title: SZD-7 Osa
text: # SZD-7 Osa
  
  The SZD-7 Osa was a single-seat developmental glider aircraft that was designed and built in Poland at Szybowcowy Zakład Doświadczalny (Glider Experimental Works) in Bielsko-Biała in 1950. Only one example was built.
  
  ## Development
  
  The SZD-7 or IS-7 Osa (Wasp) was based on the IS-2 Mucha, with a laminar flow aerofoil section developed by Tadeusz Kostia. Little information on laminar flow aerofoils was available but Kostia was able to design the aerofoil for the SZD-7 Osa to achieve laminar flow to at least 18% chord. As well as the laminar flow wings, the Osa introduced the SZD plate-style airbrakes, which were installed aft of the mainspar. The first flight of the Osa took place at Bielsko airfield piloted by Adam Zientek on 16 August 1950. The prototype was registered as SP-1047.
  
  ## Specifications (SZD-7 Osa)
  
  Data from http://www.piotrp.de/SZYBOWCE/pszd7.htm
  
  General characteristics
  
  * Crew: 1
  * Length: 6.8 m (22 ft 4 in)
  * Wingspan: 15 m (49 ft 3 in)
  * Height: 1.6 m (5 ft 3 in)
  * Wing area: 14.1 $m^2$ (152 sq ft)
  * Aspect ratio: 16
  * Airfoil: Kosti laminar flow
  * Empty weight: 237 kg (522 lb)
  * Gross weight: 327 kg (721 lb)
  
  Performance
  
  * Maximum speed: 250 km/h (155 mph, 135 kn)
  * Stall speed: 56 km/h (35 mph, 30 kn)
  * g limits: +4.5 / -3
  * Maximum glide ratio: 26.1 at 81 km/h (50 mph/44 kts)
  * Rate of sink: 0.80 m/s (157 ft/min) at 73 km/h (45 mph/39 kts)
  