Avia B 634
1936
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Avia B 634

The B 634 represented the ultimate in the aerodynamic development of the basic B 34 single-seat fighter biplane design, and was to be numbered among the cleanest aircraft in its category ever flown. Tested in 1936, the B 634 was powered by an Avia-built HS 12Ycrs engine mounting a 20mm Oerlikon FFS cannon, two 7.7mm Model 30 machine guns being installed in the upper fuselage decking. There was virtually no commonality of components between the B 634 and the B 534.1 from which it was derived. By comparison with the earlier fighter, the upper wing of the B 634 featured increased chord while the lower wing had reduced chord, the wingtips were redesigned, the ailerons were broader, the gap was reduced (increasing the splay of the interplane struts), the stagger was greatly increased, and cut-outs were introduced on the lower wing roots. The curvature of the engine cowling and cockpit sill was refined, cantilever undercarriage legs were adopted and the radiator bath was faired cleanly between the leg roots. Despite a substantial reduction in drag, performance offered an insufficient improvement over that of the B 534 to warrant series production, the disappointing results provided by the B 634 being due primarily to a substantial increase in structural weight.

3-View 
Avia B 634A three-view drawing (1633 x 1230)


Specification 
 MODELB.634
 CREW1
 ENGINE1 x 850hp Avia-Hispano Suiza 12Ycrs
 WEIGHTS
    Take-off weight2340 kg5159 lb
    Empty weight1710 kg3770 lb
 DIMENSIONS
    Wingspan9.40 m31 ft 10 in
    Length8.35 m27 ft 5 in
    Height3.06 m10 ft 0 in
 PERFORMANCE
    Max. speed415 km/h258 mph
    Cruise speed362 km/h225 mph
    Ceiling11000 m36100 ft
    Rate of climb960 m/min3150 ft/min
    Range500 km311 miles
 ARMAMENT1 x 20mm, 2 x 7.7mm

Comments
Psellos, 25.10.2010

Two prototypes built - second one different than the one shown here. It had enclosed canopy and different undercarige. Both B-634 were pressed to service in 1938.

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