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Not sure.What problem should've the sleeve valves solve for the Japanese?
Air cooled sleeve valve engines seemed to weigh a bit more more per displacement, but put out 10-15% greater power for said displacement.
Their diameters were about the same as - or a bit smaller than - a poppet valve engine of equivalent power?
Sleeve valve engines seemed to be able to run reliably at a bit higher rpm.
'British' in this case are Bristol, and Napier and RR. Bristol did a good job, Napier and RR did not - Sabre was depenant on Bristol-made sleeves, while Exe was neither a powerful engine nor it was trouble-free.From what I am aware of, the Japanese would not have had any particular problem manufacturing sleeve valves and their drive train - at least no any more than the British did.
For military-grade high power engines?From what I am aware of, the Japanese would not have had any particular problem manufacturing sleeve valves and their drive train - at least no any more than the British did.
What stroke, rpm, number of cylinders, displacement, power and weight are the targets?Also, the British followed a particular design philosophy for their engines (for the most part) but that does not mean that the Japanese had to follow the same philosophy. An example is that they could have used a shorter stroke for their sleeve valves engines, solving a significant part of the higher rpm problem that the British ran into with the Taurus, allowing greater power to weight (maybe) and reduced diameter (drag), if they could solve the cooling issues.
Have the British really concluded that?Plus, what would the US and UK development timeline of the sleeve valve vs the poppet valve have been like if they had been limited to lower quality avgas? In theory at least, the British concluded that the sleeve valve held significant advantages when both types of engines are limited to 87, 91, 93 octane.
Yes.For military-grade high power engines?
That I cannot answer definitively. It depends too much on when we are talking about starting the development. Did the Japanese see a need for a larger engine in the original timeline 1936? In our alternate reality are we saying that they did?What stroke, rpm, number of cylinders, displacement, power and weight are the targets?
Have the British really concluded that?
Is there a good & easily available source that covers the Japanese sleeve-valve military-grade high-power aero engines ?Yes.
Ho-5 was relatively big for the time, 37.5L. From Japanese Wikipedia (never mid the longevity commnet):That I cannot answer definitively. It depends too much on when we are talking about starting the development. Did the Japanese see a need for a larger engine in the original timeline 1936? In our alternate reality are we saying that they did?
Sakae 12 was a 1701 in3 displacement engine that gave 940 BHP for TO and 950 BHP at 13,800 ft.
Sakae 21 gave 1020 BHP for TO, 1100 BHP at 9,300 ft, and 980 BHP at 19,800 ft.
Taurus II was a 1550 in3 displacement engine that gave 1130 BHP for TO and 1050 BHP at 5000 ft.
All three engines weighed ~1300 lbs+/-.
The Taurus II was rated on 87 octane, while the Sakae was rated on 92 octane. (The Taurus XII was a detail improved II, and the improvements seemed to have resulted in a very reliable engine.)
The Japanese superchargers were significantly better than the Bristol counterparts of pre- and early-war. Match the equivalent single-stage single-speed Sakae 12 or the single-stage 2-speed Sakae 21 supercharger to a 1701 in3 Taurus? RPMs and ultimate BHP would depend on how well the Japanese solved the cooling problems - from what I have read the Sakae 12/21 had no significant problems running at 950/980 BHP for prolonged periods.
What would the rating be on the Japanese O Ushi-Za engine (1701 in3 Taurus) with the better supercharger and 92 octane?
Japanese taking note on the 2-stage supercharged European engines of the 1930s for altitude records (Bristol Pegasus of such flavor including) would've gave them a far better return of investment than going with the sleeve valves.OK, OK, not the British, but the various parties involved in the development of the sleeve valve engines in Britain.
The problem is that the Nakajima people were trying to build the highest output radial engine on a power per liter basisNo problem as I see it.
The way I read it, it is a veiled praise to the Nakajima people.
Nakajima tried with the Mamoru. A 55L engine, a bit heavier than the Homare, 200mm greater diameter. Here is from the Japanese Wikipedia, my edit:
Despite the fact that it was under development, Nakajima strongly requested that it be installed in the Tenzan and Fukayamamountains[aircraft], but production was discontinued after only 200 units due to the lack of the specified output, high vibration, lack of reliability, and a series of failures.
Use the Kasei on a fighter, and hope for 380 mph as-is?
A 'classic' 18 cyl engine, like the Ha 42, was 110-120 kg heavier than the Homare, of a greater diameter, and was supposed to be as good on just 92 oct as the Homare was on 92 oct + ADI. OTOH, Nakajima made far more Homares than what the production of the Ha 42 was - Mitsubishi getting rid of the Zuisei might've increased the tempo of the Ha 42 production.
The 'no free lunch' rule applies as ever.
Is there a good & easily available source that covers the Japanese sleeve-valve military-grade high-power aero engines ?
The problem is that the Nakajima people were trying to build the highest output radial engine on a power per liter basis
of all of the engine manufacturers in all of the countries.
While building the lightest high powered radial on a power to weight basis.
While using among the worst fuel. (Germans were using better ? fuel in the BMW 801)
While suffering from raw material shortages.
What could possibly go wrong
Wright had a lot of trouble with the so called 'easy' R-3350 even after 6 years of development.
The Mamoru used the same diameter cylinder as an R-2600/3350 but used 10mm more stroke.
The same stroke as the Kasei/Ha 42.
Japan waited too long to really address the big engine problem. The Homare sounds good on paper, but it is a very ambitious engine.
Something a bit less ambitious might have gone into service sooner or had less trouble in service.
So the question is could Mitsubishi have made a reliable 2400 ps A18E by late 1943 if they had been paid to do that and only distracted by the Kinsei 60 and Kasei 20 series? The A18E (Ha-214) was 1,340 mm wide and weighed 1,235 kg. For comparison, a Centaurus VII had a 1,405 mm diameter and weighed 1,222 kg. The Centaurus was more powerful but a Sea Fury with a reliable A18E would still be formidable even if one of its tanks had to hold water/methanol.
A good example of this I always cite is the Sakae 31. The Navy couldn't get it to work until mid-1945, meanwhile the army got it on the Ki-43-III by the beginning of 1944. Obviously better engine choices existed, but this is a strong example for me personally. Co-operation would mean a working A6M6 by The Battle of the Phillippine Sea.To begin with - cooperation between the army and the navy without duplicating development, the same calibers of weapons and so on.
For example, Daimler sold an aircraft engine license to the Army (Kawasaki) and the Navy (Aichi)!
Japan is the only nation whose military had aircraft carriers and whose navy had ground forces (and I don't mean the SNLF as marines).
We can say that Germany lost the race in the development of the atomic bomb because they had 5 ? independent and non-cooperating teams, but Japan had two parallel military forces that (mostly) did not cooperate.
A fairly early but possibly not immediately published report came from Colonel Henry Watson, who was not impressed when he tested a G8N1. The turbosuperchargers had been disabled by Japanese engineers before the surrender, presumably because of unreliability. He reported that the engines would sometimes surge, pitch control of the propellers was difficult and de-feathering was not possible. Three of the engines would not deliver full rpm and all four had to be frequently readjusted as throttle and fuel feed controls would wander. Engine temperatures were erratic and each had to have its cowl flaps individually adjusted. Even with cowl flaps closed, the aircraft vibrated seriously, which Watson was advised was endemic to the engines, which he was unable to keep synchronised (all from Goodwin and Starkings, page 180).@ anyone - what was the 1st known instance that 'Homare is/was unreliable' appeared in the Western press?
Thank you.A fairly early but possibly not immediately published report came from Colonel Henry Watson, who was not impressed when he tested a G8N1. The turbosuperchargers had been disabled by Japanese engineers before the surrender, presumably because of unreliability. He reported that the engines would sometimes surge, pitch control of the propellers was difficult and de-feathering was not possible. Three of the engines would not deliver full rpm and all four had to be frequently readjusted as throttle and fuel feed controls would wander. Engine temperatures were erratic and each had to have its cowl flaps individually adjusted. Even with cowl flaps closed, the aircraft vibrated seriously, which Watson was advised was endemic to the engines, which he was unable to keep synchronised (all from Goodwin and Starkings, page 180).
Page 10 of the T-2 Report on the Ki-84 notes that pilots had no lack of confidence with the Homare engine during testing, but this is post-war US testing with a nearly ideal Ki-84 running on 96 octane so take it with a grain of salt.Thank you.
Is there anything about the Homares on the 1-engined aircraft?