I was at my daughters swim practice when this just poped in my head, with the Merlin being superior to the Allison at altitude why was it never installed on the P-38 I have never read anything anywhere saying this was done does anyone know different? Yes this is what happens when you have kids you start losing your mind…
The reason being as the production was being used for other types, such as the P-51 the Spitfire and others that I cant recall. Add in the fact that the Lightnings performance was satisfactory with the Allisons and I think you get the picture.
Yes but with the performance gain with the P-51 I would think that you could see similar results in the P-38 and I am surprised that it wasnt at least tryed.
the P-51’s were used for long range escort and needed the added performance at greater altitudes. the lightning was a ground hugger designed for ground attack and close in troop support. i’ve never heard of a P-38 with merlins, but i’m far from an expert in this subject.
The P-38 was designed as an interceptor. It escorted bombers going to Germany, along with the P-47, until (and after) the Mustang went into service. With its Allison engines, it was almost as fast as the P-51and could go about as high. Don’t tell Maj. Dick Bong (40 confirmed kills) that his Lightning was a groundhugger meant for close troop support, although they could be fitted with rockets or bombs (as could the Mustang) for ground attack. As far as I know, the P-38 was never fitted with Merlins.
Well the Allison in a P-38 did have a turbocharger and this more than made up for the two speed two stage supercharger on the Merlin. I remember seeing some chart from WWII graphing out the different performance curves of different models of Merlins v. Allisons. I do distinctly remember the turbocharged Allison on the P-38 being more powerful at higher altitude than the Merlin.
You also have to compare apples to apples here. There were different versions of each engine. For instance most Allisons had a single stage supercharger that in the case of the P-38 was supplemented by a turbocharger. While the P-51 and most Merlins used a two speed two stage supercharger.
However there were single stage Merlins out there too for instance the P-40F had a single stage two speed Merlin producing 1300hp takeoff while the Allison engined P-40K produced at the exact same time made 1325hp takeoff.
Thats the closest comparison between the two I know of. The induction was similar and for takeoff both were making close to the same numbers.
So basically to me its all how they were equipped. It wasnt really the Merlin in its self that was magic, it was its two speed two stage supercharger!
I’ve always heard that the Allison engine’s performance fell off at higher altitudes
–say, above 12 to 15 thousand feet, which is why it was eventually withdrawn from bomber escort duties since this task usually took place at high altitude. The P-38 was such a huge success in North Africa & the Pacific because the nature of the conflict in these theatres dictated that combat took place at lower altitudes. Wouldn’t the fitting of Merlin engines in the Lightning also have meant
that the engine nacelles would have had to be redesigned? Would a Merlin have fit in a P-38? The Lightning was a pretty complex design as it was–maybe
it was thought that it wasn’t worth the trouble to mess with an airplane that already worked perfectly well. Good question though. I’ve wondered about that
before.
Alot of it also had to do with the turbochargers being less effective in the cold air in the skies over Europe. The engines and turbos worked well in the warmer and more dense air at lower altitudes in the warmer climates.
For the P-38’s they where with drawn from 8th AF because the pilots wanted the P-51, Lucky Chucky Lindberg shown the pilots in the Pacific how to double the range and stricking distance of the 38 by leaning out the engines this put the P-38 at GREATER Range then the P-51’s, but like I said the European USAAF’s pilot wanted the Mustang because it was a little bit more maneuverable and smaller then the 38 but the 38 had great capabilities at altitude as with the 51’s but like all pilots they want the newest toys offered
i am no P-38 expert, but i thought that there were models used for recon and photo missions.
i would expect that such missions would have been flown at high altitudes.
did these variants use other engines or variants of the Allison, or is the belief of
poor high altitude performance mistaken?
A standard Allison of the time did have a huge performance drop off at higher altitudes, but the P-38 had a turbo feeding the Allison in addition to its own single stage supercharger. That is just about the exact same induction arrangement that most of the US heavy bombers employed. The B-17, B-24 and B-29 all had turbos feeding the engine mounted single stage supercharger. The B-29 and B-32 had two turbos feeding their single stage engine mounted superchargers.
Im sure that a Merlin could have been fitted to the P-38, after all the P-51 was originally an Allison powered aircraft. I would say that the reason not to change to the Merlin was that everything was in full swing and was performing well so why fix what isnt broke!
I seriously dont believe though that cold air at higher altitudes was the main reason they werent used in Europe as the P-47, B-17 and B-24 operated at those altitudes and the turbos functioned just as they should. One thing to look at however is the location of the P-38’s turbos. Theyre on top of the boom, exposed to rain and everything else, plus the fact that England doesnt have the nicest weather around. Personally I believe the explanation 72Cuda gives… the P-51 was the new hot ship.
The photo version of the P-38 was the F4 or F5, you can read about them here http://www.p-38online.com/recon.html or here: http://home.att.net/~jbaugher1/p38_11.html These were equipped with the same engines that any other P-38 of the same model type had. For instance the F-5 was the photo version of the P-38G, both used Allison V-1710-51/55.
Ill say again however that it was the two speed two stage supercharger that really made the Merlin perform! There were later versions of the Allison equipped with two speed two stage superchargers that made 1700hp at altitude, these were used in later versions of the P-82 Twin Mustang as well as the XP-51J . In contrast the Merlins with a two speed two stage supercharger used in the P-51B/C produced 1450hp and the P-51D made 1695hp at altitude.
Also the 38’s Allison engines have more cubic inches then the Merlin ( V-1710 to the V-1600 ) and the Allison engines where a little bit heavier too, but the early Merlins had big problems when they where carburated they stalled out when the planes where pulling out of a dive while being in a dog fight, and the Damiler Benz engines where pressure injected, the Allisons really didn’t have this problem but the 38’s suffered compressability problems from going to fast ( around 750 mph ) in the dives and the controls locked up and couldn’t recover, like the 47’s, as said before the P-38 was designed to be a High Speed/High Altitude Intercepter, which she was designed with the turbosuperchargers for high altitude in mind, and twin engines to give it speed, she was the fastest plane in the world right at 425 mph when she first came out, but enough about the 38 but think of the power of 2 engines compaired to 1, you have 1600 + BHP per engine x 2, compaired to 1650 + per engine x 1, so you have 3200 + BHP on an airplane compaired to 1650 BHP airplane, if you take a plane at maximum alititude for the throttle at flight cruise and push the stick ( or Yoke ) back and the plane will just pitch up and stall out, but if you push the throttle in and leave the stick ( or Yoke ) alone you’ll gain altitude because of the thrust of the props and power increase of the engine (s) will take you higher until the air & thrust will equilize out and this is you maximum altitude for that engine power setting, now you have a lighter plane with a more powerful engine the the speed & altitude will increase, so the Merlin engine mated with the P-51 had a high power to low weight ratio, the P-38 had a high power to low/Medium weight ratio this is the difference between the 2 fighters and most European pilots wanted to have a very fast plane with range and they refused to beleave in Lindberg’s theories of leaning out the fuel mixtures and wanted a newer fighter, the Jug would have the same range as the 51’s too if the pilots just leaned out the engines, if you look at the P-47N series they where long range fighters too and besides having more fuel carried but the engines where tuned for more leaner mixtures to gain more range, also the Jug’s performed very good at high altitudes and went very fast ( 750 + mph and broke the sound barrier ) in dives but you never hear the 51’s ever doing this, the P-38’s also did this too and after the compressability problems where solved the 38’s did this almost all the time when in dog fights and if you talked to a fighter pilots from the European theater who flew P-38’s & P-47’s will say if you want to pick up a girl tell her you fly the P-51 but if you want to fight & live you’ll fly the 38 or 47, more 38 & 47’s flew back home shot up then P-51’s did, also a P-38E played Chicken ( and Rammed it )with a BF-109 and won if a 51 did the same both pilots would be flying with their own wings but with no planes though
On top of all this there may have also been something to do with supply and demand: High demand but not as great a supply. Also, with the Merlins being built under contract from Rolls Royce I think there may have been something to do with the cost of the licensing. It may have been a wee bit on the expensive side to crank out all those Merlins while the Allisons may have provided satisfactory service at a lower cost to produce.
Eric
Well Rolls did license Packard Auto works to produce the Merlin in the US so the P-51’s didn’t have to wait for shipping from England for the engines and they also knew that the US War Production will out produce them within a few weeks and the US had unlimited supply of resorces to produce the engines too so supply & demand really didn’t have a thing with the usage of the engines but the Brit’s rather work on their own equipment inwhich they where trained on for their planes & things, the P-51 was supposed to have the Allison engines but when the Brit’s didn’t like the performance of the 51 they tried the Merlin in it and this made the plane become what it’s now today, and the Allisons where coming along but until the Merlin woke everyone up in the A/C engine industry then Allison started new experiments with their engines and after the was when the F-82’s where out they flew with the Allisons which had more power & more fuel effecient then the Merlins will ever be, and grant it the Merlins also had teething problems when they where carburated and needed 100% glycol coolant they where out classed by the Damiler Benz engines
Mach 1 in a prop fighter? I thought Chuck Yeager broke the sound barrier? I am looking at an article right now concerning the P-47 holding the record for maximum recorded speed in a dive from 30,000 ft. 545 mph indicated airspeed. Test was performed at Wright Patterson in 1945. This event is documented at the Dayton AF Museum .Even the jug would suffer from compressibilty in a dive @750mph, I would think that even in low altitude dense air that the elevators would be completely frozen at this speed, it would take super human strength to pull out of this dive. The test pilot in the real test started his pull out at 6000 ft, when he leveled out…altitude was 400 ft.!
Some P-38s did report over 700mph dive speeds but the pitot tube was undergoing compression just like the rest of the airframe. It was later found that these readings were wrong and that even though they registered over 700 mph their true speed was in the mid 500 range.
Herb Fisher was the test pilot of the P-47 that performed all the high speed dives that crockett is referring to. He wasnt trying to make the P-47 go supersonic. However he WAS testing experimental Curtiss Supersonic propellers.
Okay gentlemen, here’s the definitive answer to the Merlin powered Lightning. I found this by accident while hunting down lost series designators. The beast is called the P-38K
http://home.att.net/~C.C.Jordan/P-38K.html
Hope this settles the dust.
if everyone remembers that most pilots who incountered the compressability problem never recovered except upon impact with the ground, but from the pilots who incountered this problem where calling for help on how to get out of the death dives, and Kelly Johnson finially figured how to get the problem solved before more pilots where killed,
There is an awsome book out there called P-38 Lightning the Forked Tail Devil or Two Planes With One Pilot it goes over the P-38 from Idea to Retirement of Service, and this book has a few stories of the Compressability Problems on the P-38’s and talked about the same with the P-47’s, and Chuck Yeager broke the Sound Barrier while flying level flight not in a high speed dive and made it home for dinner but the others never made it in level flight only in dives and with compressability on the pitot tubes the air going into the tube will be going slower then the outside air, kind of like blowing accross the top of a soda bottle,
Personally Im not buying it. All I have ever read and heard has always supported that P-38 pilots would report such speeds but that the actual speed was much lower.
Heres an excerpt from the Baugher site:
"When earlier J-series Lightnings went into a high speed dive, their controls would suddenly lock up when a certain speed was reached and the nose would begin to tuck under, making recovery from the dive very difficult. The problem would begin at Mach 0.65 to 0.68, accompanied by vigorous buffeting and a strong nose-down pitch. As speed increased, it became progressively more and more difficult to recover from the dive, larger and larger stick forces being required for a pullout. At Mach 0.72, dive recovery became for all practical purposes impossible, and runaway dives that got this far out of hand usually had fatal results. The onset of severe buffeting would, of course, usually provide adequate warning for a pilot in a diving P-38 that he was about to encounter a problem, but it is easy to get distracted while in the stress of combat. This dive recovery problem was so severe that the Lightnings found it very difficult to follow German fighters in a dive, allowing many Luftwaffe fighters to escape unscathed.
The problem was eventually traced to a shock wave that formed over the wings as the Lightning entered the transonic regime, the shock wave preventing the elevators from operating. In order to counteract this problem, starting with the P-38J-25-LO (Model 422-81-23) production block, a small electrically-operated dive flap was added underneath each wing outboard of the engine nacelles and hinged to the main spar. These dive flaps would change the characteristics of the airflow over the wing, offsetting the formation of the shock wave and permitting the elevators to operate properly. This innovation largely solved the problems encountered by diving P-38s.
The P-38J-25-LO production block also introduced power-boosted ailerons. These consisted of ailerons that were operated by a hydraulically-actuated bell-crank and push-pull rod, making it easier for the pilot to maneuver the airplane at high airspeeds. This boosting system was one of the first applications of powered controls to any fighter, and required only 17 percent of the previous stick forces. The hydraulic aileron booster system vastly improved the roll rate and thereby increased the effectiveness of the P-38 in combat. P-38Js with power-boosted ailerons proved to have the highest roll-rates of any fighter.
210 P-38J-25-LOs were built.
In March of 1944, Colonel Benjamin Kelsey reached an indicated speed of more than 750 mph during a high-speed dive in a P-38, which would have made the P-38 the first supersonic fighter. However, it was later discovered that compressibility effects on the airspeed indicator at about 550 mph had given a greatly exaggerated reading. Nevertheless, the Lightning handled quite well at high speeds, and its strong airframe withstood the excessive aerodynamic loading produced by these high-speed dives. "
Heres the direct link: http://home.att.net/~jbaugher1/p38_13.html
Heres another excerpt from an article about test pilot Herb Fisher:
“Despite having a propeller that was designed to be more efficient at these speeds, the fact remained that the drag rise across the prop was so great that it functioned like a giant disk shaped air brake. Fisher had proved beyond any doubt that all previous claims of exceeding the speed of sound while diving a prop driven aircraft were untrue. There is little doubt that the pilots who reported speeds in excess of Mach 1 were honestly and accurately reporting what they has seen on their air speed indicator. However, due to the extreme rate of descent, the pressure differential in the static pressure airspeed indicator lags far behind the actual altitude of the aircraft. Air speed indicators of the era were not designed to cope with descents that could exceed 40,000 feet per minute. This difference between outside pressure and that within the system would indicate wildly ambitious speeds. These pilots had simply been fooled. When we stop and consider that the ultra-sleek P-80A Shooting Star jet fighter was never able to exceed Mach .94, how can anyone believe that a prop driven fighter could even come close?”
And the direct link: http://home.att.net/~historyzone/Fisher.html
Dave B. - I’m with you buddy,all the way. Back to the subject, the mix of American and British technology to create the merlin/mustang miracle is one of those rare instances where engineering and art combine to create a machine of incredible beauty and lethality. I believe Kelly Johnson designed the Lightning with the Allisons in mind from conception. The Allison concept was sound, just not fully developed for high altitude performance at the beginning of the war. The P38J was the definitive revision of the design. A vision of a '38 with Merlins and four bladed props is exciting to say the least.