Polish Aviation Museum

31-864 Kraków,
al. Jana Pawła II 39
phone: (12) 640 99 60,
(12) 642 40 70
e-mail: info@muzeumlotnictwa.pl

a cultural institution of the Malopolska Region

Małopolska – Kraków Region

Mecenas Muzeum

Kraków Airport

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Patroni Medialni

Skrzydlata Polska

Motor glider: Borzęcki Altostratus

Borzęcki Altostratus


  • Technical data

Span 10 m (32.8 ft)
Length 5.5 m (18 ft)
Wing area
Empty weight 90 kg (198 lb)
Take-off weight 160 kg (353 lb)
Glide ratio 20
Sink rate 0.9 m/s
Maximum speed 100 km/h (54 kt)
Minimum speed 48 km/h (30 kt)
Max. diving speed
Powerplant :
Four-cylinder two-stroke RB2 flat piston engine rated at 18 kW (24 hp)


A homebuilt motor glider, designed by Józef Borzęcki.

During 1952–1961 Józef Borzęcki designed and built a motor glider called Stratus. It was initially powered by an engine from a Czech chainsaw and wings from Żuraw (crane) glider. It initially featured classic flight control system with a control stick and rudder pedals, subsequently replaced by a “coupled” control system, designed by Borzęcki, in which the stick was used to control the aircraft in all axes (pitch, roll and yaw). It was aimed at facilitating flight training and increasing comfort in non-professional conditions. During 1961–66 the Stratus was flown illegally and in secrecy.

In late 1960s the constructor undertook a rebuilding process. The aircraft was fitted with wings from Komar (mosquito) glider, lighter and providing better glide ratio and flat two-stroke four-cylinder RB2 engine, designed by J. Borzęcki out of two connected Riedel starter engines from German Junkers Jumo 004 turbojet engine from World War II. After this rebuilding the motor glider was named Altostratus and first flew in 1972. It remained in use until 1982.


Dofinansowano ze środków Ministra Kultury i Dziedzictwa Narodowego
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