PROJECTS OF YUGOSLAV LIGHT FIGHTER IN THE MID-1950S
The ten-year plan for the development of the JRV (the Yugoslav Air Force) provided for development and introduction into service of a light fighter that was supposed to be a counterpart to the then contemporary British Midget ultra-light fighter. Three projects B-12-V, ML-1 and PL-1 were submitted on the competition announced by the JRV Command. The project of Bešlin’s light fighter B-12-V went to the farthest distance, but it was not pass to the prototype phase. Instead, two British Gnat Mk. 1 were purchased.
B-12-V Bešlin’s light fighter
The Yugoslav Air Force received its first jet aircraft T-33A on 10 March 1953 and on 9 June 1953 the first F-84G fighter-bombers arrived.
The ten-year plan (1953-1962) envisaged the construction of 3 B-12 aircraft in 1955. However, this plan did not include the possible production of this aircraft if it succeeds in being adopted. However, the prototype of the B-12 aircraft was still under construction in 1955. By the end of 1957, the making of a mock-up was completed and about 50% of the prototype was made.
At the time when military aid from the West was stopped in 1957, the B-12 model was in the supersonic tunnel in the UK (since at that time there was still no supersonic tunnel in Yugoslavia). As the survey of the model yielded unsatisfactory results, the development was discontinued. The variant B-12-OR remained in the study phase.
B-12 data:
takeoff weight 2256 kg,
wing area 10.9 sq.m
wing loading 207 kg/sq.m.
aspect ratio 5.0
wingspan 6.6 m
sweep angle 45 degrees
the narrowing of the wing 2.3
average chord 1.65 m.
[My understating is that B-12-V was to have two Viper engines and B-12-OR - one Orpheus]
ML-1 light fighter
The ML-1 light fighter was to be equipped with the ARDAG engine. The static thrust of this engine was to be 2500 kp and its weight 1000 kg.
ML-1 data:
takeoff weight 5380 kg
wing area 23.0 sq.m
wing loading 235 kg /sq.m
thrust-to-weight ratio 0.47
aspect ratio 3.35
wingspan 8.76 m
sweep angle 43 degrees
taper ratio 2.3
average chord 2.63 m
chord at the axis of symmetry 3.66 m
chord at wingtips 1.59 m
thickness-to-chord ratio 8%
armament 4 20 mm guns (100 rounds per gun)
maximum speed at the sea level 1070 kph (Mach number 0.872) for take-off mode
1004 kph (Mach number 0.818) for maximum permanent regime
rate of climb speed at sea level 43.7 mps
max. altitude 14000 m (with the assumption that 50% of the fuel is used for climbing 14600 m)
PL-1 light fighter
The PL-1 was to be equipped with two Hispano R.800A turbojet engines. The static thrust of each of the engines was 1100 kp or 1450 kp (with afterburner).
PL-1 data:
takeoff weight 4370 kg
wing area 19 sq.m
wing loading 230 kg/sq.m
thrust-to-weight ratio 0.5 or 0.66
aspect ratio 3.35
wingspan 7.97 m
sweep angle 43 degress
taper ratio 2.1
average chord 2.38 m
chord at axis of symmetry 3.22 m
chord at wingtips 1.535 m
thickness-to-chord ratio 8.0%
armament three 20 mm guns (100 rounds per gun)
internal fuel 1000 kg
maximum speed at sea level was 1153 kph (Mach number 0.94) for the take-off mode and 1120 kph (Mach number 0.923) for the maximum permanent regime.
Rate of climb at sea level (thrust = 1100 kp) 49.6 mps
Rate of climb at level (thrust with afterburner 1450 kp) 78.5 mps
Max. altitude 15300 m (with the assumption that 50% of the fuel is used for climbing 16080 m)
SOURCE:
Небојша Ђокић, Авиони конструкторске групе Бешлина, Шумадијски анали 8, Крагујевац 2015, 146 - 179 ;
Nebojša Đokić, AIRCRAFT OF BEŠLIN DESIGN GROUP, Shumadian Annals No 8, Kragujevac 2015, pp. 146 - 179
U radu je dat istorijat razvoja aviona konstruktorske grupe Bešlin u pedesetim godinama XX veka.
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