Transtage

Transtage, given the United States Air Force designation SSB-10A, was an American upper stage used on Titan III rockets, developed by Martin Marietta and Aerojet.

Transtage

A Transtage
Manufacturer	Martin Marietta
Country of origin	United States
Used on	Titan III
General characteristics
Height	4.57 meters (15.0 ft)
Diameter	3.05 meters (10.0 ft)
Gross mass	12,247 kilograms (27,000 lb)
Engine details
Powered by	2 AJ10-138
Maximum thrust	8,000 lbf (36 kN) each[1]
Specific impulse	311 seconds (3.05 km/s)
Burn time	440 seconds
Propellant	Aerozine 50 / N2O4

History

Artist's conception of a Titan III Transtage burn

Transtage was developed in anticipation of a requirement to launch military payloads to geostationary orbit; a contract for development of the stage was issued on 20 August 1962.^[2] Transtage used a pressure-fed two-chamber configuration, using Aerozine 50 fuel and nitrogen tetroxide as oxidizer; the thrust chambers were gimbaled for steering and each produced 8,000 lbf (36 kN) of thrust.^[3] The design specification required up to three restarts during the first six hours of a mission.^[4]

Forty-seven Titan III launches are known to have used Transtage upper stages;^[5] of those, three are known to have suffered launch failures.^[6] The first launch, boosted by a Titan IIIA, occurred on 1 September 1964;^[7] the Transtage failed to pressurize, resulting in premature engine cutoff, and a failure to reach orbit.^[6] The second launch, on 10 December, was successful, and all ensuing launches used the Titan IIIC launch vehicle. The last launch of a Transtage was on 4 September 1989, boosted by a Titan 34D rocket.^[6]

See also

• Centaur (rocket stage)
• Inertial Upper Stage
• RM-81 Agena