“Il” planes for space conquerorsIn preparation for Cosmonautics Day OJSC “Il” representatives visited Chkalovsky Airport — the base of the unique Il-76MDK, zero-g training aircraft. They are used for cosmonaut training, medical experiments and biomedical research, for testing of space equipment, devices and units in zero gravity. These aircraft also allow imitation of lunar and Martian gravity (hypogravity).
As compared to the default Il-76MD, the Il-76MDK has a reinforced fuselage and wing construction, fitted hydraulic accumulators and upgraded fuel and hydraulic systems to provide their operation in zero gravity. Walls and ceiling of the cargo compartment are covered with a soft flame-resistant material, urethane foam mats are attached to the floor. The cargo compartment itself is fitted with additional lamps and hand-rails. In the front part of the compartment there are workplaces of engineers and doctors, who control the performance of equipment and oversee the physical condition of space flight candidates. The cockpit also has some additional elements: control units of the fuel tank and oil accumulators, zero-G gauge with glycerin.
To create zero-G conditions on board pilots use a special flying technique — the Kepler’s parabolic curve. First the aircraft accelerates to the maximum speed, then it climbs and when the angle of climb reaches 45-50 degrees a zero plunge acceleration is created in 1-2 seconds by the movement of the control column. This maneuver allows people on board to experience zero gravity condition that lasts for 25-28 seconds. The plane meanwhile begins to dive at a 45-50 degree angle and levels out with a 2g plunge acceleration. After the aircraft switches to horizontal flight again it takes 3-5 minutes to turn and reload fuel and oil accumulators, although according to technical instruction the aircraft can perform up to 3 “zooms” without this procedure. The Il-76MDK averages up to 10 parabolic curves in a 1.5 hour flight, and the maximum allowed number of zero-G maneuvers in one flight is 20. During the flight maximum acceleration reaches 2g. It takes 10-12 flights for space flight candidates to acquire fundamental skills of working in zero-G.
From the preparation for the first space flights special modifications of Tupolev Tu-104, Tu-134 and Tu-154 were used as flying zero gravity labs. But the fuselage size of all these aircraft limited the experiments.
In May 1970 cosmonaut G.T. Beregovoi, who was very interested in the spacious cargo compartment of this aircraft, made his second visit to the assembly hall with the second prototype of the Il-76.
July 24, 1972 — on the basis of the guidelines, offered by the Yuri Gagarin Cosmonaut Training Center, and the technical proposal of Ilyushin design bureau the commission of the Council of Ministers of the USSR made the decision to build a flying lab Il-76K.
G.V. Novozhilov recalls:
“The drawings for this modification were prepared very quickly, but, to be honest with you, nobody was eager to put this aircraft in mass production. And cosmonauts always reminded us that they needed this plane. We flew to Tashkent with cosmonaut V.A. Shatalov and met the management, the workers and especially the young specialists of the factory, who patronized the building of this plane and helped to finish the building of Il-76K faster.”
The Il-76K made its maiden flight on August 2, 1982 on the airport of the Tashkent Aviation Production Association named after V. Chkalov. During this flight S. Bliznyuk’s crew practiced “zoom” maneuvers to create the longest possible “zero gravity condition” on board. The parabolic paths were calculated by the bureau lead engineer V.V. Smirnov. All this made it possible to extend zero-G time from 15-16 seconds for Tu-104AK up to 23-25 seconds for Il-76MK.
Originally the tail part of the plane was fitted with a spin recovery parachute in order to prevent an uncontrolled spin during “zooms”. On the next aircraft this item was removed — the plane proved to be almost impossible to put into the spin.
The “space” Il-76 was exposed to significant acceleration, and its life was reduced by a factor of more than 10 as compared to a standard aircraft. Usually after 120 “hills” the aircraft had to be removed from service, but that was the price of space flights.
A total of three Il-76K aircraft were built: USSR-76766 (61-08), USSR-78770 (66-05) and USSR-78825 (72-08). All aircraft were given to the V. Seregin 70th Separate Test and Training Aviation Special Purpose Regiment (STTASPR) that belongs to the Yuri Gagarin Cosmonaut Training Center and is based in Chkalovsky.
The Il-76K aircraft were used for cosmonaut training for almost ten years, till the early 1990s. The aircraft USSR-86638 made its last flight on December 14, 1988, after that it was handed over as an educational aid to the Perm Military Aeronautical Technical School, where it was scrapped in 2001. Two other Il-76K received new numbers in 1994 — RA-76372 and RA-76430, and from 1997 they operated with different (mostly African) commercial airlines as regular transport planes.
The first Il-76MDK, built on the base of the Il-76MD to replace the Il-76K, made its maiden flight in Tashkent on August 6, 1988. The captain was V.I. Sviridov. By the time STTASPR already operated one flying lab based on Tu-154 USSR-85055, which was joined by another Tu-154M-LK1 USSR-85655 in 1989. From 1983 Tu-134LK (tail number – 03 red) and Tu-134-LK2 (03 red) operated under this program. The first one presumably was scrapped in 2011-2012 in Fujairah (the United Arab Emirates), and the second one crashed during landing approach in bad weather in Brazzaville airport (Republic of the Congo) on November 30, 2012.
A total of three Il-76MDK aircraft were built: USSR-76766 (61-08), USSR-78770 (66-05) and USSR-78825 (72-08). The first one of them arrived at the Chkalovsky airport on August 31, 1988, beginning from 1994 it was occasionally used for commercial transport and in 1999 returned to “space” flights.
The second aircraft received the name Il-76MDK-II and arrived at the Cosmonaut Training Center at the end of December, 1990.
The third (also Il-76MDK-II) — at the beginning of 1991. In 1994-99 the aircraft operated as a regular cargo plane with Tubelair Company (Tunisia).
Starting from 2010 all three Il-76MDK aircraft became part of the state aviation of Federal Space Agency (Roscosmos), based on the 70th Separate Test and Training Aviation Special Purpose Regiment, and received new numbers: RF-75351, RF-75-352 and RF-75353. The aircraft are operated by the Aviation Agency of the Yuri Gagarin Cosmonaut Training Center, which in its turn is also part of Roscosmos.
OJSC “IL” congratulates all Russian cosmonauts on this holiday and wishes them to win the international space exploration contest!