P-38 with Roll-Royce Merlins

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That seems the be the information provided in the 'Vee's for Victory' book. The turbocharged Allison still had it's single-stage blower, so it was in effect a two-stage set up. The V-1710 was also used in early turbo-compounding experiments (where the turbocharger shaft is geared to the crankshaft to provide extra power, as on late R-3350's)
 
helmitsmit said:
Yeah the turbo compounding was a great idea they should have used it on more engines.
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There was no reason to as the jet engine came onscene and further development of recips basically halted after the war.
 
Well, as far as the military combat aircraft were concerned, the emphases was certainly on jets, but both Pratt and Whitney and Wright continued to develop the piston engine after the war. Pleanty of military cargo and civilian airliners to power. Look at what the R-2800, R-3500 and R-4360 were capable of in the late 50's.
 
There was not a lot of new innovations in recips, putting it simply the research was going into jets. With all the post war recips being operated into the late 50s, not much has changed since the 1940s.

I worked on P2Vs, an S2F, a PBY and was involved in painting a late model Connie - there was little difference in the technology that went into their powerplants, even though she had late model engines. From what I dealt with the major large recip manufacturers of the 50s (Curtiss Wright, Pratt and Whitney) they did little to their products except accommodate for post war airliner installation (DC-7, L1649)
 
I was thinking along the lines of turbo-compounding and fuel injection, both innovations first tried during the war, but more widely used after the war. But yes, a techical dead end. One look at the flight engineer's panel on a Super Connie, DC-7, or KC-97 and you knew it was over.
 
V-1710 said:
I was thinking along the lines of turbo-compounding and fuel injection, both innovations first tried during the war, but more widely used after the war.
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That was about all that was done with recips after WW2. Pressuration and airconditioning technology was also improved with aircraft like the DC-7, and L1049, but no major engine advancements...
 
That is kind of like saying that there haven't been any engine advancements since 1941 because the Whittle jet was flown then and we have jet engines today!

The hp increase of the postwar civil Merlin and Wright 3350 is a bit remarkable from 1945 to the late fifites.

I think there were some big advancements based on logical evolution to create more efficient, reliable and usable engines. This is similar to the evolution of the jet engine since the centrifugal flow design to the high bypass fans today.

Granted, we all are into old stuff or we wouldn't be on this site, and it is a history based interest. So progress has left the piston behind as far as development. The modern day piston manufacturers are way behind as well, mostly because of the need to remain in the FAA's certification envelope. Diesels are coming fast as seen by the cool little Diamond twin engine diesel powered airplane that has won certification here in the US. That is truly a positive direction to see manufacturer's going and it is the future of general aviation, which is mostly piston aviation.

It isn't new technology on the face of it, but it is very evolved and refined.

Chris...
 
One big problem with those high performance reciprocating engines is the need for expensive high octane fuel. The jets used cheap kerosine fuels.

Even for the 1950's when gas was cheap, fuel costs were a big componant of any commercial endevour.

Plus those big complex compound engines were expensive to maintain and repair, as compared to jet engines.
 

I think you hit the nail on the head Chris. I remember when I was in college an instructor spoke about electronic ignition and FADEC on recip aircraft engines but also said he doubted they would ever be certified by the FAA. We had seen the Feds budge a little with recip "innovations" but not much has changed since WW2 - especially on round engines.
 
 
The P-38 was in production and service before Packard got the contract to produce the Merlin.

Refitting the P-38 to accept the Rolls-Royce Merlin was out of the question (especially since Britain was hard pressed to supply the Merlin to her own production lines) and by the time Packard landed the contract, it was a moot point.
 

As I understand it, Lockheed proposed installing Merlins in the P-38 three times.

First was with the Merlin XX (V-1650-1). The proposal was after Packard was awarded the contract to build Merlins, so any Merlins for P-38s would have come from Packard.

The second proposal was the Merlin 61. And the last was with the "advanced Merlin", which was the 100-series Merlin, which included the V-1650-9 that was fitted to the P-51H.

The service introduction of P-38s was in mid-to-late 1941, though the aircraft was not considered combat ready at that time.

Packard signed the contract to build Merlins under licence in 1940.
 
The P-38 was in production and started deliveries when the first V-1650 engine was bench-run in summer 1941.

There is a HUGE difference between the time a contract is signed and when the first product comes out the door.
 
GrauGeist said:
The P-38 was in production and started deliveries when the first V-1650 engine was bench-run in summer 1941.

There is a HUGE difference between the time a contract is signed and when the first product comes out the door.
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You've moved the goal post.

GrauGeist said:
The P-38 was in production and service before Packard got the contract to produce the Merlin.
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That the P-38 was in production did not stop Lockheed from considering the Merlin. It happened at various stages through the war.

The initial proposal may have been in response to the Packard contract being awarded and its requirement that 1/3 of production be for USAAF use.
 
GrauGeist said:
The P-38 was in production and started deliveries when the first V-1650 engine was bench-run in summer 1941.

There is a HUGE difference between the time a contract is signed and when the first product comes out the door.
Click to expand...

Wasn't the Allison Mustang also in production, yet that didn't stop the Packard Merlin being installed in the Mustang.
 
A few considerations,
1. Packard was not able to build Merlins in numbers exceeding handfuls per month until the very end of 1941/ beginning of 1942.
2. The Merlin in question offered 1150 hp at 18,500ft while the turbo Allison offered about the same at 25,000ft so I am not sure where the advantage comes in.
3. The Allison powered version was supposed to do about 8% better in fuel economy when cruising.
4. Without some major changes in contracts/production every Merlin P-38 built is two P-40Fs not built.

That is just of the top of my head for the early Merlin. Granted they didn't know about some of the problems with the early turbo installations.
 
What was the power output at high altitude of the Merlin vs the turbocharged 1710? I seem to recall that by the time the P-51 was at 30k, hp was down to ~900hp, but this is going by memory and could be way off. Also, turbochargers extract "waste heat" from the exhaust to power the compressor, vs using engine output. In theory, the turbo setup should burn less fuel, all else being equal.

I always thought an intercooler package (liquid) like the Merlin got would have been an interesting update to the (Allison turboed) '38, rather than the core-type air-air intercoolers it got on the J models. The J model got considerably more power, but only a slight increase in speed due to the added drag. A new wing design to address the compressibility issue (assuming it would do so), a new intercooler design and some attention to cutting drag might have made a significant difference. The real shame is that there was only one source until the very end of the war, when Vultee finally built ~100 planes, none of which made it into service.
 
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