SZD 20x Wampir 2
Role	Glider Type of aircraft
National origin	Poland
Manufacturer	PZL Bielsko
Designer	Jan Dyrek
First flight	9 September 1959[1]
Number built	1

The SZD-20x Wampir II (Szybowcowy Zakład Doświadczalny - Glider Experimental Works) was a single-seat tail-less research glider designed and built in Poland from 1959.

The SZD-20X Wampir II (vampire II) was designed to compare a flying wing designed to Standard class rules with a more conventional standard class glider. Main designer was Jan Dyrek. Based on experience with the earlier SZD-6X Nietoperz and SZD-13 Wampir tail-less gliders, the SZD-20X was an all wood flying wing, with the pilot sitting in a pod extending aft of the trailing edge on the centreline, and large swept fins & rudders at approx 2/3 span on each wing.

The SZD-20X was associated with the number 15, having a 15m span, aspect ratio of 15 and wing area of 15m², whether this was by design or accident is not known.^[1] Early flight trials commenced with hops towed behind a car to test control responses, followed by an aero-tow launch on 9 September 1959, piloted by Adam Zientek. Flight trials revealed a marked sensitivity to turbulence resulting in flutter, and during trials at stalling speed, the SZD-20X entered a spin, which the rudders were unable to recover the aircraft from, only when the pilot shifted his weight as far forward as he could, did the SZD-20X recover from the spin.^[1] Flying in the SZD-20X continued until 6 October 1959, when turbulence-induced flutter tore the aircraft apart, the pilot escaping with parachute.^[1]

Data from The World's Sailplanes:Die Segelflugzeuge der Welt:Les Planeurs du Monde Volume II ^[1][2]

General characteristics

• Crew: 1
• Length: 6.2 m (20 ft 4 in)
• Wingspan: 15 m (49 ft 3 in)
• Height: 1.7 m (5 ft 7 in)
• Wing area: 15 m² (160 sq ft)
• Aspect ratio: 15
• Airfoil: NACA 23112
• Empty weight: 171 kg (377 lb) equipped
• Gross weight: 268 kg (591 lb)

Performance

• Stall speed: 50 km/h (31 mph, 27 kn)
• Never exceed speed: 200 km/h (120 mph, 110 kn)
  
• Aerotow speed: 120 km/h (75 mph; 65 kn)
• g limits: +4.5 -2 at 91 km/h (57 mph; 49 kn)
• Maximum glide ratio: 24.4 at 82 km/h (51 mph; 44 kn)
• Rate of sink: 0.84 m/s (165 ft/min) at 72 km/h (45 mph; 39 kn)
• Wing loading: 17.8 kg/m² (3.6 lb/sq ft)

Aircraft of comparable role, configuration, and era

• Horten H.IV
• SZD-6X Nietoperz

Related lists

• List of gliders

• Taylor, J. H. (ed) (1989) Jane's Encyclopedia of Aviation. Studio Editions: London. p. 29

Wikimedia Commons has media related to SZD-20 Wampir 2.

• http://www.vintagesailplanes.de/SZD_20.htm