Kawanishi N1K1-J with Kasei ??

When the Mitsubishi Kasei powered Kawanishi N1K1 floatplane was re-purposed into a land based fighter one of the changes made was replacing the original engine with a Nakajima Homare engine.

What if the designers for the N1K1-J had stuck with the Kasei engine instead of the Homare?? Later versions of the Kasei were rated 1850 HP, almost as much as the 1990 HP book value for the Homare. Considering reports of manufacturing issues with the Homare, the actual power from a Kasei might have been as much as a Homare.

But what would have staying with the Kasei in the N1K1-J have done to weight and balance issues, fuel consumption, maneverability, etc.???

My opinion is that a Kasei powered N1K1-J would have been just a good as the historic Homare powered fighter and a lot less trouble.

When the Mitsubishi Kasei powered Kawanishi N1K1 floatplane was re-purposed into a land based fighter one of the changes made was replacing the original engine with a Nakajima Homare engine

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Original engine, as fitted in N1K1 floatplane, gave 1460HP. It is likely that the more advanced versions you refer to were not fully developed and that it would take certain time before they became available. The version you refer to did not see much use, so it is difficult to say how it would have fared. In any case, theShiden had a lot of problems with manufacturing and reliability.

I've read a interview with Saburo Sakai, he had a very low opinion of the Shiden, but he only mentioned build quality issues.

alejandro_ said:

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Original engine, as fitted in N1K1 floatplane, gave 1460HP. It is likely that the more advanced versions you refer to were not fully developed and that it would take certain time before they became available. The version you refer to did not see much use, so it is difficult to say how it would have fared. In any case, theShiden had a lot of problems with manufacturing and reliability.

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It looks like all of the Kasei 20 series engines, such as the Kasei 22, were rated at 1850 HP. The H8K2 flying boat had them, and as far as I know, it appeared in the late 1943 early 1944 time frame. Agreed, the change in engine would not have helped with build quality in the rest of the airplane.

That is very interesting! I did not know that the floatplane had the Kasei.

Of course the Kasei was considered to be unsuited for fighter planes because of its very wide diameter. But then the guys at Mitsubishi proved them all wrong by fitting it into the J2M Shiden, which was an excellent fighter plane.

So technically, it should have been possible, but I guess the guys at Kananishi simply believed it couldn't be done.
Kris

Considering the fact that most of Japanese fighters in 1943, and maybe in 1944, were Oscars and Zeroes, Kasei + Shinden seem like a gift from the gods in that time frame. Even later if/when more powerful variants of the engine can be installed.

This sounds like an interesting idea. The fuselage of the N1K1-J would not be wider as it could already take the Kasei in its N1K1 float-plane form (althought the shape would need to change). Thus if the Kasei gave the same power as the Homare, we might expect the same performance. The problem with this is that, at least according to sites such as q‹ó‹@ƒGƒ"ƒWƒ"ˆê——E"ú–{ŒR, the Homare was significantly more powerful than the Kasei, especially at medium to high altitudes. For the military power we have 1300 hp at 5500m at 2500 rpm for the Kasei 21 and 1700 hp at 6400m at 3000 rpm for the Homare 21. A R-2800-10 may give an early F6F-3 1,800 at 2,700 rpm at 15,500 ft according to Wikipedia (WEP?), so we might expect a slightly smaller N1K2-J to go slightly faster with roughly the same power.

However, it is widely reported that the Homare did not show the expected power at high altitudes and the J2M5 with a Kasei 26a was considered superior to the N1K1-J as a B-29 interceptor although that Kasei is only quoted as giving 1310 hp at 7200m.

So what is going on? It appears that the problem is not due to fuel or to the water/methanol injection system as those are only relevant below the rated altitude. Poor quality bearings might cause engine failure but the power should be there until the engine blows up. By elimination I am guessing that the problem may be that the production superchargers on the Homare did not actually supply the calculated charge (does anyone have a better suggestion?).

This leaves us with the typical problem of not knowing the real performance of a late war Japanese aircraft powered by the Homare with a wide range of possible speeds and, if we take a speed, we equally do not know if it could be matched by a Kasei powered aircraft.

If we want to create an earlier acting what if, we might assume that Inoue Shigeyoshi had different views and rejected the idea of a floatplane fighter. We assume that he wanted to convert all the IJN's floatplane carriers into aircraft carriers (Chitose, Chiyoda, Nisshin and perhaps even Mizuho) and wanted an aircraft able to combine the role of fighter with dive bombing (alternatively, he believes that the Battle of Britain has shown that specialized divebombers are too vulnerable). Thus in September 1940, instead of offering the specification leading to the N1K1 to Kawanishi, he asks them to produce a fighter powered by the Kasei with the ability to carry a 250 kg bomb to a target at 400 km. What the IJN gets is a Kasei powered N1K2-J flying in very early 1942 (earlier than the N1K1 because of not having a contraprop) and arriving in service in early 1943.

The early Homare engines suffered from production quality control problems affecting the intake passages. Other engines were also affected, but the effect on the Homare was larger because of the high engine rotational speeds that the engine was intended to operate at.