Rogožarski IK-3: Pre-War Agility

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Rogožarski IK-3, Royal Yugoslav Air Force, 1940-1941
Part of the Yugoslav Air Tree suggestion

Introduction:

The Rogožarski IK-3 was a low-wing monoplane fighter designed for the needs of Yugoslavia’s air force in the lead-up to the Second World War. It was subject to various modifications during its short lifetime, and the 12 produced planes proved as powerful as contemporary fighters of the major powers like the Bf 109 E and the Hurricane.

Variants:

The IK-3 No.1/prototype mainly differed from the production version in having a French 12Y29 engine and a hub-firing HS.404 20mm cannon.

IK-3 production fighters had a Czech version of the Hispano-Suiza 12Y engine, and used an Oerlikon FF 20mm instead of the HS.404.

The IK-3 No.7 was used to test modifications for the planned second series, including a re-designed radiator, 15-20 km/h faster top speed, pilot seat armor and self-sealing fuel tanks.

It is unknown if the IK-3 with the DB 601 engine was completed or not, but it would improve the aircraft’s performance at the cost of losing the central 20mm cannon, leaving it with only two 7.92mm machine guns.

Unbuilt projects for the IK-3 were the fitting of Rolls Royce Merlin II engine and the Hispano-Suiza 12Y51 engine.

Specifications (IK-3 production):
Crew: 1

Dimensions
Length: 8.00 m
Wingspan: 10.30 m
Height: 3.25 m
Wing area: 16.50 m²

Mass
Empty: 2.068 kg
Max take-off: 2,630 kg

Propulsion
Engine: Hispano-Suiza HS 12Y29crs
Engine power: 690 kW (925 hp)

Performance
Maximum speed: 527 km/h
Climb rate: 667.55 m/min (11.1 m/s)
Range: 600 km
Flight ceiling: 9,400 m

Armament
1 x 20mm Oerlikon FF (60 rpg)

2 x 7.92mm Browning FN (500 rpg)

History:

Developing a New Fighter
Ljubomir Ilić and Kosta Sivčev were two of the aeronautical engineers sent to France on a Yugoslav state program of the late 1920s to acquire more knowledge on aircraft construction. Upon their return from abroad, they quickly started working on their private project for a high-wing monoplane fighter that would grow to become the IK-2. As the first tests of that prototype began, they returned to an earlier concept for a low-wing fighter, the future IK-3. Due to the high workload, experienced engineer Slobodan Zrnić was asked to join them. There is a theory that the fighter’s name was originally IKZ, adding Zrnić’s name to the initials only for the Cyrillic Z to be confused in documents as a 3, but it is disputed.

After promising results at the Eiffel wind tunnel, all documentation was handed to the military in mid-1936, but delays meant the order for a prototype to be built only came in March of 1937. The first test flight was held on April 14, 1938, and the IK-3 prototype flew with a Hispano-Suiza 12Y29 engine, a 20mm hub-firing HS.404 and two FN machine guns. Emphasis was placed on maneuverability, and the test pilots compared the IK-3 favorably to foreign fighters they had flown in that category. In mock dogfights with Yugoslav Bf 109 E-3s, IK-3s could go from being on their enemies’ tail to an attack position in a few turns. A fatal crash of the prototype on January 19, 1939, put a stop to the flight tests, but the order for 12 production fighters had already been placed with the Rogožarski factory from November 1938.

Production and Variants
The production aircraft had small differences trom the prototype, mainly a Czech license-produced version of the same engine, an Oerlikon FF instead of the HS.404, and various other changes. Deliveries of the 12 fighters started in March 1940 and were completed by July. The German invasion on April 6, 1941, found only six of the IK-3s operational. One had been lost the previous year in a training accident, two were undergoing maintenance, two were under repair, and one was in the process of being modified to the “Series II” standard.

The IK-3 No.7 was used as a testbed for a series of small modifications that would be implemented in the future second series of fighters. This included a re-designed radiator and a lower profile, giving it a 15-20 km/h higher speed, armor in the pilot’s seat and self-sealing fuel tanks. It was delivered to the air force just one day after the invasion on April 7th, and used by the most successful Yugoslav pilot, Milislav Semiz.

At the time of the war, there was also one IK-3 airframe undergoing conversion in Rogožarski to use the German DB 601A engine from the Bf 109E, a concept already proven on a Yugoslav Hurricane. It is unknown whether the conversion was completed, as there is no photographic evidence, but it is possible that the converted IK-3 was the one later sent to Germany for testing.

Wartime Service
On the opening day of the German attack, the IK-3s had to contend with waves of bombers and the accompanying Bf 109 fighters. Intense dogfights took place over Belgrade, with IK-3 pilots claiming several aerial victories, but leaving only three of the fighters operational by the end of the day. Semiz would leave his damaged IK-3 to get on the newly modified No.7, scoring 4 claimed kills in total. The last three operational IK-3s were transferred to Veliki Radinci, where they were set on fire by their crews to prevent their capture by the Germans. In the end, seven IK-3s, four of them complete, were captured by the Germans and one of them was sent to Germany for testing. The rest were scrapped.

Though none survived the war, the IK-3 would serve as the basis for the design of the first Yugoslav post-war fighter, the piston-powered Ikarus S-49.

Gallery:

Gallery

IK3 1
IK-3 prototype, 1938

IK3 2
IK-3 cockpit view


Technical drawings

IK3 4

IK3 5
Captured IK-3 at Zemun airfield, 1941

Sources:

Sources

http://vazduhoplovnetradicijesrbije.rs/index.php/istorija/rogozarski-ikz-ik3

http://www.airwar.ru/enc/fww2/ik3.html

Rogožarski IK-3 | Plane-Encyclopedia

Maketar Magazine: Rogozarsky IK-3 (you can find it here)

Aircraft Profile 242: IK Fighters (you can find it here)

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Why not make full aviation TT to go with already existing ground & naval tech trees?

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Yugo stuff always gets a +1

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Yes, the plan is to post a full aviation tech tree down the line. I’ve mostly completed it, but I’m still gathering info for the main aircraft that will go on separate pages first.

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That’s awesome to hear looking forward to it!!!

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