J.Zynk Polish Aircraft 1893-1939 (Putnam)
Zalewski W.Z.II
Wladyslaw Zalewski was determined to begin flying at the earliest opportunity, and as the work on his W.Z.I biplane absorbed more and more time and the completion of the machine had to be put back year by year, the young constructor grew impatient and decided to find simpler and cheaper ways to satisfy his desire to fly. Early in 1912 he designed a primitive monoplane glider, retrospectively designated W.Z.II, and with the help of his brother Boleslaw built this aircraft in Milanowek in three weeks in the spring of 1912, at a total expense of only 24 roubles (some ?2.50).
The design was completely original, but initial tests conducted in 1912 revealed some shortcomings in the structure. After modifications, which included the additional stressing of the fuselage frame with extra wires, to improve rigidity, and the slight revision of the vertical tail surfaces, the results of the flight attempts became more satisfactory, and, as the designer gained experience in handling the glider, they grew progressively better. All the gliding was carried out from small hills in the Milanowek area in winds of 6-8 m/sec (13-17 mph). The glider was launched by means of two ropes pulled by Zalewski's friends, and the pilot had to bounce his feet off the ground a few times to become airborne. At first, 'hops' of some 30 m (98 ft) were made at a height of about 1 m (3 ft), but in 1913, when four or six people, instead of two, worked the ropes, longer distances were covered. The aircraft, which proved to be stable and quite easy to control, was frequently pulled by young boys at a leisurely run for 50-100 m (164-328 ft) and then began a short free glide.
The W.Z.II was damaged on a number of occasions, but never seriously and its pilot was never hurt. Only once was it involved in a more severe mishap, when the wooden lever operating the wing-warping control broke away in the air. Zalewski intended to replace it by a steel device, but circumstances prevented him from finishing this modification and he had to abandon further flights. The craft could be dismantled quickly to facilitate storage and for easy transport to suitable gliding sites.
Construction: The W.Z.II was a single-seat braced high-wing monoplane glider of wooden construction. The wing, with an area of 9.5 sq m (102.3 sq ft), was built up of a main spar, two auxiliary spars (the front one forming the leading edge), and curved ribs, and was covered with fabric on the lower surface only. The wing panels, which were individually braced by a kingpost system, were attached to the longerons of the fuselage frame, the trussing of the wing and the fuselage being arranged from a supporting cabane on top of the forward fuselage frame. To maintain lateral stability a wing-warping system was employed. The fuselage consisted of the rectangular horizontal frame with a reinforced forward portion, to which the inverted V cabane and two transverse Vs, carrying a long single landing skid, were attached. A bicycle-type saddle was carried on wires under the main fuselage frame. The frame longerons rested on the pilot's shoulders and were secured to them by straps. The cruciform monoplane tail unit, a wooden structure with fabric covering, consisted of a fin, a divided rudder and an undivided hinge-mounted elevator, which was attached to the rear of the fuselage frame. The top part of the rudder was operated jointly with the wing-warping system by movements of a hand-lever, the elevator being operated by another hand-lever, while the lower part of the rudder was operated independently by a rudder bar. The shock-absorbing skid, used for landing in the case of greater impact resulting from a steep descent, was below the pilot's knees. Dimensions included a span of 7.5 m (24 ft 7 1/2 in) and a length of 4.8 m (15 ft 9 in). Empty weight was 24 kg (53 lb).
