Ilyushin IL-40 (Brawny) Ground-Attack Aircraft Prototype
The Ilyushin IL-40 Brawny ground attack platform existed in only seven prototypes before the design was dropped from contention.
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Following World War 2 (1939-1945) the ground attack role was still very much a consideration for world air forces. It was envisioned that the next war in Europe would take place between the Soviet Empire and European powers as well as the United States. With this would come a major ground war involving many tanks and, to counter this threat, dedicated ground attack aircraft were still in need.
The early 1950s saw the first frontline combat use of jet-powered fighters (through the Korean War) and bombers were soon surpassed by jet-powered designs. Additional work on turbojets meant that they were made more efficient, compact, reliable and powerful. Single engine jets were becoming commonplace and proven in such stellar designs as the Soviet Mikoyan-Gurevich MiG-15 and the North American F-86 "Sabre" lines.
Work on a new ground attack platform for the Soviet Air Force began in 1950 by the Ilyushin concern with jet powerplants being the focus. Up to know, the company was well-known for its World War 2-era contribution of the two-seat, prop-driven IL-2 "Sturmovik" which was more or less an armored flying tank of sorts. For the new design, the engine installations became a pair of Mikulin AM-5 turbojets developing 4,740 pounds thrust and set in nacelles alongside a largely tubular metal airframe. The cockpit was set aft of a long nose cone assembly and a conventional, single-finned rudder approach was given to the tail with mid-set horizontal planes featured. The wing mainplanes were swept back 35-degees and given large boundary layer fences for the needed control at high speeds. A tricycle undercarriage, wholly wheeled and completely retractable into the design, added a most modern element. Three dive brakes allowed for improved control when coming into an attack action. The crew was two and they seated in tandem with full cockpit armoring planned due to the low altitude levels the aircraft was expected to attack in. Each crew position was also to feature an ejection seat.
Proposed armament was 6 x 23mm Nudelman-Rikhter NR-23 series cannons fitted to the nose section. An additional NR-23 system would be fitted to a tail barbette to protect the aircraft's more vulnerable "six" from interception. Beyond this fixed, standard armament set the aircraft was also being designed with a bomb-carrying capability in mind, this through in-wing bomb bays and underwing rack support. Underwing bombs could be supplanted by either air-to-surface rockets or fuel tanks (the latter improving operational ranges). Much of this armament suite was based on Ilyushin's experience in delivering its classic IL-2: this cannon-and-machine-gun-armed beast was produced in over 36,000 examples from 1941 to 1945 and supported air-to-surface rockets. Its rear was defensed by a machine gun. The IL -2 proved the ultimate "tank-buster" and ground-attack aircraft for the Soviet Air Force of the Second World War.
During January of 1952, Ilyushin finalized the IL-40 and submitted it for possible consideration. Authorities like what it promised and contracted for a single prototype to be built. The completed prototype recorded its first flight on March 7th, 1953 with success. By the end of the month, the cannon armament was fitted and actively tested but it was here that the IL-40 showcased its critical shortcoming - firing of the six guns affected the engines to the point that the systems flamed out due to ingesting the gun's propellant gasses. Thus four AM-23 series cannons were substituted and new gun mounting hardware installed. Firing ports were moved further forward to better deflect the outgoing gasses and keep these form the jet intakes.
This work delayed the program considerably as the aircraft was not transferred for official Soviet Air Force trials until early 1954. Issues with the guns persisted but the aircraft was a good gunnery platform and high-speed performer at its core. To remedy the gun issue even further, a new prototype design was pushed through which relocated the guns to a position under the nose and the engine intake openings were noticeably lengthened forwards, by way of additional ductwork, beyond the original nose of the aircraft. Tumansky had also delivered an improved form of the AM-5F engine, the RD-9V, by this time which promised to increase general performance of the jet aircraft.
Soviet authorities were sold on this revision and funded the second IL-40 prototype which became the "IL-40P". This aircraft saw its own first flight on February 14th, 1955 and ensuing trials revealed the aircraft to be better than its original offering. The Air Force was compelled to order the attack platform in some forty examples. However, before production could really pick up steam (and after five production-quality examples were already completed), the IL-40 project was cancelled by the Air Force in lieu of changing battlefield doctrine and a growing reliance on nuclear weapons to take over the role of dedicated ground attack aircraft.
A total of seven IL-40 related aircraft were produced during the short-lived program. Several other forms, including a torpedo bomber (IL-40T) and artillery spotter (IL-40K), were also planned but came to naught. The IL-40 emerged as a contender in the latter part of the 1960s once more (as the IL-102) but lost out to what became the T-8 from rival Sukhoi. The IL-102 saw its first flight in 1982 and flew 367 total test flights, receiving good reviews from its test pilots. The T-8 evolved to become the Su-25 "Frogfoot", a dedicated Close-Air Support (CAS) platform that still serves the Soviet Air Force today (2015).
The IL-40 was around long enough to earn the NATO nickname of "Brawny".