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Tupolev TU-126 Moss - Flight Testing

In the fall of 1961 the first prototype Tu-126 (#68601, in a number of official documents the aircraft has the number 61[M]601) was finished. The tests of the first experimental Tu-126 began in January 1962, and 23 numbers crew headed by the test pilot I.M. Sukhomlinom, navigators - Rudnev and Iksanov, flight engineer - Dralin, completed the first departure. This was under the leadership of test brigade of the OKB, N.V. Lashkevich, the legendary chief engineer for the Tu-70 and Tu-95, who knew how to rescue the catastrophes of these machines. For his deputy was appointed V.M. Korolev.

The first seven test flights, in course of which were determined the flight performances Tu-126, were carried out with the mock-up of the "Livna / Liana" radar. Then the machine flew to Moscow [Lukhovitsakh] were they installed the real RLS. Soon began the first stage of joint testing, which was being continued until February 8, 1964. Since it was considered that initial Tu-114 was already sufficiently worked out, by then the primary task of this stage was determined to be the finishing of station "Livna / Liana" and the verification of compatibility of radio-electronic equipment. But this was not all that was needed to bring complex to the working order.

General technical requirements of the Air Force [VVS] unambiguously provided for testing the entire complex for with the armament aircraft regardless of the fact of whether it completely new or built on an already existing base. For this purpose even in the stage of mock-up, there was created in the GK NII VVS (State Red Banner Scientific Testing Institute of the Air Force) an individual test brigade under the management of M.G. Kononova, with the deputy D.G. Matvienko. The chief military test pilots Tu-126 were consecutively G.M. Barkhatov, V.I. Kuznetsov, V.V. Dobrovolskiy. In some flights the crew of the experimental Tu-126 was headed I.K. Vedernikov, were drawn other well-known pilots.

The full-scale study [LTKH] of the Tu-126, and also the stability parameters and controllability, began after redeployment to Vladimirovku on May 24, 1964. In the piloting the machine itself appeared sufficiently strict. The "mushroom" radar dome overshaded the fuselange, and created noticeable additional resistance, which decreased the range and set serious limitations on the flight envelope. Having mass on the order of 12 tons and diameter of 11 meters, it displaced the centering and focus of aircraft to the rear, which led to a change of the stability parameters and controllability in the longitudinal direction. Furthermore, its resistance was the reason for the noticeable pitching moment,that depending on velocity head, and this hampered balancing the aircraft. The "mushroom" xerted also a certain negative influence on takeoff and landing data of the aircraft. Sometimes it led even to the dynamic instability. Thus, immediately after retraction of flaps the Tu-126 for some time fell into the longitudinal swaying.

An increase in the resistance led not only to the decrease of the radius of action of the aircraft, but also to reduction in the maximum speed of flight at high altitude to 805 km/h, which was 100 km/h is less than the Tu-95. Upon reaching this speed the aircraft began to shake, but controllability was not disrupted. Performance characteristics were also reduced at low altitudes. It was necessary to considerably limit the maximum permissible speed. If on the Tu-95 the corresponding indicated speed was 630 km/h, and on Tu-114 - 580 km/h, then on Tu-126 it was only 530 km/h. An increase in the mass of fuselage and equipment inside it in comparison with Tu-95 led to a reduction in the permissible overload from 2,5 to 1,8 and corresponding worsening in the maneuverability.

In the second stage of joint testing, which was completed in November 1964, interaction Tu-126 with the ground-based and ship control centers was checked, along with the reliability of the transmission of information, combined actions with the forces and the air defense weapons were perfected. Tests also investigated the possibility of detecting the aerial targets at high altitudes above the water areas of Barents and Kara Sea, and also selection of missions above the land and the ice cover.

The important stage of further tests was finalizing with testing of refueling Tu-126 in air. For this aircraft of #66[M]622, the plant in Kuybyshev equipped the plane with the appropriate equipment. Testings conducted the crew of GK NII VVS (State Red Banner Scientific Testing Institute of the Air Force) under the command of V.V. Dobrovolskogo. The task of the first flight, which was took place on August 29, 1967, was only to clarify behavior in the wake of the dispenser. The folded configurations of tests were flown also by I.M. Sukhomlin. Together with V.V. Dobrovolskim they verified the consequences of the engine failures in different situations: during the takeoff before and after of reaching critical speed, immediately after detachment and so forth despite the fact that analogous tests for Tu-114 passed successfully, the need for this work arose in view of the presence of additional surfaces, change in the flight masses and centerings. On April 26, 1969 a flight was executed with two shut-down engines. In all these cases combatant crews obtained detailed procedures.

In 1962-63 the experimental Tu-126 years was twice demonstrated to the highest military-political management of the country on the airfield in Kubinka, and in May 1964 a showing in Akhtubinske to the chairman of the VPK L.V. Smirnov took place the to management of the Ministry of Defense. Judging by everything, the aircraft was perceived very benevolently.

From the course of of tests solving VPK of #275 dated November 27, 1963, the aircraft was selected into series production at the plant of #18 in Kuybyshev. Besides the first experiment machine of #61[M]601, in the period since 1965 prior to the end of 1967 eight series Tu-126 were built: in 1965 - #65[M]611 and 65[M]612, in 1966 - #66[M]613, 66[M]621 and 66[M]622, in 1967 - #67[M]623, 67[M]624 and 67[M]625. Production aircraft were equipped with the system of in-flight refuelling, which practically without change were transferred Tu-95[RTs] and Tu-95[KD]. Fairing with the fuel pipe was mounted on the starboard of fuselage, and a servicing rod with the fuel-receiver - above the navigator's compartment. Three aircraft (#65[M]611, 66[M]613 and 66[M]621) were returned to the customer without the equipment, and on them were placed only the automatic weapons of the discharge of dipole reflectors. The aircraft of #65[M]612 beginning from #67[M]622 were given to the customer with the new elongated tail section, which together with the dipole reflectors was placed the complete set SPS-100 "mignonette". In connection with the fineness ratio of fuselage the area of the keel-crest under the fuselage was somewhat decreased.

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Page last modified: 09-07-2011 13:23:37 ZULU