The Zmaj R-1, a prototype twin-engine bomber, was produced by Zmaj aircraft in former Yugoslavia during the 1930s.
Despite its potential, it remained a prototype due to various testing challenges.
Dušan Stankov, Zmaj’s technical manager, began the design and construction of a reconnaissance-bomber in 1936.
Following successful wind tunnel tests in Warsaw and approval from the Yugoslavian Air Force, the aircraft was officially named Zmaj R-1.
Engineer Djordje Ducić, with a team of designers and young engineers, completed the prototype before an extensive aerospace workers’ strike in April 1940.
The final assembly was conducted at the military section of Zemun airport.
The inaugural flight took place on April 24, 1940, with reserve Lieutenant Đura E. Đaković, an Aeroput company transport pilot, at the controls.
Early tests confirmed the aircraft’s superior aerodynamics and performance.
However, a mishap occurred during the third flight when the pilot could not retract the landing gear, resulting in a forced landing with the gear down, which damaged the propellers and engines.
Consequently, the necessary replacement parts for the propeller and landing gear had to be sourced from Germany and France, leading to considerable repair delays.
The aircraft underwent reconstruction to resume testing by the end of March 1941; however, early April saw the Zemun airport bombing, which once again damaged the Zmaj R-1 prototype.
By late June 1941, the Germans had dismantled the aircraft.
This twin-engine, mid-wing aircraft featured two Hispano-Suiza 14AB engines, each producing 750 PS (552 kW; 740 hp) and was constructed using a variety of materials.
It boasted a robust armament, including two 20 mm (0.787 in) Oerlikon cannons and four 7.9 mm (0.311 in) machine guns, along with a fuselage bomb bay capable of holding 1,600 kg (3,500 lb) of bombs.
The reconnaissance version was equipped with cameras, additional fuel tanks, and space for three crew members, foregoing the standard armament of guns and bombs.
Specifications
Crew
3 – 4
Length
12.78 m (41 ft 11 in)
Wingspan
14.40 m (47 ft 3 in)
Height
2.50 m (8 ft 2 in)
Wing area
33.80 m2 (363.8 sq ft)
Empty weight
2,600 kg (5,732 lb)
Gross weight
5,094 kg (11,230 lb)
Max take-off weight
5,664 kg (12,487 lb)
Powerplant
2 × Hispano-Suiza 14AB,
14-cyl air-cooled radial piston engine,
552 kW (740 hp) each
Propellers
3-bladed
Performance
Maximum speed
450 km/h (280 mph, 240 kn)
Cruise speed
320 km/h (200 mph, 170 kn)
Range
1,000 km (620 mi, 540 nmi)
Service ceiling
10,000 m (33,000 ft)
Rate of climb
5.55 m/s (1,093 ft/min)
Armament
Guns
2x 20 mm (0.787 in) Oerlikon cannon
&
4x 7.9 mm (0.311 in) machine guns
Bombs
1,600 kg (3,500 lb) of bombs carried internally.
Sources One Hundred Years of the Serbian Air Force, 1912-2012-Miroslav Jandrić. Short History of Aviation in Serbia-Čedomir Janić & Ognjan Petrović. Yugoslav Fighter Colours, 1918-1941, Vol 1-Ognjan Petrovic & Djordie Nikolic. Yugoslav Fighter Colours, 1918-1941, Vol 2-Ognjan Petrovic & Djordie Nikolic. Serbian Aviation, 1912 – 1918 – Srpska Avijatika.
