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Engine Model: Castor 4. Manufacturer Name: TX-526. Other Designations: Castor 4. Designer: Thiokol. Gross Mass: 10,534 kg (23,223 lb). Empty Mass: 1,269 kg (2,797 lb). Propellants: Solid. Thrust(vac): 407.200 kN (91,542 lbf). Thrust(sl): 355.700 kN (79,965 lbf). Isp: 261 sec. Isp (sea level): 228 sec. Burn time: 54 sec. Diameter: 1.02 m (3.34 ft). Length: 9.07 m (29.75 ft). Chambers: 1. Country: USA. First Flight: 1975. Last Flight: 1989. Flown: 342.

Series of motors used as Delta strap-on boosters and as first and upper stages for low-cost all-solid-propellant designs.

Engine Model: Castor 4A. Manufacturer Name: TX-780. Other Designations: Castor 4A. Designer: Thiokol. Gross Mass: 11,578 kg (25,525 lb). Empty Mass: 1,457 kg (3,212 lb). Propellants: Solid. Thrust(vac): 478.300 kN (107,526 lbf). Thrust(sl): 426.200 kN (95,814 lbf). Isp: 266 sec. Isp (sea level): 237 sec. Burn time: 56 sec. Diameter: 1.02 m (3.34 ft). Length: 9.20 m (30.10 ft). Chambers: 1. Chamber Pressure: 47.20 bar. Area Ratio: 9.29. Country: USA. Status: Out of production. First Flight: 1982. Last Flight: 2004. Flown: 304.

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.

Engine Model: Castor 4AXL. Manufacturer Name: TX-780XL. Other Designations: Castor 4AXL. Designer: Thiokol. Gross Mass: 14,851 kg (32,740 lb). Empty Mass: 1,723 kg (3,798 lb). Propellants: Solid. Thrust(vac): 599.800 kN (134,840 lbf). Isp: 269 sec. Burn time: 60 sec. Diameter: 1.02 m (3.34 ft). Length: 12.28 m (40.29 ft). Chambers: 1. Chamber Pressure: 42.30 bar. Area Ratio: 8.64. Country: USA. Status: In production. First Flight: 2001. Last Flight: 2006. Flown: 40.

The 4AXL version, extended by 2.44 mm, was first tested May 1992. Its 30% performance increase would improve performance of vehicles, such as Atlas and Conestoga. 4AXL was combined with 4B's TVC system to create the stage 1 motor for CTA's ORBEX small launcher.. Length: 12.279 m with nose-cone adapter, 13.711 m with nose-cone. Diameter: 1.0185 m. Propellant Type: TP-H8299 HTPB Polymer, 20% Al, and 68% AP. Propellant Shape: forward cylindrical perforate with seven aft longitudinal slots. Propellant Mass Fraction: 0.884 ground ignited strap-on. Burn Time: 60.1 sec. Thrust (kN, vac): 599.81 average with 700.5 maximum. Isp: 269.2 sec vacuum. Itotal: 34.679 Mns vacuum. Pressure: 41.70 atm average with a maximum of 54.42 atm MEOP. Nozzle Throat Diameter: 318.8 mm. Nozzle Length: 1216.8 mm. Nozzle Exit Diameter: 937.3 mm. Nozzle Materials: 4130 steel with graphite phenolic throat insert, and a carbon phenolic exit cone. Casing Material: AISI 4130 steel 0.28 mm thick. Igniter Type: TX544 (>500 units flown successfully) forward internal pyrogen, with 2.45 kg TP-H8027 propellant that is cartridge loaded. Specific impulse with 15:1 nozzle 382.4 seconds.

Engine Model: Castor 4B. Manufacturer Name: TX-780B. Other Designations: Castor 4B. Designer: Thiokol. Gross Mass: 11,400 kg (25,100 lb). Empty Mass: 1,400 kg (3,000 lb). Propellants: Solid. Thrust(vac): 430.600 kN (96,803 lbf). Thrust(sl): 337.100 kN (75,783 lbf). Isp: 281 sec. Isp (sea level): 220 sec. Burn time: 64 sec. Diameter: 1.02 m (3.34 ft). Length: 9.20 m (30.10 ft). Chambers: 1. Chamber Pressure: 32.50 bar. Area Ratio: 12.10. Country: USA. Status: Out of production. First Flight: 1982. Last Flight: 1982. Flown: 3.00.

The Castor 4B, which incorporated thrust vector control in the series for the first time, was developed for ESA's Maxus (first flown in 1991).

Engine Model: Castor 4BXL. Manufacturer Name: TX-859. Other Designations: Castor 4B. Designer: Thiokol. Gross Mass: 11,482 kg (25,313 lb). Empty Mass: 1,513 kg (3,335 lb). Propellants: Solid. Thrust(vac): 429.000 kN (96,443 lbf). Isp: 267 sec. Burn time: 61 sec. Diameter: 1.02 m (3.34 ft). Length: 8.98 m (29.48 ft). Chambers: 1. Chamber Pressure: 31.10 bar. Area Ratio: 8.55. Country: USA. Status: In Production.

CTA's ORBEX used the Castor 4BXL version, which combined the 4XL motor with 4B's TVC system (6 degree).. First Flown: May 8, 1991. Flown: 2 to end of 1993 (100% success). Propellant Type: Tp-H8229 HTPB Polymer, with 20% Al. Propellant Shape: radially slotted center perforate. Propellant Mass Fraction: 0.868 (9969 kg). Itotal: 26,141 kNs vacuum at 25 Celsius. Pressure: 50.6 atm maximum and an average of 30.7 atm. Nozzle Throat Diameter: 30.84 cm. Nozzle Length: varies - SL, with altitude and canted available. Nozzle Exit Diameter: 90.2 cm. Nozzle Materials: 4130 steel. Casing Materials: 4130 steel.

Castor 4 used on Rocket Stages
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