The Avia B.534 was the most important Czech aircraft of the period between the two world wars, with production totalling 566, more than that of any other type. It was a classic single-seat fighter biplane, representing the penultimate stage in the evolution of this type. The final stage being provided by biplanes with retractable landing gear, such as the Soviet Polikarpov 1-153 and the Grumman fighters for the US Navy.

Designer Frantisek Novotny had re-engined the unsuccessful Avia B.34/2 prototype with a Hispano-Suiza 12Ybrs engine, redesignating it B.534/1. It first flew in August 1933, piloted by Vaclav Koci, and showed great promise. The aircraft was an unequal-span staggered single-bay biplane, with splayed N-struts carrying the upper-wing centre section above the fuselage. Wing bracing was by N-struts and there were ailerons on both upper and lower wings. The two-spar riveted steel wing had fabric covering, while the carefully streamlined fuselage was a riveted and bolted steel-tube structure with detachable metal panels forward and fabric covering aft. The horizontal tailplane was strut-braced and the split-type landing gear, with half-axles hinged beneath the fuselage, was oleo-sprung. The second prototype (B.534/2) had an enclosed cockpit, an enlarged rudder and revised landing gear with mainwheel fairings. It established a Czech national speed record on 18 April 1934, reaching 227.27 mph (365.74 km/h).

Development was held up when both prototypes were damaged in crash landings during 1934, but the decision had already been made to orderthe B.534 for the Czech air arm. The Avia B.534-I, the first production version, closely followed the design of the second prototype. The prototype's metal propeller was replaced by a wooden unit and, as on the first prototype, the pilot had an open cockpit. The main landing gear units were without spats.

Production of the B.534-1 totalled 46 aircraft. Armament comprised twin fuselage mounted light machine-guns and two more in fairings on the lower wing. Production of the Avia B.534-II series reached 100. This version differed in having all four machine-guns mounted in the fuselage sides, with consequently enlarged fuselage side blister fairings to house them. Underwing racks for light bombs were fitted, since the new fighter was considered suitable also for ground attack. The 46 B.534-III aircraft ordered next had mainwheel fairings, and had the carburet tor air intake moved forward under the nose. Six of this version were exported to Greece and 14 to Yugoslavia. The B.534-IV had an aft-sliding cockpit canopy and raised aft fuselage decking. Total Czech orders for this version were 253. The Avia Bk.534 was a cannon armed version, but otherwise similar to the Series IV aircraft. It was intended that its Hispano-Suiza 12Ycrs engine would have a 20 mm Oerlikon cannon mounted in the Vee of the engine cylinders, with its muzzle in the hollow propeller boss. However, as a result of a shortage of the Oerlikon weapons, many Bk.534s flew with only three machine-guns, two mounted in the fuselage sides and one in place of the moteur canon. Some B.534-IV and Bk.534 fighters had the standard tail skid replaced by a castoring tailwheel.

At the Zurich International Flying Meet in July 1937, the B.534 demonstrated excellent manoeuvrability and good overall performance, proving itself in competition as the outstanding biplane fighter. 

By the time of the Munich crisis in September 1938, B.534s formed the equipment of 21 front line Czech fighter squadrons. After the occupation of the country by the Germans in March 1939, the puppet Slovak government used some B.534s in the brief border war with Hungary. Three Slovak squadrons subsequently took part in the invasion of the Soviet Union along the Ukrainian Front, but by mid-1942 all had been re-equipped and the type was relegated to training. During the winter of 1939-40, 8ulgaria received 72 B.5345, which equipped five fighter squadrons. These were retained on Bulgarian territory and their only combat sorties were against Consolidated B.24 Liberator bombers returning from the disastrous 'Tidal Wave' bombing raid on Ploesti oilfields in Romania, on 1 August 1943, The B.534s were handicapped by their inadequate performance and soon afterwards were replaced by French-built Dewoitine D.520 monoplanes,

The Luftwaffe used other B.534s and Bk.534s as advanced trainers and as tow-planes for training gliders. Some were fitted with all-round-vision cockpit canopies and others, with arrester hooks, were used for deck landing trials and training in connection with the aircraft carrier 'Graf Zeppelin', which was launched but never completed. Finally, three Avias were used by the insurgents at Tri Duby airfield during the Slovak National Rising in the late summer of 1944. Two were lost on the ground during Luftwaffe raids and the third was burned to prevent it from falling into German hands.
 

The remarkable Avia B.534 is commemorated by a remarkably accurate full-scale replica, completed in 1975, and currently on proud display at the Air Force and Army Museum at Prague-Kbely.

Variants

Avia B.234 - A projected re-engined development of the B.34, but never built.

Avia B.334 - A second projected re-engined development of the B.34, but never built.

Avia B.434 - A third projected re-engined development of the B.34, but never built.

Avia B.634 - Ordered as a 'cleaned up' development of the B.534 in 1935, the B.634 appeared as an aerodynamically refined aircraft, with carefully streamlined and spatted cantilever main landing gear legs. The upper wing had greater chord than that of the B.534, while that of the lower wing was reduced in comparison with that of the B.534, and the amount of wing stagger was also lessened. Despite careful overall attention to streamlining, increased weight resulted in only marginal performance improvements. Data includes a powerplant of one Avia-built 850 hp (634 kW) Hispano-Suiza HS 12Ycrs inline engine, with a maximum speed 415km/h (258 mph), initial climb 960 m (3,150 ft) per minute, range 500 km (310 miles), empty weight 1710 kg (3,770 lbs), span 9.40 m (30 ft 10 in) and length 8.35 m (27 ft 4 3/4 in)

Specifications (Avia B.534-IV)

Type: Single Seat Fighter

Design: Frantisek Novotny

Manufacturer: Avia

Powerplant: One 850 hp (634 kW) Hispano-Suiza HS 12Ydrs inline piston engine.

Performance: Maximum speed 245 mph (394 km/h) at 14,435 ft (4400 m); cruising speed 214 mph (345 km/h); initial climb rate 2,953 ft (900 m) per minute; service ceiling 34,775 ft (10600 m).

Range: 360 miles (580 km) on internal fuel.

Weight: Empty equipped 3,219 lbs (1460 kg) with a maximum take-off weight of 4,674 lbs (2120 kg).

Dimensions: Span 30 ft 10 in (9.40 m); length 26 ft 10 3/4 in (8.20 m); height 10 ft 2 in (3.10 m); wing area 253.61 sq ft (25.56 sq m).

Armament: Four fixed 7.7 mm (0.303 in) synchronised Model 30 machine-guns in the forward fuselage, plus up to six 44 lbs (20 kg) bombs on underwing Pantof racks.

Variants: B.534/1, B.534/2, B.534-I, B.534-II, B.534-III, B.534-IV, Bk.534, B.234, B.334, B.434, B.634.

Avionics: None.

History: First flight (B.534/1) August 1933; (B.534/2) set Czech speed record 18 April 1934.