Buran orbiter

The Buran orbiter is a class of reusable spaceplanes built as part of the Buran program in the 1980s and early 1990s.

The orbiter was conceived as a response to the Space Shuttle and was designed to launch on the Energia carrier rocket and carry up to 30 tonnes of cargo to Low Earth Orbit. Unlike the Shuttle, where the system’s main engines were located on the orbiter, Energia’s propulsion was independent of the Buran orbiter, which was merely its payload—an Energia rocket could also be configured to launch payloads other than Buran, and it did so during its maiden flight, carrying the Polyus spacecraft.

As the Space Shuttle Program’s ambitious launch cadence and mass to orbit projections and the Shuttle’s impressive technical characteristics were judged by the Soviet leadership to represent a military threat, Buran orbiters were designed to match or exceed the Space Shuttle’s capabilities, however potential those may be. As a result, the orbiter was built around a 18.5 meter long, 4.5 meter diameter payload bay, with a double delta wing configuration to match the Shuttle’s crossrange capability and enable single-orbit missions. The orbiter would be capable of delivering 30 tonnes to a 51.6° orbit and returning a 15 tonne payload.

With no technical requirements beyond matching the Shuttle specified during the initial pre-approval phase of the program, at one point the proposed design was a near copy of the American orbiter, with an identical double delta aerodynamic configuration, three reusable hydrogen-oxygen main engines on the orbiter and an expendable External Tank. When new requirements were issued, a radically different in-line mounted and vertically landed design was proposed, followed by a return to a design outwardly similar to the Shuttle; a side-mounted, horizontal landing orbiter with a smaller double-delta planform, main engines relocated to the external tank, and a pair of turbofan engines installed either side of the aft fuselage. From that point, the configuration evolved further into the final Buran orbiter, with the design freeze in 1979.

As many as five operational orbiters were ordered for the program, however, by 1989 the planned fleet was reduced to three orbiters, of which only one, 1K Buran, ever flew to space, conducting a two-orbit uncrewed test flight on 15 November 1988.

General characteristics

The reusable Buran orbiter is a winged spacecraft designed to deploy payloads to orbit, deliver crew, cargo and modules to space stations, carry out servicing missions and conduct standalone research flights, civilian or miliary in character, either completely uncrewed or with a crew of two to ten cosmonauts. Buran orbiters are launched side-mounted to the Energia carrier rocket and, after conducting in-orbit operations, perform a deorbit burn, reenter the atmosphere at a high angle of attack and glide to a runway landing.

The orbiter is 36.37 meters long, has a wingspan of 23.92 meters and a structural height of X meters. With its landing gear deployed, the highest point of the orbiter is 16.35 meters above the runway surface. The 5.5 meter wide fuselage contains the 18.5 meter long, 4.5 meter diameter payload bay, enclosed from the top by a pair of four-segment payload bay doors.

The orbiter’s double delta wing is mounted low on the fuselage and its forward leading edge blends into the forward fuselage. Pitch and roll control during the atmospheric phase of flight is exerted by a pair of elevons at the trailing edge of each wing. Mounted atop the aft fuselage is the vertical stabiliser, fitted with a four-element rudder-airbrake, which controls yaw by deflecting all elements to one side or operates as the airbrake by deflecting the elements outwards. The airbrake also provides a pitch-up moment on the orbiter when deployed, which, by letting the elevons deflect less, increases the lift-to-drag ratio during final approach. A body flap is located at the rear edge of the aft fuselage at the extension of the lower contour of the fuselage. It is used to trim the vehicle during descent and compensate for the shift in the center of gravity.

The orbiter uses retractable landing gear in the conventional tricycle configuration. The main landing gear is stowed in the wing consoles and the nose landing gear is stowed in a compartment at the forward end of the mid-fuselage. Three drag chutes are deployed upon touchdown to help slow the orbiter during rollout.

max payload 17.0 m, 4.5 dia