Alcor (also known as Zebra or 30-KS-8000) was a solid rocket engine, originally developed by

Aerojet Aerojet was an American rocket and missile propulsion manufacturer based primarily in Rancho Cordova, California, with divisions in Redmond, Washington, Orange and Gainesville in Virginia, and Camden, Arkansas. Aerojet was owned by GenCorp, ...

for the

US Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...

as the third stage of the Athena test vehicle. Its main appeal was a high mass fraction due to the Aerowrap chamber fabrication process. However, production issues with joint sections limited its use. Alcor engines were used from 1960 to 1977. The original version was used on a series of rockets: Blue Scout Jr,

Blue Scout Junior The Scout family of rockets were American launch vehicles designed to place small satellites into orbit around the Earth. The Scout multistage rocket was the first orbital launch vehicle to be entirely composed of solid fuel stages. It was also t ...

, Astrobee 200, Blue Scout Jr SLV-1C, RAM B, Blue Scout Jr SLV-1B(m),

Athena RTV The Athena RTV was a research missile, developed by Atlantic Research Co., designed to simulate the re-entry conditions of intercontinental ballistic missiles. It was primarily launched from Green River, targeting White Sands Missile Range in New ...

, Strypi VI and Strypi VIIAR. Athena-H

Initially produced with

polyurethane Polyurethane (; often abbreviated PUR and PU) is a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term ...

propellant, it transitioned to

polybutadiene Polybutadiene utadiene rubber, BRis a synthetic rubber. It offers high elasticity, high resistance to wear, good strength even without fillers, and excellent abrasion resistance when filled and vulcanized. "Polybutadiene" is a collective name fo ...

, leading to the Alcor 1A (23KS-11000) variant. This variant featured improved nozzle, chamber insulation, and expansion ratio, increasing the mass fraction from 0.886 to 0.906. Both Alcor 1 and 1A were used in Astrobee 500 and 1500 vehicles. Alcor 1A was used on the Athena H. Another improvement occurred late in 1965, with the introduction of an all welded

titanium Titanium is a chemical element; it has symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...

chamber, resulting in the Alcor 1B variant. Alcor 1B was used on the Strypi VIIR.

References

{{Suborbital rocket engines Solid-fuel rockets Rocket stages