The Ilyushin Il-22 was a jet bomber aicraft that had the honour of being the first Russian jet-bomber to fly.
Ordered by the council of ministers on 12th February 1946, Ilyushin started to work on a bomber that would be powered by the new TR-1 jet engines. As experiments with jet-powered fighters showed, there were many high speed flight problems, and Ilyushin worked hard to mitigate them. Therefore, in spite of the conventional looking shape of the unswept wing, it was designed to improve lateral stability at high angles of attack and to prevent the onset on tip stall.
It was also discovered that jet fighters unexpectedly dropped a wing at high speed and altitudes. An investigation on this problem traced its roots on manufacturing defects in the wings that made no difference at low speeds and altitudes, but meant that each wing had a slightly different airfoil and therefore, a different amount of lift. In order to counter that problem, Sergey Ilyushin and his team developed a new manufacturing technique which, although it imposed a small weight penalty due to new welding techniques, had the advantage of greatly accelerating the assembly process as the internal equipment could be installed before the halves were joined together, allowing that way to various teams to work on a single sub-assembly before they were mated.
The engines, four Lyul'ka TR-1 with 12,75KN (2870lbf) each, where chosen to be placed ahead and below the wing leading edge in short horizontal pylons, unlike most of the jet-bomber of its time, which had the engines either buried into the fuselage (increasing the risk of a total failure in case of fire, albeit offering better aerodynamical improvements) or having them into nacelles attached directly to the underside of the wing.
The chose configuration proved to be beneficial acting as an anti-flutter weights and proved to be more efficient than underwing nacelles, keeping one of the main advantage of the nacelles, which was the easy access for ground crew to the engines.
As neither fuselage or wings offered enough space to store the main landing gear, the fuselage was designed as flattened oval to give them as wide a track as possible. That fuselage configuration also gave plenty of space to the fuel depots, as it could carry 9300kg (20500lb) of fuel stored in three bags, one placed each ahead, above and behind the bomb bay which had a payload of 300kg (6600lb) of bombs and the nose was rounded and largely glazed (like the Boeing B-29, Heinkel He.111 or Arado Ar.234, among others) to reduce drag.
It had a crew of five, with two pilots in the nose, a bombardier-navigator in front of them, a dorsal gunner who was also the radioman just behind the pilots and the rear-gunner just behind the tail.
It had a defensive armament of a single fixed 23mm (0.91in) Nudelman-Suranov NS-23 autocannon on the lower starboard side of the nose which could be fired by the pilot and was aimed with a rather primitive ring-sight. Dorsal turret was equipped with two 20mm (0.79in) Berezin B-20E guns and was capable of traversing 360º with special microswitches that prevented the gunner from shooting the aircraft tail. It was remotely controlled by the radio operator and was powered by electric motours both for traversing and elevation. A small observation blister was added for the gunner and his gunsight at the rear of the main crew compartment to help laying the guns on their target, and the sight automatically compensated for parallax between the gunner and the turret and also for the required amount of target lead and the shell's ballistics. The remote turret system offered many advantages including a smaller turret which offered less drag, the guns could be fixed more rigidly to their mounts, the sight wasn't exposed to vibrations from firing and could track targets softer and gunner's confort did not have to be sacrificed to better operate the turret.
Anyway, the major disadvantage was that the analog computer remote control system was too complicated for the period and was prone to breaking down, just like the systems present also at the Boeing B-29. The rear gunner was placed behind the tail, at the very end of the fuselage in order to optimize his field of fire in an electro-hydraulically powered Il-KU3 turret which mounted another 23mm NS-23 cannon. That turret could traverse a total of 140º with an elevation of 35º and a depress of 30º.
The prototype was hastly assembled and flew for the first time on 24th July 1947. It showed docile flying characteristics, but it was seriously underpowered as the TR-1 engines provided only 80% of the required thrust. When it was tested by the manufacturers, it made the first ever Soviet jet-assisted takeoff on 7th February 1948 with a pair of SR-2 boosters attached. As thrust engines couldn't be increased in time, Ilyushin decided to no submit the bomber for state acceptance trials as its performance didn't meet the requirements made back in 1946.
Sources:
1. https://en.wikipedia.org/wiki/Ilyushin_Il-22
2. http://www.aviastar.org/air/russia/il-22.php
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