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They were rare.I'd say that the Merlin X in 1938, as well as the 1940-vintage M-105 and M-88 with 2-speed S/C were very, very rare engine types.
Now the information in Jane's is certainly not enough to design anything but it shows the potential benefits and it shows them using 87 octane fuel.
Maybe the Japanese were too busy just getting the 14 cylinder radials to work with single speed superchargers?
But taking 3-4 years just to get a 2 speed drive on a supercharger is slow progress.
The first Soviet two-speed SC was introduced by Mikulin on the M-34 in 1932. Two-speed SCs were installed on the M-62 (1937), M-63 (1938), M-64 (1939), M-65 (1939), M-81 (1939), M-82 (1940), M-88 (1938), M-104 (1939), and M-105 (1940).By 1940 the Soviets were building two speed superchargers on the M-105s and on the M-88 radials and planning them on the newer engines.
No, two speed. One impeller driven by a two gear ratio drive system.But I have a suspicion that what is really meant is two-stage superchargers...
Not that a great an achievement although it does show that keeping up the rest of the world was important to the Soviets.Two-speed SCs were installed on the M-62 (1937), M-63 (1938), M-64 (1939), M-65 (1939)
I never told about a great achievement. Just mentioned that _even_ the Soviets had six engines with 2-speed SC in mass production (or close to the adoption to mass production or already cancelled mass production) to 1940.Not that a great an achievement although it does show that keeping up the rest of the world was important to the Soviets.
The 2-speed SC was not succeed, whereas the single-speed one worked properly.The supercharger used in the M-34 didn't work. Problem with the drive or problem with the supercharger itself????
The thing is that using a 2 speed supercharger is an easy "fix",IMO - Japanese figured out how to make very good, if not excellent radials; their problems were allocation of the engines (leaving most of the fighters with weak engines), inability to make them as much as they needed, and insisting too much with low-powered types until too late; yes, the superchargers used were not up the task from 1944 on.
As always, good comment. I would also like to add that the frontal areas of Japanese engines were oftentimes very small, compared to similar output engines from other nations. As pointed out by Greg (from YouTube, not these forums), some of the better Japanese engines used RPMs to achieve higher output and lower displacement/frontal area. In general, Japanese aero engines were very well engineered and of technical sophistication similar to countries in the West.Japanese engines were getting pretty good power/weight ratios as a rule, Homare is nothing out the ordinary for them. The feather-weight Kinsei 60s were making 1600-ish HP with water injection, for example; the Ha 109 was also very light for a 1500 HP engine on 91-92 oct fuel and no ADI.
Later in the war, effect of direct and indirect Allied 'brake' to the supply of the raw materials (nickel, chromium, tungsten etc.) + bombing + suspicious octane rating of the fuel (91-92 oct was the 'book' value, the actual oct value was ??) + dubious supply of spare parts = it will be a miracle if the book values were obtained in everyday service.
Homare was noted as 'new tech' engine, perhaps the 'old-tech' 18 cyl Ha 104 was less susceptible to the glitches, while weighting 25% more - sometimes going conservative has it's appeal.
Western engines, like the R-2800 or BMW 801, might've been over-built? Nothing wrong with that, but it might result in the over-weight an/or over-sized fighters. The 2-stage B-series R-2800s were with small impellers, that were also not refined (the straight vanes, instead of the curved ones), so it might be argued that a more refined and big impeller on the Homare was as good as it gets.
As always, good comment. I would also like to add that the frontal areas of Japanese engines were oftentimes very small, compared to similar output engines from other nations. As pointed out by Greg (from YouTube, not these forums), some of the better Japanese engines used RPMs to achieve higher output and lower displacement/frontal area. In general, Japanese aero engines were very well engineered and of technical sophistication similar to countries in the West.
What Greg didn't mention is that Japanese engines have higher oil consumption. The big reason is that Japanese engines have loose tolerances. Meaning, they aren't as tightly sealed and fitted as US and British engines. The loose fit is because of economic reasons. Rather than relying on expensive imported industrial equipment, Japan's war machine relied on a large number of less expensive skilled machinists. Because of hand finishing, their engines had looser tolerances and leaked oil constantly.
And that's an understatement.Seems a bit oversimplified.
I know the Ha-43 was also high RPM but I think there may have been other prototype late-war models that had over 2,800 RPMs.
Steve Twomey's excellent Countdown to Pearl Harbor focuses on how that attitude help make the Pearl Harbor attack possible.And that's an understatement.
The intellectual damage done by many American and British authors in the 20th century when describing non-American and non-British ww2 stuff cannot be overstated. Also, a lot of them haven't limited the damage done by themselves just to the non-Anglo-American stuff.
It's amazing how invulnerable the J8M is, and how instantly effective it and the Zeros are against the usually sturdy B-29s and P-51s.If we talk about the speed only, including such an experimental model like A7M, here is J8M with 890km/h.
Combat result with a P-51 would have been like this
View: https://www.youtube.com/watch?v=c1Pi6cxiLbU&t=23s
The Ha-43 had the smallest frontal area relative to output out of all 2,200-HP radials at the time of its production, even compared to prototype radials from other nations. But it wasn't reliable nor was it fully developed due to a lack of official support from the Japanese military IIRC (their brass had picked the Homare over the Ha-43 for most applications). It's important to note that a key US advantage was in being able to cost effectively build high performance, high reliability hardware in massive numbers.This is all in light of Japanese engines, late-war examples in particular, supposedly being similarly powerful to Western counterparts.