Bug 174 on 12lbs boost. Review please.

[41Sqn_Banks]

Originally Posted by Skoshi Tiger

This posses the questions, were there any modifications to the merlin XII engine that allowed it to work at the higher boost for the extended periods in 1941?

Or was it a decision based on accepting reduced engine life to keep the aging MKII competitive in air combat?

Or were the 1940 limits too conservative so they were increased?

A higher "emergency" boost than the rated +9 was definitely used from 21 August 1940 on, there are combat report and ORBs that proof this.

http://www.wwiiaircraftperformance.o...3aug40-orb.jpg
http://www.wwiiaircraftperformance.o...1aug40-orb.jpg
http://www.wwiiaircraftperformance.o...g40-orb541.jpg
http://www.wwiiaircraftperformance.o...-21aug40-1.jpg
http://www.wwiiaircraftperformance.o...-21aug40-2.jpg

Kurfürsts has the theory that the whole squadron called the regular climbing/rated boost of +9 boost in this instance "emergency boost". However he didn't came up with an explanation why they would do this.
Note that this reports explicitly mention "emergency boost" and don't mention "emergency power", the later could be interpreted as the normal "All out" setting of +9 and 3000 RPM, which was only allowed for emergencies. But as this is not the case it's clear that a boost higher than +9 was used in this instance.

There are also other reports from November 1940 that show the use of the boost control cut-out. The use of the cut-out only makes sense to increase boost beyond the rated +9 or when there is a failure in the boost control.

http://www.wwiiaircraftperformance.o...son-2nov40.jpg
http://www.wwiiaircraftperformance.o...en-30nov40.jpg