A 'proper' way to have a 24 cylinder liquid-cooled aero engine for the ww2?

[Shortround6]

DB 606

I don't know what size props the DB 601 engines in the HE 111P used but the HE 111H used 3.5 meter props on the Jumo 211.
The Bomber engines used different reduction gears to suit the different propellers. Merlins used different reduction gears on bomber and transport aircraft to suit the airframes rather than trying to use fighter propellers.

The 3% different in drag is from an old William Green book /chapter on the He 177. It could be in error.

The "bolted together" W engines were always going to have packages difficulties compared to a single crankcase engine.

I would be a little leery of using maximum "box" dimensions as they can be sometimes misleading. A lot of engines had a few lumps and bumps that added to the basic structure of the engine and it many cases, were a number of feet back from the front of the engine. Yes, they 'counted' for the square feet of the frontal area but but by the time the cowl fastened on some of these lumps and bumps disappeared into the contour of the cowl.
BTW the square ft of a normal seated male is just over 7 sq ft and that is counting only 525mm (under 21in) of width. Germans did reduce the height by angling the legs out but most cockpits are going to exceed the frontal area of most inline piston engines.

 

[wuzak]

As noted previously, the Griffons fit into Spitfires. They probably would have fit into Mustangs if jets had not come along.

It was a point of discussion when the Merlin Mustang was in is early stages of development.

Many changes were made to the Mustang to fit the 2 stage Merlin, even more would be required to fit the Griffon.

 

[Howard Gibson]

It was a point of discussion when the Merlin Mustang was in is early stages of development.

Many changes were made to the Mustang to fit the 2 stage Merlin, even more would be required to fit the Griffon.

If they can install a Griffon engine in a Spitfire, they can install one in a Mustang. Installing a Vulture, Sabre, or Double Wasp for that matter, will be way more difficult.

Apparently, the two-speed Merlin XX was considered to not fit in a Spitfire.

 

[wuzak]

The Vulture and Sabre were developed at the same time. They went with the Sabre.

They went with both of them.

The Vulture's development was delayed during the Battle of Britain as improving the Merlin was imperative. Other Rolls-Royce projects also suffered from their development being slowed or stopped during this period, including the Griffon. Most were cancelled shortly after, often at the behest of Rolls-Royce.

Vulture development was, possibly, cancelled at Rolls-Royce's suggestion.

Napier didn't have any engines in production that were being used in the BoB, nor did they have very many projects under development, so their work on the Sabre was not affected.

The Merlins were doing something like 2600HP by running 150 octane fuel and water injection. All the numbers I have seen for Griffons were with 100/130 octane, and no injection. The Griffons were capable of 3000+HP.

The RM.17SM was able to make 2,600hp on the test bench. It used higher rpm (3,150rpm), higher boost +36psi, ADI and required the use of PN160 fuel (PN150 fuel with extra TEL). It also had larger supercharger impellers (12.7"/10.7" vs 12.0"/10.1") and never went into production.

http://www.spitfireperformance.com/griffonhp_b.jpg

+21psi and +25psi boost was only available with PN 150 fuel.

Which Griffon model could produce 3,000hp?

With +25psi boost the Griffon could make a bit over 2,400hp (Griffon 57 could make 2,500hp at take-off using ADI). For 3,000hp more rpm would be required. It seems the Griffon was very much restricted to 2,750rpm.

If you can replace a Spitfire's Merlin with a Griffon, you can do it with the heavier Mustang. I think Rolls Royce investigated a Griffon Mustang. For the USA, that means setting up production of Griffons somewhere. By 1944, it was pretty obvious that the next important fighter aircraft were going to be the Gloster Meteor, the de Havilland Vampire, and the Lockheed P-80. There was no point in upgrading the Griffon. They even stopped manufacturing the now excellent Napier Sabres.

As mentioned above, Rolls-Royce and NAA discussed the possibility of installing a Griffon 61 into the Mustang as early as 1942. NAA said that there were too many changes required.

Rolls-Royce started developing the Flying Test Bed a little later. It used parts from the P-51, including the wing, mated to a fuselage carrying a mid mounted engine driving tractor propeller via an extension shaft and with a forward cockpit. It never proceeded beyond the mock-up.

SECRET PROJECTS:Rolls-Royce’s own fighter concept

The involvement of Rolls-Royce’s Hucknall plant in fitting the North American P-51 Mustang with its Merlin engine...

www.key.aero

 

[wuzak]

If they can install a Griffon engine in a Spitfire, they can install one in a Mustang. Installing a Vulture, Sabre, or Double Wasp for that matter, will be way more difficult.

Apparently, the two-speed Merlin XX was considered to not fit in a Spitfire.

The Spitfire III was to be fitted with a Merlin XX.

The Spitfire III had many changes besides the engine which meant that production would have been delayed, which was deemed unacceptable.

Installing the Merlin XX into the Spitfire I/II airframe was also possible, but also would cause production delays. Instead the Merlin 45 was used. The Merlin 45 could be installed in the Spitfire with the fewest number of changes, so production would not be altered much. This would be the Spitfire V.

 

[Howard Gibson]

The Spitfire III was to be fitted with a Merlin XX.

Anything is possible with enough time and resources. Rolls Royce's job was to manufacture Merlins. The Griffon was a better use of finite resources than the Vulture. They had the Napier Sabre.

 

[Howard Gibson]

Which Griffon model could produce 3,000hp?

None of them. They did not make the effort. Without jet engines in the pipeline, further development of the Griffon would have kept Spitfires and Mustangs competitive.

 

[GrauGeist]

None of them. They did not make the effort. Without jet engines in the pipeline, further development of the Griffon would have kept Spitfires and Mustangs competitive.

During the war, jet engines were not counted on as a reliable platform.
They were quirky, fuel hungry and literally viewed as a novelty.

The development of piston powered fighters was still a priority right up to the day that Japan surrendered.

 

[Howard Gibson]

During the war, jet engines were not counted on as a reliable platform.
They were quirky, fuel hungry and literally viewed as a novelty.

The development of piston powered fighters was still a priority right up to the day that Japan surrendered.

The Americans were working hard on the Lockheed P-80. This probably lacked the range to escort bombers over Japan. The British had the Gloster Meteor in squadron service, and they were working hard on the de Havilland Vampire. They were also working on the de Havilland Hornet, which again was expected to have sufficient range to escort bombers to Japan. The Hawker Fury with the Sabre_VII was an amazing aircraft, but clearly, the future was jets.

There was some question about landing jets on carriers, which is probably why the Royal Navy ordered Sea Furys, and the US Navy ordered Grumman F8F Bearcats.

 

[GrauGeist]

The Meteor still had engine and flight issues ("snaking") and the few P-80s in service during the war were YP-80s, meaning they were still in the development stage.
The US had the P-59, YP-80 and several prototypes during the war and at no point, did they stop developing faster, further and better armed piston types (P-51, P-47, F8F, P-82, etc.) and the same goes for Britain.

Jets were simply not an option to place all their eggs in one basket, at the time.

If we fast forward to Korea, we'll see that even then, five years after WWII, piston types were still dominant because first and second generation jets still had limitations.

 

[MiTasol]

My first thought would be that one would want to limit the engine to banks of six cylinders, so this means only the X (and and possibly hex), double-V (like the Allison V-3420), and H layouts are likely (the W layout would have 3 banks of 8). Of the three, my preference would be an X-configuration, as it would have only one crankshaft, which eliminates all the issues with phasing plus, since the crankshaft is the heaviest moving component in any engine, probably saves some weight.

My tendency, if I wanted to get an engine into production soonest, would also be to eschew sleeve valves, especially for a company that's not done it before.

I would tend to agree and using articulating rods minimises the bearing issues but would increase weight.

 

[MiTasol]

One way that worked if you had time and materials was Dobrynin VD-4K - Wikipedia

That pretty much follows the same concepts as the Napier Nomad engine and both were post war not pre war

Napier Nomad Compound Aircraft Engine

The Napier Nomad was a compound piston/turbine aircraft engine designed shortly after WWII. Despite its complexity, the engine achieved new levels of fuel economy, but it could not compete with gas…

oldmachinepress.com

 

[MiTasol]

I'm not aware of any "flat H" engines with poppet valves in the power range we are talking. I suspect that having poppet valves with their associated springs and cams made the engine too wide for the air frame guys. I've seen the drawings for the Merlin "vertical H" engine, and it is seriously tall.

I still think a double Peregrine has merit as you could start double Kestrel in '35 and get 5 years experience in before you are at war with your 1,750hp double Peregrine. Makes for a very different looking Typhoon...

Well reasoned even tho I disagree with several statements and I totally disagree on one item. Sleeve valve cylinders are just as high or higher than poppet valve cylinders because of the junk heads that support the "top" of the sleeve and they also require a cooling airflow which adds to the height even more.

 

[MiTasol]

Too long, as I understand it the crankshaft twists.

as do the camshafts

 

[MiTasol]

And the Firefly.

and Lincolns

 

[MiTasol]

Yes, it caught fire, possibly because the engines were inverted and the inner exhausts went straight down. Oil leaks would then get on the hot exhausts and ignite. The fault is not completely with the engine, though, as the installation seemed to be poor. For instance, the He 177 did not have a firewall behind the engine.

Essentially the He 177 was a 4 engine aircraft. But with only two propellers.

Other aircraft fitted with the DB 606/610 didn't seem to have as many issues, though they weren't built in large numbers.

And it was not the only engine with fire problems - the R-3350s in the B-29 also had that issue so it is not exclusive to German liquid cooled engines.

 

[MiTasol]

The following 24 cylinder engines actually flew: the Napier Dagger, Napier Sabre, Fairey Monarch, Lycoming XH-2470, Rolls-Royce Eagle and Arsenal 24H (all H arrangements), the Rolls-Royce Vulture and Rolls-Royce Exe (X engines like the unflown DB-604), the Junkers Jumo 222, Dobrynin VD-3TK and Dobrynin VD-4K (all hexagonal), and the Daimler-Benz DB 606, Daimler-Benz DB 610, Allison V-3420 and Aichi Ha-70 (all built by coupling two V12 engines together).

Of those, the Napier Sabre, Rolls-Royce Vulture, Daimler-Benz DB 606 and Daimler-Benz DB 610 actually made it into combat. The Sabre was far the most successful and powered one of the best fighters of WW2, the Tempest, and one of the fastest prototypes, the Sabre Fury.

The Fairey Monarch is interesting because it was designed to be safe rather than to give the maximum power to weight and power to frontal area. It was basically two independent engines, either of which could function if the other was damaged, powering contra-rotating airscrews. The idea was to give twin engined safety to an aircraft that could land on a carrier without asymmetric thrust and whose wings could be easily folded.

My take is that each arrangement, H, X or hexagonal could work if enough resources were thrown at the problem. Certainly the late war Sabres and the 1951 VD-4K were excellent engines. However, because the need for engines giving 2,500 hp was only perceived rather late, only the Sabre made a significant positive contribution to its nations effort.

Edit: Should add the Packard mentioned above.

And you should add the Italian Fiat AS.6 Fiat AS.6 - Wikipedia to the list of engines that flew.

3100 hp in 1934.

That had as much potential as some of the other types discussed and solved the torsional twisting of crankshaft(s) and camshafts issues that would have eliminated L12 and probably V18 engines.

 

[MiTasol]

Griffon powered Mustang. Cool.

At least one Reno racer was a Mustang with a Griffon.

 

[MiTasol]

It's a wonder that the greatest 24 cylinder engine of them all hasn't been mentioned - the Fairey P.24 with 4 speed, 2 stage supercharging!

Second greatest to the Fiat AS.6 which powered the aircraft that still holds the floatplane world speed record. Like the Rolls Royce R it could have been developed.

 

[MiTasol]

The OP's requirement was for a 24 cylinder engine of 1,500+ hp in '39 (which just about guarantees 87 octane fuel), that will be up-gradable to remain relevant until VJ-Day. The only engine that historically meets the '39 date in the Vulture.

Hmm - let me think. 3100 hp in 1934 beats the 1500 hp in 1939 Vulture hands down.

Therefore you should have said The only engines that historically meets met the '39 date is the 3100hp Fiat AS.6 and 1500hp Vulture.

Even derated to use regular fuel the Fiat would possibly have topped 2500 hp in 1939