Yugoslavia (1940)
Fighter Plane – 12 Built

History

The first domestic aircraft factory in Yugoslavia was established in Novi Sad under the name “Ikarus” on November 20, 1923. In 1924, Ikarus delivered two new training planes for the armies of the Kingdom of Serbs, Croats, and Slovenes which were designed in the factory. The first trainer model was delivered in April 1924 designated the “Мали Брандербург-Serb” (Small Brandenburg), which was a direct copy of Brandenburg B.I. The second plane was delivered in June 1924, a copy of school hydroplanes “IIIM” (School Mercedes/Школски Мерцедес-Serb.). Both of these aircraft did not fall far behind foreign aircraft in terms of its technical and flying characteristics, of the same intended roles which strengthened the morale of the Army and the domestic constructors, opening prospects for the domestic production of new planes.

In April 1924, another aeroplane factory was built in Belgrade: “The first Serbian aeroplane factory Živojin Rogožarski – Прва Српска фабрика аероплана Живојин Рогожарски-Serb.” They joined Ikarus as the only aircraft factories in Yugoslavia. Živojin Rogožarski was initially only building parts for the aircraft but later they began to build entire planes. From 1928, these two factories supplied around 100 training aircraft and seaplanes to the army of the Kingdom of Serbs, Croats and Slovenes and Maritime Aviation.

During the late 1930’s and early 1940’s, the company Ikarus started to design and later produce two new types of fighter aircraft, the IK-2 and IK-3. The IK-2 was a “high wing” plane, with the wings set on top of the fuselage, equipped with the Hispano-Suiza 860 hp engine and armed with one 20 mm cannon and two machine guns set above the engine. The machine guns were initially Darn type caliber 7.7 mm but this was later replaced with the new Browning 7.92 mm. The IK-2 was constructed by a team of engineers Ljubomir Ilić and Kosta Sivčevićem. Ikarus built small batch of 12 aircraft plus two prototypes in 1939. While in production the IK-2 was considered obsolete and production of the fighter ceased, nevertheless, the IK-2 saw some use in World War ll but all the planes were lost.

Designed as a successor to the older IK-2, the IK-3 was Yugoslavia’s first modern single-seat fighter. It was conceived in 1933 as a fighter utilizing the cantilever low-wing with a cockpit that was fully enclosed as well was fully retractable landing gear. On the tail or fuselage, the planes would carry a small black military-tracking number. The IK-2 used numbers from 2,101 to 2,112 and the IK-3 used 2.151 to 2.163. At the time of its construction, the IK-3 was equally matched to its contemporaries, representing a very advanced solution behind which stood a team of ambitious and young engineers Ljubomir Ilić,  Kosta Sivčevićem, and Slobodan Zrnić j.

Prototype

After some statistical and aerodynamic calculations in 1936 were completed, a 1:10 wooden scale model of the IK-3 was built. The model was tested in the Eiffel wind tunnel in Paris. The planned Hispano-Suiza 12Y Engine had already been tested in earlier IK-2 aircraft. The contract to build the prototype IK-3 was signed on March 31, 1937 with Rogožarski. The first prototype IK-3 was completed on 14 April 1938, piloted by Captain Milan Bjelanović. By the end of 1938, the first factory tests were completed. Despite the good flying qualities, the pilots noticed some problems. The complaint by pilots was related to the shape of the windshield and canopy of the cockpit, while the army suggested adding two additional machine-guns in the wings. Some additional problems cropped up including engine overheating and unsuitable landing gear doors. The majority of these problems were corrected in the first batch of planes produced.

On 19 January 1939, an accident occurred while examining the behavior of the plane in flight, the right wing completely separated from the fuselage. This accident claimed the life of pilot, Captain Milan Pokorni. No domestic or foreign investigators were able to clearly determine the exact cause of the crash. In any case, the wings were reinforced during wing construction and production continued.

Production

The loss of the IK-3 prototype did not postpone the production of new fighters. On 26 November 1938, a contract between the state and the factory was signed which authorized the production for a new batch of 12 aircraft. Delivery of the planes was planned for the end of 1939, but the beginning of World War II affected the production process. Delays in deliveries and the rising costs of raw materials postponed the completion of the first batch. The first aircraft of the series were delivered on 15 December 1939. The deliveries and production were again postponed due to a worker strike in the aviation industry, lasting until July 1940.

In March of 1940, the factory offered an improved version of the IK-3 called the IK-3 ll. The factory originally offered the production of 50 new aircraft but this was rejected by the state who instead ordered production for only 25 aircraft. It was thought that the production of 50 aircraft could not be achieved because it was impossible to obtain the necessary materials and equipment from abroad due to the war. The Command of the Royal Yugoslav Army demanded improved aerodynamics, a more powerful engine, self-sealing fuel tanks, armored glass, armored seats etc. In the end, only one plane (number 7) from the first series was modified into a prototype for the second series.

Prior to the War

After the end of production, all operational aircraft were allocated to the 51st Independent Fighter Group at Zemun which was part of the 6th Fighter regiment. Squadrons 161 and 162 were both given 6 aircraft.

In its first year of service, an IK-3 was lost when one of the squadron commanders, Captain Anton Ercigoj, was making a “mock attack” on a Potez Po.25 over the Sava and Danube rivers. After passing below the Potez, he went into a climb with the intention of performing a loop. His rate of climb was too steep and the aircraft fell into a spin at low altitude and hit the water. Caption Anton Ercigoj did not survive the crash.

The introduction of new planes offered the opportunity for pilots of the IK-3 to test it against the Yugoslav Messerschmitt Bf 109E in “mock dogfights”. The evaluation after the dogfight concluded that the IK-3 had several advantages over the Bf 109E. The IK-3 was more maneuverable in level flight, enabling it to quickly get behind a pursuing Bf 109E by making tight horizontal turns.

In combat

For the attack on Yugoslavia, the Axis forces amassed around 2236 warplanes in Austria, Hungary, Italy, Bulgaria, and Romania with some 1062 bombers, 289 reconnaissance planes, and 885 fighter planes.

The Yugoslavian Air Force had around 420 combat aircraft, in various conditions. They had about 147 modern bombers including the German Do. 17, Britain Bristol Blenheim, and the Italian SM.79. There were also about 131 reconnaissance planes, including 11 British Bristol Blenheims, about 120 outdated Brege 19 and Potez Po.25 aircraft, and over 100 combat aircraft including 61 German Me-109E, 35 British Hawker Hurricanes, some of which had been built in the “Zmaj” factory in Zemun. Yugoslavia also had a whole series of IK-3 aircraft, minus one lost in pilot training. In addition to these forces, Yugoslavia also controlled 30 two-engine Hawker Furys, 8 IK-2’s, 2 Avia BH-33’s, and 2 two-engine Potez Po.63’s. In essence Yugoslavia controlled a much smaller force than Germany but it was made up of some of the most modern aircraft of the time.

Out of the 12 IK-3 of the first series, only 6 were fully operational by 5 April 1941. One aircraft was lost in the 1940 accident, and 5 were in different states of repair: 3 in the Rogožarski factory, and two in the aviation workshop at Zemun airport. The units equipped with the IK-3 had the task of preventing the deployment of the enemy air force above the territories of Northern Serbia and parts of Vojvodina. The majority of the IK-3’s were used in the defense of the capital Belgrade, bolstered by fighters from the 102nd fighter squadron equipped with Me-109E’s.

On 6 April 1941, at about 0600, the commander of the First Air Base, Major Marko Konrad, informed the commander of the 6th Fighter Regiment that the Germans attacked Yugoslavia and that air attacks on Belgrade should be anticipated. At about 0645, the observation service TVO (teritorijalne vazdušne osmatračke službe-Territorial airborne observation services) reported two large formations of aircraft were flying in from the north towards Belgrade. At about 0650, commander of the 6th Fighter Regiment, Major Adum, ordered all three squadrons 161, 162, and 102 up for patrols. These patrols were led by First Class Captain Gogić, Sergeant Semiz, First class Captain Poljanec, Sergeant Vujić, and Lieutenant Borčić.

In their first battle, pilots with their IK-3’s shot down six German planes while only losing one IK-3, in which Lieutenant Dusan Borčić was killed, and one lightly and two heavily damaged aircraft that did not participate in any further combat. By the end of the day, two more German bombers were shot down, but this group remained with only three operational IK-3 aircraft.

On April 7, Sergeant Semiz, during an intercept with German bombers, was hit by German machine guns fire. 36 bullets hit his plane and 20 bullets hit his engine and ignited it. Although he was wounded, he managed to return to the airport in Zemun. The loss of his aircraft was compensated by the IK-3 ll (the only aircraft of the second series to be constructed) that was under repair in the Rogožarski factory. The combat state of this unit remained at three operational aircraft.

By the end of the day on April 7, the remaining aircraft were relocated to the auxiliary airport, Veliki Radenci II. Commander Major Adum was replaced, and Captain First Class Gogić was promoted to this position. In the following days, there was no action due to bad weather. On 11 April, at around 1000, one German Me-110 attacked Veliki Radenci II but did not cause any damage. Sergeant Samiz with his plane pursued and managed to shoot it down. On the same day at around 1200, a group of about 20 Me-110’s were attacking the airport Veliki Radenci I. Several of the 51st group took off, the pilots were First Class Captain Gogić and Sergeant Vujičić, managing to shoot down two attacking German planes.

At around 1700 on 11 April, a German armored column was spotted approaching from the North. Part of the non-flying group of the Yugoslavian Air Force had been ordered to withdraw in the direction of Sarajevo, airplanes and pilots stayed at the airport. On 12 April, they were supposed to be transferred to Sarajevo, but this did not happen. Because of the speed of the German attack and the inability of pilots to fly in time, they decided to destroy all the remaining planes in order to prevent them from falling into German hands.

Operators

• Kingdom of Yugoslavia (Kraljevina Jugoslavija) – Were used during the “April War” and most were lost in combat or were destroyed
• Nazi Germany – Captured at least 5 to 7 planes in different states. One complete surviving IK-3 was used for flying test performance.
• Turkey – Was considering the possibility of buying the license for the production of the IK-3, but World War II prevented any plans for this program.

IK-3 Specifications
Wingspan	33 ft 10 in / 10.3 m
Length	26 ft 3 in / 8 m
Height	10 ft 8 in / 3.25 m
Wing Area	178 ft² / 16.5 m²
Wing Loading	32.6 lb/ft²  /  159.4 kg/m²
Engine	One 980hp (731kW) Avia-built Hispano-Suiza 12Y29 liquid-cooled V-12 piston engine
Maximum Take-Off Weight	5799 lb / 2630 kg
Empty Weight	4560 lb / 2068 kg
Fuel Capacity	330 L
Climb Rate	16,000 ft / 5,000 m in 7 minutes
Maximum Speed	328 mph / 527 kmh
Cruising Speed	249mph / 400kmh
Range	488 mi / 785 km
Maximum Service Ceiling	30,800 ft / 9,460 m
Crew	1 (pilot)
Armament	One Oerlikon FF 20 mm cannon – fixed forward-firing cannon in the propeller hub  Two 7.92 mm Browning/FN machine guns with 500 rounds per gun – fixed forward-firing machine guns in the upper part of the forward fuselage

Gallery



Sources

Kratka istorija vayduhoplovstva u Srbiji, Čedomir Janić i Ognjan petrović, Beograd 2011., Babac, D. (2008). Elitni vidovi jugoslovenske vojske u Aprilskom ratu. Beograd: Evoluta., Chant, C. (1999). Aircraft of World War II. London New York: Friedman/Fairfax Publishers Distributed by Sterling Pub. Co., Rogožarski IK-3. (2017, July 4). In Wikipedia, The Free Encyclopedia., Military Factory. (2015). Rogozarski IK-3 Fighter., Paquet, B. (n.d.). Rogozarski Ik-3. Passion Aviation. Images: All photographs in this article are in the public domain, Plane Profile Views by Ed Jackson