THE MYSTICAL MERLIN POWERED P-38

FLYBOYJ · Jun 21, 2020

This has been an on-going discussion on this forum since I first joined. Many have talked about a proposal undertaken by Lockheed to see the feasibility of installing a Merlin XX into a P-38 airframe. In 1982 I attended a Lockheed Management Club dinner where Kelly Johnson was the guest speaker. He did say that the Merlin was looked at but Allison and even the AAF pushed back on any Merlin proposal. Then you had the P-38K that gave the performance many were looking for out of the P-38. I just learned that after this aircraft was flight tested and later rejected by the AAF, it was converted to a P-38L and later destroyed during a ferry flight to North Carolina. Incident Lockheed P-38L Lightning 42-13558, 22 Oct 1945

As for the Merlin P-38 - it seems some sources indicate that Rolls Royce attempted a modification with a P-38J-10-LO S/N 42-67488. This was shown on several databases to include Joe Baugher's;

"67488 (42-67488) fitted with Rolls Royce Merlin engines by Rolls Royce at Hucknall, England May 1944. Performance greatly improved but project stopped by authorities in Washington."

I found an individual on an other forum post the following;

"In 1944 an eight Air Force P-38 was flown from
Bovington to Hucknall for a trial installation of single-stage two speed
Merlin XXs. Rolls-Royce test flew the aircraft a number of times
unmodified, until word came down to return the aircraft immediately! It
seems the decision was political in nature due to the fact the stop work
came from Washington." The first reference is "Birch,
David, Rolls-Royce Co. Archivist and Editor of 'Archive,' interview and
correspondence with author, 1992 - 1994. the second is...(drum roll):
Colman, P.A., "P-38 Performance Allison and Rolls-Royce Engines, Lockheed
Aircraft Corp., Burbank, Calif, 9 Feb 1944."

So here's the lost Arc - "P-38 Performance Allison and Rolls-Royce Engines, Lockheed Aircraft Corp., Burbank, Calif, 9 Feb 1944."

When I worked at Lockheed I spent many hours in the old Burbank library looking for such a document!

nuuumannn · Jun 21, 2020

Excellent info, Joe.

FLYBOYJ said:
The first reference is "Birch,
David, Rolls-Royce Co. Archivist and Editor of 'Archive,' interview and
correspondence with author, 1992 - 1994.

David Birch is the archivist for the Rolls-Royce Hertage Trust and has authored a few books for that organisation, including Rolls-Royce and the Mustang, the story of how RR worked toward getting the Mustang fitted with the Merlin engine and features correspondence between those in the USA and Britain to get it all going. I just looked to see if there was any mention of the P-38, but sadly not.

Reluctant Poster · Jun 22, 2020

Does anyone have the Rolls Royce Heritage Trust book on Hucknall? I would imagine it would mentioned in there.

MarkP · Jun 25, 2020

Just wondering if any documents might be at the Marietta Museum of History's aviation branch at Dobbins ARB/Lockheed-Martin Marietta? I was told when I was working there several years ago that Lockheed sent all files on the P-38 to Marietta. What I saw were tens of thousands of original drawings, blueprints, manuals and all items pertaining to the P-38. I asked about them a few years ago and was told that one of the volunteers was organizing and securing the documents.

FLYBOYJ · Jun 25, 2020

MarkP said:
Just wondering if any documents might be at the Marietta Museum of History's aviation branch at Dobbins ARB/Lockheed-Martin Marietta? I was told when I was working there several years ago that Lockheed sent all files on the P-38 to Marietta. What I saw were tens of thousands of original drawings, blueprints, manuals and all items pertaining to the P-38. I asked about them a few years ago and was told that one of the volunteers was organizing and securing the documents.

Interesting! I worked at Burbank and there was a library down the street from the main plant that housed a lot of these reports. Hard blueprints were kept in "the vault." I never knew where that was at but I do know some historical drawings were able to be ordered. I was told that when Burbank shut down many documents were tossed so hearing this is great news.

MarkP · Jun 26, 2020

FLYBOYJ said:
Interesting! I worked at Burbank and there was a library down the street from the main plant that housed a lot of these reports. Hard blueprints were kept in "the vault." I never knew where that was at but I do know some historical drawings were able to be ordered. I was told that when Burbank shut down many documents were tossed so hearing this is great news.

I am not sure of the timeframe that the P-38 archive was transferred to Marietta but it might have been as early as the 1980s. Some old Lockheed/Martin-Marietta employees started the museum at Dobbins and when Burbank closed, or sometime shortly before, an amazing volume of documents was sent. There were several giant wooden crates with what was described to me as the entire P-38 engineering and production records. The old guys were very careful about who was allowed access to it because, as they realized, it was important and many of the large engineering plans had great value. It would be wonderful if it were all documented and digitized.

Skyediamonds · Jun 26, 2020

Flyboy,
I used to live in the San Fernando Valley about 30+ years ago. I worked for Pacific Airmotive in Burbank off of Pass Avenue. I used to pass the old Lockheed plant almost daily. Always had a keen interest in several unusual early projects such as the XP-58 Chain Lightning. Wondered if such detailed drawings would still be available or at least in storage.
Gary

chuter · Jun 28, 2020

Would the single-stage two-speed Merlin been an improvement on the turbo Allison? They seemed to help the non-turbo P40F/L a bit.

Deleted member 68059 · Jun 28, 2020

chuter said:
Would the single-stage two-speed Merlin been an improvement on the turbo Allison? They seemed to help the non-turbo P40F/L a bit.

In certain respects yes, firstly the turbo V-1710`s (certainly early on) had their built in superchargers downspeeded from about 8:1 to 6.3:1, so its not quote giving you the results you might expect from a two-stage supercharger (which it in effect ought to be). The Wright-Field correspondance files in the "Sarah Clarke" section at US National Archives college park have some material on it, and it was (roughly calculated) that the Merlin XX was in certain altitudes a bit better than the turbo-allison, mostly due to the fairly large saving in weight with not having the turbos, pipework, and associated systems.

There was no proper performance curve in the files I copied, and annoyingly it does not suggest what the high altitude performace would have been (I suspect that at 35,000 the Allison would have been better), but up to 25,000ft the Merlin XX variant was reckoned to be maybe 5% faster.

The results all look very optimistic across the board, even from the 1710 version, from which they were hoping for 440mph from the P-38 at 25,000 feet ! - So clearly these calcs were what in the UK we would call "back of a cigarette packet" standard. They also had the V-1710 P-38 about 4000lb underweight in the data-table, that might well have contributed....

Skyediamonds · Jun 28, 2020

Snowy:
Excellent response! I learned much about the Allison versus Merlin supercharger engines. Had no idea such data was even available.
As an aside: the famous Int'l Reno Air Races was canceled due to the Coronavirus. I live here in Reno & should (partially) explain my interest in this discussion.

Gary

gjs238 · Jun 28, 2020

Snowygrouch said:
In certain respects yes, firstly the turbo V-1710`s (certainly early on) had their built in superchargers downspeeded from about 8:1 to 6.3:1, so its not quote giving you the results you might expect from a two-stage supercharger (which it in effect ought to be). The Wright-Field correspondance files in the "Sarah Clarke" section at US National Archives college park have some material on it, and it was (roughly calculated) that the Merlin XX was in certain altitudes a bit better than the turbo-allison, mostly due to the fairly large saving in weight with not having the turbos, pipework, and associated systems.

There was no proper performance curve in the files I copied, and annoyingly it does not suggest what the high altitude performace would have been (I suspect that at 35,000 the Allison would have been better), but up to 25,000ft the Merlin XX variant was reckoned to be maybe 5% faster.

The results all look very optimistic across the board, even from the 1710 version, from which they were hoping for 440mph from the P-38 at 25,000 feet ! - So clearly these calcs were what in the UK we would call "back of a cigarette packet" standard. They also had the V-1710 P-38 about 4000lb underweight in the data-table, that might well have contributed....

Interesting.
Seems to beg the question, "then how would the 2-stage Merlins perform?"

wuzak · Jun 29, 2020

Snowygrouch said:
and it was (roughly calculated) that the Merlin XX was in certain altitudes a bit better than the turbo-allison, mostly due to the fairly large saving in weight with not having the turbos, pipework, and associated systems.

I presume that the Merlin XX P-38 was being compared to the earlier P-38s with wing leading edge intercoolers, rather than the later chin intercoolers of the P-38J and L?

If so, that would present an opportunity for additional fuel tanks on the P-38-Merlin XX compared to the regular P-38s. The P-38J added fuel tanks where the leading edge radiators used to be, of course.

Deleted member 68059 · Jun 29, 2020

gjs238 said:
Interesting.
Seems to beg the question, "then how would the 2-stage Merlins perform?"

I do not know the answer to that and have no proper data or archive reports on it to share.

My "personal" opinion, which is merely my private view, is that a P-38 with Merlin-61`s would have been very special.
(ignoring the cabin heating and compressibility issues).

Gnomey · Jun 29, 2020

Interesting!

FLYBOYJ · Jun 29, 2020

Skyediamonds said:
Flyboy,
I used to live in the San Fernando Valley about 30+ years ago. I worked for Pacific Airmotive in Burbank off of Pass Avenue. I used to pass the old Lockheed plant almost daily. Always had a keen interest in several unusual early projects such as the XP-58 Chain Lightning. Wondered if such detailed drawings would still be available or at least in storage.
Gary

Hi Gary - 'worked for Lockheed for over 10 years, lived in the SFV as well, we probably drove past each other at rush hour!

I actually knew someone who worked on the P-58. He said when it worked it was a beast but on the same note he said it was a maintenance nightmare!

FLYBOYJ · Jun 29, 2020

Snowygrouch said:
I do not know the answer to that and have no proper data or archive reports on it to share.

My "personal" opinion, which is merely my private view, is that a P-38 with Merlin-61`s would have been very special.
(ignoring the cabin heating and compressibility issues).

Agree "almost" 100%.

The cabin heating issues were addressed on the P-38L (too little too late for the ETO) but at the same time the aircraft was never envisioned to be escorting B-17s over Europe at 20,000' over Germany in the middle of the winter. Now comprehensibility! Those issues never really went away, they were just "band-aided." Imagine a P-38 that could easily top 440 MPH! Gives me goosebumps but at the same time the aircraft gets to the comprehensibility envelope that much quicker!

This was from on old Google group discussion, you're probably aware well aware of the book mentioned.

"A new book about the Allison V-1710, Vee's for Victory, Daniel Whitney,
Schiffer, has the details of P-38 studies with merlin XX, 61 and a hypothetical
2000hp merlin. The Merlin 61 figures come out almost the same as the P-38J. The
merlin '2000' comes out at 468 at critical alt, which I don't believe any 38
could do, being mach .71 at 36,000ft. Any attempt to add power beyond what was
available with a 38L would give the lightning 'compressibilty' problems on the
level. Would climb well though...."

more here..

Google Groups

Skyediamonds · Jun 30, 2020

FlyBoy,
Thank you for that brief insight on " The Beast" P-58 Chain Lightning. If anyone has any detailed drawings or photos it would be great to see them.
Gary

Reluctant Poster · Jun 30, 2020

FLYBOYJ said:
Agree "almost" 100%.

The cabin heating issues were addressed on the P-38L (too little too late for the ETO) but at the same time the aircraft was never envisioned to be escorting B-17s over Europe at 20,000' over Germany in the middle of the winter. Now comprehensibility! Those issues never really went away, they were just "band-aided." Imagine a P-38 that could easily top 440 MPH! Gives me goosebumps but at the same time the aircraft gets to the comprehensibility envelope that much quicker!

This was from on old Google group discussion, you're probably aware well aware of the book mentioned.

"A new book about the Allison V-1710, Vee's for Victory, Daniel Whitney,
Schiffer, has the details of P-38 studies with merlin XX, 61 and a hypothetical
2000hp merlin. The Merlin 61 figures come out almost the same as the P-38J. The
merlin '2000' comes out at 468 at critical alt, which I don't believe any 38
could do, being mach .71 at 36,000ft. Any attempt to add power beyond what was
available with a 38L would give the lightning 'compressibilty' problems on the
level. Would climb well though...."

more here..

Google Groups

The air at 20,000 feet is very cold the world over. There is no excuse for not designing proper cockpit heating for an aircraft designed for a service ceiling of over 30,000 feet.
This was not some unknown fact. The plot of the prewar movie Dive Bomber revolves around how cold it gets at altitude above sunny San Diego.
It's a must watch movie for a snapshot of USN aviation just before Peal Harbor.

gjs238 · Jun 30, 2020

Reluctant Poster said:
The air at 20,000 feet is very cold the world over. There is no excuse for not designing proper cockpit heating for an aircraft designed for a service ceiling of over 30,000 feet.
This was not some unknown fact. The plot of the prewar movie Dive Bomber revolves around how cold it gets at altitude above sunny San Diego.
It's a must watch movie for a snapshot of USN aviation just before Peal Harbor.

The P-38 was under-developed. Like they say on Wikipedia, that article should have been allowed more time to incubate as a draft.

FLYBOYJ · Jun 30, 2020

Reluctant Poster said:
The air at 20,000 feet is very cold the world over. There is no excuse for not designing proper cockpit heating for an aircraft designed for a service ceiling of over 30,000 feet.
This was not some unknown fact. The plot of the prewar movie Dive Bomber revolves around how cold it gets at altitude above sunny San Diego.
It's a must watch movie for a snapshot of USN aviation just before Peal Harbor.

There is if the customer never specified a requirement for specific heating requirements!

At what altitudes do you think aerial combat was being undertaken in 1937????

The design spec for the P-38 (Circular Proposal X-608) only specified the aircraft must climb to 20,000 feet in six minutes. No one, to include Lockheed's initial and primary customer, the AAF ever thought the P-38 would be operating over 20,000, let alone 30,000 feet for sustained periods. It was designed as an interceptor, not a long range escort fighter!

Besides, Burbank is a lot warmer than San Diego! (Lived in SoCal for many years)

Kidding aside, it's amazing how the same aircraft was operated in Alaska and there's been little discussion about the cockpit heater from that theater!!!

What was not a known fact was what was going to happen in 5 years!

BTW, great movie! A young Fred MacMurray!

THE MYSTICAL MERLIN POWERED P-38

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