As others have mentioned tracker is almost essential to PDU:off R&D planning, if you are doing it for the first time. Also the upgrade paths for some squadrons are changed in DBB from stock. The same may be the case for other mods. I do not know.
Some Notes on the various airframes and engines:
1) Nakajima 35 engine bonus is crucial, in my opinion, in PDU:off, because you have fewer factories to dedicate to R&D and must move through the complete tree for the A6 line and through the Ki-43 IIIa, at least. Therefore, your actual early-war air production of Oscars, Zeros, and Ki-45s probably should be less than in a PDU:ON game. For example, if you produce 540 Nakajima 35 engines per month and have 8 factories dedicated to the A6 line and 4 to the Oscar line, you only have 180 engines for Ki-45s, A6M2s, and Ki-43s remaining. With the Ki-45s using 2 per airplane (60 if you have 1 size-30 factory), this leaves only 120 engines for Zeros, Oscars, Lillies, and Kates.
2) In my opinion, the importance of R&D on Tony and Tojo is amplified in PDU:off, because 40% of your 1944-45 air groups will be equipped with these frames. So you want the development of these lines to keep pace with allied technology. Something along the lines of 4 factories on each: one of which can be converted to production when the first model is available.
3) Overall, you have fewer factories available for R&D because you must produce a greater assortment of aircraft. It is helpful to assign a few small factories (size 5 or 6) to the various models that are in limited production in the beginning: i.e. Petes, C5M2 Babs, and Tinas come to mind. Once 40-50 of these aircraft are in the pool, switch these factories to later-war limited production models (such as Hickories, A6M2 Rufes, and so forth).
4) The A6 line is complex, as you know. Most groups upgrade from the A6M2 to the A6M3a before moving on to the A6M5s, A6M8, and then the Sam. So the question you must ask at the start is whether you want to slow R&D on the later models (A6M5-A6M8) to bring the A6M3a into production early or whether you want to skip A6M3a R&D and move directly into the A6M5. If you want to skip the A6M3a, then you set your factories to the A6M2-Rufe at start and upgrade to the A6M5, beginning in March probably. If you want to advance the A6M3a, then you set your factories to the A6M3 and switch to the A6M3a in April or May. This will set back your progress on the A6M5 line by 3 or 4 months, but give you a very marked advantage in the quality of your CV air in late 1942. The drawback, however, is that the A6M8 will not be available, probably, when the Hellcat appears, which will give the allies a marked advantage in CV-air quality for 3 or 4 months in 1943. In both stock and DBB, you have one large LBA Zero group (6th Sentai, I believe) that upgrades directly from A6M3 to A6M5. You also have several Pete squadrons that upgrade to the A6M2 Rufe and then directly to the A6M5. Keep this in mind. These small squadrons can provide you with some A6M5s on your CVs in mid 1942 if you skip the A6M3a.
In both stock and DBB, there are 4 or 5 groups that withdraw in mid-late 1944 that never upgrade beyond the A6M5. Therefore, you will want 2 factories producing A6M5s. One you will upgrade to the A6M5b, A6M5c, and then A6M8. The other, smaller factory will remain on A6M5s until late 1944.
5) The Ki-43 line is similar to the A6M line in that many groups do not upgrade to the Oscar IIa. Therefore, at start, you probably want 2 factories producing Ki-43 Ics. One you will upgrade to the Ki-43 IIa. The other, smaller factory (size 20 is sufficient) will remain on the Ki-43 Ic until that IIb is available. In stock R&D on the Ki-43s beyond the IIIa is mostly optional in my opinion, because most groups upgrade to the Frank or the Tony after the IIIa. In DBB, R&D on the IIIa is optional, in my opinion, since many groups upgrade from the IIb to the Frank, Tony, or later-model Tojos.
6) I find that I have enough factories to assign 8 to Frank and 4 or 5 to Sam if I have 8 on the A6M2, only 4 on the Ki-43, 4 on Tony, and 4 on Tojo. I also have 1 size-30 on a few late-war models, such as the Ki-94. In stock, most A6M squadrons upgrade to the A7M2 before the A7M3. One of the most frustrating aspects of DBB for the Japanese player is that most IJN LBA squadrons do not upgrade to the A7M2 from the A6M8. They upgrade to the A7M3. This dimishes the quality of the late-war IJN significantly in DBB. Therefore, I think it is helpful to have at least 1 size-30 factory on the A7M3 with the hope that luck will repair this factory sooner than the norm. In stock, it is not necessary to assign any factories to the A7M3, because the A7M2 is sufficient.
7) You will probably want 1 factory on the important night-fighters: the A6 night-fighter, the Ki-46 III Dinah Night Fighter, and possibly the Randy Night Fighter. You probably want 2 factores on the J1NI. One you will need to convert to production. The other you will want to advance the J1 model with radar. As you probably know, it is not entirely helpful to advance the nightfighters before the date when the air-search radar is available (June 1944, I believe), so 1 factory on each shoud be sufficient to advance most to June 1944.
< Message edited by Aurorus -- 3/21/2018 6:09:55 PM >