Above it there was a short triangular fin, reaching back to the trailing edge of the tailplane, carrying a taller, full rudder with a straight, sloping edge but rounded top and heel. The rudder projected below the fuselage but was protected on landing by a small tail skid. The tail surfaces were all fabric covered behind the ply leading edges. After its first flight on the Wasserkuppe in May 1928, the Rhöngeist joined the annual national competition there and made its mark with a flight on 6 August 1928, flown by Robert Kronfeld who found a thermal under a cloud, flew to mountains and slope soared, then returned against the wind to the Wasserkuppe, aided by more thermals en route. Almost immediately other pilots began to find lift under clouds. Plans for the Professor were widely sold to commercial manufacturers and to clubs both in Germany and abroad, though the total number of Professors built, sometimes with small variations, is not known. One at least, constructed in Germany, came to the UK and was flown by Philip Wills. Two were built in the United States as Heller Hawks. Like other high performance gliders of it day, it was slow to come out of turns and with its strongly tapered wing, prone to tip stalling. The Professor II, first flown in 1929, addressed some of these problems by increasing the mean overall wing chord with fuller, curved ailerons, modifications first applied to the prototype Rhöngeist. The Professor II also had new horizontal tail with a fixed, swept tailplane mounting constant chord, rounded tip elevators with a cut-out for rudder movement.