Spitfire & Hurricane flight model & engine performance thread. (1.09 patch)

[klem]

Originally Posted by JtD

Also with the Merlin XII. You would need to modify the automatic boost control so that it would be limited to 12 lb boost when disengaged. IIrc, this was done with reducing the cross section of the bypass.I agree, but I'd look at it the other way round - I can't be sure it always had. Do you have the Merlin XII handbook?

There appears to have been two methods of bypassing the boost control.

The throttle had a gate, at which the normal max 9lbs boost was produced. At the gate you could shift the throttle to the left then forward to achieve +12.25lbs for takeoff.

Emergency combat boost of +12lbs was also available with the throttle at the normal max position (+9lbs) by pushing forward the red tab we are familiar with froim the Spitfire MkIa/100 octane.

Why there should have been two methods I don't know. I have the attached on my hard drive for the Spitfire MkII, I'll try to find out more if we have a copy of an original Manual at the museum.