Category Archives: Yugoslavia

Ikarus MM-2

Yugoslavia flag Yugoslavia (1939)
Prototype Advanced Trainer – 1 Built

The MM-2 prototype had an unusual color scheme with a combination of red and polished aluminum.

With the emergence of new fighter planes in the years leading up to the Second World War, it became necessary to replace the older biplane trainer aircraft, which were too slow, in order to efficiently train new pilots to fly the newest fighters. Thus, it was logical that more modern advanced trainer aircraft would be needed. The MM-2 was an experimental Yugoslavian solution to this problem.

First Steps

At the end of the thirties, the Yugoslav Air Force was equipped with modern planes, such as the German Me-109, the indigenous IK-3, and the British Hurricane, highlighting the need for an updated trainer. There were several older aircraft in use for the role, like the FP-2 and the Rogožarski PVT, with a maximum speed of around 140 mph (230 km/h) but there was a need for a much faster and modern aircraft trainer.

The designer of the MM-2 trainer, Captain Dragutin Milošević.

To fill this gap, Air Force engineer and pilot Captain 1st Class Dragutin Milošević, on his own initiative, began to work on a new advanced trainer in 1936. The first aerodynamic calculations, choice of engine, structure, and the design were done by 1937. This new plane was conceived as a two-seater with seats one behind the other, with an enclosed cockpit and dual controls. It had a low wing, mixed construction, with a single engine and retractable landing gear. The engine would have been the Renault 6Q-02, giving 162 kW (220 hp). Milošević never gave a designation for this plane, but was later simply named the M-1.

Captain Dragutin Milošević submitted this project to the Yugoslav Department of Aviation in 1937. The Department analyzed this proposal and, while on paper it would have had great flying performance, a decision was made to reject it because the parts necessary for its construction had to be imported from abroad.

This decision did not discourage Captain Milošević, and he made attempts to improve his design. He proposed replacing the Renault with the license-built Gnome-Rhone K-7 309 kW (420 hp) air-cooled 7-cylinder engine. By adding this engine, the length of the plane would be reduced from 23 ft 7 in to 20 ft 4 in (7.2 m to 6.7 m) but the total weight increased to 2,160 lbs (980 kg). To improve the landing characteristics of the aircraft, it would have been necessary to increase the distance between two front landing wheels from 6 ft 2 in to 7 ft 10 in (1.9 m to 2.39 m). All aerodynamic and statistical calculations were finished by 1939. The second version was named M-2 and it was, in essence, the basis of the future MM-2 aircraft.

One wooden model (1:10 scale) was built by the Albatros factory in Sremska Mitrovica. This model would be used to test the aerodynamic properties and accuracy of earlier calculations. Aerodynamic properties were tested in the Paris wind tunnels on the 17th and 18th of July 1939. After these trials, the fuselage length reverted to the original 23 ft 7 in (7.2 m).

Later, Captain Milošević did new calculations that showed that certain changes to the design of the aircraft were necessary. Adding weapons and increasing fuel capacity would lead to an increase of the mass of the M-2 by 242 lbs (110 kg), some 60 lbs (30 kg) in fuel and 176 lbs (80 kg) in armament. After all the other modifications, the total mass reached 2,782 lbs (1,262 kg) compared to the initial 2,160 lb (980 kg). The wing area had to be increased from 129 to 146 sq ft (12 to 13.6 m²) and the wingspan from 27 ft 10 in to 30 ft 3 in (8.5 to 9,23 m).

Adoption of a Prototype

Captain Milošević submitted a letter, together with documents, plans and calculations, to the supreme headquarters of the Yugoslavian Air Force, notifying them of the test results of the proposed M-2 aircraft. Since he did not receive any kind of response, he asked Major Đorđe Manojlović, also an aviation engineer, for help. Although Đorđe Manojlović did not have a direct impact on the design of the M-2, his great influence and connections in the Supreme Air Force Command lead to the continuation of the project. The cooperation of these two men lead to the final approval for construction of the M-2 aircraft project.

The only MM-2 prototype during its construction by Ikarus.

When the Air Force Headquarters of the Army of the Kingdom of Yugoslavia accepted the M-2, construction of this project was given to the Ikarus factory. The contract was signed on the 25th March 1940. It was planned to build one prototype aircraft for testing in order to ascertain if the M-2 was fit to be accepted for serial production. The project was monitored by a team composed of engineer Sava Petrović, Air Force Major Vojislav Popović and the technician Stefan Lazić. The prototype was ready by the first half of November 1940.

Origin of the Name

In the Kingdom of Yugoslavia, there was a custom of using the initials of the names of the designers as the official designation for most of new types of aircraft in service (like the IK-2/3), and MM-2 was no exception. MM comes from the initials of the surnames of Captain Dragutin Milošević and the constructor and engineer Major Đorđe Manojlović. There is sometimes confusion about the exact name of this aircraft. It is sometimes also called MiMa-2. In some documents found after the war, it is also called M.M. 2. In this article, the MM-2 name will be used, as it is the most common.

Technical Characteristics

Captain Dragutin Milošević’s first drawing of the MM-2. Note that the engine nose design appears to be for an inline engine, different from the actual prototype.

The MM-2 was designed as an advanced two-seater trainer, with seats one behind the other, with dual controls and a fully enclosed cockpit. It was a low wing, mixed construction, a combination of wood and metal, single engine aircraft with retractable landing gear.

The wings had a trapezoidal shape with a rounded top. They were constructed by using two racks which were made of steel tubes welded together. The racks were welded to the plane’s hull and the wooden ribs were connected to them by rivets. The wings were covered with canvas, except for the central parts, which were made of aluminum sheet. This was done so that the technicians and repair crews could have easy access to the inside of the wing. The ends of the wings were made of wood that were held in place by steel fittings. The flaps were covered in canvas and operated either manually or hydraulically.

The MM-2 hull was of mixed construction. The main body was made by using welded pipes. The front part was covered with aluminum sheet and the rear with canvas. The tail was made mostly of wood and covered with canvas.

The main engine was the Gnome-Rhone K-7, which supplied 310 kW (420 hp). It was domestically built under license from Franch aircraft manufacturer Rakovica. It was hoped to use a two-bladed metal propeller but, due to the lack of resources, wood was used. The maximum estimated speed (never achieved) was around 250 mph (400 km/h), with an effective range of 475 mi (764 km) with some 40 gallons (150 l) of fuel capacity. Climbing to 6,500 ft (2,000 m) could be achieved in 3 minutes and 9 seconds, but the maximum service ceiling was never adequately tested.

The landing gear was supposed to be of the ‘Nardi’ type imported from Italy, but it was planned to domestically build the landing gears for the production version, to avoid being dependent on foreign countries. On the prototype, no radio was installed but it was hoped to equip all future production aircraft with the FuG VII radios.

The main armament consisted of two wing-mounted 7.7 mm Darn-type machine guns with 175 rounds of ammunition for each gun. The total bomb load consisted of four 10 kg bombs carried under the wings. It must be noted that the armament was never installed on the prototype, as testing was interrupted by the beginning of the war.

First Test Flights

MM-2 Side View

The first test flights were made by the beginning of the 1941 at the Zemun airport. The pilot for these flights was Vasilije Stojanović, the test pilot of the Ikarus factory. By the end of March 1941, some 45 flights had been made with a total of 20 flying hours. The pilot assessed the flying performance of this plane as excellent. The results of these tests indicated that this aircraft had good flight performance. The controls were adequate, both instructor and the students cockpits had enough room with a good field of view and, during flights, the aircraft did not present any tendencies for sudden unpredictable movements. Due to its good air brakes and flaps, take-offs and landings were quite easy. There were no major objections from the test pilot about the MM-2.

The MM-2 could very easily reach speeds of up to 217 mph (350 km/h). The design maximum speed was never tested, but calculations suggested that it could be as high as 250 mph (400 km/h). This was never confirmed due to the outbreak of the war. The MM-2 prototype had an unusual color scheme with a combination of red on most of the rear fuselage and wings, and polished aluminum on the majority of the fuselage and the engine section, with a small Yugoslav flag painted on both sides of the tail.

On the 25th of March 1941, a contract was signed between Ikarus and the Air Force. According to this contract, Ikarus was to prepare for production of MM-2 trainer planes in the near future. Before the production would begin, a last series of tests was to be conducted by a test group at an airfield near city of Kraljevo. An order was given to Stojanović to fly the MM-2 from Zemun to the Kraljevo airfield. Once there, it was planned to do some more flight performance trials in order to examine the limit of the flying characteristics of the MM-2 aircraft. Stojanović completed the flight on the 4th April. Final production was never achieved due to the German invasion of Yugoslavia that started only a few days later.

Operational Service

The MM-2 did not see any active service in the Royal Yugoslav Army because of the beginning of the April war, the German attack on Yugoslavia in April 1941. After the defeat of the Yugoslav army, the Independent State of Croatia, or NDH, was created. In order to form the new NDH military air force, it was necessary to find and obtain planes to equip these new units. Like many other former Yugoslav planes, the MM-2 was also pressed into NDH service in a very limited role.

It seems that the MM-2 had some engine problems (possibly sabotaged) when it was captured by the Germans at airfield near Kraljevo. It is possible that it was in a bad condition since the Germans did not even bother to repair it and put it into operational use.

The MM-2, together with other Yugoslav captured aircraft, was collected and handed over to the NDH. After a while, the MM-2 was repaired under code name No. 6301, and returned to active service. Additional flight tests were conducted by Georgije Jankovski, a test pilot for Dornier-Werke. In September 1941, the plane was transferred to the Zemun airport and handed over to Croatian Major Ivan Pupis for future use. Major Pupis was the leader of the group responsible for the repair, reception and later transfer of all Yugoslavian aircraft captured during the April war. When the MM-2 was repaired and ready for active service, Pupis to keep it for his personal use rather than handing it over to the military.

On the May 13 1942 pilot Vid Saić, he lost control of the aircraft and crashed due to inexperience. The MM-2 was deemed too complicated and expensive to repair.

The MM-2 was ‘owned’ by Pupis until March 23rd, 1942, when he received a direct order from the Croatian Aviation Command to transfer the MM-2 to the ‘Rajlovac’ airfield near the city of Sarajevo in Bosnia. The aircraft arrived at the beginning of April 1942. The MM-2 was given to the 17th Squadron (Jato) which was part of the 6th group (Skupina) under the Command of the Major Romeo Adum. The MM-2 was used mostly for limited test flights. On May 13, 1942 while piloted by Vid Saić (from the 18th Squadron), the plane crashed. The pilot survived the crash with no injuries. A commission was formed to investigate the causes of the crash and found several irregularities: The pilot did not ask for permission and had no orders to fly on the MM-2 that day, and he also did not know anything about the flying characteristics or the condition of the plane. The conclusion was that the pilot was guilty for the accident and, as punishment, Vid Saić lost his Pilot rank. The damage to the MM-2 was estimated to be around 90%. There was no point to try to rebuild it from scratch and the remaining parts were destroyed. There is no information whether it was equipped with any armament in Croatian military service.

Production

Due to the outbreak of war on April 6th, 1941, except for the prototype, no other specimen of this aircraft was ever built. In some documents and letters found after the Second World War, it was discovered that the Ministry of Aviation planned to order around 50 copies of the MM-2 aircraft. Along with this, the Yugoslav military negotiated with Germany for the purchase of Arado Ar 96 training planes, but nothing came of this.

After the war, the new communist Ministry of Aviation and the Ikarus factory representatives were also interested in restarting the production of this aircraft but, as the chief designer had died in one of the many German prison camps and the necessary machines and tools were lost during the war, this was too difficult and was abandoned.

Operators

  • Kingdom of Yugoslavia – Built and tested the single prototype.
  • Independent State of Croatia NDH – Used the MM-2 captured during the April war, but it was lost in an accident.

MM-2 Specifications

Wingspan 30 ft 6 in / 9.23 m
Length 23 ft 7 in / 7.20 m
Height 9 ft 6 in / 2.89 m
Wing Area 14.6 ft² / 13.60 m²
Engine One Gnome-Rhone K-7, 309 kW (420 hp) air-cooled 7-cylinder engine
Empty Weight 1,071 lbs / 894 kg
Maximum Takeoff Weight 2,290 lbs / 1,330 kg
Fuel Capacity 150-160 l
Maximum Speed 250 mph / 400 km/h
Cruising Speed 390 mph / 630 km/h
Range 475 mi / 764 km
Maximum (estimated) Service Ceiling 6,600 ft / 2,000 m
Climb speed Climb to 2,000 m in 3 minutes and 9 seconds
Crew Two, instructor and student pilot
Armament
  • Two Darn M30 7.7 mm machine guns in wings
  • Total bomb load around 40 kg.

Gallery

Illustration by Haryo Panji https://www.deviantart.com/haryopanji

Ikarus MM-2 Side View [Haryo Panji]
MM-2 Front View
MM-2 Rear View

Sources

Ikarus IK-2

kingdom of yugoslavia flag Yugoslavia (1935)
Fighter Plane – 12 Built

The Ikarus IK-2 was the first all metal, high wing monoplane fighter built designed and built in Yugoslavia, for the Royal Yugoslavian Air Force. The transition from biplane to monoplane gives this high-wing fighter a distinctive appearance, not unlike a gull in flight. The Ikarus’ powerful engine and impressive armament paved the way for Yugoslavia’s later advanced monoplane, the IK-3. Its performance in key areas gave it an advantage over the Hawker Fury. The IK-2 saw combat against Germany’s advances in the early 1940’s.

History

At the beginning of the 1930s, the Yugoslav Air Force was mainly equipped with the old  (Czech) Avia BH-33 biplane fighters built by “Ikarus” under license. During the second half of the thirties and early forties the company “Ikarus” designed and later produced the first Yugoslav all-metal, high wing, monoplane fighter aircraft named IK-2. The IK-2 was constructed by a team led by engineers Ljubomir Ilić and Kosta Sivčevićem.

The first prototype was named IK-1L. The capital “I” is for Ilić “K” for Kosta, the “L” was for fighter, Ловац-Serb. (on some sources it was mark as IK-L1) The prototype was completed in 1934, and was ready for its first flight testing by April 1935. It had a Hispano-Suiza 860 hp engine, and it was planned be armed with a 20mm cannon, and two Darn type machine guns caliber 7.7mm.

The wing was braced with two struts on each side of the fuselage, the fixed and conventional landing gear was spatted and mounted off the wing struts. The half glazed cockpit was located behind the wing. The horizontal stabilizer on each side was braced from below with two rigid braces from the lower tailcone, and tied from above with two flying wires from the vertical stabilizer.

IK-1L had a difficult start, due to a disagreement between the manufacturer and military top brass, but also by individual pilots like Captain Leonid Bajdak who was a great supporter of biplane aircraft. Unfortunate for the constructors a decision was made, that Leonid Bajdak would be the first test pilot for the IK-1L to determine if the plane had the potential for further development and eventual production. The first test flight was conducted on 22 April 1935 at Zemun airfield near Belgrade. In these tests, which were scheduled for several days, a light fuel load was used and the plane was not equipped with any weapons.

A crashed IK-2

The following day, Bajdak put the IK-1L into several aerobatic maneuvers, and at that time there were no major problems. But during the third test flight there was an accident in which Bajdak made several unplanned aerobatics and in one of them he failed to cope with the loss of power and was forced to bail out with a parachute, while the IK-1 crashed to the ground. Although he insisted the plane was unsuitable as a fighter plane, a detailed analysis of the incident revealed that the accident was a consequence of poor build quality. Despite the opposition of some pilots, including Bajka, Ikarus company decided to build a second prototype with more reinforced wings construction and  with much better assembly.

Second prototype got the name IK-02 (or simply IK-2 depending on the source) and it took about ten months to be built and was completed in June 1936. The main difference from the IK-1L was that the IK-02 had wings covered with metal sheeting, leaving only the rear fuselage and tailplane fabric covered. Other changes were a radiator of reduced size and improved shape, and modified air intakes, making for a more streamlined fuselage. This prototype was armed with one 20mm cannon, and two machine guns mounted above the engine. Machine guns were initially Darn type caliber 7,7mm but were replaced with the new Browning 7,92mm.

After several tests flights, there were some minor changes, like the new improved cockpit layout. IK-02 also participated in several mock (16 to some sources) dogfights against Hawker Fury biplane which was already part of the Yugoslav Air Force. In this mock dogfights IK-2 showed complete superiority in all respects over the biplane.

The interesting fact during this tests flights, there was a fierce discussion between two pilots of the “old school” Captain Leonid Bajdak and the  new test pilot 1st Lieutenant Janko Dobnikar, that resulted in a “fly duel”, IK-02 vs. the Hawker Fury. The conditions of the duel were:

  • Taking off and climbing up to 4000m above sea level, at Zumen Airfield,
  • Race on the route Belgrade-Novi Sad-Belgrade (some 140 km)
  • A mock dogfight above Belgrade.

The first two rounds were easy victory for the IK-02. The final round was a spectacular aerial battle over the Capital Belgrade. Despite his experience, Bajdak simply could not put his Fury in position behind the IK-02, while Dobnikar once was in position of the Fury, he kept on his nose until the end. Bajdak had to end the fight and acknowledge defeat.

Unfortunately the fate of this plane was similar to the first one. It was lost in an air accident during June of 1940 when flying in bad weather and hit by lighting. The pilot managed to save himself with the parachute, but the plane was lost.

Since additional testing and postponing the start of production took a lot of time, only a small batch of 12 aircraft were built until 1939 six were delivered in December 1938 and six more in February 1939 by the Ikarus. But while still in series production this plane was obsolete, and the planned later production was dropped, but nevertheless they saw some use in the April war German invasion of Yugoslavia 6th -18th April 1941.

In Combat

Before the start of the German attack on the April 6th 1941, all available IK-2 fighters were located in the 2nd mixed Air Brigade, which consisted of the 4th Fighter Regiment and the 8th Bomber Regiment in total 20 Hurricanes, 8 IK-2s and 23 Blenheims were based in Bosanski Aleksandrovac, Bosnia. The primary mission of The 2nd mixed Air Brigade was to defend the territory of Croatia, Bosnia and Slovenia from possible enemy attacks and to provide fighter support for the 8th Bomber Regiment.

On the first day of the war, The 2nd MAB only carried out scouting missions in the direction of Austria and there were few encounters with enemy planes without losses on either side. During the following days, performing their primary task, the 4th Fighter Regiment tried to stop a German air attack on the airport of Rovina near Banja Luka, at which the 8th Bomber Regiment was based. Some eight Hurricanes and six IK-2s attacked a group of 27 German Me-109s. Although it seemed that they did not have any chance, thanks to the knowledge of the hilly terrain and the cloudy weather they managed to surprise the German fighters. In the battle that followed, three Yugoslav and two German fighter planes were shot down. For this air battle, we could say that the Yugoslav fighter emerged as winners, because the primary goal of airport security and safety of the 8th Bomber Regiment was achieved.

The same day, these bombers were sent on to carry out bombing runs on the enemy territory of Hungary. Of 13 planes that had left the airport without the support of the fighters only 4 survived.

IK-2 belonging to the Royal Yugoslav Air Force

On April 9th, the Germans launched new air attacks on the 8th Bomber Regiment Aerodrome. At first only one IK-2 intercepted German aircraft. The lone IK-2 managed to get out of the fight with no damage. Soon almost all available Yugoslav fighters joined the battle Six IK-2s and eight Hurricanes in total 14 Yugoslav vs. 27 German aircraft. The battle was somewhat chaotic, Yugoslav fighters attacked individually or in pairs, while the Germans attacked larger groups. The battle lasted around 10 minutes, as the Me-109s were running out of fuel, they left the battle. Yugoslav losses were two Hurricanes and one IK-2. German losses are unknown, but it is estimated they sustained one or two losses.

After the 9th of April, because of the bad weather, there were very few flights. In the days that followed the 4th Fighter Regiment shot down one more German plane, a Ju-88. As German ground forces approached the airport on April 14 all planes were destroyed by the ground crew.

At the end of the April War, the Germans allocated three IK-2s to the Independent State of Croatia “NDH”. In order to equip existing aircraft with spare parts and fuel, and thus extend their operative use, Croatian Air Forces with German approval tried to collect as many military materials from airports and factories located in Serbia.

IK-2s were stationed in the 6th Air Group in Sarajevo by the end of 1941. Participation of these planes in the war was limited. By the 1944 they were removed from operational use, because of the lack of any spare parts, their final fate remains unknown.

Operators

  • Kingdom of Yugoslavia (Kraljevina Jugoslavija) – Eight were used during the April War.
  • Independent State of Croatia NDH (Nezavisna država Hrvatska) – Used few planes supplied by the Germans, their service was limited.

IK-2 Specifications

Wingspan 37 ft 5 in / 11.4 m
Length 25 ft 10 in / 7.8 m
Height 12 ft 7 in / 3.84 m
Wing Area 190 ft²  / 18 m²
Engine One Hispano-Suiza liquid-cooled V-12 piston engine 860 hp (640 kW).
Maximum Takeoff Weight 4,094 lb / 1857 kg
Empty Weight 3,311 lb / 1502 kg
Fuel Capacity 200 L
Climb Rate 16,000 ft / 5,000 m in 5’ 25’’ minutes
Maximum Speed 270 mph / 435 km/h
Cruising Speed 155 mph / 250 km/h
Range 435 mi / 700 km
Maximum Service Ceiling 39,370ft / 12,000m
Crew 1 (pilot)
Armament One 20mm cannon Hispano-Suiza HS.404 – fixed forward-firing cannon in an engine installation.

Two 7.92 mm Browning/FN machine guns with 250 rounds per gun.

Gallery

Yugoslav IK-2 107 Eskadrila, 34 Grupa, 4 Lovacki Puk – 2108
Croatian IK-2 – 2903
Yugoslav IK-2 107 Eskadrila, 34 Grupa, 4 Lovacki Puk – 2104

Sources

  • Kratka istorija vazduhoplovstva u Srbiji, Čedomir Janić i Ognjan petrović, Beograd 2011.
  • Elitni vidovi jugoslovenske vojske u Aprilskom ratu. Dušan Babac.
  • Zrakoplovstvo nezavisne države Hrvatske 1941-1945, Vojislav V. Mikić, Target Beograd 2000,
  • Lovačka Avijacija 1914-1945. Zlatko Rendulić, TEOVID Beograd 2014,
  • http://zlatibor.tv/kultura/ik-2-prvi-domaci-jugoslovenski-lovac/10735/
  • http://www.airwar.ru/enc/fww2/ik2.html

 

IK-3-161.Eskadrilla,-51.Grupa-No.10 - April 1941

Rogožarski IK-3

kingdom of yugoslavia flag 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

IK-3 Prototype
IK-3 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

IK-3 fresh after construction without camouflage
IK-3 fresh after construction without camouflage

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

IK-3 51st Independant Fighter Group, Belgrade-Zemoun, April 1941
51st Independent Fighter Group, Belgrade-Zemoun, April 1941

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

IK-3 No. 2158
IK-3 No. 2158

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.

IK-3 Summer of 1940 flown by Savo Poljanec, commander of 162nd Squadron
IK-3 during Summer of 1940, flown by Savo Poljanec, commander of 162nd Squadron

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

IK-3 Prototype - 1940
IK-3 Prototype – 1940
IK-3 51.Grupa, 6.Lovacki Puk No.2158 Br.9 April 1941
IK-3 161.Eskadrilla, 51.Grupa No.218 April 1941
IK-3-161.Eskadrilla,-51.Grupa-No.10 - April 1941
IK-3 161.Eskadrilla, 51.Grupa No.2159 Br.10 – April 1941
Possible markings for captured IK-3 being tested by a German research unit
IK-3 Prototype
IK-3 Prototype
IK-3 Prototype
IK-3 Prototype
IK-3 51st Independant Fighter Group, Belgrade-Zemoun, April 1941
51st Independant Fighter Group, Belgrade-Zemoun, April 1941
IK-3 without camouflage
IK-3 without camouflage
IK-3 No. 2158
IK-3 No. 2158
IK-3 fresh after construction without camouflage
IK-3 fresh after construction without camouflage
IK-3 Summer of 1940 flown by Savo Poljanec, commander of 162nd Squadron
IK-3 during Summer of 1940, flown by Savo Poljanec, commander of 162nd Squadron

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