Encyclopedia Astronautica
Alcor


Aerojet solid rocket engine. Originally developed for the Air Force as a third Stage for the Athena sounding rocket; in some applications known as Zebra. One of its main attractions was a very high mass fraction First flight 1960.

The Alcor was originally developed for the Air Force as a third Stage for their Athena sounding rocket, and in some applications was known as the Zebra. One of its main attractions was a very high mass fraction as a result of using the Aerowrap process of chamber fabrication. This process was used in early Minuteman developmental chambers, but never went into production because of problems with the joints between the cylindrical section and the ends. Only a few Alcor 1 units were produced when Aerojet shifted from polyurethane to polybutadiene propellant in the Minuteman, and a similar change was made in this motor family, which was designated the Alcor 1A. Other changes were made in the nozzle, chamber insulation, and expansion ratio. This resulted in a change from 30KS-8000 to 23KS-11,000 and a gain in mass fraction from 0.886 to 0.906. Both of these motors were used on stages of Astrobee vehicles (Astrobee 500 and 1500).

The Alcor 1A was qualified by a six motor demonstration test program, and six more were subjected to static test firings. A total of 57 units was delivered, with 24 having been flight tested and demonstrating 100% reliability. A second major product improvement (the Alcor 1B) occurred late in 1965 with the introduction of an all welded titanium chamber. All other features and performance were the same, but the mass fraction improved from 0.906 to 0.916, with a spin capability of 300 RPM, which is one of the highest performance levels in the industry. The nozzle used a graphite throat insert and silica phenolic tape entrance and exit sections with a glass roving structure.

Propellant Formulation: Polybutadiene.

AKA: Zebra; 30-KS-8000.
Number: 31 .

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Associated Countries
See also
Associated Launch Vehicles
  • Blue Scout Junior American suborbital launch vehicle. Smaller Air Force version of Scout used for suborbital military tests. More...

Associated Manufacturers and Agencies
  • Aerojet American manufacturer of rockets, spacecraft, and rocket engines. Aerojet, Sacramento, CA, 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...

Bibliography
  • Gatland, Kenneth, Spacecraft and Boosters, Iliffe Books. London, 1964.
  • Dorman, Bernie, et. al., Aerojet: The Creative Company, Stuart F Cooper Company, Los Angeles, 1995..

Associated Stages
  • Alcor Solid propellant rocket stage. Loaded/empty mass 520/50 kg. Thrust 35.59 kN. Vacuum specific impulse 230 seconds. Masses, specific impulse estimated. More...

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