51 seems more streamlined.

[V-1710]

I think a P-51 has a longer nose. I am no too familiar with a P-51's internal layout, but I know there isn't much room behind the Allison in a P-40. The glycol tank is back there, and plumbing to the radiators. With a 2 stage supercharger, you basically have 2 superchargers, one behind the other.

[V-1710]

I think a P-51 has a longer nose. I am no too familiar with a P-51's internal layout, but I know there isn't much room behind the Allison in a P-40. The glycol tank is back there, and plumbing to the radiators. With a 2 stage supercharger, you basically have 2 superchargers, one behind the other.

[Glider]

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