Affiliated to D.W.L., the Warsztaty Szybowcowe – glider workshops produced the Bᾳk, designed by Antoni Kocjan, 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.
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 5 U.S. gallons (19 L; 4.2 imp gal) of fuel. It also won a record for altitude, reaching 15,075 ft (4,595 m).[3]
VariantsEdit
Bąk I
The prototype and first production machines fitted with an 13.4 kW (18 hp) Kroeber M4 Köller, two- cylinder, horizontally opposed, two-stroke air-cooled engine, (SP-692 and SP-1102 are two known glider registrations).[1]
Bąk II
Production aircraft fitted with a 23.9 kW (32 hp) Sarolea Albatros two-cylinder horizontally opposed air-cooled engine, 25 built.[1]
kocjan, bąk, bąk, horse, single, seat, motor, glider, designed, built, poland, from, 1936, role, motor, glidernational, origin, polandmanufacturer, warsztaty, szybowcowedesigner, antoni, kocjan, first, flight, march, 1937, number, built, least, contents, devel. The Bak Horse Fly was a single seat motor glider designed and built in Poland from 1936 Kocjan BakRole Motor GliderNational origin PolandManufacturer Warsztaty SzybowcoweDesigner Antoni Kocjan 1 First flight March 1937 1 Number built at least 27 1 Contents 1 Development 2 Operational history 3 Variants 4 Specifications Bak II 5 See also 6 References 6 1 Notes 6 2 Bibliography 7 External linksDevelopment EditAffiliated to D W L the Warsztaty Szybowcowe glider workshops produced the Bᾳk designed by Antoni Kocjan 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 Bak 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 Bak 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 Bak II s was the 32 hp Sarolea Albatros engine driving a twoblade fixed pitch Szomanski propeller Designer of the Bak Antoni Kocjan became part of the Polish Underground resistance and was killed in the Warsaw Uprising 2 Operational history EditThe Bak won a FAI world record for duration of flight in a Class D motorglider The aircraft flew 5hr 24 minute on less than 5 U S gallons 19 L 4 2 imp gal of fuel It also won a record for altitude reaching 15 075 ft 4 595 m 3 Variants EditBak I The prototype and first production machines fitted with an 13 4 kW 18 hp Kroeber M4 Koller two cylinder horizontally opposed two stroke air cooled engine SP 692 and SP 1102 are two known glider registrations 1 Bak II Production aircraft fitted with a 23 9 kW 32 hp Sarolea Albatros two cylinder horizontally opposed air cooled engine 25 built 1 Specifications Bak II EditData from Polish Aircraft 1893 1939 1 General characteristicsCrew 1 Length 6 m 19 ft 8 in Wingspan 12 2 m 40 ft 0 in Height 1 45 m 4 ft 9 in Wing area 13 2 m2 142 sq ft Empty weight 207 kg 456 lb Gross weight 325 kg 717 lb Fuel capacity Fuel 40 L 8 80 imp gal 10 57 US gal Oil 4 5 L 0 99 imp gal 1 19 US gal Powerplant 1 Sarolea Albatros 2 cyl air cooled horizontally opposed piston engine 24 kW 32 hp Propellers 2 bladed Szomanski wooden fixed pitch propellerPerformance Maximum speed 152 km h 94 mph 82 kn Cruise speed 130 km h 81 mph 70 kn Never exceed speed 180 km h 110 mph 97 kn Endurance 4 hours Service ceiling 5 200 m 17 100 ft Rate of climb 2 5 m s 490 ft min Rate of sink 1 5 m s 300 ft min at 70 km h 43 mph 38 kn engine off Wing loading 24 6 kg m2 5 0 lb sq ft Power mass 0 0747 kW kg 0 4545 hp lb Take off distance to clear 8 m 26 ft 70 m 230 ft See also EditAircraft of comparable role configuration and era Scheibe SF 24 MotorspatzReferences EditNotes Edit a b c d e f Cynk Jerzy B 1971 Polish Aircraft 1893 1939 London Putnam ISBN 0 370 00085 4 William B Breuer Daring missions of World War II Sport Aviation August 1958 a href Template Cite journal html title Template Cite journal cite journal a Missing or empty title help Bibliography Edit Taylor J H ed 1989 Jane s Encyclopedia of Aviation Studio Editions London p 29 Cynk Jerzy B 1971 Polish Aircraft 1893 1939 London Putnam ISBN 0 370 00085 4 William B Breuer Daring missions of World War II Sport Aviation August 1958 a href Template Cite journal html title Template Cite journal cite journal a Missing or empty title help External links EditRWD aircraft manufacturer Retrieved from https en wikipedia org w index php title Kocjan Bak amp oldid 1126160721, wikipedia, wiki, book, books, library,
