LANDING GEAR AND DRAG CHUTES

Buran’s landing gear was arranged conventionally, consisting of a nose landing gear and left and right main gear. All three gear wells were covered by one door each (as opposed to the two doors on the Orbiter’s nose gear). Each gear was actuated by a single hydraulic cylinder. If the hydraulic systems failed, there was a back-up pro­cedure to deploy the gears pyrotechnically. The wheels, two on each gear, were about twice as light as similarly loaded wheels on aircraft thanks to the use of tubeless tires made from natural rubber and beryllium brake disks. Because of the heat that accumulates in the brakes during roll-out, the main landing gear wheels were cooled with nitrogen gas right after the completion of the landing roll-out. During long missions the landing gear was maintained at the proper temperature by electric heaters and also by circulating hydraulic fluid through it.

Buran as well as the BTS-002 atmospheric test vehicle were equipped with drag chutes to relieve the stress on the brakes and reduce the landing roll-out distance by 500 m. Stored in a container under the vertical stabilizer, the drag chutes were automatically activated by a pyrotechnic system as soon as the main landing gear touched the runway. The three chutes (each having an area of 25 m2) were extracted by three small pilot chutes and then jettisoned once the speed had been reduced to 50 km/h. Heaters and thermal protection ensured that the temperatures inside the parachute compartment did not drop below — 50°C in orbit and did not exceed + 100°C during re-entry [11]. NASA originally also planned to have drag chutes for the Orbiter flight tests, but deleted them in 1974 because it was reasoned that the lakebed runways at Edwards Air Force Base were more than long enough. However, they were eventually introduced on Endeavour in 1992 and later installed on the other Orbiters as well.