Ikarus 451
The Ikarus 451 is a family of research aircraft designs built in the former Yugoslavia in the 1950s by the Belgrade-based manufacturer Ikarus, all sharing the same basic airframe, but differing in powerplants and cockpit arrangements. One member of the family Ikarus 451M became the first domestically-built jet aircraft to fly in Yugoslavia on 25 October 1952. It was succeeded by the Ikarus 452.
Design, development, and variants
To research prone pilot cockpit arrangements and controls, the Yugoslav Government Aircraft Factories developed the Ikarus 232 Pionir, a small twin-engined low-wing monoplane, powered by 2x Walter Mikron III piston engines.Type 451
An enlarged version of the Pionir was developed as the Type 451, powered by 2x Walter Minor 6-III six-cylinder piston engines of each. The Type 451 had a 6.7 m wingspan, a maximum speed of 335 km/h, and a ceiling of 4750 m. It first flew in 1952.It also accommodated the pilot in prone position, but was an otherwise conventional low-wing monoplane with retractable tailwheel undercarriage, the main units of which retracted backwards into the engine nacelles mounted below the wings.
451M Mlazni
By the end of 1952, the Type 451 was followed by the 451M Mlazni which had conventional seating for the pilot. In place of the two Walter Minor 6-III inline engines of the original Ikarus 451, the 451M was fitted with Turbomeca Palas turbojets.In this version, the undercarriage retracted inwards. Provision was made to carry one 20 mm Hispano Suiza 404A cannon under the fuselage, plus six RS rockets under the wings. Further developments were aimed at developing a viable military aircraft from this basic design.
S-451M Zolja
The S-451M Zolja that flew in 1954 featured a stretched fuselage, folding wings, and redesigned engine nacelles, now in the same plane as the wing rather than being hung under them. In 1960 a S-451M Zolja set an airspeed record with a takeoff weight from to, flying at 500.2 km/hour.J-451MM Stršljen
The S-451 Zola was developed into an armed version, the J-451MM Stršljen intended for the close air support role, with Turbomeca Marbore engines boasting over twice the thrust of those used on earlier aircraft, and an armament increased to two HS.404 cannon carried under the fuselage. The J-451MM Stršljen also differed from preceding designs in having a tricycle undercarriage.S-451MM Matica
The J-451MM Stršljen configuration then formed the basis for the S-451MM Matica two-seat trainer that set an airspeed record for aircraft weighing between and, achieving 750.34 km/hour in 1957. It was also developed into the T-451MM Stršljen II single-seat aerobatics trainer.No member of the family was produced in any number. The 451, 451M, and J-451MM are all preserved at the Aeronautical Museum Belgrade.