P-38 engine question

[John Beyl]

Thanks SparrowV12. That was going to be another question! Hears another. Why didn't they put two Merlins int a P-38?

Rgds Cking

Cking,

I'm pretty sure Merlin powered Lightnings were experimented with. As I recall it was decided that the P-38 would get the Allison because it was felt that Packards production volume of the V-1650 would not be able to keep up with demand supporting both the P-51 and the P-38. Adding the turbo to the Allisons on the P-38 gave it enough boost to make sufficient power at altitude. Later on Allison engineers designed and built an "auxiliary" second stage blower that was added to the V-1710 and was installed in the P-63 and later I believe the P-82. It's worth noting that the last versions of the V-1710 were powerhouses and developed as much if not more HP than the best Merlin produced.

John

[retroaviation]

Weren't the Allisons that powered the F-82's rated at 2,200 hp? Could be wrong, but for some reason that sticks in my head.

[John Beyl]

Weren't the Allisons that powered the F-82's rated at 2,200 hp? Could be wrong, but for some reason that sticks in my head.

Right you are Gary! It had the odd ball aux blower I mentioned earlier. It made the power but was a big, ungainly package. It almost reminds me of a Griffon 59 with that dumb aux accessory block powered by a drive shaft off the end of the engine.

See...the hot water 12's were capable of making respectable power...and they didn't poop oil all over the ramp and hangar in the process!

Sorry man! I love the big roundies too...just pimpin' ya!

John

[SparrowV12]

The Allisons that were used in the P-82's were the G6 Allisons or the V-1710-143 & 145. They were rated @ 3200 & 100".

Hot water???? That's better than those oil slingin' fire bleching backfiring leaky round things!!!! (That oughta start something!!) Can't help it--you know us inline guys! I've been to the dark side too, worked on an awful lot of radials, even overhauled them for awhile.

Sparrow

[v1710]

One thing more to do to change the direction of rotation is to change the starter. As to Merlins, they were talked about, but as far as I can find out, none were ever tried in a P-38. As already stated, there just weren't enough Merlins to satisfy the demands. Another reason for this is that the Allison was more fuel efficient and in the South Pacific with the long missions, this was very important. Also, the Allison with the turbo chargers were capable of flying at higher altitudes than the merlins. Once the problems with the early turbo chargers were solved, the Allisons proved to be very reliable engines.

[ehokuf]

If any one is more interested in this subject they definately need to get a copy of Daniel D. Whitney's "Vee's for Victory The story of the Allison V-1710" (ISBN 0-7643-0561-1). This book has everything any one could ever want to know on the Allison engine all rolled into one package. There is entire chapter on comparing the V-1710 to V-1650 in different airframes. In this chapter he gives the numbers of the Merlin installed in the P-38 airframe, as I recall this setup had Ham Std. props.
According to Whitney the V-1650-19/21 powered Lightning compared to the V-1710-89/91 had the exact same numbers at 20,000 and 25,000 ft except the 1650 burned 85 gph and the 1710 burned 64 gph this was 25,000ft 272mph. Doesn't seem like a good idea to stop production to install an engine that burns more fuel and isn't available just because it was succesful in another airframe (my opinion).

Anyways everyone interested in any engine that burns gas should have a copy of this book![/i]

[Cking]

Very interesting!
I agree Warhawks1. If it wasn't going to improve the P-38 why change it? I've got just one more P-38/V1710 question, then I think we'have beaten the subject to death!!
Who made the Turbochargers for the P-38? Was it Allison, Lockheed or somebody else?

Thanks in advance Cking

P.S. I've got a few questions about the Allison instalation in the P-63, but I think I'll let the dust settle first!!

[ehokuf]

General Electric made the turbos. Pretty much the same turbo that was in the B-17, P-47, and others.

[phil65]

Because of G.E. work with turbos is why they got the Whittle jet engine and not Pratt or someone else.

[henry]

am i right in assuming then that allison engines don't use an offset pin in the pistons? (as if they did you would have to turn them 180deg to keep the offset right.) or when someone says "turn the crank end to end" do they mean the whole crank/rod/piston assembly?
thanks.
henry.

[Bill Greenwood]

I would be pretty skeptical about someone pushing the Allison as superior to the Merlin, although I have not read that book. That idea is not borne out by facts in actual use, either in wartime or postwar. If the Allison was so superior in fuel consumption, why did the postwar airliners use Merlins, the "transport engine". If the last Allisons were superior in power, why did the Mustang not switch back to them for the H, and why doesn't this super Allison dominate at RENO post war. In unlimited hydroplane racing where was this super Allison? Recently a P-51A was raced, went pretty fast, looked cool, but was still 50 mph slower than a Merlin 51D. Please read my post under the recent P-63 forum on Allison testing. I suspect the use of Allison in 38 s is probably due to GM being able to produce a lot of them. However there is probably a nationalists or competive factor also since GM could have made Merlins instead.

[John Beyl]

I would be pretty skeptical about someone pushing the Allison as superior to the Merlin, although I have not read that book. That idea is not borne out by facts in actual use, either in wartime or postwar. If the Allison was so superior in fuel consumption, why did the postwar airliners use Merlins, the "transport engine". If the last Allisons were superior in power, why did the Mustang not switch back to them for the H, and why doesn't this super Allison dominate at RENO post war. In unlimited hydroplane racing where was this super Allison? Recently a P-51A was raced, went pretty fast, looked cool, but was still 50 mph slower than a Merlin 51D. Please read my post under the recent P-63 forum on Allison testing. I suspect the use of Allison in 38 s is probably due to GM being able to produce a lot of them. However there is probably a nationalists or competive factor also since GM could have made Merlins instead.

Hi Bill,

I can’t help your skepticism but maybe I can address some of your other questions or comments. I’ve worked on Merlin’s and like it….don’t love it but I like it. I know you’re a Merlin fanatic and I’m not trying to pee in your Cheerios but in my opinion it is not the best mouse trap out there.

If the Allison was so superior in fuel consumption, why did the postwar airliners use Merlins, the "transport engine"?

That I am aware of, none of the hot water 12’s, including the Merlin, enjoyed a long post war civil career since they were not well suited to the job. There big down fall was ease of maintenance (Or lack of it) a cooling system which added complexity and shorter TBO’s than round motors (Airlines are in business to make money, not hemorrhage it like governments can afford to with their military fleets).

If the last Allison’s were superior in power, why did the Mustang not switch back to them for the H, and why doesn't this super Allison dominate at RENO post war. In unlimited hydroplane racing where was this super Allison?

Simple: Size does, after all, matter! The later Allison’s that were able to put out the high horsepower figures had the auxiliary blower I mentioned earlier and it was a larger and more ungainly package than the Merlin. It would not have fit in the Mustang airframe without significant modification that would likely have destroyed the airframes superior characteristics for a long range escort fighter. The P-82 offered that additional space and had the aux blower set up installed in it. As far as Reno racing and unlimited hydro’s are concerned, same thing goes size, space and weight are paramount considerations. The larger Allison package are not be suitable.

Recently a P-51A was raced, went pretty fast, looked cool, but was still 50 mph slower than a Merlin 51D.

Before you dismiss that lil’ Allison powered “A” model, how hard was it being pushed? How modified was it compared to the Merlin’s and oil slingers it was competing against. Let’s be fair. Let’s compare apples to apples.

Please read my post under the recent P-63 forum on Allison testing. I suspect the use of Allison in 38 s is probably due to GM being able to produce a lot of them.

Without question GM was capable of a lot of production capacity and if need be, it is possible it could have increased output of the Allison. Keep in mind they were already producing other engines and airframes. I suspect the Allison was used in the P-38 because Packard could not produce enough 1650-7’s and later -9’s to keep up with airframe and spare requirements. With the additional space in the P-38 and the new GE turbo’s that were available the 1710 was very capable of getting the job done. It’s record proves that point. Why a better integral blower was not designed for the Allison is a mystery to me. Perhaps it was in the works and never made it into production. Historians on the type please chime in.

However there is probably a nationalists or competive factor also since GM could have made Merlins instead.

History buffs willing to dig deep into Roll Royce history might find out some interesting facts surrounding this. What I’ve read and been told is that Rolls was not crazy about sharing the Merlin design with outside sources and in fact was downright reluctant to do so. In the end they were forced to out of their own inability to manufacture enough of the engines to sustain the need. Packard was building them under LICENSCE from Rolls Royce and outside of them, there may have been agreements prohibiting other companies from building the Merlin. Many companies contributed to Merlin production in the US, including Buick and Maytag to name a couple.

The ultimate Allied V-12 would have been to join the Merlin’s blower and intake system to the Allison’s power section.

John

[John Beyl]

am i right in assuming then that allison engines don't use an offset pin in the pistons? (as if they did you would have to turn them 180deg to keep the offset right.) or when someone says "turn the crank end to end" do they mean the whole crank/rod/piston assembly?
thanks.
henry.

Henry,

My recollection is that is was a symetrical piston but I'm not 100% sure. I would have to do a little research on that point to be sure.

John

[Bill Greenwood]

John, You may more time working on these engines, than I have flying them, but I've got to doubt your sanity a little bit; anyone that willingly spends the Winter in Minn.! Seriously, what I meant about nationalism is that America and Lockheed may have wanted to use US engines if possible. I would not be surprised if Rolls was reluctant to share their hard earned technology with the colonies. They were a private for- profit company after all. There is an interesting book "Not Much Of An Engineer" by Stanley Hooker who was hired as a boffin (theorist) knowing little about engines and became Sir Stanley by improving the Merlin supercharger. The 1st part is great about Rolls and the Merlin, and the last part about the jet engine development. Also a more technical, less entertaining one "Merlin In Perspective". Thank God England had a genius in Reginald Mitchell and the Spitfire and a company equal to it in Rolls Royce. Yea, I' ve got a warm spot for the Merlin, as do thousands of Spit, Hurri, Lanc, Mossi, Mustang etc. combat pilots from Bader to Yeager.

[bdk]

Don't some of the highly modified Merlins at Reno use Allison connecting rods?