In WWII BoB the Spitfire and Hurricane had identical engines and propellers but different airframes. Their maximum rate of climb was achieved at different forward speeds and angles of attack. Bearing in mind that the performance of the engine and propeller changed with altitude as did the wing how did the pilot know he was getting the best climb performance. Was it a forward speed or angle of attack at a certain altitude or just a "feeling" holding the plane on the edge of stall *hanging on the propeller".