Rikko - asset or resource waste?

[mack8]

Exploring another angle on IJN/IJNAF. Would they have been better off instead of building the rikkos, to use the same resources for conventional single engine carrier aircraft, like the US and UK did? (i know about late or postwar US and UK twin-engine piston carrier aircraft, but it's outside the period i want to explore)

OTL they build something like 1000 G3M, 2500 G4M and 1100 P1Y, so about 4600. Assuming for a moment, taking the engine number as a base, that they build 2 kanko or kanbaku (B5N, D3A, D4Y, B6N, B7A etc.) for every rikko, they could have built over 9,000 of these.

On one hand without the rikkos they won't have the long range land-based strike capability, and useful scouting platform to supplement the likes of H6K/H8K, on the other hand the rikkos were massacred whenever encountering strong resistance. Their most notable success is the siking of PoW and Repulse, and a few other lesser ships later on, like Chicago, and i guess useful contributions early in the war such as bombing Phillipines or Wake and other objectives.

On the other hand, having 9,000 extra kanko and kanbaku, or a combination of kanko, kanbaku and kansen, means the carriers are kept filled to capacity with planes and pilots, and not only the CVs and CVLs but the CVEs too. It also means they will be the primary, and only long range strike assets. They might put more emphasis on enlarging the carrier fleet within their means (i am aware of the limitations of the japanese shipbuilding industry), like additional conversions such as the Kamakura-Marus, or Mizuho or Nisshin. There will still be land-based groups, but with just single-engine planes, so they will have to put emphasis on building airfields closer to the objective (about 300 nm at most) where practicable.

PS: Not quite a rikko, but i'll add the J1N here too, imo 900 plus Zeros are far more useful than the about 470 Gekkos.

 

[Shinpachi]

rikko = 陸攻 = land-based attacker
kanko = 艦攻 = carrier-based attacker
kanbaku = 艦爆 = carrier-based bomber or dive bomber
kansen = 艦戦 = carrier-based fighter

Long-ranged attackers/bombers were not necessary after Saipan fell in July 1944 as the Japanese had to concentrate on the homeland defense.

 

[tomo pauk]

On the other hand, having 9,000 extra kanko and kanbaku, or a combination of kanko, kanbaku and kansen, means the carriers are kept filled to capacity with planes and pilots, and not only the CVs and CVLs but the CVEs too. It also means they will be the primary, and only long range strike assets. They might put more emphasis on enlarging the carrier fleet within their means (i am aware of the limitations of the japanese shipbuilding industry), like additional conversions such as the Kamakura-Marus, or Mizuho or Nisshin. There will still be land-based groups, but with just single-engine planes, so they will have to put emphasis on building airfields closer to the objective (about 300 nm at most) where practicable.

Making extra 9000 A/C means that thousands of extra pilots are needed - quite a tall bar for the Japanese military. Perhaps go 'mid way' - make 2-engined bombers, but not as much, with emphasis being increase of carrier-based attackers 1st? This will require a doctrinal shift from China as main enemy for the Navy towards the USN as the main enemy, and make such shift a few months before Pearl Harbor?

PS: Not quite a rikko, but i'll add the J1N here too, imo 900 plus Zeros are far more useful than the about 470 Gekkos.

Gekko was neither here nor there, so making something else instead is a good call. Me, I'd try with more D4Ys, or more combat-proof C6N.
(again a few hundred of extra pilots is needed)

 

[mack8]

Well, roughly 5000 of them would be certainly assured of aircrews, and as the rikkos had up to 7-9 crew including pilots and copilots, most of these copilots could be trained as pilots for the others.

What you propose, a partial reduction of rikko production, has merits too, for instance if Nakajima is not contracted to build 400 plus G3M from 1941 and instead keep building extra 800 B5Ns, it's a much better situation for the carrier kankotais in 1941-43 period. Then Aichi and Hiro build 480 D3As instead of the OTL 480 B5N production.

Continuing the trend, if say 1000-1500 less G4Ms are build, then that's an additional 2000-3000 D4Y (definitely with a radial engine, another subject but inserted here as well as it's an idea i greatly favour)/B6N/some C6N/J2M etc. instead. As to the P1Y, a good aircraft but i'd rather replace those 1100 with 2000 plus of the magnificent B7A (same engine), or a combination of say 1000 B7A and 1000 plus N1K-J Shidens (they need every fighter they could get at this time).

More and smaller attackers would have a better chance of getting to the US carriers later in the war than the large and quite lumbering rikkos except the P1Y, but it's still too large/expensive, maybe only build couple hundred P1Ys as nightfighters, but that's about it.

 

[Shinpachi]

You must consider Japan's insufficient fuel stock for not only operation but training due to the oil embargo by the US in August, 1941.
This is why Japan decided the sudden attacks in December hoping the war would end soon before the fuel stock ran out.

 

[tomo pauk]

Well, roughly 5000 of them would be certainly assured of aircrews, and as the rikkos had up to 7-9 crew including pilots and copilots, most of these copilots could be trained as pilots for the others.

Truth to be told, 1-engined A/C are usually easier for the new pilots to master than 2-engined types.

What you propose, a partial reduction of rikko production, has merits too, for instance if Nakajima is not contracted to build 400 plus G3M from 1941 and instead keep building extra 800 B5Ns, it's a much better situation for the carrier kankotais in 1941-43 period. Then Aichi and Hiro build 480 D3As instead of the OTL 480 B5N production.

Continuing the trend, if say 1000-1500 less G4Ms are build, then that's an additional 2000-3000 D4Y (definitely with a radial engine, another subject but inserted here as well as it's an idea i greatly favour)/B6N/some C6N/J2M etc. instead. As to the P1Y, a good aircraft but i'd rather replace those 1100 with 2000 plus of the magnificent B7A (same engine), or a combination of say 1000 B7A and 1000 plus N1K-J Shidens (they need every fighter they could get at this time).

The D4Y with a radial engine in the nose from day one should've been a priority anyway, IMO. 2-speed Sakae, Ha 41/-109, Kinsei, Kasei - anything goes.
P1Y idea was good, but it was too late. Perhaps making a tad more of G3Ms and earlier 'jump' on the P1Y (small aircraft, not as big as the G4M, thus the turn of speed on same engines was much better)? Means that a few thousand of 2-engined bombers is not built, so double the amount of 1-engined attackers (and better fighters) can be made?

We also have a whole thing of 'what Kawanishi is supposed to make?', but I guess that's for another thread.

 

[mack8]

Been pondering what kind of performance a Ginga sized G3M would have, ie go for small ad fast rikkos from the beggining. Interestingly, the roughly contemporary Ki-21-I with 1080 HP Ha-5 engines was doing 432kph, compared to 375kph for the G3M2 with 1000 HP Kinsei engines. I think i have read somewhere the G3M was slow because of it's draggy Junkers type wing among other things.

So a more aerodynamic, smaller G3M with say only 4 crew, pilot, copilot/navigator, rear gunner/radioman, front gunner/bombardier (i keep the copilot because of the pilot fatigue on long overwater flights), should be much faster, say 50-60kph. And at least a minimum level of fuel tank protection such as the IJAAF planes had is a must.

Same applies for the G4M, overall smaller, 4 crew max, even if just 50-60 kph faster that still means about 480-490kph on 1500 HP Kasei engines, and another 20-30 kph when switching to the 1850 HP Kasei-20, ie almost as fast as the Kasei powered P1Y2. Again, even partial fuel tank protection is a must.

This kind of performance would seriously embarass the F4F-4 of 1942. These ATL rikkos would then be more survivable, and more effective pound for pound, but still a higher number of carrier bombers and attack planes so that the carriers are filled to capacity must have priority first.

And despite being a good machine, i would still have the fighter like B7A built instead of the P1Y. Reading how sometimes the D3A challenged F4Fs in 1942 and outmaneuvered them (but greatly handicapped by the light artmament of just 2x 7,7mm frontal guns), i'm thinking a B7A could actually go head on with an F6F and still have a chance, those 20mm guns could kill even the sturdy american planes.

 

[tomo pauk]

And despite being a good machine, i would still have the fighter like B7A built instead of the P1Y. Reading how sometimes the D3A challenged F4Fs in 1942 and outmaneuvered them (but greatly handicapped by the light artmament of just 2x 7,7mm frontal guns), i'm thinking a B7A could actually go head on with an F6F and still have a chance, those 20mm guns could kill even the sturdy american planes.

How about making a capable fighter 1st, and then bomb-up it? Sorta Japanese Hellcat (not the A7M), or japanese Bearcat? Or a no-nonsense J2M (with 'normal' engine for the starters)?
But then again, a D4Y or a combat-ready C6Y (both types with mandatory self-sealing tanks) certainly have their appeal IMO.

This kind of performance would seriously embarass the F4F-4 of 1942. These ATL rikkos would then be more survivable, and more effective pound for pound, but still a higher number of carrier bombers and attack planes so that the carriers are filled to capacity must have priority first.

Total for G3M, G4M and P1Y seems to be ~4600 (1048+2435+1102). With just two designs produced, and to the total of ~3000, there is enough of material to make extra 2x1600 = 3200 of 1-engined attackers - quite a number.

Unlike for Western powers, were payload was the king many times (so the attacked factories will require less sorties to be destroyed), main targets for the Japanese aircraft were the tactical ones - even against the Chinese - thus 1-engined A/C are very viable proposals.

 

[taly01]

Early WW2 most nations had to find out how there designs worked in a serious war. The G4M had fantastic range which was a priority for Japans pre-war empire and further plans, however unprotected fuel tanks and light defensive armament was a disaster as shown in Solomons fighting. The other flaw was that the A6M did not have the range to escort G4M to fullest (even with drop tanks). In March 1942 G4M had to attack US Lexington task force without A6M escort and was slaughtered.

The P1Y was the correct response a faster smaller plane with less crew, a real attack plane, but choice of and problems with Homare motor meant it came 2 years late.

An attack version of J1N is an interesting idea that would have been available in early 1942, 315mph unloaded is hard to catch.

 

[mack8]

How about making a capable fighter 1st, and then bomb-up it? Sorta Japanese Hellcat (not the A7M), or japanese Bearcat? Or a no-nonsense J2M (with 'normal' engine for the starters)?
But then again, a D4Y or a combat-ready C6Y (both types with mandatory self-sealing tanks) certainly have their appeal IMO.



Total for G3M, G4M and P1Y seems to be ~4600 (1048+2435+1102). With just two designs produced, and to the total of ~3000, there is enough of material to make extra 2x1600 = 3200 of 1-engined attackers - quite a number.

Unlike for Western powers, were payload was the king many times (so the attacked factories will require less sorties to be destroyed), main targets for the Japanese aircraft were the tactical ones - even against the Chinese - thus 1-engined A/C are very viable proposals.

A japanese Bearcat or at least Sea Fury is what i think the A7M should have been, the OTL Reppu was simply too big for the Homare engine and the MK9 engine wsa far too late. There are many permutations, but less emphasis on the rikkos and more on carrier planes should allow Mitsubishi to have the small A7M (say length 10 metres, span 12,5 metres) flying already in 1942 (instead of the J2M). If the resulting aircraft at least equals the F6F-3 in performance (about 600 kph speed, four 20mm cannons, good dive speed, reasonably protected fuel tanks), it's already a huge advance for IJNAF. But like always the engine is the problem, Kasei is too big and doesn't have enough power, Homare is a bit late and unreliable, my solution being an ALT- Mamoru (48litres, 18 cylinder, 1900 HP initially then 2100 HP with MW injection, basically and earlier Ha-219), which should be ready in 1942. Or if all else fails maybe the Ha-104, comparable in size to the R-3350 or Centaurus from the Sea Fury, but iirc of smaller diameter, but still bigger than the alt-Mamoru.

If there is going to be another fighter from Nakajima or Kawanishi, should also be carrier capable as a complement for the ALT-A7M. something along the lines of the low wing Shiden-Kai (which i understand could fly off cariers), build either by Nakajima from 1941 (instead of the J1N) or by Kawanishi from 1942 instead of the N1K1 Kyofu (they can put floats on it later if they want).

So then the IJNAF fighter force would remain formidable right until the end of the war.

As to the carrier attack and bomber planes, the design resources freed by less emphasis on the rikkos can mean the B6N flies in 1941 (instead of the utterly useless G8N) with the Kasei engine, and maybe it's combat ready by autumn 1942, could take part in an ATL Santa Cruz where it will be an absolute nightmare for the F4F-4 to stop (so Enterprise gets killed too? though of course with more carrier planes, enough to say fill Zuikaku and send it there too, Midway could and should end quite differently).

The D4Y had structural issues in steep dives, not sure if there's a way to sort that quickly or become aware of it during design. If that would be sorted quickly, with a radial and reliable Kinsei or indeed any other available radial like Ha-109 or Kasei as you suggest (though in this case it has to be bigger to take the bigger engine and more fuel, hence needing a folding wing and opening another can of worms? on the other hand the late war D4Y5 version was built around the Homare, so i don't know - but probably better to stick with the Kinsei variant that we know works), possibly it could also be available at Santa Cruz. It will be as fast as the F4F-4 so even harder to catch, and if fitted with 500kg SAP bombs any hits on US carriers or ships are much more damaging.

With such a Kido Butai carrier airgroup of A6M3s, B6N and D4Ys, the USN would have been in a world of hurt in 1942-1943. And A7Ms, A8Ks Shidens from 1943 and B7As plus C6N recons in 1944 would have allowed IJNAF to still be formidable opponents in 1944-45. They may still lose the war, but there will be much less of a turkey shoot in 1944-45 and probably some painful carrier losses for the Big Blue Fleet.

 

[mack8]

Early WW2 most nations had to find out how there designs worked in a serious war. The G4M had fantastic range which was a priority for Japans pre-war empire and further plans, however unprotected fuel tanks and light defensive armament was a disaster as shown in Solomons fighting. The other flaw was that the A6M did not have the range to escort G4M to fullest (even with drop tanks). In March 1942 G4M had to attack US Lexington task force without A6M escort and was slaughtered.

The P1Y was the correct response a faster smaller plane with less crew, a real attack plane, but choice of and problems with Homare motor meant it came 2 years late.

An attack version of J1N is an interesting idea that would have been available in early 1942, 315mph unloaded is hard to catch.

As i understand, there was no escort for the G4Ms becasue the drop tanks for the Zeros hadn't arrived yet, otherwise iirc at 420 miles away drop tank Zeros (maximum of 600 nm radius) could have easily escorted the rikkos.

Perhaps the OTL P1Y should have had the Kasei engine from the start, at least it was more reliable, even if draggier, the P1Y2 was doing 325 mph with Kasei engines, a bit less then the 340 mph of the Homare variant, but still quite fast.

Imo as i outlined above i think it's far more useful for IJNAF to have Nakajima design the B6N and have it flying in 1941 instead of the J1N, that way the slow and vulnerable if still formidable B5N can be replaced asap on carriers and land-based units by the much faster and survivable (in 1942 at least) B6N.

 

[EwenS]

mack8
If there is going to be another fighter from Nakajima or Kawanishi, should also be carrier capable as a complement for the ALT-A7M. something along the lines of the low wing Shiden-Kai (which i understand could fly off cariers), build either by Nakajima from 1941 (instead of the J1N) or by Kawanishi from 1942 instead of the N1K1 Kyofu (they can put floats on it later if they want).


The only carrier capable Shiden Kai models were

N1K3-A Shiden Kai 2 Model 41 (based on the 2 prototype N1K3-J Shiden Kai 1 Model 31) - none produced
N1K4-A Shiden Kai 4 Model 42 (based on the 2 prototype N1K4-J Shiden Kai 3 Model 32) - one prototype built at the Naruo factory, produced in 1945. This had an improved 2,000hp NK9H-S Homare 23 radial engine.

 

[tomo pauk]

If the resulting aircraft at least equals the F6F-3 in performance (about 600 kph speed, four 20mm cannons, good dive speed, reasonably protected fuel tanks), it's already a huge advance for IJNAF. But like always the engine is the problem, Kasei is too big and doesn't have enough power, Homare is a bit late and unreliable, my solution being an ALT- Mamoru (48litres, 18 cylinder, 1900 HP initially then 2100 HP with MW injection, basically and earlier Ha-219), which should be ready in 1942. Or if all else fails maybe the Ha-104, comparable in size to the R-3350 or Centaurus from the Sea Fury, but iirc of smaller diameter, but still bigger than the alt-Mamoru.

I'd suggest that the new brave fighter is designed around the Kasei, and for 1942, despite the engine not being all that compact. By 1943, the power is just fine with arrival of 20 series. Once Homare is around, retrofit it on the fighter.
A small form factor might be the Ha 109, hopefully outfitted with water injection (Nakajima was not as fast on the ball here as Mitsubishi on their engines).
The Ha 104 on a fighter sounds gets my votes any time it is suggested.

All of these options offer the ability for the resulting fighter to be outfitted with a decent bomb.