Use of 'blocks' for Mark numbers

[gingerbob]

Hi all,

I suppose this is the most appropriate place to ask the question.

I suspect that blocks were first used on engines (Merlin X, XX, 60) and I'd like to know when that started, but I'm really after its application to aircraft. The Spit IV became the Spit XX in early 1942. I think that by then blocks had been used for some overseas production- Australian Tiger Moth, Canadian Hurricane? Any information welcome!

bob

[pigsty]

It's not very systematic and the Spitfire is actually quite a bad place to start, as the numbering for that wasn't really a system at all. So far as I can tell, reserved blocks of Mark numbers began properly after the war. Fleet Air Arm variants of land-based aircraft had numbers in the twenties (eg the Sea Vampire and Sea Venom), whereas original FAA equipment started at Mk.1. (During the war, some licence-produced aircraft had had Mark numbers in the twenties, eg Australian Beaufighters.) The thirties were reserved for Australian and other overseas production, though not widely used (eg the Lincoln Mk.30, 31 and 32). The forties have tended to be for exports to nearer countries, mainly Europe (eg the Sea King Mk.41 for Germany), while some export programmes, particularly the Hunter and the Hawk, have made it even more complicated. Hunter exports started with the fifties (mainly to Europe) but rebuilt versions (mainly further afield) used the sixties, seventies, and even the eighties. The Hawk started this way but after the sixties gave up and skipped straight to 100 - although I suspect this is because the company, not the MoD, has been assigning Mark numbers and wanted to make a point about the newer variants.

The difficulty is reading this back to earlier practice. For example, the Mosquito reached over forty different variants without interruption, so the higher numbers aren't related to overseas or naval production. Spitfire and Seafire Marks were originally both started at I, but when the Griffon Seafires came in, Seafire Marks were interleaved with Spitfires (hence there's a Seafire 17 but a Spitfire 18). So many Mark numbers were being assigned so rapidly that odd fish like the Mk.IV got caught in the flow and had to take the next available number regardless.

[gingerbob]

It's not very systematic and the Spitfire is actually quite a bad place to start, as the numbering for that wasn't really a system at all.

Thanks Sean, the later data is interesting, but not really what I was after! I think you're right about the 100s- the companies were sometimes given leeway even if it went against the way things were supposed to be done.

Spitfire numbering IS logical, if you trace the evolution of policy. There are, of course, one or two exceptions! The thing is, the policy changed about three or four times along the way. The Mosquito did use blocks, with Canadian being XXs and Australian being, umm... was it 40s? Obviously the Mosquito is not fresh in my brain! These two types had a lot to do with the revision of policy because they were being developed so rapidly and seemed well suited to numerous tasks.

But what I'd like to know is when it became officially acceptable to jump ahead with (reserve) blocks, and for what applications? As I said before, it appears to start with overseas production, but I may well have missed some other early examples. The Spitfire XX may be the first time it was done to recognize a 'generational' level of development.

bob

Edited September 18, 2010 by gingerbob