Jim Macklin wrote
5 and 7 thousand

Running on (faulty) memory again, Jim?

How about 7,500' and about 12,500', ISA of course.

See my previous replies to this thread for a real chart
answer.

The formula answer is:

bhp at altitude equals bhp at sea level times the quantity
(density ratio minus the quantity(1 minus density ratio divided by 7.55))

Works out to 76% at 7,500' and 64% at 12,500', or thereabouts.


Bad information is worse than no information at all.

Bob Moore