Early models of 150 had a different aerofoil section from later models (G onwards and all 152's) which was much more efficient at low speed. I was taught in 'F' models; for short takeoff; 10 flap; full throttle on the brakes; brakes off, rotate at 45 mph, climb at 52 mph. Frightened you to death first time; don't try that in a 152 though!