Japanese doing things different in for before and during ww2?

[tomo pauk]

...
However, if we are into fantasy, a Ki-61 powered by a DB 605A and with a radiator designed following the principles first suggested by Junkers (and used in Bf 109F) but called the Meredith Effect in Britain and the USA might be interesting. For late war, we could have a DB 605 D with a radiator copied from a P-51 (we know that a Spitfire V flew well with a DB 605, so the radiator should work).
...

We can argue that radiator of the Ki-61 used Merredith effect, people at Kawasaki were quick to come out with a radiator much improved over what Ki-60 had. What they lacked on the Ki-61 was the boundary layer splitter.
Japanese judged that Ki-61 with Ha-140 (=1250 HP at 5700m - same as the DB 605A on 2600 rpm) will gain 30 km/h vs. the one with Ha-40, -> 610 km/h. The 16% thick wing (at root), with same series of 2R profiles as on the Bf 109, was probably not all that conductive for very high speed on what was a modest power for 1944 and on.
Granted, the DB 605D will add to the performance, especially with water/alcohol injection - quirk being getting it in Japanese service in numbers and in time.

 

[tomo pauk]

(I knew there is another Japanese what-if thread around ...)

If the Ki-44 still enters the production, install the 2-speed Sakae (yes, Army used different nomenclture for basically the same engines) on it so the Ki-43 can be phased out from production by 1943. Will roll and dive much better than Ki-43, while possesing better speed and firepower, and representing a smaller target. With hopefully the DB 601 saga not happening at Kawasaki, the Ki-60 and Ki-61 need to be designed around a radial engine from the get go.
Ha-109 engine needs to replace the Sakae engine as the most-produced Nakajima's engine sometime in 1943, that by 1944 is outfitted with water injection.

No J1N Gekko (Irving), no Saiun (Myrt) - IJN use instead the Suisei (Judy) for night fighting and LR recon job. Make the Homare-powered Suisei recon and NF by early 1944, and have Kinsei-powered Suisei ASAP (ideally, the DB 601/etc sorry saga does not happen at Aichi).

 

[yulzari]

Training, training, training.

 

[tomo pauk]

The possible Ki-60-II (a Ki-60-based fighter powered with Ha-115 engine, same as the Ki-43-II). Wing area 174 sq ft, vs. 179 for the Ki-44 and 230 sq ft for the Ki-43. Four Ho-103 HMGs, speed in-between the Ki-44-II and Ki-43-II, ie. ~570 km/h.
(bash between Ki-43 front and Ki-60 rest)



Next is the alternative J2M, with 'normal' engines (ie. no extension shaft and fan) and better canopy. Not my work, found it on the 'net years ago:

 

[cherry blossom]

The possible Ki-60-II (a Ki-60-based fighter powered with Ha-115 engine, same as the Ki-43-II). Wing area 174 sq ft, vs. 179 for the Ki-44 and 230 sq ft for the Ki-43. Four Ho-103 HMGs, speed in-between the Ki-44-II and Ki-43-II, ie. ~570 km/h.
(bash between Ki-43 front and Ki-60 rest)

View attachment 609886

Next is the alternative J2M, with 'normal' engines (ie. no extension shaft and fan) and better canopy. Not my work, found it on the 'net years ago:

View attachment 609887

I tried a different method of producing a J2M without the extension shaft by imagining a Kasei powered F8F in this post Japanese Zero vs Spitfire vs FW 190 which produced several informative replies. My idea was that we have the Bearcat's performance at normal rating, well below the WEP rating, and that a late Kasei flat out gives approximately the same power as an R-2800C at normal (max continuous) rating. Replies pointed out two weaknesses to my argument: Firstly that the R-2800C had less cooling drag than the earlier R-2800 and possibly less cooling drag than the Kasei and secondly that Japan may not have been able to manufacture as efficient a propeller as that of the F8F.

 

[tomo pauk]

I tried a different method of producing a J2M without the extension shaft by imagining a Kasei powered F8F in this post Japanese Zero vs Spitfire vs FW 190 which produced several informative replies. My idea was that we have the Bearcat's performance at normal rating, well below the WEP rating, and that a late Kasei flat out gives approximately the same power as an R-2800C at normal (max continuous) rating. Replies pointed out two weaknesses to my argument: Firstly that the R-2800C had less cooling drag than the earlier R-2800 and possibly less cooling drag than the Kasei and secondly that Japan may not have been able to manufacture as efficient a propeller as that of the F8F.

Ideally, Japanese should've copied Fw 190 (yes, I'm boring now with that proposal ), powering it with Ha-109, Homare, Kasei, Kinsei...
Raiden strikes me as a superfluous aircraft. Mitsubishi and other companies should've been making the next-gen carrier-borne fighter (to replace the Zero) that could be also used from land bases- Granted, the IJN's blessing is needed for this. Shove the Kinsei 50 series on the Zero in the meantime, the same engine the G3M3 had already in second half of 1941.

Back to the Raiden itself. The fuselage was too thick, in fashion of F4F and F2A, instead in fashion of the Zero, Hayate or Fw 190. Big fuselage will also mean that retrofit with a narrower engine will gain nothing.
I'm not sure how and when the water injection was used with regard to the speed data by Japanese, either. American data claims speed of 410+ mph with water injection ( ~1780 HP at 16600 ft) and around 400 mph at 1560 HP, while Japanese data states 365-370 mph on ~1500 HP at altitude for later models.
Using the 'ordinary' Kasei woukd've shaved some weight from engine vs. the Kasei that was used, and, more importantly, would've made job much easier for the Mitsubishi's engines' branch.

Wing of the Bearcat was 19% thick at the root, I'm not sure that is better than what Japanese had on their fighters' wings (bar Ki-43 and N1K?). Bigger/better prop should've help, but probably more for climb rather than for speed. Seems like Haytate's prop was doing it's job fine.

 

[cherry blossom]

A smoothly curved fuselage might have lower drag than a narrow cylindrical design CELERA 500L — OTTO AVIATION. However, the Fw 190 uses its exhaust and cooling air reduce the drag of its tapering fuselage. I am almost tempted to enter the how could a plane be better designed thread and suggest that the P-39 could have been a world beater if its extension shaft had been pointed back to create a pusher.

 

[P-39 Expert]

A smoothly curved fuselage might have lower drag than a narrow cylindrical design CELERA 500L — OTTO AVIATION. However, the Fw 190 uses its exhaust and cooling air reduce the drag of its tapering fuselage. I am almost tempted to enter the how could a plane be better designed thread and suggest that the P-39 could have been a world beater if its extension shaft had been pointed back to create a pusher.

Bell did that on the ill-fated Airacuda that preceded the P-39. Larry said that pilot interviews revealed that they didn't like the propeller in back, feared problems on bail out.

I always liked the pusher arrangement, whether flying wing, canard or twin boom arrangement.

 

[tomo pauk]

A bit about the engine production, this time what was made at Mitsubishi. They were producing 3 separate families of 14 cyl engines that were their own design, one 18 cyl design, while trying to come out with a brand new 18 cyl engine (Ha 43) of small diameter and with all sorts of superchargers (1-stage, 2-stage, turbo added), plus a pusher version. Kasei was made as 'vanilla' engine, then as a counter-rotating prop version, and the extended shaft with fan version.
They also made Ha-5 engine under licence (Nakajima's design).
Let's try to slash the number of engine types here. IJN and airframe companies need to forget the fancy versions of the Kasei. The Zuisei was installed in either obsolete aircraft (like the 'Pete' floatplane biplane), or was installed in 2-engined A/C, like the Ki-45 fighter. The Ki-45 was not that a great fighter, for the two 14-cyl complete powerplants installed and the resulting airframe it offered neither performance nor firepower. Thus we'd have the IJA requesting 1-engine cannon-armed fighters exlusively (basically Spitfire equivalent, not Whirlwind equivalent) from Kawasaki instead already in 1940. Install some cameras on it so it can do the recon job (again taking the page from Spitfire), thus very much negating the need for the Ki-46. That way the production of the Ha-31 engines can be phased out at Mitsubishi by some time in 1942, with Ha-33 ('medium' 14 cyl) and -32 lines ('big' 14 cyl) production increase by many dozens and then by hundreds a month by 1943. (yes, shamelessly mimicking the Peregrine cancellation back at RR)

FWIW,some production tables:

 

[tomo pauk]

The 'alt Ki-109' - Sakae engine installed on the Bf 109V21 airframe. Initially two 7.7mm under the cowling, two 12.7mm in the wings. 485L fuel + drop tank facility.
(not my work, past where the guns should go)

 

[tomo pauk]

A little bump, hopefully other people also have constructive stuff to post

 

[tomo pauk]

Guess we'd rather move the current conversation here

The Army tells the aircraft maker what guns they want, not the other way around. For some strange reason the Japanese Army and the Navy hardly ever (if ever) agreed on guns.
The type 92 7.7mm machine gun may have been the last time. The Zero's cannon were manufactured in a plant owned by ex navy officers.

All of that is very true.

The engines used in the Ki-45 were not quite the same power as the as the Zero, subtle but true. The two first Zero prototypes used the Mitsubishi engine that was later used in the Ki-45, but it didn't provide enough power at the time and Mitsubishi had to use the Nakajima engine.

To the best of my knowledge, the 800 HP Zuisei (or whatever is the Army designation) was never installed on a Ki-45. The lowest power engine on the Ki 45 being the ill-conceived Ha 20 (820 HP at 3900m), and then the Ha 25 on actual machines (970 HP at 3400m, same as on the Ki-43).
The 2-speed Ha-102 ('main' engine on the Ki-45) was doing 950 HP at 5800 m vs. the Ha-115 (on Ki-43-II) 980 HP at 5600m, and vs. 980 HP at 6000m (Sakae 21 on the A6M3 and 5; later Sakaes were better).

(added: the earliest mention of a Ha 102 engine that I'm aware is the competition of the Ki-46-II, that happened in March of 1941; deliveries of the Ki-46-II started in July of the same year - that is one month before the Sakae 21-powered zero was delivered; Zuisei was just a tad smaller and lighter than Sakae)

After all of this back and forth - the earlier the Zuisei is either forgotten or outsourced, the better.

The Ki-45 might well have benefited from a change in armament. That modified antitank gun under the belly wasn't doing it any favors in air to air combat. It was almost as powerful as a Hispano but fired a lot slower (rate of fire).

Several options - all-HMG battery, or two 20mm cannons with big drums? But then again, a 1-engined fighter will be more than able to carry these provided it has a reasonably powerful engine (ie. no Zuisei, no Sakae).

Very true. But the very nice 1500hp engines don't show up until 1943/44
Ki-96 prototype using some Ki-45 parts.

Ha 109 will want to have a word with you. So will the Kasei.
The nice 1500 HP engines will make a Japanese fighter very competitive vs. the Allied aircraft in 1942-43, and make them less of a target practice after that.

 

[Thumpalumpacus]

Were I in charge of the Japanese economy, I'd encourage the consolidation of subcontractors supplying parts for the aircraft industry, if only to take advantage of the economies of scale. Couple that with reducing the plethora of types under development and perhaps we see a more efficient aviation sector producing fewer types in greater quantities?

The Germans will have to begin sinking US escorted convoys once the Lend Lease starts up to Russia. So, Germany declares war on USA by winter 42/43 with Stalingrad going poorly, if not before.

Much American LL to Russia was shipped via the North Pacific. I'm not sure courting war with America over Russian LL without being able to sever those Pacific supply lines would be useful.

 

[tomo pauk]

Post-Zero fighter possibilities to the IJN, mooted after the Zero's combat debut; bespoke designs:
- a full-blown carrier-based fighter (something that J2M was not) designed around the Kasei by Mitsubishi instead of the J2M
- similar, but designed by Kawanishi, engine can be Kasei, Ha-41 or -109 (Kawanishi is not required by IJN to make the Kyofu in the 1st place in order for this to happen)
- Nakajima designing an 1-engined long-range carrier-borne fighter; engine is Ha-109, with switch to the Homare later (IJN does not go with the LR land-based fighter program, that materialized as the J1N historically)
- Nakajima gets another chance later, where IJN cuts the C6N program and instructs Nakajima to make a fighter instead of the C6N

Obviously, any of these can do the land-based fighter duties, just like the A5M and A6M did, just better.

 

[EwenS]

Much American LL to Russia was shipped via the North Pacific. I'm not sure courting war with America over Russian LL without being able to sever those Pacific supply lines would be useful.

War between the US and Germany would have been likely a lot sooner than winter 1942/43. The incidents between US warships (let alone merchantmen) and German subs were already piling up in late 1941.

Pre-U.S. Entry Into WWII

Pre-U.S. Entry Into WWII The first action between the U.S. and German navies occured on April 10, 1941, when USS Niblack (DD-424) neared the Icelandic coast to pick-up three boatloads of survivors from the Dutch freighter Saleier, which was sunk the previous day. When a submarine was detected...

www.history.navy.mil

The majority of trans Pacific LL was made in Soviet flagged & manned ships, albeit that many such vessels were themselves supplied under LL. From mid-1943 the supply route to the Persian Gulf was shortened by the re-opening of the Med to traffic that could then use the Suez Canal.

There were some restrictions on what could be supplied via the Pacific route due to neutrality concerns with the Japanese. Certain routes to the Russian Far East were iced in for parts of the year for example.

And the Arctic route was closed for periods in 1942, 1943 and 1944 while the Home Fleet was busy elsewhere.

 

[tomo pauk]

Possible Japanese long-range high-speed bombers:
- introduce something like the P1Y much earlier, eg. instead of the G4M; there was nothing revolutionary about the P1Y, it's advantage vs. the G4M was that it was much smaller and sleeker and thus a better performer on same engines' power
- design the Ki-46 as a bomber 1st - again, it's small size meant that it was quite a performer even with low-powered engines, let alone when the power was good
- the D4Y, but with radial in the nose from the day 1 and with protected tanks (yes, this will eat into fuel capacity)

 

[Shortround6]

- design the Ki-46 as a bomber 1st - again, it's small size meant that it was quite a performer even with low-powered engines, let alone when the power was good

The Japanese may have made the plane a bit too light. It had about 38% more wing area than a Whirlwind, a two man crew and carried well over twice the fuel (1657liters for the Ki-46 II, and weighed less than Whirlwind with bombs, granted it wasn't lugging around a quartet of 20mm guns either. The Ki-46 also suffered a number of landing gear failures on landing.
Maybe you can replace the fuselage tank and some of the camera stowage with an internal bomb bay. Resorting to external bomb racks and leaving fuel out to compensate is going to result in both slow speed and short range.

the D4Y, but with radial in the nose from the day 1 and with protected tanks (yes, this will eat into fuel capacity)

I have having some doubts on this one. The Radial engines worked unlike the V-12s but performance may not be what you want/desire.

One book, could be wrong says K-61 did 302mph at sea level on 1175hp (?) While the Ki-100 did 317mph at 1000 meters and had 1500hp at sea level for take off.
15mph give or take for an extra 300hp?
If you are trying to use the 50 Series Kinsei engines you may not reach your performance goals due to drag.

 

[tomo pauk]

Maybe you can replace the fuselage tank and some of the camera stowage with an internal bomb bay. Resorting to external bomb racks and leaving fuel out to compensate is going to result in both slow speed and short range.

Bomb bay is mandatory - it should be a fast bomber, after all
It will be far easier to convert a fast bomber into a fast recon, than the other way around.

If you are trying to use the 50 Series Kinsei engines you may not reach your performance goals due to drag.

I will certainly not get 355 mph as it was the case with D4Y3 with the 50 series Kinseis, but might get 330-340? This is still very good for 1942. For 1943, Kinsei 60s seem to be available, and Homare from 1944.
Another option is the Ha-109, without the water injection it was comparable with water-injected 60 series Kinseis.

Japanese can also try with a land-based 1-engined bomber powered by the Kasei by 1941, and later switch to the Ha-42 or Homare (with more powerful Kaseis mid-war as these became available). Being land based and without the requirement for carrying a torpedo can allow designers to make it of more modest proportions than the B7A.

 

[Admiral Beez]

Training, training, training.

And production…. Get more planes.

 

[Macandy]

Japanese take note of the British (and Germany's) use of land-based and shipborne radar, and by early 1941:

1) Purchase radar kits and training from the Germans
2) Decide to become leaders in radar-directed carrier aviation, putting CIC (combat info centres) in all carriers
3) Enact new doctrine for Kidō Butai aviators, focused on disciplined, radio-guided formations and direction from CIC (as opposed to everyman for himself samurais)

By Coral Sea, all IJN carriers have radar and expertise in aircraft detection and direction. They still don't understand good damage control and their carriers are still made of eggshells, but they'll be no surprises at Midway, for example.

Bit of a problem - the huge choke point in pilot training.
It was very tough and selective program that was barely turning out 200 carrier qualified pilots per year in the early years.
Excellent pilots - but not enough to keep up with anything more than basic attrition. Midway killed off much of the skilled IJN pilot cadre.