Really big powerful liquid-cooled engines - the best approach?

[tomo pauk]

Hello, gentlemen,
Under 'really big' engines, I mean the 40-70 liter piston engines, ie. the types that should be able to develop 2000+HP already from early ww2 on. What was the best approach that actually worked any time in ww2? What 'path' should've the countries follow, to suit their needs?

 

[dobbie]

For American liquid cooled engines, the only choice I see is the Allison V3420 which never was fully developed. Perhaps the R-R Griffon might have been the better candidate? And neither one was fully developed early in the war.

 

[davebender]

Both engines were good and probably could have been placed into mass production.

 

[bob44]

Bigger engines were complex and troublesome even later in the war and after the war.
Also lower fuel grades early in the war limited power output.
Then there is the size of a really big engine, try and fit one of these into a fighter would be something.

 

[wuzak]

Twin crank engines would be the easiest route - like the Sabre (2240ci), Eagle (2800ci) or the V-3420 (3420ci).

Single crank engines had problems - but not insurmountable. The Vulture (2600ci) could have been cured if the resources were available, and was basically a 2000hp engine at the beginning of the war - but couldn't be run reliably at that in service.

The Pennine (I know it was air cooled) was able to give about 1hp/ci (about 2750ci). A liquid cooled version of that would give more.

 

[wuzak]

Of course there was the Lycoming XR-7755 -

 

[johnbr]

How about the r-4090.

 

[johnbr]

R 4090L
The R-4090 possessed similar power and weight characteristics to early Pratt Whitney R-4360 engines. While developing the Cyclone 22, Wright was preoccupied with serious developmental issues of the very high priority R-3350 engine and ongoing development of the 42-cylinder R-2160 Tornado; not much time or manpower remained for the R-4090. As a result, only a few examples of the Cyclone 22 were built, and it is doubtful that the engine ever flew. Perhaps three R-4090 engines were completed: two XR-4090-1 engines with a single propeller shaft and one XR-4090-3 engine with a co-axial prop shaft for contra-rotating propellers. The XR-4090-3 weighed an additional 30 lb (13.6 kg) for a total of 3,260 lb (1,478 kg). In addition, the XR-4090-3 was to have a two-speed nose case to maximize propeller and engine speed efficiency for maximum power and cruise power. Ultimately, the R-4090 Cyclone 22 was abandoned so that more resources could be used for the R-3350 Cyclone 18.

Radial engines with 11-cylinder per row are very rare. With so many cylinders, the engine diameter becomes very large, and the valve train can be crowded and complex. In addition, difficulties can arise with so many power pulses on each crankpin.

 

[tomo pauk]

Thanks for the data about the Cyclone 22. It was air cooled, however

The UK has another candidates, namely the Fairey's twinned 16 and 24 cyl Princes.

 

[Piper106]

As has been stated many times, the DB 606, 610, and 613 with a red hot exhaust collector at the bottom center of the cowling were a less than ideal arrangement. Gravity works, and when the normal and expected leakage of oil and fuel drip to the bottom of the cowling --> BIG trouble. That later versions of the he 177 were able to not catch on fire was in spite of, not because of, this design.

No manufacturer was able to get more than two cylinders per crank pin to work at the the rpm and boost levels of a liquid cooled engine after any reasonable development period, the Vulture and the Jumo 222 being the two prime examples.

I favor the two crankshaft 24 cylinder engines. I think we would have had a winner if Rolls Royce had built the Vulture as a two crankshaft engine. Two side by side 120 degree bank angle V-12s on one crankcase. Not much wider than the historic single crank Vulture, I feel it still would have fit into the Hawker Tornado.

 

[Piper106]

Don't forget that Rolls Royce investigated doubling the Merlin, 24 cylinders and two crankshafts in a single crankcase casting in a vertical H arrangement, with standard Merlin cylinder blocks. Had a good chance of being a winner. 2400 reliable HP early in the war, 3000 HP by 1944, and 4000+ HP before V-J day. It would have been an interesting upgrade for the Avro Manchester. The Shackleton could have been two engines, like the American P2V Neptune.

Hispano Suiza did the same thing, doubling their 12Y and 12Z engines into 24 cylinder two crankshaft vertical H arrangements.

Nothing would have stopped either Daimler Benz or Junkers from building a similar 24 cylinder vertical H using DB601 or Jumo 211 parts respectively. We sort of got a look at what could have been, for Arsenal in France continued Junkers wartime work on the Jumo 213, and came up with post war a 24 cylinder 2 crank version of the Jumo 213.

 

[Nick Sumner]

Both engines were good and probably could have been placed into mass production.

Which would have helped the Allied cause no end!

The DB604 was canned in 1942 (IIRC) with a plethora of other immature DB projects, to compel DB to focus on the few projects that might be bought quickly to fruition and benefit the war effort rather than the ridiculous numbers of projects they were trying to make work distracting from those which had genuine potential.

The Jumo 222 was a train wreck that insured the Bomber B program was a failure. Junkers claimed they got it right the day before allied tanks overran the factory, but they would, wouldn't they...

 

[wuzak]

No manufacturer was able to get more than two cylinders per crank pin to work at the the rpm and boost levels of a liquid cooled engine after any reasonable development period, the Vulture and the Jumo 222 being the two prime examples.

I don't think the Vulture's problems were due to the crank. Mainly due to the connecting rod arrangement. This could have been much improved, and was for the Pennine (2750hp, X-24 single crank).

The DB 604 seemed to go just fine, but there isn't much info on them.

P&W built the "Yellow Jacket" R-2060 with 5 cylinders per crank throw, but decided to concentrate on thei air cooled engines.

I favor the two crankshaft 24 cylinder engines. I think we would have had a winner if Rolls Royce had built the Vulture as a two crankshaft engine. Two side by side 120 degree bank angle V-12s on one crankcase. Not much wider than the historic single crank Vulture, I feel it still would have fit into the Hawker Tornado.

The Vulture was 35.8" wide x 42.175" high. The height had, no doubt, something to do with the carby.

Twin cranks requires space between them. So there is little doubt that a twin V-12 Vulture would be wider, even given the 120° vee angle. It would also be taller. It may have still fitted in the Typhoon - mainly because that was a huge beats!

Gearing two engine halves together is no bed of roses either.

I'm sure you've seen the reduction gear setup for the Sabre? Lots of added weight in that.

Allison also had some difficulty with it, and had to alter the phasing between the halves.

 

[wuzak]

Don't forget that Rolls Royce investigated doubling the Merlin, 24 cylinders and two crankshafts in a single crankcase casting in a vertical H arrangement, with standard Merlin cylinder blocks. Had a good chance of being a winner. 2400 reliable HP early in the war, 3000 HP by 1944, and 4000+ HP before V-J day. It would have been an interesting upgrade for the Avro Manchester. The Shackleton could have been two engines, like the American P2V Neptune.

The H-Merlin was about 3600-4000lbs. Still lighter than the Eagle H-24, though.

The problem was the duplication of the ancillaries. It required 4 intercoolers (one to feed the top and bottom banks for each halve), had 2 complete 60-series 2 stage 2 speed superchargers and carby, et al.

An H-Merlin with geared together cranks, single supercharger system would have proved interesting. Allowing for any difficulties in gearing engine halves together.

btw BRM built an H-16 for Formula 1 for 1966/67, using twin cranks. It was a nightmare.

 

[Dogwalker]

In general, at the beginning of the war, were just ready, often after nearly a decade of development, the inline engines of 1000-1100 hp in a well known and "simple" configuration as the V12. It is utopian to think that could be ready for operational use, engines with twice the power and more complex configurations.
Having said that, the easiest way to double the power of an engine, is to use two of them. In theory, if the base engine is ready, it does not take long to connect two Merlin, or two Allison V-1710, facing one another, like a Fiat AS6, or side by side.
The problem is that, in this way, we double, beyond the power, also the weight and size of the engine. And this is reflected directly on the weight and size of the aircraft, to the point to cancel the advantage (also an increase in performance, should be compared with the higher costs of production, maintenance, and with the fact that an engine twice the size is a target twice the size)
to have an increase in power (with the same gasoline) without having a correspondant increase in weight and size, the rows of cylinders must have the basement in common, or at least be arranged so as to minimize the size.So, the most "useful" configurations are W18 (three cylinder banks with a single shaft), X24, H24 (it has two crankshaft, but at least it is more compact than two-V12) and the various asterisk configurations (basically, liquid-cooled radial engines).

 

[Dogwalker]

Among the "asterisk" configuration, we can list the Alfa Romeo 1101 RC.37/87.

It was designed by the Spanish engineer Wilfredo Ricart, that was the chief of the Alfa Romeo Special Project section between 1938 and 1945. It had 28 cylinder (seven banks of four), displacement of 50.24 litres, direct injection, 2000hp at takeoff, and a two speed supercharger, with critical altitudes at 3700 and 8700 m. It seems that it run at the bench for about 20 hours, 7 of them at max power, first than the armistice.
In July 1944, an attack of the Resistance blown up the Armeno workshop, where the parts were ready for the first pre-production run of 20 AR 1101, destroying engines, parts, machinery, and related documents.

The pictures do not permit to estimate the dimensions, but from the designs of the possible installation on the Caproni Vizzola MTC we can compare it with the known dimensions of the DB 605, obtaining a diameter of about 1244mm.

An offspring of the 1101 engine was the Alfa Romeo 1001-B naval engine, 200hp at 1500rpm, made with a single bank of the 1101.

 

[swampyankee]

iirc, Wright had a 42 cylinder liquid cooled radial. Given the kind of hard limit on bore for high-speed spark ignition engines of about 6 in (155 to 160 mm), and a rough limit on power/piston area of 6.5 or 7 hp/in^2 means that high speed spark ignition engines are limited to about ("about" means I might be 25% off ) 250 hp/cyl.
...
so, if you want more than 3,000 hp/engine, you've got to go to more than 12 cylinders. I know that 42 cylinder radials have been produced (the Soviets produced a 42 cylinder radial main propulsion diesel. The engine was not notorious for its spectacular reliability).

 

[Shortround6]

The Wright engine was about 2180 cu in. They were trying for High speed. The engine was supposed to be modular and could be stacked in 14 cylinder groups.

It was a complete waste of time and money.

 

[swampyankee]

The Wright engine was about 2180 cu in. They were trying for High speed. The engine was supposed to be modular and could be stacked in 14 cylinder groups.

It was a complete waste of time and money.

I wouldn't say a complete waste. It did demonstrate that the idea wouldn't work. The various "advanced" engines that were prototyped at about that time -- the IV-1430 (Continental), the XH-3130 (P&WA), the XIV-2220 (Chrysler) -- were largely useless, possibly because the targeted power was too low (by 1940, the minimum target for a fighter engine probably should have been no less than 3,000 hp).

I'm not sure what was going in on the Dept of the Army and Dept of the Navy regarding aircraft engine development at the time. Other than the "hyper" program, which did not seem to be taken very seriously, there seemed to be relatively little effort to develop specialized engines for combat aircraft. I'd like to be mistaken here, as I've little time researching US military R&D efforts in the period leading up to WW2, but I'm not sanguine.

 

[Shortround6]

Well, the XIV-2220 Chrysler had a chance but most everybody underestimated the time it would take to bring a new engine to production standard. P W were probably right when they said they couldn't get the XH-3130 sorted in time to anything for the war and went for the R-4360 instead ( four rows of seven R-2800 cylinders, what could go wrong and the Wright R-3350 was just a R-2600 with two extra cylinders per row and Wright had already made thousands of 9 cylinder single row radials what could go wrong

AS for the Wright Tornado:

The crankshafts of the 14 cylinder modules were not connected, instead gear trains brought the power out to the green lay shafts in the drawing and the lay shafts drove the gear trains to power the accessories and the propeller. There were 7 lay lay shafts and the size was kept small by using high rpm. The idea of a small engine of high power was attractive but the mechanical complication was a lot less attractive. Servicing 84 spark plugs may have been a real joy for the mechanics too.