Bartel BM 6
General information
Type	Trainer aircraft
Manufacturer	Samolot
Status	Prototype
Primary user	Polish Air Force
Number built	1
History
First flight	8 April 1930

The Bartel BM 6 was a Polish biplane trainer fighter aircraft of 1930. It did not advance beyond the prototype stage.

The aircraft was designed by Ryszard Bartel in the Samolot factory in Poznań, as a trainer-fighter plane. The BM-6 prototype, designated BM 6a, was flown on 8 April 1930 in Poznań. Its advantage was an easy construction and maintenance, according to Bartel's design philosophy. A distinguishing feature of all Bartels was an upper wing of a shorter span, because lower and upper wing halves were interchangeable (i.e. the lower wingspan included the fuselage width). It first introduced a mixed construction to Bartel's designs.

After trials, the prototype was modified in July 1930. The prototype was later redesignated BM 6a/II after it was substantially modified. It offered quite good flight characteristics and was capable of aerobatic flight. It was demonstrated in a fighter-plane competition in Bucharest in 1930, along with the similar PZL P.1.

The second prototype BM 6b, with a Wright Whirlwind 220 hp radial engine, was ordered, but work upon it ceased with closure of the Samolot factory in mid-1930. The PWS works, which inherited many of Samolot's projects, did not continue the project, for it had its own similar design, the PWS-11.

Mixed construction biplane. Steel framed fuselage, rectangular in cross-section, canvas covered (engine and upper sections - aluminum covered). Rectangular two-spar wings with rounded ends, plywood and canvas covered. Upper wing span: 7.36 m, lower wing span: 8.10 m. Lower and upper wing halves were interchangeable. Single pilot, sitting in open cockpit, with a windshield. The V8 engine Hispano-Suiza 8Be was modified to lower power output (from 220 hp to 180 hp). Radiator below the fuselage. Fixed landing gear, with a rear skid. Two-blade wooden propeller of fixed pitch. Fuel tank in fuselage: 168 L capacity.

After state trials in 1931, the prototype was used in an advanced training school in Grudziądz, then in an aviation training center in Dęblin.

 Poland

• Polish Air Force (single prototype)

Data from Polish Aircraft 1893–1939^[1]

General characteristics

• Crew: 1
• Length: 6.35 m (20 ft 10 in)
• Wingspan: 8.09 m (26 ft 7 in)
• Height: 2.8 m (9 ft 2 in)
• Wing area: 17.6 m² (189 sq ft)
• Empty weight: 697 kg (1,537 lb)
• Gross weight: 985 kg (2,172 lb)
• Fuel capacity: 170 L (45 US gal; 37 imp gal)
• Powerplant: 1 × Hispano-Suiza 8Be V-8 water-cooled piston engine, 130 kW (180 hp)
• Propellers: 2-bladed Heine fixed pitch propeller

Performance

• Maximum speed: 194 km/h (121 mph, 105 kn) atsea level
• Never exceed speed: 420 km/h (260 mph, 230 kn)
• Service ceiling: 3,800 m (12,500 ft)
• Time to altitude: 4 minutes 24 seconds to 1,000 m (3,300 ft); 18 minutes 57 seconds to 3,000 m (9,800 ft)
• Wing loading: 56 kg/m² (11 lb/sq ft)
• Power/mass: 0.138 kW/kg (0.084 hp/lb)

Armament

• Guns: 0.303 in (7.7 mm) Vickers machine gun in a fuselage, with a synchronising gear

Aircraft of comparable role, configuration, and era

• Bristol Bulldog
• Fiat CR.32
• Gloster Gladiator
• Polikarpov I-15
• PWS-11

• Glass, Andrzej (1977). Polskie konstrukcje lotnicze 1893–1939 (in Polish). Warsaw: WKiŁ.
• Nelcarz, Bartolomiej & Peczkowski, Robert (2001). White Eagles: The Aircraft, Men and Operations of the Polish Air Force 1918–1939. Ottringham, UK: Hikoki Publications. ISBN 1-902109-73-2.

• Photos and drawings
• Ugolok Neba site (in Russian)