Pelzner was a builder of doppeldecker hangegleiter. In 1921 and 1922 he carried off many prizes. He built all his own craft and developed a simple structure that proved strong enough to carry him safely on flight after flight without serious mishap, yet light enough for him to control flight by bodily movements, changing the centre of gravity to trim the aircraft and overcome the upsetting effect of gusts or turbulence.
Pelzner’s gliders were astonishingly cheap despite financial trouble and inflation in Germany they cost him less than 20 marks to build. Derigged, they were small enough to be loaded onto a passenger train as traveller’s luggage at no extra charge; the parcel measured about 2.7m long, 1.3 m high, but only 50 cm thick.
The various Pelzner gliders differed a good deal in size and detail, although all were built roughly to the same basic scheme. The earlier models were built smaller and very light; 5.4 m span with total wing area of 14 sq.m. The weighed less than 10 kg. The later types spanned up to 7 m with areas of 16.5 sq.m, and weighed twice as much. Probably as Pelzner’s skill improved he was able to control bigger and more efficient gliders.
The framework was two tapered longerons, a shoulder width apart, running fore and aft with the lower wing main spars running cross wise and attached with bolts. At the rear these two main members were drawn together to support the tail unit, and from the tail to the upper end of the main wing struts two diagonal members ran. This basic framework was of oval or streamlined section timber, 2.5 cm by 4 cm in cross section where the loads were greatest, thinning down to 2 x 3 cm elsewhere. The upper and lower wings both had two spars, the front spars being 4 cm by 0.5 cm section, the rear spars 3.5 x 0.8 cm on the lower wing and 3.6 x 1.1 cm on the upper. Light curved ribs were bound to the spars, and the two wings were joined by light vertical struts, the outer ones being spindled I section to save weight. The whole structure was braced with wire.
Pelzner covered his surfaces with oiled paper, glued onto the underside of the ribs of wing and tail. The leading edge of the lower wing was formed by the front spar, but the upper wing apparently had a light front member of wood or wire which gave a stiff entry to the primitive aerofoil. Some models had double thickness paper covering around the leading edge. The earliest models had no movable control surfaces at all, but later Pelzner fitted a rudder which he controlled by means of a sling around his right hand – a forward movement for a left turn, a backwards push for a right turn.
To manage these craft Pelzner worked out an athletic style of flying. At the 1921 meeting he accumulated a total flying time of 38 minutes, higher than any other pilot. He did this in a total of 62 flights aeraging over a half a minute each, some of them covering 400 and 500 m at his best glide ratio of about 6 to 1. In cash prizes he paid for his gliders hundreds of times over.
After monoplane glider flights the future was clearly not biplanes. Pelzner played little in the subsequent development of gliding.