P-38 with Roll-Royce Merlins

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wuzak said:
" 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. "

Would that have caused a compressibility problem?
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Don't believe so. It's more of a cost problem. You can get 2 Mustangs for the same price and they fly farther. What benefit do you get out of changing the production lines? Losing production!
 
Interesting - I thought I had some traction with Ms LeVier in doing his bio in 2005-2006 timeframe, had arranged a trip to meet with her but was apparently shut down by her new male companion/husband?

I once engaged in correspondence with Bodie during research on a project I never finished due to lack of reliable data and reports. At one time (1990timeframe) I envisioned a Performance comparison between the F4U-1, P-51B-1, P-47D-16 and P-38J-10/-15 for escort requirements in ETO. At that time I was seeking complete Drag build ups for each airframe - but only the NAA data was complete enough. Bodie never responded to the request and my attempts to get the source data from Lockheed were never successful.

Candidly, I doubt that any reports/data on the other airframes outside the 1943-1946 NACA Drag studies for full scale tests will ever be available and consolidated.

I respect Bodie, but his perspectives and apologies for the failures of the ETO P-38 (results to expectations) tainted an objective perspective that he could never quite overcome. Additionally, he took Kelsey's narratives to him (WRT Mustang sponsorship) at face value and never presented Kelsey animosity toward NAA as a fighter design contender in the 1938 through 1941 timeframe - or his lukewarm support for the Mustang (post XP-51 flight test at Wright) in Jan -1942. I attribute Kelsey attitude in that timeframe to his subordinate relationship to Echols - who undisputedly opposed NAA/Mustang entry into AAF inventory, then opposed Merlin allocation priority until over ridden by various folks in Plans and ultimately by Arnold himself in fall 1942 and again in summer 1943. By that time Kelsey had escaped from Material Command to Operations and may have changed his opinions at that time.

If you read this narrative from Wikipedia you need to need to hold your nose - If Kelsey had any finger on 'ordering Mustangs while Chief, Pursuit at Material Command, it was because his boss (Echols) was crushed into submission by General Muir Fairchild Chief Requirements - Plan Division AAF HQ in March 1942 to force Echols (and Mat'l Div) to place the order for the A-36. The '150 Mustang' order referenced by Wiki for 1941 was by the BPC for the Mustang IA. After the A-36 was rammed down Echols throat, he attempted to limit the A-36/(and P-51A discussions) to a max of 500 the force NAA to kill the Mustang line and convert to B-25s.

Kelsey was more influential while assigned to IX AF - but he had no direct oversight to the IX AF Engineering office until November 1944 and certainly not 'leading' design improvement recommendations for the Mustang. Enough - we should all value his service. Echols? not so much - he was a vindictive autocrat while leading Material Div until everyone in ETO noticed that insufficient testing (responsibility of MD) was leading to long delays in mod centers to ready the P-47C/D for combat and Flight testing was yanked from MD and replaced by Eglin Field group. Echols continued to champion the XP-75 turkey even after detailed criticism by Bradley proved it would never work in combat.

Benjamin S. Kelsey - Wikipedia
 
By the way, relative to Mr. Bodie's remarks on the dispersion problems with fuel in the Allison manifolds, that seems to be a problem mainly limited to the J and L models. The liquid cooled intercooler/aftercooler used on the Merlin 60 series had the immense advantage of having easy temperature regulation via a simple thermostat as used in automobiles. The air cooled chin intercooler used on the P-38J and L had no temperature regulation at all, and at high altitudes the fuel condensed into a liquid , with disastrous consequences. At the 9th Photo Recon in India they solved this problem by blocking off part the exit area of the intercooler cooling air flow with aluminum blocks. The photo recon mission focused on long range high altitude flights and not much in the way of jockying around with the throttle, so they could figure out the right amount of airflow and just set it that way. At least some J and L models were equipped with cowl flaps to enable the pilot to make adjustments - as if the P-38 pilots did not have enough buttons, knobs, and switches to fiddle with.

As for the "British fuels were a problem" my friend Ward Duncan said they used fuels from the same sources in India and had no problems relative to that. Not all fuels used in England were made there.

Finally Warren Bodie mentions problems with Champion spark plugs. Not long ago I was surprised to find out that the V-1650 in the Mustangs required special spark plugs, something they found out the hard way. One pilot even described having his engine quit while on an early mission over France because the standard spark plugs failed.
 
wuzak said:
" 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. "

Would that have caused a compressibility problem?
Click to expand...

The Only flight test comparison between the single K (differing from J with different prop and gearing) was with the K at 600 pounds under combat load and J at combat load. It was slightly faster at 25K but both in the 420-425 TAS range. No results posted for higher altitudes and no reason to suspect any significant difference w/same engine/turbo just to the prop/gear ratio change.

The only time a 440mph posting for the late model J/L was made was from Lockheed marketing. Flight test results are missing .

At 30K 440mph = 0.65M well into compressibility and high total Drag rise for the P-38. With 1475 BHP in fully functional cooling/turbo system it might have been possible - but not with the K as described in the 2/44 flight test.
 
So, pardon my ignorance, but what ever happened to Echols? I hope he ate a metric sh!t ton of crow after the Mustang got it's glorious career off the ground so to speak.

*EDIT* Just read Echols' bio on wikipedia, I see what you mean, couldn't get through all of it and no mention of his attempts to kill of the Mustang I see.
 
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Do you have, or have you seen, the "2/44" flight test?

I was looking to see what the P-38J could do at 40,000ft, and it appears to be around 300mph TAS. If the P-38K was 40mph faster at 40,000ft that would put it at around 340mph TAS. Was wondering if that would be in the compressibility range?

It is also interesting to note that The P-38K was supposed to outperform existing types, but the Spitfire XIV and P-47D could both do about 400mph at 40,000ft. Maybe the P-51B could have too?

Regarding the change of gearing, wasn't that due to a larger propeller, not just a broader chord "high activity" unit? I would think that the "high activity" wouldn't require a change of gear ratio.

Looking quickly through Graham White, R-2800, Pratt & Whitney's Dependable Masterpiece, it would appear that all P-47Ds used the same reduction ratio on their R-2800s - before and after the "high activity" broad chord props were introduced.
 
The profile is somewhat contradictory on the P-38K. It says the prototype K was a modified E and had -89 and -91 engines. But it also says that the K was not much of an improvement over the J and was not produced due to the scarcity of its -75 and -77 engines.

According to "Vees for Victory" the -75 and -77 engines had a 2.36:1 gear ratio between the prop and the crankshaft and had a Military Rating of 1425 hp at 3300 rpm at 54 in HG at 27,000 ft. Only 6 of -77 and 19 of - 75 were built

The -89 and -91 engines had the usual 2:00:1 gear ratio between the prop and the crankshaft and had a Military Rating of 1425 HP at 3000 RPM at an altitude of 24,500 ft.

It seems that the -75 and -77 drove a prop that had wider blades at lower RPM. Now, would interfere with diving ability?



 
"Information in the author's hands indicates that the engine thrust line was one inch higher than the J"

That doesn't make sense to me. That means that Allison not only changed the gear ratio, they changed the reduction gear housing as well.
 
It was the change in the thrust line that supposedly put the cat among the pigeons.

The gear teeth have to be certain size to handle the load and apparently they couldn't get the reduction ratio they wanted with a small pinion gear (or smaller than the standard gear/s) and a larger driven gear.
The K is supposed to have used larger diameter propellers and they wanted the reduction gear to keep the tip speed down.
The Late P-39s used a 2.33 reduction gear and the P-63s used a 2.227 reduction gear.
 
Yep! Recall that when they designed the C series engines they deliberately made the nose long to keep the shape sleek, on the P-40, B and C.. The higher power of the F series resulted in a new gearbox and a raised thrust line required as a result. Slowing the prop so to make it larger, broader, and more efficient raised the thrust line more.
 

Echols was 'promoted' to Chief Military Affairs and Asst Military Governor in Germany in 1945 and left AAF in 1946(?) to become President of AIA until he became President of Northrup.. possibly the first example of trading positions in the 'military industrial complex'. That said, my personal bone to pick with Echols was that he had a vindictive streak that clouded his otherwise excellent judgment. As I read between the lines in various autobiographies of Arnold and Spaatz, Arnold had a 'conversation' with Echols during the in-fighting between Material and Plans Division over the A-36 and P-51A in the spring 1942 - leading to capitulation on the Allison Mustang. He personally visited R-R during the tail end of development for the Mustang X along with a highly respected US Aerodynamicist (can't remember his name) to examine the Mustang Drag and Performance projections with the Merlin. By that time Arnold was 'involved' and issued orders that the P-51B be assigned very high priority.

His contributions to the War Production Board system of priorities and allocations were major - and eventually paid dividends to NAA when he personally approved the expansion of NAA production capacity and specialized tooling embedded in the NA-99 and NA-102 contracts as well as prioritizing tooling and Packard 1650-3/-7 production for the P-51B.
 
Paul Kennedy's book, "Engineers of Victory" has a short section on the Merlin Mustang. I found it disappointing in that it did not mention Stanley Hooker's remarkable innovation of the two stage supercharger coupled with liquid cooled intercooler/aftercooler. I guess the book is "Engineers of Victory" rather than "Engineering That Brought Victory" in that it focuses more on the people than the actual technology. But his summary of the fight to get the Merlin Mustang built is pretty good.

He does repeat that old falsehood that the Allison Mustang was designed for low altitude, which was only true of the A-36. The Mustang MK1 had its best speed at around 15,000 ft and the P-51A at about 20,000 ft.

 
It is a nice story but some of the details don't hang together very well.

The Schweinfurt-Regensburg raid in October of 1943 (?) was not really a turning point in the P-51 story. Some sources claiming that 400 P-51Bs were ordered Aug 26th 1942 and this order was had 1350 more aircraft added at a later date.
NAA Dallas receives and order for 1350 P-51Cs on Oct 8th 1942 (perhaps the extra 1350 aircraft mentioned above?)
Jan 1943 sees the US order over 2000 P-51Bs (or that is number on order?) in any case outstanding P-51A orders are to be completed as P_51Bs as of the Jan date. The June 1942 order for 1200 P-51As sees only 310 completed as P-51As and the rest are completed as P-51Bs.

To show how far ahead planing was compared to deliveries (or demands from combat theaters) On Feb 27th 1942 the 201st and 202nd P-51B-10s (months away from being actually built) are set aside as manufacturing prototypes for the P-51D model ( this over two months before the first production P-51B is delivered)

NAA gets a contract for 2500 P-51Ds on April 13th 1943, about 3 weeks before the first production P-51B flies, And this first production P-51B flew 2 days after another order for 2500 planes was placed with NAA Dallas (or modified an earlier order?) to comprise 400, P-51Cs, 800 P-51Ds and 1300 P-51Ks. Again months before even the Aug 1943 Schweinfurt-Regensburg raid let alone the October one.


The time it took for American aircraft to get from the factory door to combat seems to confuse many authors, The LAST A-36 left the factory in March of 1943, the FIRST combat mission by an A-36 was on June 6th 1943 for example. There was little or no "feedback loop" from combat reports to guide new versions of the Mustang. The XP-51D flying for the first time on Nov 17th 1943 which was several weeks before the first combat mission flown by P-51Bs in Europe. Any story that claims combat performance of the various P-51 versions influenced the design or equipment of later versions (except for the H? and the contract for the light weight P-51 program--XP-51F, G and J was signed July 20th 1943) should be viewed with at least some scepticism.

As for Packard and the Merlin story, most sources agree that the initial contract was for 9000 engines and the British were to get 2/3rds. production was to reach 800 a month. Follow up contract details seem to be a bit thin. After struggling for a bit in early 1942 Packard ends up putting out the required 800 engines a month for five straight months in the 2nd half of 1942. Packard does deliver 850 Merlins in Dec of 1942 and 850 and 864 in Jan and Feb of 1943 respectively. Total production then drops for several months (result of tooling up for the two stage engine?). In any case Packard is producing over 1800 engines a month by the end of 1943 and peaks at 2.239 engines in June of 1944. (1114 of them are single stage engines for the British). Now in order to achieve such numbers Packard either needed divine intervention (on the order of immaculate conception) OR it needed the war production board to OK and release materials for plant expansion (concrete and structural steel) it needed more machine tools (always in tight supply) and it needed both additional labor and raw materials. You don't make 1800 crankshafts from 900 forged billets and steel supplies were controlled by the production board.
 
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I think you need to check some of those dates (years) and re edit. Otherwise, good.
 

With respect to that book, it might be useful to know from a veracity perspective what those references in the text "point" to (#43>#51), are they primary sources, (e.g. papers from Rolls-Royce, or Freemans letters) or are they just referencing other peoples books ? - not that there appears to be any actual gross errors, but it would be interesting to know hows its been referenced.
 
This is a very good article that misses only on a few key points:

The spring of 1942 was momentous for the P-51:
The Army Close Air Support acolytes were the internal 'force', coupled with Plans Division, to drive the acquisition of the Low Altitude Pursuit (A-36) which had been under design development since Nov 1941. In parallel, Eaker, then Arnold and Spaatz visited NAA and came away impressed with the P-51 and reports from 'the field' from fighter pilots of the 20th Wing that "the Mustang was a better airplane than the P-39/40/38" as well as Kelsey flying and respecting the airplane in Jan 1942. Arnold was under pressure from 'Lovett" to create a close air support capability to rival the Luftwaffe late in 1940.

The major attributes (save the internal fuel fuselage tank) were introduced by the A-36 ---- Wing racks, internal plumbing for external fuel tanks.

General Schlatter who had Air Defense Directorate was also THE decision maker for ALLOCATIONS and assignment of US based fighters. Close friend of Echols and a P-38 bigot. Echols had a very strong 'relationship' with Burdette Wright and gave Curtiss every chance to become next generation Pursuit (XP-46 and XP-60) when the Mustang emerged from NAA. Echols' push on NAA to build P-40s was to unlock Curtiss manufacturing for the P-46. The single biggest factor of Echols' animosity toward NAA was that Kindelberger defied him. All that said, the Mustang CAS survived via the A-36 and The P-51A was the next gen CAS fighter - which a.) stripped dive bombing requirements, and b.) stipulated that the P-51A contract could be converted to P-51B Merlin powered. One of the key doctrines of CAS in 1942 was that the "pursuit" so allocated also be cable of air superiority over the battlefield (hence, exit A-24/25 and 32). THIS is how the P-51B was planned for IX AF/Invasion and 12th AF MTO campaigns to replace P-39 and P-40. Remember the 354th and 363rd and 357th were training in P-39s in 1943 destined for IX AF. The XP-51B design went full throttle in May 1943 and prevented from flying first due to reliability struggles with the 1650-3 in summer through Fall 1942.

Arnold takes personal responsibility for not getting the P-51B into operations much sooner, but a.) he did meet with Freeman, Winant and Hitchcock in London in May 1942 to discuss the Merlin Mustang - acknowledging that they didn't seem fully knowledgeable about the project. Hitchcock was key in the fall of 1942 to break through to Arnold the necessity of bringing the Mustang in production - BUT there is evidence in correspondence at Material Command that 'the boss wanted the Mustang) in July 1942. This was critical as the Merlin 61/1650-3 was allocated to NAA for NA-101 project in July 1942. IMO Arnold's only true relationship with the delay of the P-51B was not realizing that Schlatter had dedicated all Mustangs to CAS roles (MTO, ETO, CBI) which he had to fix in fall of 1943.

The drag attributes of design with second and third order curves gave the best possible lowest change to velocity gradient for the fuselage, the NACA 45-100 gave the Mustang the same drag attributes of the Spit despite a much fatter wing giving the P-51 greater internal space for fuel and armament, but the cooling system design enabled high speed Hp recovery over Spit and Hurricane schemes.

The disastrous Blitz Week late July 1943 was a key factor in that it drove Arnold to over ride Schlatter for the assignment of Mustangs as 'ground support. Concurrent with Blitz Week, NAA had already been pushed by Barney Giles (as well as Lockheed and Republic) to increase internal fuel - and flew the first 'prototype 90 gallon SS fuse tank' in July - well in advance of the P-38J and P-47D-25. Arnold's former boss Genneral Delos Emmons and Asst War Lovett were doing an inspection tour of 8th and 9th and, along with Eaker put out the plea for the P-51B and P-38. Arnold complied and beginning Aug 1942 all new P-38 groups activated were assigned to 8th AF. The battle for re-assignment of the P-51B was intense between Spaatz and Leigh-Mallory and finally resolved by temporary subordination of 354/357 and 363 to operate with 8th AF (during November through January timeframe) until late May - to then transfer back to 2TAC control. By all accounts (Doolittle, Spaatz, Arnold), dealing with Leigh-Mallory was a nightmare.
 
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drgondog said:
By all accounts (Doolittle, Spaatz, Arnold), dealing with Leigh-Mallory was a nightmare.
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That was also the opinion of German intelligence.... who`s dossier on British air staff includes a paragraph on him. It doesnt say anything very nice,
annoyingly I cant find the document right now on my PC to give you a quote... but most of the information in their Dossier came from interrogations of downed british airmen - so its contents are proably a pretty good reflection of general pilot sentiment.

(I would point out that the same document heaps praise on Keith Park.... so its not as if all the downed pilots were just taking the chance to spout off about "management")
 
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