Encyclopedia Astronautica
Castor 120


Thiokol solid rocket engine. 1650 kN. Isp=280s. Motor similar in size to the Peacekeeper missile stage 1 motor; filled the gap between Castor 4A and the large segmented motors. First flight 1989.

A motor similar in size to the Peacekeeper missile stage 1 motor. It fills the gap between Castor 4A and the large segmented motors. Unit cost would be about $3.5 million for volume production, rising to $7.5 million for one annually. Further applications include using it as a strap-on for launchers, such as Delta. It can be used in a stage 1 or 2 strap-on since the forward and aft ends can take tension and compression forces. A (5.5 degree thrust vector control is provided by a movable nozzle. The grain can be changed (tailored) by adding aft slots to reduce thrust during maximum-q, and by adding forward slots for high initial thrust.. First Flight. November 1994. Propellant Type: TP-H1246 HTPB, 19% Al, and 69% AP. Propellant Shape: three machined aft conical slots with formed forward slot. Propellant Mass Fraction: 0.923 (49,032 kg). Burn Time: 81 sec.. Thrust: 1650 kN vacuum average. Isp: 280.1 sec vacuum. Itotal: 133,440 kNs vacuum. Pressure: 101 atm maximum and 78 atm average. Nozzle Throat Diameter: 368 mm. Nozzle Length: 1448 mm. Nozzle Exit Diameter: 1600 mm. Nozzle Materials: glass epoxy and polyisoprene flex bearing. 3D carbon-carbon throat. carbon phenolic exit cone. aluminum stationary shell. steel throat support. Casing Materials: carbon epoxy, lined with silica-filled EPDM rubber EPM.

Thrust (sl): 1,313.900 kN (295,376 lbf). Thrust (sl): 133,987 kgf. Chamber Pressure: 79.00 bar. Area Ratio: 24. Propellant Formulation: HTPB.

Gross mass: 53,118 kg (117,105 lb).
Unfuelled mass: 4,086 kg (9,008 lb).
Height: 9.02 m (29.59 ft).
Diameter: 2.36 m (7.74 ft).
Thrust: 1,650.00 kN (370,930 lbf).
Specific impulse: 280 s.
Specific impulse sea level: 229 s.
Burn time: 81 s.
Number: 18 .

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Associated Countries
See also
Associated Launch Vehicles
  • Taurus American all-solid orbital launch vehicle. Pad-launched launch vehicle using Pegasus upper stages and Castor-120 first stage. First launch used slightly larger Peacekeeper ICBM first stage instead of Castor-120. Under a 2002 contract from Boeing, Orbital developed a three-stage version of Taurus to serve as the interceptor boost vehicles for the US government's missile intercept system. The firm portion of the company's contract, awarded in early 2002, was valued at $450 million and extended through 2007. More...
  • Athena-3 American all-solid orbital launch vehicle. Planned but never flown heavier-lift version of Athena. More...
  • Athena-1 American all-solid orbital launch vehicle. Basic version of the Athena with a Castor 120 first stage, Orbus second stage, and OAM Orbital Adjustment Module. More...
  • Athena-2 American all-solid orbital launch vehicle. The Athena-2 version featured a Castor 120 first stage, Castor 120 second stage, Orbus third stage, and OAM Orbital Adjustment Module. More...

Associated Manufacturers and Agencies
  • Thiokol American manufacturer of rocket engines and rockets. Thiokol Corporation, Ogden, UT, USA. More...

Associated Propellants
  • Solid Solid propellants have the fuel and oxidiser embedded in a rubbery matrix. They were developed to a high degree of perfection in the United States in the 1950's and 1960's. In Russia, development was slower, due to a lack of technical leadership in the area and rail handling problems. Solid propellants have the fuel and oxidiser embedded in a rubbery matrix. They were developed to a high degree of perfection in the United States in the 1950's and 1960's. In Russia, development was slower, due to a lack of technical leadership in the area and rail handling problems. More...

Associated Stages
  • SR118 Solid propellant rocket stage. Loaded/empty mass 53,020/4,211 kg. Thrust 1,606.59 kN. Vacuum specific impulse 286 seconds. Modification of Peackeeper ICBM first stage. More...

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