Yuku free message boards

Note: Shane did not have the time to massage this into a useful shape, so he delegated the job to me. Using a large wooden club.

I will adjust the Japanese aviation apper to reflect this.

Cheers: Mark

Background: In OTL the IJNAF wanted to meet a requirement for a point defence high altitude interceptor, and to promote Hitachi into the ranks of first-class acft manufacturers. In OTL, they selected the He-100D0. The program collapsed due to non-delivery of the jigs by Heinkel. This was caused by Barbarossa, which cut the rail link.

In FFO, Barbarossa is delayed and this delivery occurs. The acft goes to Hitachi's new Chiba plant with the jigs etc, Hitachi also builds the engines, and Heinkel assists the entire process.

The major impact of this is that J2M dies: it was the OTL 'emergency response' to the collapse of the Hitachi project. The effect of this is that Jiro Hirokoshi is not pulled off the A7M program, so it goes ahead as planned by the IJN.

The He-100 project became a serious issue within FFO. Below is a précis of the process between Shane and Frank which successfully resolved this matter.

Dealing with the Issue

Shane noted that it was necessary to compromise and the He-100, Ki-61 and Ki-44 issues had to be defined first and not lumped together.

"Well we must reap what we sow my friend. The Ki-61's engine issues can only be improved by longer contact with Germany and the original manufacturer. The Ki-44 was sent for acceptance trials in early September 41 OTL, its biggest problem being a lack of speed. Better fuels are a direct aid here, allowing the engine to be tuned to reach higher outputs without major engineering changes. As for the Ki-100 I don't believe it even exists in FFO unless you mean the service version of the AXHe?

I must say I would rather look at each problem individually, rather than lump three aircraft together like this. But if that is how you would like to do it, I'm happy to oblige J

So we need a compromise."

Shane and Frank then sorted out the 3 types and where they fit into OTL Japanese planning.

Ki-61

It was decided that there was no way around the IJAAF development of Ki-61. There are two FFO drivers playing on it, both of which impact its OTL issues directly.

A/ Better fuels means more can be had from the DB-601 without major modification.

B/ Better tooling and longer direct contact with DB in Germany can only improve Japanese manufacturing and tuning.

C/ more exposure to He100

These 3 FFO drivers act to consolidate the OTL drivers, removing any real room to manoeuvre in FFO. Both accepted this point.

Ki-44

Shane and Frank explored the modifications they put the Ki-44 through in prototype form OTL, they mostly seemed to be about improving engine breathing, with six changes of intake design. They were trying to get a lot out of a medium power engine and better fuels in FFO will help this. However higher octane fuel is no good if it has not got enough air to burn, the Ki-44 was a medium-high altitude fighter, flying up where the air is thin, so air supply is a critical issue. Here Shane noted room to compromise; leaving the KI-44 to run close to OTL - but letting them have the first squadron in service by the December 1941, rather than the handful they rushed to Saigon. It is only a small change (originally put forward by Jacques in the canon) and can be ascribed to reflect the fuel change. This is easily possible within the production scheduling as the changes are restricted to a single area (the intake/engine cowling) so they can start making the rest of the aeroplane in anticipation of a finalised design because the fuel WILL give them some improvement on OTL so the intake work is refinement looking to get the last edge in performance.

He.100

Both Shane and Frank decided to "step back and look at what is going on here." At this point I (Mark, acting ONLY as 'secretary' here) feel it important to switch to first person to clearly show the issues Shane and Frank sorted out.

Shane: This is how I see events in OTL and FFO

OTL

1 - In 1939/40 the Japanese started to worry about strategic bombers, using the B-17 as a model of their potential foe.

2a - In response to this the Japanese Army commissioned Nakajima to design what will become the Ki-44.

2b - This was not an urgent Naval priority at the time (late 39/early 40), and there was a shortage of design capacity. Therefore, starting a new fighter would impede more important programs. But they could not ignore it either, so by 1940 they had started to form a plan. They decided to buy in a design from Germany, and use it to promote a new manufacturer into the first rank. This worked around the shortage of capacity in both design and manufacturing, plus it gained the IJNAF access to the latest technology. By early 1941 they had settled on the He100D0 as the aircraft, and Hitachi as the manufacturer.

(Validation data by Mark: this was the standard Japanese industry development model, in use since 1922. It involved 'soft loans' to the selected company from Treasury, and direct support of the company by the experienced design and manufacturing personnel from the Air Arsenals. There is nothing unusual about this process in Japanese industrial history and they use a similar process even today.)

3 - June 22nd 1941 Barbarossa

This makes no difference at all to the Japanese Army so far as Ki-44, that project is progressing and nothing changed due to Barbarossa in OTL.

However, this was not true of the IJNAF. The OTL Barbarossa placed the Japanese Navy's program into deep trouble. They had NOT received the full He100D0 technical package from Germany; all they had was three aircraft, some basic drawings, a collection of spare parts and a factory under construction at Chiba. They had no other alternative but to start a new design (J2M) and this emergency response placed them under a great deal of time pressure.

However, they found that the log jam of other projects in 1940 had cleared somewhat, so they could afford to divert one of their key designers (Jiro Hirokoshi) with his design team and set them to work on J2M Raiden.

FFO

1 - In 1939/40 the Japanese started to worry about strategic bombers using the B-17 as a model of their potential foe.

2a - In response to this the Japanese Army commission Nakajima to design what will become the Ki-44.

2b - This was not an urgent Naval priority at the time (late 39/early 40), and there was a shortage of design capacity so starting a new fighter would impede more important programs. But they could not ignore it either, so by 1940 they started to form a plan. They decided to buy in a design from Germany, and use it to promote a new manufacturer into the first rank. This worked around the shortage of capacity in both design and manufacturing, plus it gained them access to the latest technology. By early 41 they had settled on the He100D0 as the aircraft, and Hitachi as the manufacturer.

3 - June 22nd 1941 Barbarossa is delayed by 9 months

This makes no difference at all to the Japanese Army so far as Ki-44, that project is progressing and nothing changes due to Barbarossa being delayed by 9 months.

(Remember that in OTL this put the Japanese Navy's program on the other hand into deep trouble, as they had NOT received the full He100D0 technical package from Germany; all they had were three aircraft, some basic drawings, a collection of spare parts and a factory under construction. They had no other alternative but to start a new design (J2M) under a great deal of time pressure. However the log jam of other projects in 1940 had cleared somewhat, so they could afford to divert one of their key designers (Jiro Hirokoshi) with his team and set them to work. THIS is what changes so significantly with the FFO delay to Barbarossa.)

Getting back to the FFO stream:

This also makes no difference at all to the Japanese Navy so far as AXHe, that project is progressing. The bulk of the technical package (jigs, documents, samples, more acft in component form etc) from Germany is due by rail soon. The only changes due to Barbarossa being delayed must improve the Japanese technical position with respect to He100 and so AXHe.

- They have all the technical package they paid for.

- They have more contact, more time to have questions answered fully in writing rather than by condensed telegram.

- They have more time to have factory representatives from Heinkel come out to advise Hitachi and for Japanese technicians to visit Germany.

- They have more time to buy tools and equipment from Germany to speed up the productionising process for the aircraft.

The key difference from OTL here, is that in FFO the Naval Staff believe they have nothing to worry about at this point. This is all what they expected to happen - where in OTL they were thrown into a panic.

Shane: So it seems to me that Barbarossa unlocks Hirokoshi from the OTL path whatever the argument about He100/AXHe. At this critical point, they haven't enough of the He100 on hand in Japan to make any authoritative judgments about it, because if they had, they would have moved Horikoshi earlier in OTL. OTL they reacted to Barbarossa NOT to any findings they had made on the He100/AXHe, therefore without Barbarossa they must continue moving forward with AXHe as they intended to - from this point.

Shane noted that he understood the French position is that He100D0 is technically impossible to make into a practical fighter in Japanese hands. It is critical to note Shane's comment here: he said "I agree".

Shane continued:

If they had bought the He100D1 series instead of the He100D0 it would be a different story, but He100D0 is just too objectionable and impractical on too many levels.

I'd like to take another look at what the IJN were hoping to achieve with the AXHe program.

1/ Side step their industrial bottle necks to:-

2/ Gain an Interceptor suitable for protecting its bases from B-17 type bombers.

3/ Gain a new manufacturer of first rate aircraft - Hitachi

4/ Gain practical experience in the design, manufacture of operation of the latest in cutting edge fighter technology - latest 'best practice' in streamlining and stressed skin airframes, high performance water cooled inline engines (DB-601), and the bleeding edge of inline engine installation evaporative cooling.

They were talking a chance giving such an ambitious project to such an inexperienced company, but the Hitachi design office was to be reinforced by the IJN own team from the 11th Naval Air Arsenal, so they had a good measure of insurance. I believe the Air Arsenal design team would then move on to the next liquid cooled program to disseminate the experience from AXHe, that was how things had worked in the past. We have to keep in mind that this whole business was just another step in the Japanese buy - copy - improve process that had been going on since the dawn of the Meiji era.

Comment by Mark: This is historically valid. It also solves a real problem in FFO, the decision by Jacques that the IJNAF will go ahead with acquiring and producing the He-119 land recce and floatplane recce machine, which used DB-606 and evaporative cooling. The implication is obvious: in FFO Hitachi is building BOTH He-119 and He-100, and their engines and advanced cooling systems.

Shane continued: That process also had a lot to do with easing potential difficulties, the French estimate of 12 months to convert the He100D0 to full Japanese mass production might not be unreasonable if the whole design had to be reworked almost from scratch to fit in an existing manufacturing infrastructure in a Western country. For example materials would need to be translated from German standards into standard national specifications or new specs drawn up to provide a material to meet the requirement. That is a delicate job, one that takes time, skill and experience in the engineering staff to work around trouble and get a product that works as the original did. However the Japanese industrial base was founded on copying and that is reflected in their material standards, they didn't have any fixed system, instead they used a combination of everyone else's and added their own developments on top.

So if a Japanese factory needed 4140 (a US spec) steel, the steel mill made them a batch of 4140, likewise if they wanted a German W-Nr steel, a British commercial spec or a French AFNOR (if that system had been set at that time?). The same applies to alloy sheets and all the rest of it and there's no need to convert from metric to imperial either. They Japanese mill might use a different mix of elements to meet the specification and that can be a killer if there's much welding, but in a riveted aircraft - so long as the Japanese material meets the same physical (not chemical) spec as the German material there is no problem.

Shane noted that: In earlier discussions with Frank he had mentioned that the Hitachi factory COULD simply clone the He100D0 without making more than the most essential modifications to substitute standard Japanese items (instruments, oxygen systems weapons etc) for their German equivalents where those were not available. We need to remember that a number of German training aircraft and aircraft engines were being built in Japan, therefore a good deal of hardware, nuts and bolts, was already sorted out, either with the exact part being made or an equivalent already established. These are major time savings.

Shane then noted a personal view that Hitachi could start to make He100 airframes within weeks of unpacking the limited production tooling they receive from Germany.

He noted very strongly that this was not to say they could produce finished flying aircraft, but production is not a linear process. In a situation like this, the factory would be making dozens of trial components on every jig as part of the set up process. Slowly working up from practice pieces to flying quality parts, as the engineers and production staff worked out how to do the job and achieve the required standards. Plus of course they could well have staff from Heinkel on hand to assist. This a new aircraft being built in a new factory by a new manufacturer, and starting from a clean sheet of paper, and this has its benefits as well as its costs. At the end of the day, should productionisation become a serious problem they can just build it the way Heinkel did.

Shane stated very strongly that "I do not believe the He100D0 is a practical outcome as AXHe here, but it will die from its fundamental flaws long before the production side becomes a killer problem."

After Barbarossa I (Shane) see the next critical point being in mid (15th OTL) September 1941, this is when the Ki-44 is accepted for service trials, and it has given the IJN 3 months to become familiar with the He100D0 as both an aircraft and as a potential production item. It's also an important point politically, the Army now have their Interceptor, the pressure is now on the Navy to match them or lose face.

So at this point I suggest the IJN would pause to take stock of their program, and we might well do the same. I think they'd see:-

1/ Complexity.

This is not a matter of production, if we look at their OTL designs the Japanese were willing to put far more man-hours/effort into a component (cheaper labour) if they saw a reason to. The A6M has any number of examples; they hand spliced cable eyes in the control cables because it was lighter than a crimped on sleeve and cheaper to do it by hand than provide every factory and repair man with sleeve crimpers, they fabricated brackets from pressings riveted together (by hand) where normally a casting or forging would be used, as their way was lighter and cheaper to tool up for, the wing spar caps formed part of the outer surface at some cost in machining and hand work because it saved a 100mm wide strip of skin and wing rib for the full span of the wing.

The 'complexity' I'm speaking of here is simply that of design, particularly in the cooling system. The evaporative cooling system is quite honestly a horror, they all are in aircraft and this one seems overcomplicated as well. If the IJN had bought the He100D1 with the radiator they would have had a much easier time.

Contrary to popular opinion the Japanese weren't very conscious of 'tropical' conditions before their entry into the war, and Japan has a pretty European climate for much of the year. But they did appreciate hot weather and running that cooling system in the Japanese summer is not going to be much fun. In addition to overheating and complication, there are a number of unpleasant details with the rest of the system, for example the oil cooling, and the whole thing as ugly in engineering terms as it is pretty from a physicist's perspective.

We all know the Japanese are not afraid of a little complexity, but they prize elegance and economy too. The He100 was one of the worst excesses of German technical 'Uber-ism' in all its gross glory. The experienced Japanese production engineers from the Navy are going to look at it and ask - is it really worth the effort?

2/ Operational - ground

They will have had three He100D0's flying a test and evaluation program for some months, and they might even have a single Japanese made airframe, fleshed out with German components, flying. I'd guess they'd have lost at least one of the He100D0's by now and had some near misses with the others - accidents happen and this plane is far from perfect.

So they will know the He100 is a maintenance hog that probably takes more then 5+ hours of work on the ground for every hour it flies. They will have experienced the horrors of the oil cooler, struggled to stop it over heating on cool days and seen the way it eats seals and leaks like a sieve. Oh and I dare say they will have had some undercarriage problems too.

In many respects these are expected teething problems, but the He100D0's are at the upper end of the spectrum and that is not encouraging.

3/ Operational - Flying

As you suggested Frank, I don't think the Japanese pilots are going to love this aeroplane, as it conflicts with their established tactics.

They will respect its speed and performance, but object to its general handling. It also demands a high quality runway and that is another operational expense.

4/ Manufacturing

The engine installation will be seen as very complex and very expensive. It promises to be a slow plane to produce in numbers at a higher unit cost than more conventional aircraft.

5/ Training

Keeping the He100D0 flying demands a very high standard of maintenance and much specialist training for the ground crews. Plus the pilots need to be taught an 'unconventional' method of operational flying.

Conclusion

I think the IJN will see that they have gained everything they wanted from the He100D0 - except a practical interceptor. They've had all the experience they need with evaporative cooling, from running the three sample machines, just as they will have learned as much about designing such a system from preparing the He100D0 for production, and that same process will have matured Hitachi's design staff to the same degree as would have been expected by this point in time.

But they would NOT see the He100D0 as a practical fighter for mass production, as even if they can fix all its problems the plane is still too expensive to build and operate: PLUS the pilots whine about it.

Shane then continued:

So what are their alternatives at this point (early/mid September 41)

As I see it they have basic three options.

1/ Press on with the He100D0

2/ Rationalise the He100D0 to a more conventional aircraft along the lines Heinkel has already done in Germany with the He100D1.

3/ Kill the whole program and find something else to do the job.

OK I don't think any of these would be acceptable on their own, mostly due to time and politics. In service terms the Ki-44 has set the pace, and the navy must produce a result within a reasonable time frame (a few months) or be humiliated - we're talking some scapegoat at senior level committing professional or actual seppuku here. Then in strategic terms they don't know Japan will be at war before Christmas, but the pressure is mounting. A new design will take 1-2 years, they could adopt the Ki-44, and such a loss of face might be acceptable in wartime, but this is still peace.

In effect what FFO has done is move the OTL problem forward from June to September.

What are the realistic and logical options?

Option 1/ is the least change solution. It is my (Shane's) estimation that they could build He100D0's on the same basis Heinkel was, that is limited batch production by early in 1942 much as they had planned. But this is a direct clone with only the most minimal changes, and it would be a poor service aircraft.

Option 2/ (and the most logical). At any point from June 22^nd 1941 on the IJN could have gone back to Heinkel and bought the He100D1 with a conventional radiator - I believe, quite strongly, that they probably would have, if only for comparative testing against their He100D0's. This is the simplest and easiest solution they have - but it means delay.

Option 3/ Designing a new aircraft (J2M) would still be possible, but they have lost valuable time, it might only be three months, but the whole situation has moved forwards too and now they feel they have less time. So then the question becomes - could they find something else to use instead? I think they can, A6M3.

Mark Note: This would also mean either wrecking the Mitsubishi A7M carrier fighter development, now in full swing under Hirokoshi and his team, or going to another supplier, Mitsubishi not being able to accept the task.

Tactical perspective - What do they actually want in this fighter?

In the late 1930's and early 1940's the point defence interceptor evolved in response to a quite specific set of factors. Douhet's theorys on strategic bombing for the base threat, and the tactical imperatives of defending the bomber are set by detection and warning. Pre-radar, raid detection and tracing was either visual or by sound. This meant warning times were short and an intercepting fighter either had to mount a standing patrol OR have the performance to reach an intercept point very swiftly. Standing patrols are never popular as they are expensive in every respect and only offer a limited response. The bulk of fighters will always be on the ground when a raid is detected and will still have to climb like homesick angels to make an interception while the standing patrol can never be strong enough to defeat a substantial bomber formation - and this is why Baldwin stated 'the bomber will always get through'.

This is reflected in the interceptor designs of the day, maximum performance at the expense of range, because within the limits of audio-visual detection the fighter was going to be lucky to reach the raid in time, having the fuel to hang around was secondary. The He100 was a clear example of this design trend, as was the Ki-44, Spitfire, Hurricane, and to a lesser extent Me109.

But Radar changes the picture quite a bit, with a ~100 to 200 mile detection range on a large raid the fighters could have 30-40 minutes warning to gain position. Now fuel becomes a critical element, having plenty of range means the fighters can be put up early and manoeuvred into the best position, but the 'classical' short range interceptor has to be kept on the ground until quite late to ensure it has enough fuel to make the most of its intercept. This was seen quite clearly in the Battle of Britain, and why the 'Scramble' was such a feature, ADGB could see the raids coming pretty much form takeoff, but the fighters had to be kept on the ground to the last second.

The FFO BoB should show this with equal clarity if in a slightly different way, and it will certainly show the OTL limitations of short ranged fighters on the German side. If we do see a more aggressive RAF over northern France post-Dunkirk the Germans will see exactly the same issues the RAF found OTL, and all the while there are 'neutral' Japanese observers taking note. I would suggest the shift from OTL here is if the Germans take a more defensive posture in the BoB, they will see the interceptor-range issue more clearly in addition to the OTL radius of action issue, and the delay in Barbarossa has provided the Japanese with far more Radar technology than in OTL too.

In theory all these OTL 300mph+ fighters had more performance than they strictly needed just to perform their primary mission of shooting down unescorted 250mph bombers. And in theory those bombers should be unescorted, if northern France had not fallen the LW would not have been able to escort their bombers to London, and the Japanese the case is even more clear cut. In 1940 a B-17 may be able to reach Japan from some distant base, but a fighter? - Impossible! J

Thus

OTL - The Japanese specified a 'classic' short ranged interceptor

a/ before the BoB had been digested and the advantages of longer range under radar control were practically demonstrated.

b/ and at a time when they were limited to visual/sound detection and so needed an short range/maximum performance interceptor.

By the end of 1941 this COULD look quite different.

They now plan to have a radar based detection system in place within the life of any new fighter, they have some idea of what a radar directed fighter requires and have had some plain simple lessons about the handicap a lack of range can be. Yes this fighter is intended to defend critical strategic locations, most of which are in Japan, but if they go to war the ring of such locations will expand, after all that is what they are fighting for - and those forward airbases will not be so comfortable as those at home.

Going back to September 41, I (Shane) would suggest the new priorities for the IJN with respect to their interceptor program are now something like this.

1/ They need a fighter that will fill the role

2/ They would like this fighter to be 'friendly' as possible, cheap to build, easy to maintain and so on by their existing standards.

4/ They do not want to spend a fortune or take years to develop it either

5/ They do not want to 'waste' the effort put into He100D0 to date

6/ They do not want to lose face to the Army.

7/ They would like it to conform to their current fighter tactics

8/ There is a chance they would also like it to have more range

We as the authors of FFO also need to make 50 AXHe's as they are already written into the story.

(Mark Note: Study of what we know of the supply chain indicates that on cancelling AXHe production at about 50 acft, there would be components for 80-120 more acft in the system. SO total numbers produced would reflect this sort of number, as the IJNAF would not idle Hitachi and scrap the existing components. They would 'use them up' to keep the plant busy and hide the mess they have on their hands from the Army.)

What tools do we/they have to meet these demands?

a/ A limited production capacity for He100D0 - a handful a week at best.

b/ Access to a simplified He100, the D1 model with a conventional cooling system, it is a little slower than the He100D0, flies a little better (it has a larger tail plane and some minor aerodynamic tweaks), it's cheaper and easier to build, a lot more reliable and easier to maintain - but it is still a long way from perfect.

c/ A6M3 is a little further advanced (thanks to Hirokoshi not being distracted by 'the J2M emergency' and being able to support his former Chief Designer, now responsible for A6M development at Mitsubishi), and it uses the same engine as Ki-44. It has a lower wing loading and fitting extended wingtips would improve that even more, it won't climb as fast as Ki-44, but once it reaches altitude it will turn much better. OTL it's service ceiling was about 33,000', we have better fuels and perhaps the wingtip extensions so getting the same sort of altitude as Ki-44/AXHe in the 36,000' range is quite reasonable. It also has more range than either type.

d/ A7M is also three months further down the track than OTL thanks to Barbarossa leaving Hirokoshi in place.

(Mark Comment: Please note that this does not mean that A7M is three months in advance of its OTL first flight date! It means that A7M is three months into its planned OTL development, that it remains with Mitsubishi, does not get sent elsewhere, and has Hirokoshi and his entire A6M team (less a couple) working on it!

He100 Compromise

Shane therefore worked out and offered the following compromise to Frank.

Situation

1a/ Sometime between mid August and the end of September 1941 the IJN re-evaluate the He100D0-AXHe project and decide that in its existing (He100D0) form it is not viable for mass production within an acceptable time frame.

1b/ Sometime between June and September the IJN has been back to Heinkel for the HE100D1 - even if only to buy one of the 12 made for comparative testing.

2a/ There is a immediate short term need for interceptor to:-

2b/ bridge the gap between 'now' and the introduction of more suitable aircraft (3/ &4/)

2c/ Maintain face by matching the Ki-44

3/ The next full generation of conventional fighter (A7M) promises sufficient performance to meet this role or at least be adapted to it with a specialised model.

4/ A interim type adapted from the next of the A6M line (A6M3) can cover the medium term gap before A7M is available, but it will be some months before it is ready (see 3/)

Solution

1/ AXHe is ordered into immediate limited production (less than 100 total off the production line before cancellation of the type) based on the He100D1 rather than the He100D0, this is a simple change and quite possible in a very short time frame. These aircraft are to be built on the existing German tooling and as much Japanese tooling as has been completed since July.

This saves face, makes the best use of the sunk investment in He100, and allows a propaganda coup. The gains are all superficial, but the cost is low.

2/ A land based interceptor version of the A6M3 becomes part of the primary A6M program. The Hitachi plant at Chiba may be used to expand the A6M production base, and will almost certainly be incorporated into the A7M program.

Thus the He100/AXHe is a dead end as we all agree it should be, but it dies inline with a realistic (IMHO) interpretation of its potential, and the IJN react to practical drivers.

Note: Frank accepted this compromise solution, and (although not reflected here) he had extensive involvement in working though the issue at all points and levels.

CONVERGENCE

Suggested FFO development for A6M Reisen and A7M Reppu
A6M2 model 11, initial variant, powered by the Sakae-12.

As OTL: accepted for service July 1940

A6M2 model 21, with wing tip folding, and the Sakae-12. As OTL: accepted for service at 65^th acft, late 1940

FFO A6M3b Model 42 with Sakae 21, (additional tanks and round wing, ESD panels for higher diving speed).

As per OTL flight testing started July 1941, as per OTL combat service early 1942 in Japan followed by combat service in SOPAC in 'late spring (April-May) 1942.

FFO A6M5a Model 64 (OTL A6M8 with Kinsei MK8 1500HP)

As per Jacques suggestion production commence in May 43, would reach operational units in Japan in June but not be deployed outside Japan until August-September 1943.

FFO A6M5b Model 74. (FFO Kinsei MK8 engined strike version with shackles, armour and self-sealing tanks)

'Strike Reisen' developed in semi-parallel with A6M5a but behind it in timing by 3-4 months (Suggestions and reasons/drivers, Jacques?)

FFO A7M1 (OTL A7M3) first prototype August 1942 on 16-Shi (1940), second prototype batch October 1942 (reflecting 17-Shi of Feb-Mar 42), production commenced February 1943, starts replacing A6M3b Model 42 aboard IJN CV force from June 1943.