Airfoil

The airfoil should be suitable for advanced aerobatics. In difference to earlier thoughts on using a standard one of the 'no compromise' section, I changed my mind and searched for a  more 'flyable' airfoil, also more suitable for the beginner aerobatic pilot.

What does that mean..

An aerobatic symmetrical airfoil is a fly/no fly airfoil - not producing lift in case of no (0) pitch (angle of attack, angle of incidence). That also means that stall characteristics are challenging because the wing stops flying (lifting) in a moment. Otherwise flying upside down should be possible with not to much inverted pitch needed! Stallspeed is comparable high on  a symmetrical airfoil because producing lift needs pitch and therefor it needs speed.

I took the previously considered Eppler473 for a closer look. It is a thicker symmetrical airfoil specially calculated for aerobatics. With the thoughts on tame the otherwise suitable airfoil a bit, I changed the thickness of the airfoil on the upper side to 110% and the thickness on the lower side to 70%. The total thickness, with a wing root chord of 1300 to 1370mm, is about 200mm, so didn't change that much.

Now the aifoil produces lift on a straight flight path, but keeping the general characteristics almost as wanted.

Inverted flight pitch will be a little more than 3degrees pitch at a roughly estimate.

I will try to develop these thoughts a little further, because the airfoil makes sense and looks encouraging...see the print out.