[Lennart Andersson]

This post will only deal with version suffixes of German aircraft designations, Do 17E, Bf 109E-3, etc, and will not discuss other things, such as ”Me” versus ”Bf, or ”FW” versus ”Fw”.

In April or May 1932 the RVM tried to simplify German aircraft designations and the different systems used by the manufacturers were gradually unified, but with Junkers and a few others continuing to use their own variants. The manufacturers name was abbreviated to two letters, for example “He” for Heinkel, which in that case replaced “HE” and “HD” used by that company previously. Different versions of the same type were often characterised by adding a letter, normally lower case, as a suffix to the designation, for example HE 9e. In 1932 upper case letters became the norm and the HD 41a therefore became the He 41A.
It seems, however, that the RLM did not use these version suffixes very frequently in their own documents. For example the Flugzeugbaumustertabelle (table of aircraft types) dated 1 October 1936 has version letters only for the Do 17E, Do 17F, Do 17M and He 45G. All the other types lack version suffixes. Only in 1937 (Flugzeug-Beschaffungsprogramm, 1 September 1937) the use of version letters seems to be more frequent, but still not for all types. It seems that the version letter was added only when there was a real need to differentiate between the versions.
It should perhaps be noted that, although I have not practiced that here because it can sometimes be confusing, the number of the type designation and the version letter were often divided my a space: He 72 D.

V-numbers for prototypes and development aircraft
Adding a “V” and a number to the designations allotted to new prototypes seems to have started already sometime in 1934. The earliest example that I can find is a Heinkel protocol dated 8 June 1934 that mentions the He 112 V1 and V2, and there is also a table of Entwicklungsflugzeuge (development aircraft) dated 15 November 1934 with V-numbers. The Flugzeug-Entwicklungsprogramm (aircraft development program) dated 1 February 1935 does not show any V-numbers, but the one dated 8 May 1935 does.

Number suffixes to version letters
The first examples of letters with a number added for sub-versions seems to be the He 70F1, He 70F2, He 70G1 and He 70G2, normally written without a hyphen, that seems to have been invented by Heinkel in 1935. This system then appears to have been more generally adopted by the RLM in 1936. For example Ju 160D-0 D-UBIQ and Ju 86B-0 D-AHYP were registered as such in April and May 1936. An FW 56A-2 was registered in July 1936 and in March 1937 the Bü 131B-3 followed. Later in 1937 we find the Do 17E-2, Do 17F-1, Ju 86C-1, Bf 108B-1 and others in the published register.
On the other hand the Flugzeug-Beschaffungsprogramm (aircraft procurement program) of 1 April 1939 still has sub-version numbers only for the Bf 109E-1 and Bf 109E-3. In a Lieferplan (delivery plan) dated 1 September 1939 there are more examples of the sub-numbers, but it is still not a system that is generally adopted for all types in this type of document.

Conclusion
Unfortunately no original RLM document that regulates these things seems to have been found. Until this happens we will have to draw conclusions from other types of documents that do exist, and further research is necessary.
For the moment the general conclusion seems to be that version letters were not always used and while the letter plus number system for sub-versions appears to have been invented in 1936, it was not used much until 1939/1940. This means that some of the designations published by William Green in “Warplanes of the Third Reich” and in his articles (and many followers) never existed and are pure fiction. One example is what he calls the productions versions of the Heinkel He 51: “He 51A-0”, “He 51A-1”, “He 51B-0”, “He 51B-1”, etc This type of designation, with a dash and a number, did not exist when these aircraft were built and delivered. Another fact that shows that Green’s designations were invented by himself is that the He 51A and He 51B were in fact only prototypes, and the first series production versions were designated He 51C and He 51D!

It would be interesting to know if any original documents are known that throw more light on these fundamental Luftwaffe research issues.

Lennart Andersson