[jim]

Interesting ,
I have checked through a load of info and all I can find is that several trails were done on the Spit MKV with different engines and props but none were made in significant numbers.

BBMF has a VB with a four blade prop number AB910 but I have not found any info on this one.
Several MK3s with the VB wing had a 4 blade prop, but never saw service and were used as development aircraft.
A MK4 Spit was fitted with a 4 blade prop and used as a trail set up for a 6 cannon armed Spitfire!
I dont know how they proposed to get that armament into the VB wing but they built a mock up and tested it in principle.

I have found notes that tell of 3 Spits MKV with VB wing being used as high altitude test planes (this is before they built the extended wing models) these had the 4 blade prop.

I am enjoying this investigation Shamrock, its a long time since I read up on the Spitfire.
Very interesting development programme indeed and quite confusing because different marks of Spit was used to develop new marks.
The Mk1V and V11 and V111 were used to develop both the 1X and XX11 but also the MK 11a was used to develop the X1V.
I wont even begin to go into the engine variations and the upgrades to the Merlins fitted to these numerous test planes.
A standard Merlin 45 achieved the amazing output of 2000 hp under tests to see what the actual engine itself would take before it broke!

Another piece of info thats interesting is that the 11a used as a test plane achieved speeds of 400 mph in 1941 and used a four blade prop.
However to complicate things, a MKV was tested with both a 3 and 4 blade prop fixed to the Merlin 45 and no significant difference to performance was noted!

Tonight my bedtime reading will be Spitfire written Jeffrey Quill, a great book that I must reread, its many years since I read this book.
Its a must have for any Spit Fanatic.
It contains the full development story of the Spit from begining to end.