Heinkel He-111 variants; why the inconsistency?

[pathology_doc]

According to Wikipedia we have, in military service, A, B, D, E, F (C and G are civil), J (I didn't know about that one), K (German designation for Chinese export A models), P and H.

My question relates to why the definitive version is the H, why the P precedes it, and why L, M and N were skipped. (Obviously I and O are skipped to avoid confusion with numbers 1 and 0).

Is there a good book one can read (in English) that details the full development history of all marks, rather than glossing over the ones that didn't serve in WW2?

 

[Arjen]

I don't know why some letters were skipped, but in German Aircraft of the Second World War by Antony L Kay and J R Smith, Putnam 2002, as well as in Warplanes of the Third Reich by William Green, Macdonald 1970, the writers state the He 111H and P were parallel developments. The same is stated about the He 111F and J.
J and P had Daimler Benz engines, F and H had Jumo engines.

He 111F - Jumo 211
He 111J - DB 600

He 111H - Jumo 211
He 111P - DB601

A, B, D, E, F (C and G are civil), J (I didn't know about that one), K (German designation for Chinese export A models), P and H.

Both books state the He 111R was proposed as an interim high-altitude bomber in two variants:
- He 111R-1 - 2 x 1350hp Jumo 211F-2, turbo-supercharged, abandoned in favour of
- He 111R-2 - 2 x 1810hp DB 603U, Hirth 2281 or TKL 15 turbo-superchargers
None built, but a He 111H-6 became a prototype He 111R as the He 111 V32 which was fitted with two DB 603U engines and TK 9AC superchargers.

Finally, the siamese twin He 111Z.