P-51s and a P-47 are the only low winged planes I can recall hand launching.
I grip them at the "waist" to let go with an overhand push.
They all tend to zoom down at first, then it's off to the races.
I recommend learning to launch the plane with your left hand while holding your right thumb where it belongs [on the stick]. I cringe to watch guys lob the plane with their right hands then grope for the radio as fast as they can.

Always know exactly which way the wind is blowing..