BOR-4 in the shop BOR-4 in the shop prior to launch Credit: from Semenov, et. al., Buran, 1995. |
Status: Operational 1982. First Launch: 1982-06-03. Last Launch: 1984-12-19. Number: 4 . Gross mass: 1,200 kg (2,600 lb). Height: 2.80 m (9.10 ft).
After cancellation of Spiral, they were flown to test heat shield materials developed for Buran. After a circuit of the earth, the spacecraft would deorbit, perform a gliding re-entry, followed by parachute deployment, splashdown in the ocean, and recovery by Soviet naval forces.
In 1973 the VPK initiated the BOR program to accomplish research on a space glider. In order to investigate the hypersonic aerodynamic characteristics and heat shield materials of the manned Spiral OS lifting body, 1:3 and 1:2 scale models of the OS were to be built. Unlike the full-scale model, these were had fixed wings and were designated BOR (unpiloted orbital rocketplane). BOR-1, -2, and -3 were increasingly sophisticated models of the configuration, flown on suborbital trajectories. After the cancellation of Spiral in favor of the Buran, BOR-4 subscale spaceplanes were used to test heat shield materials developed for Buran. Certain essential tests of these heat shield materials could not be done in the lab. These included interaction with the plasma sheath during re-entry, chemical disassociation effects, etc. The BOR-4 was clad in 118 tiles of the type developed for Buran as well as carbon-carbon nose cap and leading edge. These BOR-4 unmanned orbiters were equipped with braking engines. After a circuit of the earth, the spacecraft would deorbit, perform a gliding re-entry, followed by parachute deployment, splashdown in the ocean, and recovery by Soviet naval forces. BOR-4 flew four successful test flights at speeds of from Mach 3 to 25 and altitudes of 30 to 100 km. These test flights confirmed the physical, chemical, and catalytic processes that operated on the selected heat shield materials in the re-entry plasma. BOR-4 also provided important data on the acoustic environment during launch and re-entry. Compared to the Spiral MiG 105-11 EPOS configuration, the BOR-4 had a flattened, wider body with a much smaller vertical stabilizer. The cruise-back turbojet of the 105-11 seems to have been eliminated, and the canted stabilizer tips were cut off at the Mach angle, a MiG trademark.
BOR-4 at Berlin BOR-4 as exhibited at Berlin side view Credit: Oliver Haßa |
BOR-4 Credit: Manufacturer Image |
BOR-4 at Berlin BOR-4 as exhibited at Berlin side view Credit: Oliver Haßa |
Uragan / BOR-4 Credit: © Mark Wade |
BOR-4 Recovery BOR-4 - Photo by Australian P-3 Naval Reconnaissance Aircraft Credit: NASA |
BOR-4 Recovery BOR-4 - Photo by Australian P-3 Naval Reconnaissance Aircraft Credit: NASA |
BOR-4 Model BOR-4 wind tunnel model used by NASA to study configuration and refine it for use in HL-20/HL-42 vehicles. Credit: NASA |
Subscale Spiral spaceplane. After 1.25 revolutions of the earth, deorbited and recovered by Soviet naval forces in the Indian Ocean at 17 degrees South, 98 degrees East, 560 km south of Cocos Islands. Made a 600 km cross-range maneuver during reentry. The recovery was filmed by an Australian Orion reconnaissance aircraft, revealing the configuration to the West for the first time.
The Vehicle Analysis Branch began investigation of the Soviet BOR-4. Small models were tested in NASA wind tunnels and demonstrated that the vehicle had good aerodynamic characteristics throughout the speed range from orbital entry interface to low supersonic speeds. The Soviet design had a 2,040 km cross-range capability and an outstandingly benign thermal profile at peak heating conditions. Therefore Langley adopted it as a baseline for a Crew Emergency Rescue Vehicle to back-up or replace the shuttle after the 1986 Challenger accident.