Ikarus T-451MM Stršljen II: Hornet from the Balkans

thanosaekk · October 28, 2023, 3:09am

[Would you like to see the Ikarus T-451MM in-game?]

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Ikarus T-451MM, Yugoslav Air Force, 1958
Part of the Yugoslav Air Tree suggestion

Introduction:
The Ikarus T-451MM was a prototype ground attack jet aircraft that proved the final step in a long line of Yugoslav aircraft designs. Powered by two turbojet engines and armed with two cannons, it was one of the most capable aircraft built by the Ikarus in the 1950s, but didn’t get further than tests.

Variants:
The Ikarus 451MM family included three prototypes, of which two were armed (the third, S-451MM Matica, being an unarmed two-seater for training).

The J-451MM Stršljen was the first to be completed and was intended for close air support. However, as it carried a mere 10 rounds in each of its two cannons and 2 rockets, I don’t think it’s a viable addition to War Thunder.

The T-451MM Stršljen II, despite being intended as an aerobatic trainer, carried a more respectable amount of ammo that would make it viable. This is the variant I’m suggesting and the stats refer to it.

Specifications (T-451MM):
Crew: 1

Dimensions
Length: 7.77 m
Wingspan: 7.70 m
Height: 2.19 m
Wing area: 10.50 m²

Mass
Empty: 1,846 kg
Loaded: 2,664 kg
Max take-off: 2,936 kg

Propulsion
Engines: 2 x Turbomeca Marboré II turbojets
Thrust: 2 x 3.92 kN

Performance
Maximum speed: 725 km/h at an altitude of 5000m
Climb rate: 5000m altitude achieved in 8 minutes, 30 seconds (-> 9.8 m/s average)
Range: 824 km
Flight ceiling: 11,050m

Armament
2 x 20mm Hispano HS.404 cannons (60 rpg)
4 x 127mm HVAR rockets underwing

*The T-451MM was equipped with a K-14 gyro gunsight from the Yugoslav-operated P-47D-40s. It is not particularly useful in-game but still a nice detail.

History:
The lineage of the 451MM project is very long-winded and starts even before the war. To sum it up, Yugoslav aircraft designer Dragoljub Bešlin had worked on a number of prototypes meant to test a new idea: the pilot flying the plane in a prone position, by lying on his stomach, to negate the extreme G forces during combat maneuvers. First was the B-5 (completed in 1940, captured and evaluated by the Germans), then the post-war Ikarus 232 Pionir (first flew in 1947) and the all-metal Ikarus 451 (first flew in 1951).

By then, it became clear that the prone configuration wasn’t the most advantageous, due to problems like bad visibility and breathing difficulty, as well as the advent of anti-g suits. Bešlin’s 9th Construction Group would receive an order to build the first jet-powered aircraft with two small Turbomeca Palas engines in the winter of 1951-52. To achieve that, the 451’s design was used, but with the piston engines substituted for the jets and the prone position abandoned for a conventional seat. The S-451M flew in 1952 and would continue being tested over the years, but there was still more ground to cover before we get to the 451MM. As soon as the blueprints of the S-451M were finished, design of an improved successor named the S-451M Zolja began.

The Zolja’s main improvement was installing the engines in the wings instead of under them, though it was unarmed. First flying in 1954, it was the basis for the three 451MM planes. The first, the J-451MM Stršljen (Hornet), was effectively a close air support version of the Zolja but with stronger Marboré II engines. It was completed in 1956, and was followed by the two-seater S-451MM Matica. The Matica differed only in its two-seat configuration and the lack of armament.

The T-451MM Stršljen II was the final evolution of the 451 family, meant to cover all the J-451MM’s shortcomings. Fuel capacity was expanded through additional tanks, the ammo load was increased, and a number of new equipment was added like air brakes, an ejection seat, an anti-g suit, and a gyro gunsight.

The T-451MM was completed in late 1958, and performed its first flight on December 3. It was subjected to numerous test flights by the VOC (Flight Test Center) throughout early 1959, and the Stršljen II as well as the Matica would make hundreds of test flights in total over the early 60s (215 in 1961, 118 in 1962). The sole copy of the T-451MM was eventually decommissioned in 1969 and given to the Belgrade Aeronautical Museum, where it can still be seen to this day.

Gallery:

Spoiler