Flight of the Yugoslav Ikarus – Part I

Ikarus AD was an aviation, vehicle and machinery manufacturer established in Novi Sad, Serbia in 1923.  The production facilities of Ikarus were destroyed in World War Two but rebuilt in 1946 and soon nationalised by the new Tito led Yugoslav communist government. The following is part one of a two-part series and covers the key glider and piston engined aircraft developed by Ikarus in the late 1940’s and early 1950’s.

A Split with the Soviet Union

Post war in the early years of Communist Yugoslavia, most aircraft operated by the Yugoslav Air Force were supplied by the Soviet Union but in 1948 the nations had a major split in political relations and supplies were cut off by the Soviets. Serviceability of the Soviet supplied aircraft started to become an issue as spares declined and aircraft had to be picked apart for parts to keep others flying. This problem with the supply of  Soviet aircraft and parts lead to the further development of a domestic Yugoslav military aviation industry to avoid such issues in the future.

Ikarus Aero 2

The first Yugoslav designed and built aircraft was the Ikarus Aero 2 basic pilot trainer. The piston engine prototype first flew on October 22nd, 1946 and once proven successful it went into production in 1948. 271 were manufactured between 1948 and 1953 (eight variants with both open and closed cockpits and tail skid or tail wheel). They were operated by the Yugoslav Air Force until 1959 then many were presented to Yugoslav aero clubs, with the last civil variants being retired by 1975

An open cockpit Ikarus Aero 2 basic trainer of the Yugoslav Air Force

Ikarus Aero 2Be variant (YU-CVB, YAF serial 0875) at the Belgrade Aeronautical Museum. This example was manufactured in 1952 with a tail wheel, enclosed cockpit and electric lighting for night flying. 40 of this variant were manufactured (photo taken during my November 2015 visit to the museum)

During the late 1940’s and early 1950’s Ikarus also worked on the design of numerous training aircraft that were ultimately manufactured by another Yugoslav aviation company, Utva. These included the 212, 213 Vihor and 251 (BC-3) trainers.

Ikarus 214 & 215

In the late 1940’s Ikarus designed the 214 and 215 aircraft for use as light reconnaissance-bombers. The Ikarus 214 first flew in August 1949 but proved too slow for this role and was used instead as a twin engine training aircraft, transport and maritime patrol/ASW aircraft. 20 were produced plus 2 prototypes and were in use with the Yugoslav Air Force from 1950 to 1967. 6 were presented to civilian aero clubs for transport and parachute jumps and all were retired by 1979.

Ikarus 214 of the Yugoslav Air Force

The Ikarus 215 first flew in 1949 and was a nice looking aircraft but during test flights it became evident the aircraft would not be suitable as an attack aircraft. Only one prototype was built and it was used in a training role for bomber pilots with the Belgrade aviation school until retired in 1957

Ikarus 215

Gliders

In the late 1940’s and early 1950’s Ikarus developed a number of gliders or sailing planes. The first in 1949 was the single seat Ikarus Orao (Eagle) and then the single seat Orao IIb/c (Eagle IIb/c) variants in the 1950’s. A 1954 Orao IIc is on display at the Belgrade Aeronautical Museum (YU-4096, c/n 185) and is the only known survivor of this glider/sailing plane type. This type was used successfully by Yugoslav gliding clubs and aero schools to set numerous flight records.

Ikarus followed the Orao glider designs with the two seat Ikarus Košava in 1953 (2 wooden prototypes built). That same year the Košava was flown at the national gliding championships and broke almost all the national two seat gliding records. In 1954 at the World Gliding Championship in the UK a Košava glider flown by its Yugoslav pilots became the two seat glider world champions. Yugoslavia followed up this success with coming second in the world championship in France in 1956. One successful design! Only one wooden Ikarus Košava survives (YU-5022, c/n 1) and it has been on display at the Belgrade Aeronautical Museum since being retired in 1968.

Ikarus Orao IIc and Košava gliders at the Belgrade Aeronautical Museum (photos taken during my November 2015 visit)

Ikarus S-49

In 1949 the home-grown Ikarus S-49 single piston engined fighter aircraft was developed to replace Soviet aircraft in the Yugoslav Air Force. The S-49 looks similar to the Yakovlev Yak-9 but was a new design based off an advanced development of the Rogožarski IK-3 fighter, previously operated by the Royal Yugoslav Air Force from 1940 to 1941.

Yugoslav Air Force Ikarus S-49C

The S-49A model (45 in service from 1950) had a Soviet Klimov M-105 engine which was later replaced in 1952 with a Hispano-Suiza 12Z-17 engine in the S-49C model (113 in service from 1952). The S-49 with a top speed of 628 km/h / 390 mph and armed with an engine mounted 20mm cannon, two 12.7mm machine guns plus underwing bombs/rockets remained in service from 1950 to 1961 (the S-49A was retired in 1957) and an S-49C is on display at the Belgrade Aeronautical Museum.

Ikarus S-49C at the Belgrade Aeronautical Museum (photo taken during my 2015 visit)

Ikarus Research Aircraft

In the late 1940’s and early 1950’s Ikarus began to develop experimental piston engine research aircraft protoypes to counter the negative effects of g-force on pilots during sharp maneuvers. These included the Ikarus 232 Pionir and  the Ikarus S-451.

None of the Ikarus experimental aircraft went into wide production but they did provide a stepping stone for future aviation technology development in Yugoslavia. By the early 1960’s aircraft development ceased at Ikarus and had been taken over by Soko based in Mostar, Bosnia-Herzegovina (Ikarus manufactures buses today).

Ikarus 232 Pionir

On October 2nd. 1947 the uniquely designed Ikarus 232 Pionir prototype conducted its first flight. The pilot was in the prone position to fly it, as this was believed to reduce the effect of g-force on the pilot (extreme g-force stress on the pilot is an issue in sharp maneuvers and dives in air combat and ground attack missions). It was a very small aircraft powered by 2 x 48 kW (65 hp) Walter Mikron III piston engines.

Ikarus 232 Pionir

Two prototypes of the Ikarus 232 were built and testing was conducted at the Yugoslav Aeronautical Test Centre until 1953. One prototype was lost in 1952 due to an accident but following more than 200 hours of test flights, it was shown that the design was beneficial in reducing g-force stress on the pilot, who could withstand up to 8 to 9 g’s in the test flights. This would lead to further development and tests in the new Ikarus S-451 prototype.

Ikarus S-451

The small Ikarus S-451 prototype research aircraft was also designed to counter the negative effects of g-forces (gravitational force) on pilots during sharp maneuvers and was intended to eventually be developed as a light ground attack aircraft. The S-451 was a further development of the smaller Ikarus 232 Pionir and once again the pilot would be in the prone position to fly it to reduce the effect of g-force on the pilot. In test flights by the Yugoslav Aeronautical Test Centre the pilot handled 9 g’s without issue but the prone position still put a lot of strain on the pilots neck, caused breathing difficulties and limited the pilots rear view.

Ikarus 451 prototype in flight. That’s one happy looking test pilot!

The first flight of the S-451 prototype one (451/I) was on September 22nd, 1951 and the second S-451 prototype (451/II) first flew on February 26th, 1952. 451/II was tested and evaluated for 2 years but the type never went into production. The afore-mentioned issues for the pilot and the introduction of pilot g-suits soon made the prone pilot concept unnecessary.

Fitted with two Walter Minor 6/III, six inverted cylinders air-cooled piston engines of 160 hp each the aircraft was underpowered but still hit a maximum speed of 335 km/h at sea level due to minimal drag from the small front surface of the fuselage. Armament consisted of a fixed 13.1 mm machine gun under the fuselage and six unguided rockets on underwing pylons.

Ikarus 451 prototype and test pilot – it was a very small aircraft

Following the end of test and evaluation flights of the S-451, my understanding is the prototypes were given to the Yugoslav Air Technicians and Engineers Training Centre for ground instructional purposes. Both prototypes were withdrawn from service by 1957 with 451/II being handed over to the Belgrade Aeronautical Museum in Serbia, where you can see it today.

Ikarus S-451 viewed from the second floor gallery of the Belgrade Aeronautical Museum (photo taken during my November 2015 visit)

Ikarus S-451 at the Belgrade Aeronautical Museum (photo taken during my November 2015 visit)

The pilot lay in the prone position to fly the Ikarus S-451 to reduce the impact of g-forces – Belgrade Aeronautical Museum (photo taken during my November 2015 visit)

Ikarus S-451 at the Belgrade Aeronautical Museum – note the single rocket rail under the wing (photo taken during my November 2015 visit)

Ikarus S-451 at the Belgrade Aeronautical Museum (photo taken during my November 2015 visit)

The Ikarus S-451 was powered by two Walter Minor 6/III, six inverted cylinders air-cooled piston engines of 160 hp each – Belgrade Aeronautical Museum – November 2015

The very streamlined Ikarus S-451 experimental aircraft at the Belgrade Aeronautical Museum – November 2015

During the 1950’s Ikarus were also designing jet powered aircraft using the basic airframe of the Ikarus 451 design plus other very unique experimental jet aircraft. More on these jet aircraft developments in my next post.

References:

Airwar.ru – 232 Pionir (in English)

Belgrade Aeronautical Museum

Wikipedia – Ikarus S-49

Wikipedia – Ikarus 451