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Bartel BM-5 / BM-300

 
 Bartel-BM5-01
BM-5b2
 
The Bartel BM-5 was designed by Ryszard Bartel with Z. Nowakowski , J. Medwecki , S. Nowkuński in the Samolot factory in Poznań, as an advanced trainer, transitory between primary trainers and bomber or reconnaissance aircraft.
 
A further development of the Bartel BM-3, it was a wooden construction biplane, the fuselage was rectangular in cross-section, plywood covered (engine section - aluminum covered). Rectangular two-spar wings, plywood and canvas covered. Crew of two, sitting in tandem in open cockpits, with individual windshields and twin controls, instructor in rear cockpit. Fixed landing gear, with a rear skid. Engine in front, with a water radiator below fuselage nose (BM-4a,b,c). Two-blade wooden propeller. Fuel tanks in upper wings and fuselage, capacity: 235-270 t.
 
 Bartel-BM5-02
BM-5a1
 
The upper panels were identical to the bottom and braced with N steel pipe and wood double links. Upper panels attached to the hull placed on the pyramid of 6 steel pipes and wood. Ailerons on all wings, covered with plywood. The fuselage of rectangular cross-section rounded at the top, was covered with plywood. The front part of the fuselage covered with removable end caps made of aluminum sheet. Trapezoidal tail welded steel pipe, covered with canvas. Tail horizontal casement, supported by struts with steel pipes, vertical tail stiffened profiled of tube.
 
The BM-5 prototype construction started in March 1928 and flown on 27 July that year in Poznań. It had good handling, high stability and spin resistance, which made it a suitable trainer for larger aircraft. The plane was transferred to the military trials, during which some changes were made. During the evaluation flights at the Ławica airport during winter 1929, skis were installed on the aircraft, which proved suitable. 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 width of the fuselage).
 
 Bartel-BM5-03
BM-5a1
 
The first prototype was designated BM-5a1 and was fitted with a 220 hp (160 kW) Austro-Daimler inline engine. The second prototype, flown on 15 April 1929, was designated BM-5b1 and was fitted with a 230 hp (170 kW) SPA-6A inline engine. Compared with its predecessor, it was heavier by 60 kg due to a larger supply of fuel. Two BM-5b1 were built. It was refitted in August with a 320 hp (240 kW) Hispano-Suiza 8Fb V-engine and redesignated BM-5c1 (it was meant to utilize engine stores from the Bristol F.2 Fighter) and was flight tested on July 29, 1929. Next 20 aircraft of each type were built: BM-5a2, BM-5b2 and BM-5c2.
 
 Bartel-BM5-04
Bartel BM-5b
 
A disadvantage of most BM-5s were old and faulty engines. From all the variants the BM-5a variant was the heaviest and had the worst performance. Several BM-5a burned in a fire in September 1929. For that reason in 1935 one BM-5 was fitted at the PZL works with a 240 hp (180 kW) Wright Whirlwind J-5 radial engine, produced in Poland (in Polish Skoda Works, then Avia). This variant was designated the BM-5d and 20 of BM-5a and BM-5b were next converted to BM-5d.
 
 Bartel-BM5-05
BM-5d
 
On March 20, 1929 a contract was signed for series production of 40: 20 version of the VM-5a and 20 versions of BM-5b, with the first five were equipped with AD225 engine, and the next five - SPA. All production aircraft received the military designation BM-5R2 and deliveries were completed in 1930. These aircraft are sometimes called BM-300. Single copies were in training regiments, squadrons and air camps.
 
 Bartel-BM5-06
BM-5c1
 
A total of 62 were built.
 
BM-5s were used in the Polish Air Force for training from 1930, in a central pilots' school in Dęblin. 5 BM-5c's were used in Naval Air Unit (MDLot) in Puck. Most were written off in the second half of 1930s and replaced with the PWS-26 in April 1938. Some survived until the German invasion of Poland in September 1939. None survived the war.
 
 Bartel-BM5-07
BM-5c2
 
Variants:
 
BM-5a
Austro-Daimler 6-cylinder straight engine, water-cooled, 220 hp (160 kW) nominal power
Wingspan: 11.2 m
Length: 7.81 m
Height: 3.18 m
Wing area: 31.0 m2.
Empty weight: 980-972 kg
Useful load: 370-432 kg
MTOW: 1350-1395 kg
Max speed of 164 kph
Cruise: 145 kph
Stall: 76-80 kph
ROC: 2.6 m / s
Ceiling: 3250 m
Range: 420-550 km
 
BM-5a2
Engine: Austro Daimler, 225 hp
Wingspan: 11.20 m
Length: 7.81 m
Height: 3.18 m
Wing area: 31.00 sq.m
Empty weight: 980 kg
Normal takeoff weight: 1350 kg
Maximum speed SL: 164 km / h
Cruising speed: 145 km / h
Practical range: 420 km
Rate of climb: 156 m / min
Ceiling: 3250 m
Crew: 2
 
BM-5b
SPA-6A 6-cylinder straight engine, water-cooled, 230 hp (170 kW) take-off power, 220 hp (160 kW) nominal power
Wingspan: 11.2 m
Length: 7.81 m
Height: 3.18 m
Wing area: 31.0 m2
Empty weight: 922-906 kg
Useful load: 378 kg
MTOW: 1300 kg
Max speed: 161 kph
Cruise: 145 kph
Stall: 70 kph
ROC: 3.4 m / s
Ceiling: 3075 m
Range: 435 km
 
BM-5c
Hispano-Suiza 8Fb 8-cylinder V-engine, water-cooled, 320 hp (240 kW) take-off power, 300 hp (220 kW) nominal power
Wingspan: 11.2 m
Length: 7.81 m
Height: 3.18 m
Wing area: 31.0 m2
Empty weight: 947 kg, 383 kg
MTOW: 1330 kg
Max speed: 172 kph
Cruise: 150 kph
Stall: 73 kph
ROC: 4.5 m / s
Ceiling: 4750 m
Range: 300-360 km
 
BM-5d
Wright Whirlwind J-5 9-cylinder radial engine, 240 hp (180 kW) take-off power, 220 hp (160 kW) nominal power
Wingspan: 11.2 m (36 ft 9 in)
Wing area: 31 m² (334 ft²)
Length: 7.6 m (24 ft 11 in)
Height: 3.18 m (10 ft 5 in)
Empty weight: 900 kg (1,980 lb)
Loaded weight: 1,290 kg (2,838 lb)
Useful load: 390 kg (858 lb)
Wing loading: 41.6 kg/m² (8.50 lb/ft²)
Power/mass: 140 W/kg (0.085 hp/lb)
Maximum speed: 172 km/h (93 knots, 107 mph)
Cruise speed: 150 km/h (81 knots, 93 mph)
Stall speed: 70 km/h (38 knots, 43 mph)
Range: 450 km (243 nm, 280 miles)
Service ceiling: 4,000 m (13,100 ft)
Rate of climb: 4 m/s (790 ft/s)
Crew: 2, student and instructor
Armament: None
 
Bartel-BM5-08
BM-5a2
 
 
 
 


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