Encyclopedia Astronautica
Castor 4A


Thiokol solid rocket engine. 478.3 kN. Out of production. Isp=266s. Castor 4A improved Delta performance by 11% by replacing the old fuel with HTPB propellant. Used in Delta 6900; Atlas IIAS; Castor 4A. First flight 1982.

Used in Delta 6900; Atlas IIAS; Castor 4A. Castor 4A began the development of a program to improve Delta performance by 11%. This was done by replacing the old fuel with HTPB propellant. The TX780-0, with an 11 degree canted nozzle is used in the ground ignited booster. The TX780-1, with a 7 degree cant, and the TX780-2, (11degree cant) are ignited at altitude. The TX780-3 & 4 were developed as the ground and altitude ignited boosters, respectively. The TX780-5, a straight nozzle, powers OSC's Prospector suborbital vehicle.. First Flown: February 14, 1989, Delta 184. Flown: 163 to end of 1993 (100% success). Propellant Type: TP-H8299 HTPB Polymer (20% aluminium). Shape: cylindrical, with 76% web fraction. transitions to four longitudinal slots. Tailored for ignition and burn-out thrust to be similar to Castor 4. Mass Fraction: 0.874 for standard loading. Burn Time: 53.1 sec web. Thrust (kN, sea level, 21Celsius): 476.661 maximum with a n average of 436.736. Isp: 237.6 sec sea level at 21 Celsius. Itotal: 23,846 kNs sea level at 21 Celsius. Pressure: 46.60 atm average with a maximum of 49.86 atm at sea level. at 21 Celsius. Nozzle Throat Diameter: 278.6 mm. Nozzle Materials: carbon-phenolic. Casing Line: standard HT polymer. Igniter Type: pyrogen, head-end.

Thrust (sl): 426.200 kN (95,814 lbf). Thrust (sl): 43,457 kgf. Chamber Pressure: 47.20 bar. Area Ratio: 9.29. Propellant Formulation: HTPB.

AKA: Castor 4A; TX-780.
Status: Out of production.
Gross mass: 11,578 kg (25,525 lb).
Unfuelled mass: 1,457 kg (3,212 lb).
Height: 9.20 m (30.10 ft).
Diameter: 1.02 m (3.34 ft).
Thrust: 478.30 kN (107,526 lbf).
Specific impulse: 266 s.
Specific impulse sea level: 237 s.
Burn time: 56 s.
Number: 304 .

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Associated Countries
See also
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
  • Castor 4A Solid propellant rocket stage. Loaded/empty mass 11,743/1,529 kg. Thrust 478.31 kN. Vacuum specific impulse 266 seconds. More...

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