Bartel BM-2 / M-2
The Bartel BM-2 was designed by Ryszard Bartel, a chief designer of Samolot factory in Poznań. It was the first Polish design of a trainer plane. Initially it was known as Bartel M-2, then BM-2 (M was for designer's wife Maryla).
A wooden construction biplane, conventional in layout. Fuselage rectangular in cross-section, plywood-covered (engine section - metal covered). Rectangular two-spar wings, plywood- and canvas-covered. Crew of two, sitting in tandem in open cockpits, with individual windshields. Cockpits with twin controls, the instructor seated aft. Fixed landing gear, with a rear skid (main gear with a common axle, sprung with a rubber rope). Radial engine in the fuselage nose, without a cowling.
A feature of the BM-2 and all Bartels was an upper wing of a shorter span, because the lower and upper wing halves were interchangeable (i.e. the lower wingspan included the width of the fuselage). Also Bartel put a stress on standardizing the construction materials used: steel pipes, metal sheet etc, in order to make production and repairs easier. A distinguishing feature of the BM-2 was the upper wing directly over the lower wing – un-staggered wings, while in later Bartel designs, the wings incorporate forward stagger.
The prototype was flown on 7 December 1926 in Poznań. In June 1927 it was shown at the first Aviation Exhibition in Warsaw. It was tested in 1927 and evaluated as quite good, but it was not built in series, because Bartel decided to design an improved aircraft, which resulted in the Bartel BM-4 trainer, which was produced in quantity. After flight testing, the prototype was removed from service.
Engine: 1 × Salmson 9 Ac, 90 kW (120 hp)
Prop: 2 blade, 2.24m diameter
Wingspan: 11.77 m (38 ft 7¼ in)
Wing area: 28.6 m² (308 ft²)
Length: 7.8 m (25 ft 7 in)
Height: 3.08 m (10 ft 1¼in)
Empty weight: 695 kg (1,529 lb)
Loaded weight: 970 kg (2,314 lb)
Useful load: 275 kg (605 lb)
Fuel capacity: 201 lt
Cruise fuel consumption: 34 lt/hr
Maximum speed: 128 km/h (69 knots, 80 mph)
Cruise speed: 100 km/h (54 knots, 62 mph)
Stall speed: 65 km/h (35 knots, 40 mph)
Range: 320 km (173 nm, 199 miles)
Service ceiling: 4,000 m (8,800 ft)
Rate of climb: 2.9 m/s (570 ft/min)
Wing loading: 33.8 kg/m² (7.51 lb/ft²)
Power/mass: 0.093 kW/kg (0.052 hp/lb)
Crew: 2, student and instructor