Its not only the tips that are thick , older airfoils tended to be reworked naca .0018 , 18 % thick .
Typically around 22-23% these days . pushes a bit more air so gets a bit more grip , fo the bigger
heavier planes . With more power to match the increased adhesion of the air .
The old cica 1960 unsilenced Fox .35 things could be down around one kilo ( 36 Ounces) , flown on
60 ft. lines , they flew like a bird on the wing .
The muffler knocked the power back and kept the heat in more , starting a vicious circle .
Next stage was maybe the Super Tigre .46 generation , up to 60 Oz and 60 in span , in the early seventies.
Then ST .60s in ships about this size , on long lines maybe, for better power reserves .This is about where the
thicker airfoils came along , to carry the weight . Jim Greenaway being one of the development pioneers in this respect.
There were Schneurle ported .40 planes in all shapes and sizes , Bob Hunt and collegues being predominant in these developments and the piped arrangement .
Nowadays theres all sorts of dedicated aerobatic engines produced utiliseing the tecnology learnt in these efforts .
The Stalker series being SuperTigre inspired , with PA & Ro Jett more tecnologically inclined , and the YatsenkoTractor Engines .