Bartel BM-5

infobox Aircraft
name =Bartel BM-5
type =Trainer aircraft
manufacturer =Samolot


caption =
designer =
first flight = 27 July 1928
introduced = 1930
retired = 1939
status =
primary user = Polish Air Force
more users =
produced = 1929-1930
number built = 62
unit cost =
variants with their own articles =

The Bartel BM-5 was a Polish biplane advanced trainer aircraft used from 1930 to 1939 by the Polish Air Force, manufactured in the Samolot factory in Poznań.

Design and development

The aircraft was designed by Ryszard Bartel in Samolot factory in Poznań, as an advanced trainer, transitory between primary trainers and bomber or reconnaissance aircraft. Bartel had worked since 1926 on his BM-3 advanced trainer design, the preliminary design for which won a military contest, but in the meantime he developed a quite successful primary trainer Bartel BM-4 and then decided to model the advanced trainer upon that plane, to obtain better durability. The result was the BM-5 design. The BM-5 prototype was built in 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. 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).

The first prototype was designated BM-5a and was fitted with a convert|220|hp|abbr=on Austro-Daimler inline engine. The second prototype, flown on 15 April 1929, was designated BM-5b and was fitted with a convert|230|hp|abbr=on SPA-6A inline engine, then was refitted in August with a convert|320|hp|abbr=on Hispano-Suiza 8Fb V-engine and redesignated BM-5c (it was meant to utilize engine stores from the Bristol F.2 Fighter). There were next built 20 aircraft of each type: BM-5a, BM-5b and BM-5c.

A disadvantage of most BM-5s were old and faulty engines. Apart from it, the BM-5a variant was heaviest and had worst performance. That is why one BM-5 was fitted in 1935 at the PZL works with a convert|240|hp|abbr=on 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.

Operational history

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. Some survived until the German invasion of Poland in September 1939. None survived the war.

Operators

;POL
*Polish Air Force

pecifications (BM-5d)

Description

Wooden construction biplane. Fuselage 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 l.

Engines used:
*BM-5a: Austro-Daimler 6-cylinder straight engine, water cooled, convert|220|hp|abbr=on nominal power
*BM-5b: SPA-6A 6-cylinder straight engine, water cooled, convert|230|hp|abbr=on take-off power, convert|220|hp|abbr=on nominal power
*BM-5c: Hispano-Suiza 8Fb 8-cylinder V-engine, water cooled, convert|320|hp|abbr=on take-off power, convert|300|hp|abbr=on nominal power
*BM-5d: Wright Whirlwind J-5 9-cylinder radial engine, convert|240|hp|abbr=on take-off power, convert|220|hp|abbr=on nominal power

aircraft specifications
plane or copter?= plane
jet or prop?= prop
ref=
crew= 2, student and instructor
capacity=
length main= 7.6 m
length alt= 24 ft 11 in
span main= 11.2 m
span alt= 36 ft 9 in
height main= 3.18 m
height alt= 10 ft 5 in
area main= 31 m²
area alt= 334 ft²
airfoil=
empty weight main= 900 kg
empty weight alt=1,980 lb
loaded weight main= 1,290 kg
loaded weight alt=2,838 lb
useful load main= 390 kg
useful load alt= 858 lb
max takeoff weight main=
max takeoff weight alt=
more general=
engine (prop)=Wright Whirlwind J-5
type of prop= 9-cylinder air-cooled radial engine
number of props=1
power main= 179 kW
power alt= 240 hp
power original=
max speed main= 172 km/h
max speed alt= 93 knots, 107 mph
cruise speed main= 150 km/h
cruise speed alt=81 knots, 93 mph
never exceed speed main=
never exceed speed alt=
stall speed main= 70 km/h
stall speed alt=38 knots, 43 mph
range main= 450 km
range alt=243 nm, 280 miles
ceiling main= 4,000 m
ceiling alt=13,100 ft
climb rate main= 4 m/s
climb rate alt= 790 ft/s
loading main= 41.6 kg/m²
loading alt=8.50 lb/ft²
power/mass main= 140 W/kg
power/mass alt= 0.085 hp/lb
more performance=
armament=None
avionics=

References

*Andrzej Glass: "Polskie konstrukcje lotnicze 1893-1939" ("Polish aviation constructions 1893-1939"), WKiŁ, Warsaw 1977 (Polish language, no ISBN)

External links

* [http://www.airwar.ru/enc/other1/bm5.html Photos and drawings] at [http://www.airwar.ru Ugolok Neba site] (in Rusian)

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