TECHNOLOGIES

THE AIRFOILS

For eta there was a special family of airfoils designed by Dr. K.-H. Horstmann and Claas-Hinrik Rohardt at the Institute of Design Aerodynamics and measured at the low speed windtunnel of the DNW in Braunschweig.

The measurement of the new airfoils were crosschecked with a measuring of the HQ 17 to have a comparable polar measured in the same wind tunnel with the same calibration.

The main wing airfoil is based upon the approved HQ 17 with enhancements at higher speed range.

The airfoil for the outer wing has a slightly higher maximum lift as the HQR 1, and sustains the effect of the chord skip of the wing geometrics. By contrast with the usual airfoils for the aileron area, laminar flow on the upper side is maintained; this generates higher lift without loss of efficiency of the ailerons.

The airfoil at the root of the wing was designed and optimized for the turbulent flow at the wing fuselage intersection and with a thickness of 16.45 % for the design of the wing joint.

The fin’s airfoil has got a lowered drag which compensates for the enlarged surface of the fin. This contributes to improved handling of the glider.

The elevator’s airfoil was designed for enough authority for control of the glider in case of faulty adjustment of the trimmable elevator.