P38 with Merlins

[Forked tail devil]

Thoughts?

 

[wuzak]

You should search through some old threads - this has been discussed before.

There really is the questions of when and what version Merlin?

Lockheed certainly thought it was worth looking into producing 3 proposals (with Merlin XX series, Merlin 60 series and Merlin 100 series) through the war.

 

[MIflyer]

Warren Bodie, who wrote the definitive book on the P-38, said that Lockheed studied it and it looked good.

I had pointed out to him that a two stage Merlin was about 400 lb heavier than a V-1710 and had a lower rated power at altitude.

A friend of mine, Ward Duncan, Maintenance Chief of the 9th PRS (9th Photo Reconnaissance Squadron) said he saw problems with fitting it to the airframe. Admittedly he was talking from the field standpoint rather than what could be done in the factory.

 

[Reluctant Poster]

Warren Bodie, who wrote the definitive book on the P-38, said that Lockheed studied it and it looked good.

I had pointed out to him that a two stage Merlin was about 400 lb heavier than a V-1710 and had a lower rated power at altitude.

A friend of mine, Ward Duncan, Maintenance Chief of the 9th PRS (9th Photo Reconnaissance Squadron) said he saw problems with fitting it to the airframe. Admittedly he was talking from the field standpoint rather than what could be done in the factory.

A Merlin weighted 400 lb more. i find that extremely hard to believe.

 

[MIflyer]

All the different marks of Merlins weighed more than the equivalent V-1710, although it is hard to say what is equivalent.

From the 1945/46 Edition of Jane's:

V-1710-F30R and F30L: 1395 lb, 1475 hp at 3000 rpm at 30,000 ft. (does not include weight of turbo and intercooler)

Merlin 61: 1640 lb, 1390 hp at 3000 rpm at 23,650 ft.

However, there appear to be some different definitions of rated power.

 

[pbehn]

A waste of both Allison and Merlin engines IMHO.

 

[tomo pauk]

Installing the Merlin does not solve the problems P-38 had that were unrelated to engine choice: icy cold cockpit above 20000 ft, low dive limit, slow rate of roll, messed cockpit, plenty of blind spots/areas, big size for a fighter, need for more training than 1-engined fighters.

USA has a surplus of Merlins? Install them on P-51s; the P-38 needs two Merlins per each airframe.

 

[wuzak]

Warren Bodie, who wrote the definitive book on the P-38, said that Lockheed studied it and it looked good.

I had pointed out to him that a two stage Merlin was about 400 lb heavier than a V-1710 and had a lower rated power at altitude.

A friend of mine, Ward Duncan, Maintenance Chief of the 9th PRS (9th Photo Reconnaissance Squadron) said he saw problems with fitting it to the airframe. Admittedly he was talking from the field standpoint rather than what could be done in the factory.

2 stage Merlin was 400lb heavier than single stage V-1710. However, the 2 stage need approximately the same weight in turbo, and ducting.

 

[Forked tail devil]

A waste of both Allison and Merlin engines IMHO.

Tell that to bong and maguire

 

[Admiral Beez]

A waste of both Allison and Merlin engines IMHO.

There have been wasteful applications of these engines, such as the North American F-82, Hawker Henley, Bell's P-63 Kingcobra and Airacuda, etc... but the Lightning is not one of them.

 

[pbehn]

There have been wasteful applications of these engines, such as the North American F-82, Hawker Henley, Bell's P-63 Kingcobra and Airacuda, etc... but the Lightning is not one of them.

That isnt what I said or at least not what I meant. The P-38 with Allisons and Turbo was a good plane able to do many things others couldn't early in the war. Swapping Merlins would not improve the performance in many respects and would make it worse in some, and would require a new plane anyway. Having done that, what would you do with the 20,000 Allison engines, you couldn't put them in a plane with the utility of the P-38 because there wasn't one. Some get "sniffy" about photo recon as if it is for sub standard planes, over Europe it was vital and only a few were capable of it.

 

[Reluctant Poster]

All the different marks of Merlins weighed more than the equivalent V-1710, although it is hard to say what is equivalent.

From the 1945/46 Edition of Jane's:

V-1710-F30R and F30L: 1395 lb, 1475 hp at 3000 rpm at 30,000 ft. (does not include weight of turbo and intercooler)

Merlin 61: 1640 lb, 1390 hp at 3000 rpm at 23,650 ft.

However, there appear to be some different definitions of rated power.

I have totaled the weight of the engines and related components for the P-38J and P-51B based on the values given in American's Hundred-Thousand (for one engine)

As one would expect, the weights are not significantly different when the weight of the turbocharger is included. Obviously these are installations in two different aircraft and there may be some differences in an actual P-38 installation.

One thing that stands out in this comparison is that the Merlin weight includes the engine accessories, which are not included in the Allison weight. When the accessories are included the Allison weighs 1526 vs 1670 for the Merlin.

The other issue is that you are attacking a straw man by comparing the performance of a Merlin 61 to the V-1710 F30. Its very common in this forum to compare the performance of the early versions of the Merlin (1942 for the 61) to the performance of later versions of the Allison (1944 for the F30). The Merlin 61 was the first production version of the two stage Merlin and relatively few of it and the similar Merlin 63 were built. It was rapidly superseded by the more powerful Merlin 66. The Merlin 66 was in front line service more than a year before the F30. The correct comparison would be the Merlin 66 or its Packard equivalent V-1650-7.

 

[pbehn]

I have totaled the weight of the engines and related components for the P-38J and P-51B based on the values given in American's Hundred-Thousand (for one engine)


View attachment 574136

As one would expect, the weights are not significantly different when the weight of the turbocharger is included. Obviously these are installations in two different aircraft and there may be some differences in an actual P-38 installation.

One thing that stands out in this comparison is that the Merlin weight includes the engine accessories, which are not included in the Allison weight. When the accessories are included the Allison weighs 1526 vs 1670 for the Merlin.

The other issue is that you are attacking a straw man by comparing the performance of a Merlin 61 to the V-1710 F30. Its very common in this forum to compare the performance of the early versions of the Merlin (1942 for the 61) to the performance of later versions of the Allison (1944 for the F30). The Merlin 61 was the first production version of the two stage Merlin and relatively few of it and the similar Merlin 63 were built. It was rapidly superseded by the more powerful Merlin 66. The Merlin 66 was in front line service more than a year before the F30. The correct comparison would be the Merlin 66 or its Packard equivalent V-1650-7.

The weights may be similar but they would not be in the same place, it would need a re design.

 

[rinkol]

The Merlin had the advantages of a compact supercharger installation and exhaust gas thrust. The first of these didn't matter much with the P-38 since the tail booms had plenty of space.

The P-38 was, aside from possibly the P-63, the only first rank plane using the V-1710. Switching the P-38 to the Merlin would have left the Allison production capability underutilized.

 

[wuzak]

The Merlin had the advantages of a compact supercharger installation and exhaust gas thrust. The first of these didn't matter much with the P-38 since the tail booms had plenty of space.

The P-38 was, aside from possibly the P-63, the only first rank plane using the V-1710. Switching the P-38 to the Merlin would have left the Alison production capability underutilized.

A Lockheed P-38 was delivered to Rolls-Royce for conversion to Merlins at some point (not sure which version, but pre -J), but the powers-that-be ordered it returned before any work was done. It is possible that lobbying efforts by GM on Allison's behalf stopped the trial conversion from happening.

 

[pbehn]

The Merlin had the advantages of a compact supercharger installation and exhaust gas thrust. The first of these didn't matter much with the P-38 since the tail booms had plenty of space.

The P-38 was, aside from possibly the P-63, the only first rank plane using the V-1710. Switching the P-38 to the Merlin would have left the Alison production capability underutilized.

The Mustang MkI was also a first rank aircraft at what it did the UK would have taken more of them up to 1944 at least. Without the Turbo that the P-38 had there were many competing aircraft but you cant make any type of aircraft that can do long distance missions or combat at high altitude as the P-38 did when it did. Using Merlins just leaves other planes without Merlins because there wasn't a surplus of Merlins until just before the end of the war.

 

[GreenKnight121]

Here is something I copied down years ago, after this same discussion on another forum.
It discusses both the proposed Merlin version and the single test example fitted with "paddle-blade" props, and the changes required for either (ideally, both at the same time).

It mentions the reason neither was actually done - the changes on the production line would disrupt production flow, which was NOT acceptable to the government. Note that the War Production Board had 100% control of what was produced, by whom, and when - and that many similar improvements to Government-contracted aircraft from many different manufacturers met exactly the same veto unless requested by the US military branch the aircraft were for, or the change could be implement with no appreciable effect on production rates.

Note the sections I have bolded:

The Story Of The Best Performing Variant Of The P-38 Lightning
The Lockheed P-38K-1-LO is now nearly forgotten. No photographs of the aircraft are known to exist today. Only the original test mule was photographed. It has been relegated to that part of history where one off prototypes and special test aircraft usually go. This is rather unfortunate for this aircraft as it was the benchmark against which all other variants of the P-38 Lightning must be compared. Simply said, it was the best performing Lightning ever to take to the sky.

From the very beginning of America's involvement in World War Two, Lockheed was looking for ways to improve the performance of the P-38. The installation of Rolls Royce XX Merlins was seriously considered. Lockheed went as far as designing the installation package. The advantages of the Merlin engine were numerous. First and foremost was the elimination of the complex turbocharger system. This would also result in a much cleaner engine nacelle. The turbo intercoolers could be removed. That would have allowed for a for more aerodynamic package, closer in shape to that of the original XP-38. Another option was to remove the Prestone radiators and place them under the engine as in the P-40. This location had the additional advantage of reducing the length of the cooling system plumbing. This, in turn, reduced the risk of battle damage to the system. Either option would result in a significant reduction in drag and weight. A further benefit would be gained by the removal of intercooler ducting in the front portion of the outer wings. This volume could be utilized for increased fuel capacity. In fact, that is what was done when the P-38J was designed with revised intercooler cores that eliminated the ducting. This increased internal fuel capacity by 110 gallons.

There were some performance areas that would suffer. While a gain in speed at medium altitudes was expected, the rate of climb would be reduced by as much as 400 feet per minute. Service ceiling would also be reduced as the Packard Merlin XX made considerably less power above 30,000 feet than did the Allison V1710. At the time, no one anticipated the engine and turbocharger problems that developed at high altitude over Europe. Unfortunately, the War Production Board was unwilling to shut down the production line for several months to retool for major design changes required for the engine swap. As a result, the Merlin project was shelved. No P-38 ever flew fitted with Rolls Royce Merlin or Packard engines. The idea of retro-fitting Merlin 61 engines was bantered about 8th Air Force Fighter Command, however there is no evidence that any such conversion ever took place. The prospect of such a modification would have been daunting. This was no simple engine swap, it required large portions of the airframe to be completely redesigned. Stories of Merlin powered Lightnings are, without much doubt, myth.

This, however, did not put an end to seeking greater performance. Lockheed paid close attention to the performance gains achieved with the P-47 when the new "high activity" Hamilton Standard propellers where first fitted on a Republic P-47C in mid 1942 (later, in mid 1943, these propellers were retro-fitted in Britain). The new "paddle" blade prop had significantly increased the rate of climb and acceleration of the "Jug". Lockheed decided that they would install the Hamilton Standard hydraulic propellers on one of the factory test "mules". Thus, was the XP-38K born. The "mule" was an extensively modified P-38E. The original intercoolers were replaced with the newer type introduced on the J model. The initial test results were very encouraging and a P-38G service test airframe (422-81, AFF serial number 42-13558) was selected to be modified.

The new propellers were not the only design changes made in the search for greater performance. This airframe was configured for the Allison V1710F-15 powerplants which were rated at over 1,875 bhp in War Emergency Power (as compared to 1,725 bhp for the V1710F-17 in the P-38L). This was the only P-38 so configured. The potent combination of the engine/propeller promised excellent performance.



There were still other modifications that were necessary. The Hamilton Standard props required a spinner of greater diameter, and the thrust line was slightly higher as well. This in turn, required that new cowlings be manufactured to properly blend the spinners into the engine nacelles. These were hand made and the fit was less than perfect. The new propellers necessitated a change to the reduction gear ratio. The Curtiss Electric props had a normal ratio of 2.00 to 1. The ratio was changed to 2.36 to 1.

Flight tests were conducted from late February through the end of April 1943. Performance was better than hoped for. Maximum speed at critical altitude (29,600 ft) was 432 mph (Military Power). At 40,000 feet, the "K" zipped along at a speed that was 40 mph faster than the current production P-38J could attain at this same height. Maximum speed in War Emergency Power, at critical altitude, was expected to exceed 450 mph. The increase in ceiling was just as remarkable. Flown to 45,000 ft on an extremely hot and humid day, Lockheed engineers predicted a "standard day" service ceiling in excess of 48,000 ft! Improvement of the cowling fit and the elimination of the heavy coat of paint would have gained even more performance. Due to the added efficiency of the new propellers, range was expected to increase by 10 to 15 %. Lockheed appeared to have a world-beater on their hands.

The plane, now designated the P-38K-1-LO was flown to Elgin Field for evaluation by the USAAF. Flown against the P-51B and the P-47D, this Lightning proved to be vastly superior to both in every category of measured performance. What astounded the evaluation team was the incredible rate of climb demonstrated by the P-38K. From a standing start on the runway, the aircraft could take off and climb to 20,000 feet in 5 minutes flat! The "K", fully loaded, had an initial rate of climb of 4,800 fpm in Military Power. In War Emergency Power, over 5,000 fpm was predicted.

In light of this incredible level of performance, you would certainly expect that the Government would be falling all over themselves to quickly get the P-38K into production. Yet, this was not the case. The War Production Board was unwilling to allow a short production suspension in order to get new tooling on line for the required change to the engine cowling. Even when Lockheed promised that the stoppage would only be for 2 or 3 weeks, their request was turned down.

The true consequences of this pig-headed thinking will never be known. What would have been the impact of such a high performance fighter arriving in force to the forward combat areas in mid 1943? How many lost fighter pilots would have survived thanks to the awe inspiring performance of the P-38K? Again, we can never know these things. What we do know, is that due to bureaucratic myopia, neither the P-38K nor a Merlin powered Lightning ever really had a chance to make an impact upon the air war. For all those pilots who died at the controls of lesser aircraft, the War Production Board bears a measure of responsibility for their fate.




RESOURCES:
Warren M. Bodie, The Lockheed P-38 Lightning.
Lockheed Martin Archives.

So, the "paddle-blade" prop would have fixed the climb issue with the Merlin, and would have improved altitude performance as well - at the cost of a major redesign of the aircraft, and a significant disruption and delay in production.

As the saying goes: "Perfect is the enemy of good enough".

More "good enough" aircraft NOW and later as well is normally preferable to a "better" aircraft later AND fewer "good enough" aircraft in the interim.

 

[Reluctant Poster]

Here is something I copied down years ago, after this same discussion on another forum.
It discusses both the proposed Merlin version and the single test example fitted with "paddle-blade" props, and the changes required for either (ideally, both at the same time).

It mentions the reason neither was actually done - the changes on the production line would disrupt production flow, which was NOT acceptable to the government. Note that the War Production Board had 100% control of what was produced, by whom, and when - and that many similar improvements to Government-contracted aircraft from many different manufacturers met exactly the same veto unless requested by the US military branch the aircraft were for, or the change could be implement with no appreciable effect on production rates.

Note the sections I have bolded:




So, the "paddle-blade" prop would have fixed the climb issue with the Merlin, and would have improved altitude performance as well - at the cost of a major redesign of the aircraft, and a significant disruption and delay in production.

As the saying goes: "Perfect is the enemy of good enough".

More "good enough" aircraft NOW and later as well is normally preferable to a "better" aircraft later AND fewer "good enough" aircraft in the interim.

I posted this comparison of the P38 J and K from Mike Williams site several years ago. It does not meet the fantastic performance claims of Bodie. Also note that the tests were done by Lockheed and not witnessed by a neutral party
http://www.wwiiaircraftperformance.org/p-38/P-38J_performance_11march44.pdf

 

[drgondog]

The Merlin had the advantages of a compact supercharger installation and exhaust gas thrust. The first of these didn't matter much with the P-38 since the tail booms had plenty of space.

The P-38 was, aside from possibly the P-63, the only first rank plane using the V-1710. Switching the P-38 to the Merlin would have left the Allison production capability underutilized.

Allison was begging Material Command for new orders in fall of 1943 as its Mustang/Allison production forecast disappeared with the advent of the Merlin Mustang production orders in fall 1942. It was projected at 50% capacity for 1944 (which was real).

 

[drgondog]

I posted this comparison of the P38 J and K from Mike Williams site several years ago. It does not meet the fantastic performance claims of Bodie. Also note that the tests were done by Lockheed and not witnessed by a neutral party
http://www.wwiiaircraftperformance.org/p-38/P-38J_performance_11march44.pdf

You are correct. The most glaring anomaly of the P-38K 2/44 test was that it was flown 600 hundred pound lighter than the P-38J comparison. About the same time Col Cass Hough and Col Ben Kingsley proposed pulling 2 P-38H from inventory and converting to Merlin 61 - which was swiftly denied by VIII AF Air Service Command. There would be no competing pull on Merlin 61/65 from Packard - All US future deliveries were to be NAA and the 1650-1 spares contract was almost eliminated to give Packard more capacity for the 1650-7 and future -9 for the P-51H