Ilyushin Il-22
| Company type | Military aircraft prototype |
|---|---|
| Industry | Aerospace |
| Founded | 1946 |
| Founder | Ilyushin design bureau |
| Defunct | 1947 |
| Fate | Project cancelled due to underperformance |
| Headquarters | Soviet Union |
| Products | Jet-powered bomber aircraft |
The Ilyushin Il-22, known in USAF/DOD terminology as Type 10, was the Soviet Union’s inaugural jet-powered bomber to take flight. Its propulsion comprised four Lyulka TR-1 turbojet engines mounted on short horizontal pylons positioned forward and beneath the wings. However, these engines underperformed, delivering less thrust than anticipated and consuming more fuel than specified. Consequently, the aircraft failed to achieve its targeted operational capabilities, leading to its cancellation on 22 September 1947.
Design and development
On 12 February 1946, the Council of Ministers commissioned the Ilyushin design bureau to develop a bomber powered by four TR-1 jet engines. Insights gained from first-generation jet fighters revealed unforeseen challenges associated with high-speed flight, prompting Ilyushin to focus considerable effort on addressing these issues. The aircraft featured a long, slender, and unswept wing that appeared conventional but was specifically contoured to enhance lateral stability at elevated angles of attack and to avert tip stall.
Another issue identified in early jet fighters was the sudden dropping of a wing during high-speed, high-altitude flight. This phenomenon was attributed to subtle manufacturing inconsistencies in wing construction that were negligible at lower speeds and altitudes but resulted in each wing having slightly different airfoil profiles and thus unequal lift generation. To counter this, Sergey Ilyushin’s team introduced an innovative manufacturing approach that reversed traditional assembly methods: instead of attaching internal structural components to the assembly jig before fitting the skin panels, the outer skin panels were first placed in jigs ensuring precise curvature and shape, after which internal supports were affixed. This method necessitated manufacturing joints along the chord lines of wings and tail surfaces, effectively splitting spars and ribs in two. Similarly, the fuselage was assembled from two halves divided vertically along its centerline. Although this technique imposed a minor weight increase, it significantly sped up assembly by allowing internal systems to be installed prior to joining the halves, enabling parallel workstreams on subassemblies.
At the time of Il-22’s design, most multi-engine jet aircraft either housed engines singly or in pairs within nacelles attached directly beneath the wings or embedded within them. Grouping engines in a single nacelle reduced overall drag and minimized interference drag but carried operational risks; an uncontained engine fire could disable adjacent engines—a critical concern given early jet engines’ limited reliability. Ilyushin opted to mount each TR-1 engine individually on short horizontal pylons ahead of and below the wing’s leading edge. This arrangement functioned as an effective anti-flutter mass and proved more aerodynamically efficient than conventional underwing nacelles. Additionally, this configuration simplified engine maintenance by enhancing ground crew access.
Due to the thin wing profile and engine placement, there was no space within these structures for main landing gear housing. Therefore, designers shaped the fuselage as a flattened oval cross-section to maximize landing gear track width while providing ample volume for fuel storage—approximately 9,300 kg distributed among three fuel bags located forward, above, and aft of the bomb bay. The bomb bay itself accommodated up to 3,000 kg of ordnance. The fuselage nose featured a largely glazed, stepless design tapering into a rounded point reminiscent of the noses seen on aircraft such as the Boeing B-29 Superfortress, Heinkel He 111, and Arado Ar 234, minimizing aerodynamic drag. The crew complement consisted of five members: two pilots seated side-by-side in the nose section; a bombardier-navigator positioned ahead at the tip; a dorsal gunner/radio operator immediately behind the pilots; and a rear turret gunner stationed at the tail.
Armament included a fixed 23 millimetres (0.91 in) Nudelman-Suranov NS-23 autocannon mounted low on the starboard side of the nose, operated by one pilot using a basic ring sight for aiming. The dorsal turret housed twin 20 millimetres (0.79 in) Berezin B-20E cannons with 400 rounds per gun and provided full 360° rotation. Microswitches prevented firing into the aircraft’s tail structure. Controlled remotely by the radio operator through electrically powered motors for both traverse and elevation, this turret incorporated an advanced sighting system compensating automatically for parallax between gunner position and turret location as well as target lead and ballistic factors. The gunner utilized a small observation blister at the rear of the main crew compartment for target tracking. Remote control offered multiple benefits: it allowed for a smaller turret profile reducing drag; guns were mounted more rigidly; sights were isolated from firing vibrations enabling smoother tracking; and gunner ergonomics were optimized without compromising turret performance. However, this analog computer-based remote system was complex for its era and prone to malfunctions akin to those experienced with similar systems on platforms like the B-29 Superfortress. The rear gunner manned an electro-hydraulically powered Il-KU3 turret at the extreme tail outfitted with another NS-23 cannon capable of traversing 140°, elevating 35°, and depressing 30°.
Testing and evaluation
The Il-22 prototype was quickly constructed and completed its maiden flight on 24 July 1947. It demonstrated gentle handling traits; however, it was significantly underpowered since the TR-1 engines delivered only 80% of the necessary thrust. In the final phase of the manufacturer's flight trials, the Il-22 achieved the Soviet Union's inaugural jet-assisted (rocket-assisted, RATO) takeoff on 7 February 1948 using two SR-2 boosters. Due to the inability to promptly enhance engine thrust, Ilyushin chose not to present the bomber for official state acceptance tests, as its performance fell short of the 1946 specifications.
Specifications (Il-22)
See also
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Notes
Bibliography
- Gordon, Yefim. Early Soviet Jet Bombers. Hinkley, UK: Midland Publishing, 2004. ISBN 1-85780-181-4
- Gordon, Yefim; Dmitriy and Sergey Komissarov. OKB Ilyushin: A History of the Design Bureau and its Aircraft. London: Ian Allan, 2004. ISBN 1-85780-187-3.
- Němeček, Václav. The History of Soviet Aircraft from 1918. London: Willow Books, 1986. ISBN 0-00-218033-2.
External links
- Il-22 at ram-home.com Archived 2008-10-23 at the Wayback Machine
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