[bongodriver]

Originally Posted by klem

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.

the 2 methods make some sense taking into account JTD's mention of the automatic cutting out of 12lbs take off boost above 1000', the use of the famous red lever should give the emergency 12lbs instead of an instant engine death boost and is available for use when above 1000', it simply stands to logic that the fabled combat boost was 12lbs, as 9lbs was achieved by default at full throttle and we know the engine could handle 12lbs for at least 3 minutes.....more than enough time for a 'tight spot' in combat.

I always thought the instant engine death boost levels were only achieved when people went and started putting matchsticks in holes they shouldn't have.