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Old 06-25-2011, 10:00 AM
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Crumpp Crumpp is offline
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Quote:
"This initial increase in maximum boost from 6 lb to 9 lb delivered a useful power growth of around 130hp at the rated altitude". This just doesn’t make sense when all the documentation available shows an increase in maximum boost from +6.25 to +12 with the Merlin III.

If you read in the July 1940 POH for the Spitfire II, it clearly lists 100 Octane as the fuel and that +12lbs is a Take Off rating and +9lbs is an Emergency rating limited for 5 minutes.