Spit IIa is now so much more inferior to the 109

[41Sqn_Banks]

By the way. The altitude of 12,250 feet that was chosen for the power curve is the altitude used for rated/international rating. This is probably the FTH for climb rating, the RPM is lower than on "All out", thus the FTH is lower under this condition.

Here are some examples for Merlin II/III:
http://www.spitfireperformance.com/L...ertificate.jpg
http://www.spitfireperformance.com/k...ertificate.jpg
http://www.spitfireperformance.com/n...ertificate.jpg
http://www.spitfireperformance.com/k...ertificate.jpg

There is another for Merlin III, but this is probably a prototype or conversion for Merlin XII.


Despite the use of 100 octane fuel the power curve is only done up to +10.6. However +12 or even more boost is possible without detonation. This pretty much spoils the idea that the values from the power curve have anything to do with the physically possible maximum.

How would they measure the engine power during flying anyway? It's likely that these were either calculated values from bench tests at sea level and even if boost above the regular engine limits were used it was under a controlled condition and certainly for very short periods.