The Bąk (Horse-Fly) was a single seat

motor glider A motor glider is a fixed-wing aircraft that can be flown with or without engine power. The FAI Gliding Commission Sporting Code definition is: a fixed-wing aerodyne equipped with a means of propulsion (MoP), capable of sustained soaring flight ...

designed and built in

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...

from 1936.

Development

Affiliated to D.W.L., the ''Warsztaty Szybowcowe'' – glider workshops produced the Bᾳk, designed by

Antoni Kocjan Antoni Kocjan (12 August 1902 – 13 August 1944) was a renowned Polish glider constructor and a contributor to the intelligence services of the Polish Home Army during World War II. Early life and education Antoni was the son of Michal K ...

, to compete with the ITS-8 which had been designed to a specification from the I.T.S.M. (''Instytut Techniki Szybownictwa i Motoszybownictwa'' – institute of gliding and motor-gliding techniques), for a cheap ultra-light aircraft suitable for converting trained glider pilots to powered flying. The Bąk I was an immediate success with excellent performance and good handling qualities, passing I.T.L. (''Instytut Techniczny Lotnictwa'' – Technical aviation institute) and airworthiness tests without problems, also proving to have relatively good gliding performance. The Bąk was built primarily of wood with plywood in a semi-monocoque fuselage and cantilevered single spar wooden wings, with plywood skinned leading edge torsion boxes and wing roots, mid set on the fuselage with marked dihedral. The tail unit comprised a fin, with rudder, integral with the fuselage and a cantilever ply and fabric covered all-flying tailplane, all control surfaces were statically balanced and mounted on ball bearings. Various engines of 16 to 32 hp could be fitted, with the majority of the production Bąk II's was the 32 hp Sarolea Albatros engine driving a twoblade fixed pitch Szomański propeller. Designer of the Bąk, Antoni Kocjan, became part of the

Polish Underground The Polish Underground State ( pl, Polskie Państwo Podziemne, also known as the Polish Secret State) was a single political and military entity formed by the union of resistance organizations in occupied Poland that were loyal to the Gover ...

resistance and was killed in the

Warsaw Uprising The Warsaw Uprising ( pl, powstanie warszawskie; german: Warschauer Aufstand) was a major World War II operation by the Polish resistance movement in World War II, Polish underground resistance to liberate Warsaw from German occupation. It occ ...

Operational history

The Bąk won a FAI world record for duration of flight in a Class D motorglider. The aircraft flew 5hr 24 minute on less than of fuel. It also won a record for altitude, reaching .

Variants

;Bąk I:The prototype and first production machines fitted with an

Kroeber M4 Köller The Kroeber M4 Köller was a 2-stroke air-cooled horizontally-opposed piston engine designed and built by Dr. Kroeber & Sohn G.m.b.H. in Germany in the late 1930s. The M4 proved relatively popular, for powering the ultra-light aircraft and motor ...

, two- cylinder, horizontally opposed, two-stroke air-cooled engine, (SP-692 and SP-1102 are two known glider registrations). ;Bąk II:Production aircraft fitted with a Sarolea Albatros two-cylinder horizontally opposed air-cooled engine, 25 built.

Specifications (Bąk II)

References

Notes

Bibliography

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

External links

RWD (aircraft manufacturer) RWD was a Polish aircraft construction bureau active between 1928 and 1939. It started as a team of three young designers, Stanisław Rogalski, Stanisław Wigura and Jerzy Drzewiecki, whose names formed the RWD acronym. History They started w ...

{{DEFAULTSORT:Kocjan Bak RWD aircraft 1930s Polish civil trainer aircraft Single-engined tractor aircraft Mid-wing aircraft Motor gliders 1930s Polish sailplanes Aircraft first flown in 1937