Thanks for all the welcomes and the responses
Firstly Gamary when you ask is it vector based, in pure terms no, not like this...

which apart from the initial pencil sketch is 100% Illustrator.
Instead I used some plans, traced it all out in Illustrator, imported the paths into photoshop to use as layer and group vector masks, combined with some normal layer masks and clipping masks so it is sort of vector based.
JMSmith I have taken on board some of the comments, the curve/bulge of the canopy which both the plan I used and the one you posted up seem to indicate is there but having had a closer look at the excellent photos seems to not be there, I used the warpaint book which it seems the illustrations also came from is actually incorrect so I need to do more homework next time.
I am however a little unclear about what exactly is meant by the curve on the turret, I'm probably missing something glaringly obvious. Despite this the criticism is greatly appreciated.
Finally Supah now that the plans seem incorrect on a couple of points I'm not so sure the wings really are that thick but I have found nothing as yet to contradict the fact.