How do cruise speeds change with altitude (standard piston prop)
Asked by: k-west 2495 views Aerodynamics, General Aviation
Ignoring all other factors (winds, time to climb, practical considerations like O2, etc...), how can you relate the maximum cruise speed to the cruise altitude for a normally aspirated (non-turbo), piston/propeller aeroplane? A C172M for example. I know that as the air becomes thinner, the engine cannot produce as much power, and the aerodynamic drag decreases. One of those makes you go slower, and the other faster, and I'm sure the relationship between the two produces a curve that may have a sweet spot that one should aim to cruise at to maximise their speed. Can you help me understand this relationship, and how to determine that sweet spot using the POH?
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