In Germany, just after the end of World War I, the 1919 Versailles treaty imposed a ban on powered flight. As a result there was a rapid increase of interest in gliding. Rheinhart Platz, the chief designer for Fokker's after June 1916, perceived a role for a glider that was cheap to buy, costing less than "one good pedal cycle", and cheap to maintain, while being robust and capable of being transported, by train or otherwise, and rapidly erected by one man.
In the winter of 1922/23 Reinhold Platz designed and constructed a glider. The idea occurred during a sailing trip on the Schelde. To a certain extent sailing on water can be compared (aerodynamically) with gliding. After several tests with small and large models, Platz constructed a full size glider. Its fuselage comprised a curved steel tube with a circular section wooden beam inserted through it at the rear. The wing spars were two wooden masts which were inserted into two receptacles welded to the fuselage tube near the pilot's seat. The “main sail”, or wing, was attached to these two masts. The two separate forward jibs were attached to jib masts, which could be moved by the pilot simultaneously or separately as required. By moving the two jibs up or down, longitudinal control was obtained. By moving one jib up and the other down, lateral control was possible. They were initially hinged together at their leading edges, but later the hinge point was moved rearwards towards the aerodynamic centre to reduce pilot load and separated only behind the hinge.
Since there were no ribs, the airfoil was determined by the airflow and the pilot, as for the sloop's jib. The main wing, a single surface stretched between the spars and the extreme tail, also had its camber determined by the airflow, like the mainsail of the sloop. Both wing sheets were produced by sewing together narrow strips of material; the longitudinal joints between them are prominent in some back lit, better quality images.
The glider had a wing span of 6.60 metres and weighed 40kg. It could be assembled by one man within 15min, and dismantled within 10min. The Platz could be disassembled into a 3,300 mm (130 in) × 350 mm (14 in) × 250 mm (10 in) pack, weighing 40 kg (88 lb) in fifteen minutes and reassembled in ten. Transport by bicycle, with care, was possible.
Free flight trials began some 50 flights without pilots and with increasing loads (up to 75 kg (165 lb)) into strengthening wind and eventually over sandhills as high as 25 m (82 ft). With a pilot in place, the glider was then flown tethered like a kite, first flying in February 1923. Several people, with weights up to 100 kg (220 lb) flew it this way, all reporting that forewing control loads were low. In February 1923 it was free flown in a moderate wind over 10 m (33 ft) dunes. Platz decided that the dunes did not provide usable soaring, their next goal, after which the experiments would end. He noted that, whilst his design could not compete with the best conventional gliders, it had met the initial targets outlined above and thought it or something similar would be of great value, seemingly content to leave others to judge his design.
Platz glider being transported
Modern copies have since been built.
Wingspan: 6.60 m (21 ft 8 in)
Wing area: 16.0 m2 (172 sq ft)
Empty weight: 40 kg (88 lb)
General layout of the Platz glider; not a scaled or detailed drawing