Actual operation of the Merlin boost regulator

[41Sqn_Banks]

Originally Posted by camber

The thing that still confuses me is that the Spit II also has a throttle gate that allows "take off boost" of +12.5psi that is only supposed to be for taking off from small fields or overloaded. I'm not sure why both systems (boost cut-off red tab, throttle gate) need to be there at the same time.

AP 2095 Pilot's Notes General (1st Edition, 1941) describes this. See attachment.

[Sutts]

Originally Posted by 41Sqn_Banks

AP 2095 Pilot's Notes General (1st Edition, 1941) describes this. See attachment.

Thanks for the extra info 41Sqn_Banks, great stuff. I feel enlightened.

[wedgehead383]

so according to the boost altitude diagramm the overboost function is only possible till 12250 feet are reached- above that altitude the pressure drops constantly and can not be raised e.g. theres no difference in engine power / thermic load between overboost mode and regular full throttle ???

[41Sqn_Banks]

Originally Posted by wedgehead383

so according to the boost altitude diagramm the overboost function is only possible till 12250 feet are reached- above that altitude the pressure drops constantly and can not be raised e.g. theres no difference in engine power / thermic load between overboost mode and regular full throttle ???

Correct. With boost control cut-out the throttle would behave different because the variable datum boost control is bypassed but otherwhise not difference.

[Versuch]

I know its an old thread but here is the boost control unit.