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

[Robo.]

Originally Posted by Kurfürst

Wishful thinking. It doesn't say +12 lbs boost, it says 'emergency boost', which we all know was +9, as per the manual. Selective and wishful use of evidence...

+9 was also climb boost (at 2850 rpm) and there was also all out setting which was +9. All out suggets just full throttle and full rpm, it is not emergency boost and pilots would not refer to it as emergency boost.

With BCC-O, Merlin XII was technically capable of pressures higher than +9lbs., it was certainly safe to operate it at +12lbs. (for that was the take-off power with the throttle gate system and also supported by simple fact that XII was improved III and III was approved for that MAP). +17lbs. is consistent with R-R raw tests but perhaps JtD is right, I don't know. I agree that as for Pilot's Notes the Merlin XII are set correctly for the sim (at +9lbs max), there is not enought direct evidence and the date of amendment is not clear, unofrtunately. The best authority at early Merlins is the Merlin in perspective publication quoted by Al Schlageter in here but it does not clarify the date of emergency boost amendment. There was no modification necessary to achieve that fore sure, it was physically possible to have boosts higher than +9lbs from day one on Merlins XII.

I agree with you that it would be great and interesting to have the BCC-O (ABC) modelled, I would not mind. It is logical and almost certain that it has been used in combat.

For the operation and technical details of both Take Off power and ABC, there were some interesting scans and description by Banks in some other thread.

[bongodriver]

I'm struggling with some of the logic behind the use of 12lbs here.......for the life of me I can't think of a single circumstance where a pilot would need to break a sealed lever to get an emergency take off boost in a single engine aircraft, take off performance should be accounted for using max available non emergency power...........OR have I got the wrong idea and 12lbs boost was available without breaking the seal but was instead achieved by use of a throttle gate and was automatically reduced above 1000' and if you hadn't climbed above 1000' on departure you were expected to reduce after a max of 3 minutes? thereafter the max boost was 9lbs?........which means that the sealed boost lever has not yet been used.......I wonder what would happen if I used it?