OK-M
Airframe no.: 0.01
Energia designation: 2M
Alternative designations: OK-ML1, OK-M
OK-M — Orbitalnyy Korabl — Maket (Orbital Ship — Model)
OK-ML1 — Orbitalnyy Korabl — Maket Letnyy 1 (Orbital Ship — Flight Model 1)
Test article OK-M was built for vibration and static load testing. Its inertial, structural and rigidity characteristics fully mirror those of a flight orbiter and the on-board equipment is represented by mass simulators. Vibration tests on flight articles and full-size test articles were carried out in stages before horizontal flight tests, transportation on the VM-T and the orbital flight test. The main objectives were to investigate aeroelastic phenomena and determine the dynamic characteristics of the airframe in test, transport and flight configurations.
OK-M on the Myasishchev VM-T Atlant. Photo: Mnogorazovaya kosmicheskaya sistema “Energiya-Buran”, 2004
Buran airframe (likely OK-M) during static testing at TsAGI. Photo: Aviatsionno-Kosmicheskiye Sistemy, 1997
Together with article OK-MT (which was used for the majority of this work) and OK-KS, OK-M was used for prototyping of the layout of the onboard equipment, including pneumatic and hydraulic connections and wiring harnesses. After that, a two stage test campaign was started at TsAGI, which aimed to validate the structural characteristics of the airframe structure, the attachment points of the thruster control blocks, the Integrated Propulsion System and the landing gear and to check the integrity of the Thermal Protection System in the case of structural deformation. Test articles OK-M and OK-MT were used in the first stage, during which static operational loads were applied to the airframes under normal climatic conditions. The airframes were outfitted with the heat resistant structural elements, but were not covered in thermal protection system tiles.
OK-M was then used for the majority of the vibration tests. During the first part of the campaign, the dynamic characteristics of the orbiter in free flight were obtained through horizontal vibration tests on a “free-floating” stand and the characteristics as part of the launch vehicle on a rigid stand, which simulated connections with the launch vehicle. During the second part, the characteristics with the launch vehicle were examined during vertical tests. OK-M was later used for air transportation tests aboard the Myasishchev VM-T Atlant, including tests of in-flight refuelling, and was then delivered to Baikonur in December 1983.
OK-M on pad 110/37. Photo: yaplakal.ru
Once in Baikonur, the orbiter was used for interface tests in MIK OK and some time later mated with Energia 4M for integration tests at the MZK from January to February 1986 (the Energia 4M — OK-M stack was designated 4MP1). Then, Energia 4M was destacked to be used for other tests and later stacked with OK-M again for fueling and dynamic tests at the UKSS and launch complex, this time under the designator 4MKS-D. Those took place between August 13 and August 28 1986 at the UKSS and between August 29 and October 4 1986 at pad 110/37, where the hydrogen burn-off system was also tested; on both occasions Energia’s tanks were filled with simulated propellants. [^4] [^5]
In June 1991, OK-M was mated with Energia test article 3D and rolled out to the newly finished SDI for dynamic testing. Before the SDI rollout, the orbiter was “on display” in MIK OK and was often shown to journalists who were visiting the cosmodrome.
After the conclusion of the test program, OK-M was placed on the test firing stand at site 254 and left to the mercy of souvenir-hungry tourists and the elements, before finally being moved next to the Baikonur Cosmodrome Museum in January 2007. The outside of the orbiter was cleaned and repainted to resemble the first flight orbiter and a museum exhibit was built inside the payload bay.
During its “operational” life, OK-M’s black tiles on the forward fuselage were arranged in a characteristic “low-rise” pattern and a wide strip on the underside of the wing near the elevons (sometimes also the elevons themselves) was light-colored instead of black. The orbiter also sported mock-up turbojet nacelles before the jet engines were cancelled.
OK-M in the anechoic chamber in MIK OK. Photo: Aviation Week and Space Technology, January 9 1989, p.23.
OK-M at the Baikonur Cosmodrome Museum. Photo: yablor.ru