1930s/40s: no 2-engined fighters as-designed

[Shortround6]

It will be interesting to see what the Japanese come up with in place of their heavy fighters Kawasaki Ki-45, Ki-102 and Nakajima J1N. The IJAF thought they had the need of a heavy companion to their lightweight Ki-43, etc., so they'll design something for the heavy fighter, but what engine?

They don't have a chance, they had no large, high power engine is service or about to be in service at the point in time the Ki-45 was designed. Their big bomber engines only offered a few hundred more HP than their fighter engines and sometimes not even that.

 

[GrauGeist]

It is possible that in the absense of the twin heavy fighters, focus would be put on the fighters being developed, like the J2M and KI-61/(KI-100)

 

[tomo pauk]

It will be interesting to see what the Japanese come up with in place of their heavy fighters Kawasaki Ki-45, Ki-102 and Nakajima J1N. The IJAF thought they had the need of a heavy companion to their lightweight Ki-43, etc., so they'll design something for the heavy fighter, but what engine?

Ki-45 was 'heavy' in sense that it used a lot of engine, but not in sense of bringing out a lot of firepower - number of cannons was mostly 1, a bad return for two engines invested. Long range part of the equation was dubious due the thing of not carrying drop tanks. After all was said and done, Ki-45 fared bad agaist P-40s.
IJA can issue a specification in 1939/40 for a fighter armed with two cannons (and presumably 2 MGs), engine can be Kasei, or from Ha-41/109 family; drop tank(s) from the get-go. Basically - an 1942 Ki-100.

Tomo is correct on the R-2180 however it may have made for a lousy fighter engine without a lot more development. All but one model used a single speed supercharger and while military power is not listed (for the most part) max continuous power seems to have been around 1000-1150hp at 9,000-7,000ft, please note that a 2 speed R-1830 running on 100 octane had a max continuous rating of 1100hp at 6100ft in low gear and and 1000hp at 12,500ft in high gear. The R-2180 twin Hornet was about 150lbs heavier and about 3 1/2 in larger in diameter. The post war version (1/2 of an R-4360) certainly made more power, it also weighed around 200lbs depending on which models you compare. It may have needed manufacturing techniques pioneered with the R-2800 C.

As an engine for army fighter, the R-2180A will get a turbo to help out.

 

[Admiral Beez]

Ki-45 was 'heavy' in sense that it used a lot of engine, but not in sense of bringing out a lot of firepower

I didn't mention the IJAF heavy fighters because they were any good. These were their twin engine fighters that we're needing to either replace or entirely delete.

 

[Shortround6]

As an engine for army fighter, the R-2180A will get a turbo to help out.

The R-2180 was 19% bigger than the R-1830 but ran 92.6% as fast, power is going to be about 10% higher unless something changes.
This is probably why P & W tossed it in the Bin and went for a bigger engine. The R-2180 and the R-2800 use the same bore and stroke.
The R-2800 is basically (ver, very basically) an R-22180 with two extra cylinders per row.

 

[Admiral Beez]

They don't have a chance, they had no large, high power engine is service or about to be in service at the point in time the Ki-45 was designed.

Is it an unlikely evolutionary leap to get to an engine in service by early 1942 that can support a Japanese single-engine heavy fighter? Something with armour, six or eight guns/cannons, bombs, 400 mph top speed, etc?

Can't we just add another bank to the 14 cylinder Mitsubishi Kinsei and Kasei or another nine pot bank to the 18 cylinder Nakajima Homare?

 

[wuzak]

The post war version (1/2 of an R-4360) certainly made more power, it also weighed around 200lbs depending on which models you compare. It may have needed manufacturing techniques pioneered with the R-2800 C.

Only 200lbs for a 1,000hp+ radial engine. Sounds like a winner! A great option for a fighter.

The R-2180 was 19% bigger than the R-1830 but ran 92.6% as fast, power is going to be about 10% higher unless something changes.
This is probably why P & W tossed it in the Bin and went for a bigger engine. The R-2180 and the R-2800 use the same bore and stroke.
The R-2800 is basically (ver, very basically) an R-22180 with two extra cylinders per row.

I think the R-22180 is more of a bomber engine. Much to big for a fighter!

 

[tomo pauk]

The R-2180 was 19% bigger than the R-1830 but ran 92.6% as fast, power is going to be about 10% higher unless something changes.
This is probably why P & W tossed it in the Bin and went for a bigger engine. The R-2180 and the R-2800 use the same bore and stroke.
The R-2800 is basically (ver, very basically) an R-22180 with two extra cylinders per row.

1400 vs 1200 HP is a 16% increase. 1500 HP (rpm 2600 vs. 2500) version was in pipeline before cancelled pre-war (data sheet attached).

They don't have a chance, they had no large, high power engine is service or about to be in service at the point in time the Ki-45 was designed. Their big bomber engines only offered a few hundred more HP than their fighter engines and sometimes not even that.

In late 1941, Kasei 11 was more ~60% more powerful than Sakae, and 70% more powerful than Zuisei (two of those powered one Ki-45). A lot of power to install not just two cannons, but also a good fuel tank and protection.
The Ha-41 can offer 30% more power than Sakae.

 

[Shortround6]

you are applying the retrospectroscope.
What were the available engines or engines in prototype form when the development of the twin engine planes was started.

The work on the Ki-45 was started in 1937, a Mock up was inspected in Dec 1937 and the Army oredred a prototype which first flew in Jan 1939 (not very well, lots of modifications needed) but the question isn't what engines were available in late 1941 but what were available in early 1939 or likely to be available in late 1939 or early 1940.

You can look at many WW II aircraft and say they were not designed well if you compare them to a plane using an engine 12-18 months later in timing.

 

[swampyankee]

Is it an unlikely evolutionary leap to get to an engine in service by early 1942 that can support a Japanese single-engine heavy fighter? Something with armour, six or eight guns/cannons, bombs, 400 mph top speed, etc?

Can't we just add another bank to the 14 cylinder Mitsubishi Kinsei and Kasei or another nine pot bank to the 18 cylinder Nakajima Homare?

Possibly, but there does seem to be a dearth of aircraft radials with three rows. I suspect that going from 14 cylinders to 18 cylinders or from 18 to 22 would be easier, albeit still difficult. (there's also a paucity of 22 or 11 cylinder radials, so that may be too difficult).

 

[tomo pauk]

you are applying the retrospectroscope.
What were the available engines or engines in prototype form when the development of the twin engine planes was started.

The work on the Ki-45 was started in 1937, a Mock up was inspected in Dec 1937 and the Army oredred a prototype which first flew in Jan 1939 (not very well, lots of modifications needed) but the question isn't what engines were available in late 1941 but what were available in early 1939 or likely to be available in late 1939 or early 1940.

You can look at many WW II aircraft and say they were not designed well if you compare them to a plane using an engine 12-18 months later in timing.

(my bold)
Kasei was certainly available in 1939, the prototype of G4M flew with it.

 

[swampyankee]

When someone says "what engine is available?" do they mean

• In production (cranking them out by the tens),
• In certification testing (say, the 150 hour certification test),
• In development testing (first run), or
• Prototype construction ("we'll run next month...")?

These are some reported first-run dates, according to Wikipedia or the AEHS. Obviously, the "single-engined heavy fighter" would only be able to use a few of these.

Pratt&Whitney

• R-985: 1929
• R-1340: 1925
• R-1535: 1932
• R-1690: 1926
• R-1830: 1932
• R-1860: 1929 (this engine was considered less than successful)
• R-2000: 1942 (this was an R-1830 with an increased bore)
• R-2060: 1932 (experimental liquid-cooled engine; no production)
• R-2180A: ? (this was based on the R-1690)
• R-2180E: 1945 (this was based on the R-4360 and R-2800)
• R-2800: 1937
• R-4360: 1944
• XH-2600: 1940 (not produced)

Curtiss-Wright

• R-540: 1929
• R-760: 1929
• R-790: 1923
• R-975: 1929
• R-1510: 1933
• R-1670: 1934
• R-1300: 1942
• R-1750: 1926 (developed into R-1820)
• R-1820: 1932
• R-2600: 1935
• R-3350: 1937
• R-4090: 1944?
• R-2160: not before 1944

Allison

• V-1710: 1930
• V-3420: 1937

Continental:

• IV-1430: 1939

Lycoming:

• O-1230: 1937
• H-2370: ? (1940?)
• R-7755: 1944

Bristol:

• Hercules: 1936
• Aquila: 1934
• Centaurus: 1938
• Perseus: 1932
• Taurus: 1936

Rolls-Royce

• Merlin: 1933
• Eagle XVI: 1925
• Kestrel: 1926
• Peregrine: 1938
• Vulture: 1937
• Griffon: 1939
• Pennine: 1945
• Exe: 1936
• Crecy: 1941

Napier

• Sabre: 1938

Somebody else will have to do German, Italian, Japanese, Soviet, and French engines.

Of these, I think the few that could be used for an aircraft being designed in 1938 would be:

• Merlin
• Vulture
• Exe
• R-2600
• R-3350
• R-2800
• Centaurus
• V-3420

 

[Shortround6]

(my bold)
Kasei was certainly available in 1939, the prototype of G4M flew with it.

From Wiki.

• MK4A [Ha-32] 11

1,530 horsepower (1,140 kW), 2450 rpm at takeoff
1,410 horsepower (1,050 kW), 2350 rpm at 1,000 metres (3,300 ft)
1,380 horsepower (1,030 kW), 2350 rpm at 4,000 metres (13,000 ft)

First flight of the G4M 23 October 1939. Obviously the engine was known about well before the G4M flew but it was also a bit smaller than a Wright R-2600 in diameter (2 in?) and several hundred pounds lighter for perspective.
It may have been a better option than the two 9 cylinder engines first used in the Ki-45 design which were quickly replaced by Sakae engines which were replaced by Mitsubishi Zeisei engines.

From Swampyankee's list

• Merlin
• Vulture
• Exe
• R-2600
• R-3350
• R-2800
• Centaurus
• V-3420

the R-3350 and Centaurus can be taken out as any plane designed for the 1938 versions is years away from production. Wright for example added 2 inches to the length of the crankcase (and crankshaft) on the R-3350 in order to make room for vibration dampers. The engines used in the B-29 were much different than the first handful of 1938/39 engines.

 

[swampyankee]

From Swampyankee's list

• Merlin
• Vulture
• Exe
• R-2600
• R-3350
• R-2800
• Centaurus
• V-3420

the R-3350 and Centaurus can be taken out as any plane designed for the 1938 versions is years away from production. Wright for example added 2 inches to the length of the crankcase (and crankshaft) on the R-3350 in order to make room for vibration dampers. The engines used in the B-29 were much different than the first handful of 1938/39 engines.

Those were engines that one could design a fairly "heavy" fighter around without its performance being too pathetic. In retrospect, the Merlin is probably on the small side, as is the (not listed) Allison V-1710. The Exe and the Vulture were, clearly, not terribly well developed and both needed a lot of work to be ready for service use. Were I a US designer, I'd probably start with the R-2600 and then switch to either the R-3350 or R-2800 (the latter would be much easier) for subsequent versions. The Sabre's first run (I completely missed Napier's engines ) was in 1938, so it should be on my list.

 

[Shortround6]

I agree that designers could try to work with those engines, however producing a successful design (one that goes into production) might be a lot harder with some.
There were number of British plans and prototypes that crashed and burned (figuratively) with the Sabre as the engine failed to be developed in time and then the low scale production forced all supplies to be channeled to the Typhoon.

 

[swampyankee]

I suspect part of Napier's problem was that the company's engineering pool was quite shallow, and the Sabre had a lot of novelty going on. While Napier had done H engines before, they hadn't done sleeve valves.

 

[Shortround6]

All of the Napier H engines were designed by Major Frank Halford. I believe (open to correction) that he was operating as a consultant and not a direct employee of Napair.
Let's remember that the Man you designed the Napier Lion had jumped ship and joined Rolls Royce around 1930. In house idea men were short supply and even the men who did the grunt work ( stress and vibration) seem to have been a bit thinly stretched.

 

[wuzak]

All of the Napier H engines were designed by Major Frank Halford. I believe (open to correction) that he was operating as a consultant and not a direct employee of Napair.

And Frank Halford designed the Halford H.1 jet engine for de Havilland, which became the de Havilland Goblin I in production.

Let's remember that the Man you designed the Napier Lion had jumped ship and joined Rolls Royce around 1930. In house idea men were short supply and even the men who did the grunt work ( stress and vibration) seem to have been a bit thinly stretched.

Arthur Rowledge, who left Napiers for Rolls-Royce in 1921.

 

[Admiral Beez]

What about another angle. If two engine fighters are out, what about three engine fighters?

Some what ifs I found online....googled "three engined fighter"

 

[Shortround6]

Dear supreme being and merciful lord,

Please save us from photoshop and other composite creations that have no relation to the real world.

Hallelujah and Amen.