My guess is that the aim with a carrier take- off would be to get as much thrust as possible from the moment the aircraft starts rolling. At max rpm you’d need the blade set at just five degrees for this to happen. The bracket prop could be re-set on the ground so its minimum pitch was this figure, but even with the 30-odd degrees available after the 1940 mods you’d struggle to get even a Spitfire’s economic cruise, let alone max speed, out of the coarsest pitch then available if you do this. With 60 degrees to play with, this would explain why Hydromatics might have been thought of for carrier operation?

I am guessing that yer basic Rotol wouldn’t offer this range.. what was the arrangement with Seafire I’s?

Thanks, mate.

Yep, one of those tables has been a bit of a revelation on two counts. One it confirms my suspicion that shaft size is not important… by which I mean there’s no reference to shaft/splines in the code system for DH prop blades (why should there be, when you think about it). There have been many red herrings previously here about that.. and secondly it shows that blade shank size is still indicated after the ’45’ (which just means ‘Hydromatic’) – ref our PM conversation, David C.

It also shows that there is a sort of system about rotation, at least with Hydromatics, which would probably carry over to bracket types after all. 0 or 1 means right-hand, 5 or 6 means left-hand. Does anyone know the reason both numbers were used in each case?

This now only leaves one number available to describe blade design – back to the drawing board?

I have had ‘Thrusting Forward’ (back to shaft sizes again) on order for months now. I must chase that, thanks for reminding me..

PS – on the other thing, I have been a bit cr*p, what with one thing and another – I will call E today!