Merlin engined P40

[CD Baumann]

I'm surprised at the number people who don't know the P40D (I think), F and L were in fact Merlin powered. Albeit the same Merlin that powered the Spitfire V IIRC.

As far as I know, it boosted the Warhawks performance to a respectable 364 mph at 20,000 feet thanks to it's 1 stage, 2 speed supercharger versus the single speed, single stage supercharger of the Allison powered E that topped out at around 340 at 15,000 feet.

Any thoughts and info? Please feel free to correct any errors I may have made.

Edit:
Well that didn't take long.
The P40 F had a Merlin 20 series engine while the Spit mk.V had a Merlin 45 series. Big thanks to W wuzak for pointing that out.
And a P40D airframe was fitted with a Merlin as an experiment, not starting with the D model. My mistake.

Edit #2
A small disagreement broke out on the comments and there was a lot of confusion on my and other people's partsabout the role the P40 and the P39 was designed for.
I got a life outside the forum and so can't keep up so I'll address it here. I'm not calling anyone stupid nor am I calling them out.

I looked up and down, high and low, left and right and I have to yet see any indication that the P40 was designed as a high altitude interceptor. It was not super charged for higher altitude so in my mind that rules it out as an interceptor along with it's not so great climb rate. It's cousin, the XP37 was an interceptor, but it had issues with its turbo and cockpit layout. A P37 is not a P40. In light of that, Curtiss sold the P40 on the promise that they could get them into production quickly. And I have it from multiple sources that the prewar idea was to have the P40 and P39 ( more on that in a bit) stay low and the care of an invading force and duke it out with any low altitude aircraft while the P38's took care of any high flying bombers. Now I don't know, maybe I'm confused and the E model onwards was meant to be a fighter bomber, tactical fighter whatever you want to call it.

The P39.
Yes the XP39 was originally designed as a high flying interceptor. HOWEVER because of her engine layout there was no way to add a turbo without causing prohibitive drag. So the YP39 and every Airacobra afterwards went INTO PRODUCTION as a low altitude fighter with an altitude limit of 12,000 feet. That's not to say neither could've been pressed into service as an interceptor. But again using the P38 as context, an interceptor, was designed to quickly climb up to 20,000+ feet (Yes I aware of all the issues she had). Again, when an aircraft can only operate up 12,000 feet that kinda rules it out as a interceptor.

Bottom line. To my knowledge neither aircraft served in Europe due to altitude limits and where sent to theatres to carry out tactical roles.

That's my story and I'm sticking to it.

 

[wuzak]

Not the same Merlin as the Spitfire V.

The P-40 F and L (not D) used the 20 series Merlin with 2 speed single stage.

The Spitfire V had the single speed, single stage 40 series Merlin.

 

[MiTasol]

The D was the first fitted with the Allison F series engine and can best be described as an E with only 4 guns instead of 6

 

[CD Baumann]

Not the same Merlin as the Spitfire V.

The P-40 F and L (not D) used the 20 series Merlin with 2 speed single stage.

The Spitfire V had the single speed, single stage 40 series Merlin.

Will correct.
Forgot that A D airframe was fitted with a Merlin as an experiment.

 

[CD Baumann]

The D was the first fitted with the Allison F series engine.

I should've been a little clearer with that. The RAF or whoever fitted a P40D with a Merlin as an experiment.

 

[MiTasol]

Do you have any details - where/when/serial?

 

[CD Baumann]

Do you have any details - where/when/serial?

Don't know where and can't seem to find it but it was done in 1941 with serial number 40-360.

 

[MiTasol]

Thanks. That checks out but I do not have the history card for that one. Buz101 may have though

 

[Geoffrey Sinclair]

P-40D serials 40-359, 40-361 to 381, total 22, accepted May and June 1941.

P-40 40-360 became the XP-40F with a Merlin engine, first flight 30 June 1941, accepted by USAAF 30 June 1942, Wright Field 31 July 1942, Lincoln 4 September 1942, class 26, recommended for disposal 16 September 1942. Packard did not officially start Merlin 28 production until August 1941. The P-40F and L were the Merlin versions.

Contract AC-12414, 26 April 1939, ended up as P-40 39-156 to 289 and 40-292 to 357, P-40D 40-359, 40-361 to 381, P-40E 40-358 and 40-382 to 681, XP-40F 40-360
Contract AC-15802, 13 September 1940, ended up as P-40B 41-5205 to 5304, P-40E 41-5305 to 5744, contract supplement 1 added P-40B 41-13297 to 13327, P-40C 41-13328 to 13520, P-40E 41-13521 to 13599, P-40F 41-13600 to 14599 except 41-13696 never flown, used for static tests.

While time wise build order, P-40, P-40B, P-40C, P-40D, P-40E, P-40F. The above ignores 39-221 was redesignated a P-40G 14 August 1941. Then comes what the French and British orders were up to.

 

[PStickney]

View attachment 793750

I'm surprised at the number people who don't know the P40D (I think), F and L were in fact Merlin powered. Albeit the same Merlin that powered the Spitfire V IIRC.

As far as I know, it boosted the Warhawks performance to a respectable 364 mph at 20,000 feet thanks to it's 1 stage, 2 speed supercharger versus the single speed, single stage supercharger of the Allison powered E that topped out at around 340 at 15,000 feet.

Any thoughts and info? Please feel free to correct any errors I may have made.

Edit:
Well that didn't take long.
The P40 F had a Merlin 20 series engine while the Spit mk.V had a Merlin 45 series. Big thanks to W wuzak for pointing that out.
And a P40D airframe was fitted with a Merlin as an experiment, not starting with the D model. My mistake.

Basically the same engine that was used on the Hurricane II.
It's worth pointing out that after the L model production run was completed, P-40 production was all Allison powered. While performance was improved with the V1650-1, it wasn't significant enough to make a major difference in effectiveness, and as the role of the P-40s in the Med moved more toward being used as Fighter-Bombers, the slight increase in altitude performance wasn't as important as originally thought.
The single-stage Merlins were excellent engines, but in truth, they really didn't become exceptional until the 2-stage Superchargers were fitted.

 

[coldkiwi1]

The time between overhaul was 100 hrs less for the V1650-1 (400 hrs) than the Allison (500 hrs). It may not sound like many hours, but when you are operating thousands of aircraft the added cost and impact on availability would be significant. Ref TO 00-25-4 .

When you combine the modest increase in performance with increased cost to operate, it made sense to revert to the Allison.

 

[CD Baumann]

The time between overhaul was 100 hrs less for the V1650-1 (400 hrs) than the Allison (500 hrs). It may not sound like many hours, but when you are operating thousands of aircraft the added cost and impact on availability would be significant. Ref TO 00-25-4 .

When you combine the modest increase in performance with increased cost to operate, it made sense to revert to the Allison.

Yikes!

I imagine tooling played a part too at that stage of the war as well.

 

[Shortround6]

There was a lot of overlap, especially between actual placement of orders and deliveries.
The P-40Ls were built between Jan and April of 1943. Production stopped over 2 months before the Invasion of Sicily. And given the weeks if not several months to actually deliver aircraft from the Factory to North Africa combat experience with the P-40L is just about nil when any production decisions were made. Anything would be based on the results of the P-40Fs and they only arrive in NA in Aug 1942 after leaving Quonset Point R.I. July 1 on the Ranger and Flown off to Accra on the Gulf Coast and then across Africa and up to the Mid east. Reaching Palestine by July 31st.

The P-40M had been ordered June 11th 1942 and manufacture started in Nov 1942 and production stopping Feb 13th 1943.

The US was only supposed to get 3000 Merlin engines (single stage, 2 speed) out of the first 9000 engine order. That order was being completed over the 1942/43 winter. Any further Merlin powered P-40s were going to have to compete with the two stage engines going to the P-51 Mustangs and/or come out of the British allotments of single stage engines that were going to Britain/Canada.
The initial contract called for 800 engine per month. I have no details on the later contracts. Packard built around 9350 single stage Merlins from May through Dec of 1943 and 2790 two stage engines.
Merlin powered P-40s may have been decided on production planning months ahead of combat reports.

 

[CD Baumann]

The time between overhaul was 100 hrs less for the V1650-1 (400 hrs) than the Allison (500 hrs). It may not sound like many hours, but when you are operating thousands of aircraft the added cost and impact on availability would be significant. Ref TO 00-25-4 .

When you combine the modest increase in performance with increased cost to operate, it made sense to revert to the Allison.

Plus I'm pretty sure the main advantage was with the Merlin the Warhawk/Kittyhawk could maintain her speed up to 20,000 feet negating some if the advantage the Luftwaffe had in the desert war

 

[ddwhitney]

The decision to build the Merlin in the US awaited an aircraft to use it. The Air Corps elected to buy 3000 Merlins for the P-40 as a way to make more Allisons available for Bell and Lockheed. The Merlin P-40F suffered poor reliability in the middle East and was eventually replaced with Allison QEC's on many. See the attached specifics from "Vee's For Victory!"

 

[PStickney]

Yikes!

I imagine tooling played a part too at that stage of the war as well.

Not really - Packard was producing the V1650-1s used in the P-40F/L, and also the 2-Speed Merlin 28, 38, and 224sseries engines used in some Hurricanes, and the Lancaster Mk III and the Canadian Lancaster Mk Xs.
Plus all the 2-stage Merlins for the P-51, Several different marks of Spitfire - It was only at the end of the War that a second American Merlin production line was set up - Continental Motors produced a few, then the war ended, and all U.S. Merlin production stopped (Licensing agreements, and demand.)

 

[PStickney]

The time between overhaul was 100 hrs less for the V1650-1 (400 hrs) than the Allison (500 hrs). It may not sound like many hours, but when you are operating thousands of aircraft the added cost and impact on availability would be significant. Ref TO 00-25-4 .

When you combine the modest increase in performance with increased cost to operate, it made sense to revert to the Allison.

It also took between 1 1/2 -> 2 times as many Man-Hours to overhaul a Merlin as it did an Allison, according to the USAAF Statistical Digest, 1941-1945.

 

[Mustangtmg]

I'm CERTAINLY not an expert, but the late Joe Baugher, in his Merlin P-40 pages, says that 600 P-40F/Ls that were reportedly "converted" with Allison V1710-81 engines is WAAAY high, and that the number of confirmed conversions was more like 70. This is directly from his P-40F page:

A number of P-40Fs were selected at random, withdrawn from operational service, and fitted with Allison V-1710-81 in place of their original Merlins. These planes were intended for training duties. These were redesignated P-40R-1. Similar conversions from the P-40L were designated P-40R-2. Army records report that over 600 such conversions were made, but only 70 such conversions can be confirmed by serial number

 

[CD Baumann]

Not really - Packard was producing the V1650-1s used in the P-40F/L, and also the 2-Speed Merlin 28, 38, and 224sseries engines used in some Hurricanes, and the Lancaster Mk III and the Canadian Lancaster Mk Xs.
Plus all the 2-stage Merlins for the P-51, Several different marks of Spitfire - It was only at the end of the War that a second American Merlin production line was set up - Continental Motors produced a few, then the war ended, and all U.S. Merlin production stopped (Licensing agreements, and demand.)

Hmmm. Have to respectfully disagree in light of D ddwhitney 's document above.

 

[CD Baumann]

Basically the same engine that was used on the Hurricane II.
It's worth pointing out that after the L model production run was completed, P-40 production was all Allison powered. While performance was improved with the V1650-1, it wasn't significant enough to make a major difference in effectiveness, and as the role of the P-40s in the Med moved more toward being used as Fighter-Bombers, the slight increase in altitude performance wasn't as important as originally thought.
The single-stage Merlins were excellent engines, but in truth, they really didn't become exceptional until the 2-stage Superchargers were fitted.

Something I've encountered a lot is when people think Merlin engine, they immediately think of the Mustang and the Merlin 61 believing it was some kind of super engine not realizing it was, as you say, the two stage two speed supercharger.

P40 's were actually designed as a fighter bomber, hence the low end super charging. In North Africa P40s were encountering a lot of air opposition but in Italy there wasn't as many axis fighters to deal with IIRC so they could carry on without being bothered as much.