No US-built Merlin: plausible developments?

[tomo pauk]

For the sake of discussion, what would be the options for the Western air forces without Merlin being produced in the USA? I'm interested in all levels of the developments, from technical (suitable replacements for the Packard Merlin) up to the strategic. Please note that Packard Merlin was used also in the British and Canadian aircraft production.

In this time-line, Packard builds either R-2800 or V-1710 (or some of the derivatives).

 

[Edgar Brooks]

Build R-R factories in the Commonwealth:- Australia, Canada, New Zealand, South Africa, while the USAAF continues to fly its P-51 at sea level.

 

[Shortround6]

Canada is the only real hope of a Merlin Production line in time to really do anything.

Australia,New Zealand, South Africa and even India do not have the needed hundreds of small sub contractors needed to support a large engine building program, at least in the first few years of the war.

Packard built (starting in the middle of 1940), 45 single stage engines in 1941, 7251 single stage and 5 two stage engines in 1942, 12,292 single stage and 2,792 two stage engines in 1943 and 7,171 single stage and 15,798 two stage engines in 1944.

Packard was a sizable motor car manufacturer, had built aircraft engines before and built the majority of the gasoline engines used in American and British Motor Torpedo Boats. It also had the support of hundreds of subcontractors for nuts, bolts, studs, pump parts, lines, fittings and so on. The majority of the new tooling needed DID not have to brought by ship from another continent.

Some of the Commonwealth countries did amazing things in WW II as far as production goes but an engine program that completes 1000-2000 engines total by wars end does not compare to a program of over 50,000 engines.

 

[davebender]

Britain would have no choice but to build additional Merlin engine factories elsewhere, probably in England. Resources required to build and operate those factories mean something else gets deleted from British military spending.

 

[wuzak]

Perhaps there is accelerated devlopment of the V-1710 and it gets put into production at Packard.

Perhaps the IV-1430 is pushed more, development taken over by someone with a clue. Packard is one of the production facilities.

Ford's proposed V12 is given backing and starts development - don't know when that will be available.

Did Packard have anything in development themselves?

Maybe the 2A-2775 of 1935 - X-24, 1900hp @ 2800 rpm. Weight 1720lb.

The 1A-5000 X-24 (5000 cubic inches), possibly rated at 3500hp, or the sleeve valve 3A-5000. Perhaps the 2A-5000 H-24 rated to 3000hp. The 1A-5000 weighing 2830lb, the 2A-5000 2750lb.

 

[wuzak]

Double post

 

[wuzak]

Looking at things from another perspective, if Merlins weren't built in the US there would be a rationlising of what gets the available Merlins.

So, Hurricane production is cut off earlier. Mosquito deliveries are slower. Spitfires are built in fewer numbers, and perhaps the Griffon engine versions pushed forward, that causing delays and cancellations for other Griffon powered models - such as the Fairey Firefly.

Most importantly, there will not be enough Merlins to power Lancasters and Halifaxes. Many Halifaxes ended up with Bristol Hercules engines, only a few Lancasters. Probably in this scenario more Lancasters get Hercules, and if this causes a supply problem then they may look to the US for alternatives - such as the R-2600.

Perhaps Rolls-Royce don't convert the P-51/Mustang with a Merlin 61. Perhaps they do, but since the RAF doesn't need a long range high altitude escort fighter they don't do anything with it. NAA don't do a similar conversion, but seeing RR's performance with the Merlin Mustang, they push Allison (and teh government) for 2 stage V-1710s.

 

[Shortround6]

Perhaps there is accelerated devlopment of the V-1710 and it gets put into production at Packard.

Possible

Perhaps the IV-1430 is pushed more, development taken over by someone with a clue. Packard is one of the production facilities.

A very bad choice. The IV-1430 had a number of questionable design features, the real wonder is that it was persisted with so long. There may have been some excuse in 1938-40. To still be fooling with it in 1943-44 means a few somebodies were not paying attention.

Ford's proposed V12 is given backing and starts development - don't know when that will be available.

The Ford V-12 (according to most accounts) isn't "proposed" until Ford had a good look at the plans for the Merlin and perhaps even a sample engine. Ford has little or no background in aircraft engines and little or no background with superchargers. Ford did do an excellent job of making P&W R-2800 engines though.

Did Packard have anything in development themselves?

Maybe the 2A-2775 of 1935 - X-24, 1900hp @ 2800 rpm. Weight 1720lb.

The 1A-5000 X-24 (5000 cubic inches), possibly rated at 3500hp, or the sleeve valve 3A-5000. Perhaps the 2A-5000 H-24 rated to 3000hp. The 1A-5000 weighing 2830lb, the 2A-5000 2750lb.

Maybe Packard could have gotten those engines to work in production form or maybe not. They may have been limited in development like the Hispano V-12. For engine of that displacement to be that light leads one to wonder if the structure is strong enough to stand up to higher boost pressures made available by later fuels? Please check the BMEP levels and consider that a Merlin III at 6lb boost was about 180 BMEP as was a "C" series Allison and both the early DB 601 and Jumo 211. later versions of some of these engines had BMEP somewhat over 250.

 

[wuzak]

A very bad choice. The IV-1430 had a number of questionable design features, the real wonder is that it was persisted with so long. There may have been some excuse in 1938-40. To still be fooling with it in 1943-44 means a few somebodies were not paying attention.

Probably, but it was the Army's baby.

Possibly a better bet would have been in the Lycoming H-2470?

The Ford V-12 (according to most accounts) isn't "proposed" until Ford had a good look at the plans for the Merlin and perhaps even a sample engine. Ford has little or no background in aircraft engines and little or no background with superchargers. Ford did do an excellent job of making P&W R-2800 engines though.

I only knew that Ford had proposed a V12 aero engine....not the timing.

Maybe Packard could have gotten those engines to work in production form or maybe not. They may have been limited in development like the Hispano V-12. For engine of that displacement to be that light leads one to wonder if the structure is strong enough to stand up to higher boost pressures made available by later fuels? Please check the BMEP levels and consider that a Merlin III at 6lb boost was about 180 BMEP as was a "C" series Allison and both the early DB 601 and Jumo 211. later versions of some of these engines had BMEP somewhat over 250.

The 2A-2775 maybe a lightweight engine that couldn't have too much development, in the form of boost, at that weight. Still, At 1720lbs dry it would have an installed weight similar to an R-2800 and as much power. And it would have been available sooner.

The BMEP at 1900hp and 2800rpm is 198psi.

Maybe development during the war sees the 2A-2775 gaining weight as it gains strength. Certainly the rpms are low for the short stroke (5").

The larger 1A-5000 and 2A-5000 made 3000-3500hp in 1939 at weights around 2800lb. The hp/l isn't pushing up there, but the power to weight is good. The document I have (from enginehistory.org) doesn't specify rpms for those two, but if the same rpm is chosen the BMEP is roughly the same (at 3500hp).

 

[fastmongrel]

I like the idea of Packard churning out R2800s these would then power the Typhoon and Tempest, no more Sabre troubles. Doubt if the Lancaster could take the R2800 but wow what a bomber that would have been with 4 turbo R2800s

 

[gjs238]

Turbocharged V-1710's may supplant some V-1650's.
For example, with no V-1650 powered P-51, P-38's take on a larger role.

Perhaps P-40 production ends earlier in favor of V-1710 powered P-51's.

 

[tomo pauk]

How about P-51 with 2-stage V-1710 (mass production, not just the prototype)? Or, maybe, going for the R-2800 for the plane?

I've made a rough sketch of the turbo-51 (w/ V-1710) a while ago. Prestone oil coolers positioned akin to the P-40, intercooler turbocharger at the back, lower hull. Major shortcoming - external exhaust ducting.

 

[Njaco]

without the Merlin, would more effort be placed on producing jet engines?

 

[GregP]

For the sake of discussion, I'd like to throw out the following. The US Congress contracted for the Allison V-1710 and development started in 1929. They anticipated a high-altitude requirement and developed a turbo-supercharger system for the Allison V-1710. It wasn't perfect but was exactly what was contracted for. After the prototype P-39 had some issue, they deleted the turbo-supercharger from the aircraft and all subsequent fighters except the P-38.

As a result, all the subsequent fighters except the P-38, while pretty good at low to medium altitude, suffered from lack of high-altitude performance.

Unfortunately, the US Congress owned the design, lock, stock, and barrel. I submit that they should have taken the simple step of appointing an Allison manager for the government and delegating him the authority to oversee improvements to the engine.

Next, he could have asked Allison to pursue a development of the 2-stage, 2-speed supercharger to augment the turbo-superchargers, which were earmarked for the strategic bombers, so they could reach high altitude. We had insufficient quantities of certain metals to allow the number of turbochargers for there to enough for the fighters, according to the war materiel board …but we didn't need those metals for superchargers.

We still would have needed the time to sort out the issues we found in Europe with the early P-38 deployment. Those issues were the intake manifolds and running on European fuels, with had a much larger percentage of aromatics than did American fuel. Once these were sorted out, the engine problems "went away" and the P-38 had no more difficulties at high altitudes. Most were transferred to the Pacific where they gave yeoman service and were the mount of our two top-scoring Aces, Bong and McGuire.

Meanwhile, if the Allison V-1710 had seen a concerted development effort to field a 2-stage, 2-speed supercharger installation, I feel pretty certain they could have closed in on a good development effort and done it in a reasonable time. In point of fact, the late model Allisons with the auxiliary stage supercharger flew at high altitude very well and made as much power as any high-altitude Merlin. But the auxiliary stage was a dead end in my mind and I am proposing they concentrated instead on an integral unit, such as the Merlin had. Maybe even if we had not built Merlins, we could have consulted with Sit Stanley Hooker on the supercharger design.

I do NOT claim we could have done it exactly quickly, but it could have been done and would have resulted in good things for the V-1710 in time to make a difference in the war.

 

[tomo pauk]

Hi, Greg,
Why do you think that the aux stage (for the V-1710) was a dead end?

 

[Balljoint]

I'm jumping in the deep end as a newbie, but I don't see this as a hypothetical. The Eighth was flying without the Merlin in 1942. 1930's doctrine said the bombers could fight their way through and reach the target. The hardly timid RAF found this not to be so, but the US brass persisted.

My suggestion would have been a change in tactics. The bombers were flying at 20.000+ ft and the Allisons ran out of breath at 12,000 ft. So why not bring the bombers down to 10,000 t0 14,000 ft and use P-39s and P-51As for escort? Drop tanks are a low tech problem. And these AC could have been available in reasonable numbers if the ill-conceive A-35 and lend lease planes were switched to escort AC.

Obviously there would have been tradeoffs in range/payload, AAA, rearm/fuel cycle for interceptors etc., but the upside of escort fighters seemingly would more be than offsetting.

Any thoughts?

 

[wuzak]

The lack of US built Merlins doesn't just affect the P-51.

There were some 50,000+ Packard built Merlins, around 17,000 P-51s (including P-51As) and a few hundred P-40Fs and Ls. The rest went to Lancasters, Mosquitos and Spitfires, and I'm sure one or two other British aircraft.

 

[Shortround6]

I'm jumping in the deep end as a newbie, but I don't see this as a hypothetical. The Eighth was flying without the Merlin in 1942. 1930's doctrine said the bombers could fight their way through and reach the target. The hardly timid RAF found this not to be so, but the US brass persisted.

My suggestion would have been a change in tactics. The bombers were flying at 20.000+ ft and the Allisons ran out of breath at 12,000 ft. So why not bring the bombers down to 10,000 t0 14,000 ft and use P-39s and P-51As for escort? Drop tanks are a low tech problem. And these AC could have been available in reasonable numbers if the ill-conceive A-35 and lend lease planes were switched to escort AC.

Obviously there would have been tradeoffs in range/payload, AAA, rearm/fuel cycle for interceptors etc., but the upside of escort fighters seemingly would more be than offsetting.

Any thoughts?

P-39s are among the shortest range fighters, no good for escort. Drop tanks are for getting to the target/first intercept, internal fuel is for fighting and getting home.

Bringing the bombers down to 10,000-14,000 ft give the Flak guns a much better chance. A short time of flight for a more accurate fuse timing and a much longer period of time in which the bombers are in range of a particular gun/battery.

B-17s and B-24s cruised where the FW 190 was beginning to fall off in performance. Cruising below 20,000ft makes the FW 190 even more effective than it was historically.

 

[davebender]

I disagree.

The Merlin engine had top priority because it powered Spitfires and Lancaster bombers. If the USA doesn't supply Merlin engines then Rolls Royce will be told to concentrate exclusively on Merlin engine production. Development of the Griffin engine and other Rolls Royce projects will sputter to a halt for the duration of the war.

 

[Balljoint]

I don't differ with you; just saying that without the Merlin it may be a good compromise. I see the bomber effort as initially an air superiority contest requiring fighter escort primarily to destroy LW interceptors and secondarily to protect bombers –though one is a function of the other. Without escort, even Ju-52s were able to stand off and fire rockets at the bomber formations.

The P-39 was included with regard to availability and the thought that it had perhaps a range of 500 mi. internal fuel. Thus it would be useful over France where the LW would have to defend transportation and provisions for channel defense. This is primarily the time period before the P-51-B was available in reasonable numbers, theP-39 and P-51A, like halitosis, would have been better than no breath at all. But the P-38s and P-47s could also operate in these areas.

Same with Flak. As long as the bombers stayed above the 20 mm stuff, the quantity wouldn't increase much though the aim and duration over Flak concentrations would somewhat.

Without fighter protection, the 190s and 109s really didn't need much performance to ravish the bombers.
My point has to do with tactics to deal with the lack of high altitude, long range escort fighters, which was the situation prior to the arrival of the P-51B. This was a terrible time for the bombers. Perhaps it would have been less so had they come down a bit. From a tactics viewpoint, the bombers set the combat altitude.