Il-28 BEAGLE (ILYUSHIN) - Design
With manual bomb sights and even a manned tail turret, the Il-28 was very much a jet-powered World War II era bomber. Two Klimov VK-1 centrifugal-flow turbojets (developed from the Rolls-Royce Nene) were mounted beneath the wings in pods, which extend beyond wings' leading and trailing edges. The high-mounted wings featured a straight leading edge and forward-tapered trailing edge with blunt tips. The unswept wing contrasts with the swept tailplane but ensures pitch control in high Mach dives. The tubular fuselage was cigar-shaped, and tapering to the rear, with a rounded, glassed-in nose and bubble canopy. The WWII-style greenhouse contains the bombardier/ navigator's electronics and visual bombsight. The tail fin is swept-back and tapered with a blunt tip. The tail of the Beagle contains the rear gunner/radio operator and two more 23mm NR-23 cannon. Flats are low-mounted on the fin, swept-back, and tapered with blunt tips. A glassed-in tail gunner compartment is to the rear of the tail.
In 1947, the S.V. Ilyushin Design Bureau developed a draft jet front-line bomber powered by the RD-45 engines (2 engines 2270 kgf each). It was designed for low-and medium-altitude missions in areas. Designers paid special attention to defensive armament by using advanced air defense. The Design Bureau weapon developers proposed a unique canon mount, the Il-K6, with a wider effective field of fire, that outperformed the further analogues abroad.
In 1947, the S.V. Ilyushin Design Bureau developed a design of the IL-24 jet front-line bomber powered by two A.A. Mikulin TKRD-1 engines (2 x 3300 kgf). But the well developed and proven RD-45 (license Rolls-Royce "Nene" engine) with a maximum thrust of 2270 kgf became available and resulted in project changes resulting in the IL-28 powered by two RD-45s.
The developed automated air-thermal anti-icing system significantly increased the combat effectiveness of the bomber, allowing the aircraft to be operated in the most difficult weather conditions and providing reliable protection against icing of the leading edges of the wing and tail. To ensure reliable navigation and combat missions at any time of the day, the aircraft provided for the installation of a multifunctional complex of communications and radio-technical air navigation equipment. Particular attention was paid to improving the working conditions of the crew, located in two sealed cabins equipped with life support systems at high altitudes. Workplaces were protected by metal and transparent armor, which protects against damage by bullets or shell fragments. In an emergency, the ejection seats of the pilot and navigator allowed the aircraft to leave at high speed. The radio gunner left the car through the lower hatch, the open cover of which protected him from the incoming air flow.
The designers paid special attention to defensive armament because the aircraft was intended for low-and medium-altitude missions, where the aircraft is capable of detecting and engaging small-size targets. The weapon developers of the Design Bureau proposed the IL-Lithium with 225 rounds per barrel canon mount with a wider effective field of fire (+/- 70o horizontal, 60o - up and 40o down), that outperformed the Boeing B-29 analogue (+/- 30o transverse and elevation aiming angles). It was armed with two 23 mm NR-23 cannon in a fixed nose installation and two 23 mm NR-23 cannon in the tail turret. Up to 3000 kg of disposable stores can be carried in a lowerfuselage weapons bay. The Il-28R variant is a three-seat tactical reconnaissance version with four or five cameras. This model was also used for electronic intelligence gathering with a revised electronic fit. The Il-28U variant is an operational conversion trainer lacking radar and armament but fitted with a second cockpit in the nose. The bombs were loaded internally. The 50-500 kg ammunition could be loaded on multiple racks, and the 1000-3000 kg - on the mask racks.
S.V Il'ushin began his work at the Il-28 after he had finished his work at Il-22/Il-24 when the Design Department by A.N. Tupolev was building the front bomber (later Tu-14), by the VVS official task. The contrastive analysis of different variants of defensive arming of bombers showed that with the help only a stern cannon installation in aggregate with corresponding maneuver of the aircraft it may effective repulse attacks of the modern fighters from the side of backward semisphere and provide a reliable defence of the engine. The creation in USSR of the 1st double cannon electrohydraulic stern installation Il-K6 defected the main design features of Il-28.
It contained the positive features by Ku-3 and Ku-4 had not their defects. The installation Il-K6 had a corner of fire 70° to the right and to the left, 40° down and 60° up. On the normal duty of the driving gear the arms moved with the speed 15-17° in a second, and on the forced regime -with the speed 36°/sec. The power of driving gear provided it effective usage with the flight speed more than 1000 km/h. It had little weight (340 kg) and a maximal outward moment 170 kg/m. The stern installation of the bombers B-29 and Tu-4 had the corners of fire considerably less (30° to the right and to the left, 30° up and down), their maximal outward moment was equaled 50 kg/m and the weight was more than the weight oh the turret of Il-K6 almost on 50 kg. Later the turret of Il-K6 was set and on the other domestic aircrafts.
The scheme of defensive arming was accepted in a part of the crew allowed to decline sharply the geometrical sizes of Il-28 in compare with Il-22: the new aircraft began almost on 3,5 m shorter, and the area of the wing declined on the 13,7 m2. Accordingly the weight of the gilder was declined and it allowed to apply the engine installation from 2 TRD «Rolls Royce Nene». They differed from the TP-1 the high reliability and the specific consumption of fuel less on the 25-30% , but they had a essential disadvantage - the middle was bigger. And the last circumstance and aspiration of designers maximal move away air inlets of engineers from the ground surface to prevention the indraft of foreign objects from the ground VPP actuated to refusal from the pier placing engineers and to the installation them to the motoballon, close pressed to the low part of the wing. In order t receive the necessary centering the engines arranged in the front parts of the motoballons. Big diameter of the centrifugal compressor and comparatively little diameter of the jet exhaust that TRD allowed comparative easy to decide it and other rather important problem connected with providing the wide wheel track and removal the main posts with the big wheels for the front bomber. The motoballon of the post fastened to the force bulkhead with the help of simple mechanism, applied for the 1st time on the low-flying air attack Il-10, during the removal turned on 90°, and the wheels laid flat in the area of the back of the compressor under the exhaust.
The crew was located the encapsulated cabins, and a pilot and a navigator might use up-ejection seat. The landing gear was optimized for usage on the ground VPP. For shortening the takeoff the designers provided for the capability of application 2 solid-rocked boosters PSR-1500-15 rod was 1600kg and time action 13 sec, jettisonable after the aircraft's tearing. Il-28 was armed by the most effective air-heat in those period POS and up-to-date complete set of aero-navigation and radio-engineering equipment: autopilot AP-5, radio compass ARK-5, height-finder radar of big and small heights, the system «blind» start on the landing OSP-48 and then SP-50 transponder of identification, command and communications transceiver.
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