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Rocket Motor, Solid Fuel, Vanguard Third Stage, also Designated X248-A2 or Altai


Display Status:

This object is on display in the Rockets and Missiles exhibition at the Steven F. Udvar-Hazy Center in Chantilly, VA.

Collection Item Summary:

This is the X248-A2 solid fuel rocket motor, also called Altair, that powered the third stage of the Vanguard III launch vehicle, launched in 1959. Altair was also used as the third stage of the Thor-Able-4 vehicle that launched the Pioneer V space probe and Tiros 1, the first weather satellite, and third stage for the Pioneer I, Explorer VI, and other launch vehicles.

The motor, built by the Allegheny Ballistic Laboratory of Hercules Inc., produced 3,070 pounds of thrust and was made with a filament-wound fiber-reinforced epoxy resin. This very strong construction, plus the motor's high performance for its small weight, made it a pioneering development in solid fuel rocket technology. This object was donated to the Smithsonian in 1968 by the Alleghany Ballistics Lab.

Collection Item Long Description:

Data Source

National Air and Space Museum


Do not reproduce without permission from the Smithsonian Institution, National Air and Space Museum

Credit Line

Gift of Alleghany Ballistics Laboratory, Hercules Incorporated


Casing, Spiralloy filament-wound fiberglass reinforced epoxy resin


Overall: 5 ft. long x 1 ft. 5 in. diameter, 203 lb. (152.4 x 43.18cm, 92.1kg)

Country of Origin

United States of America


ca. 1956-1960 [for actual motor]; ca. mid-1960's


PROPULSION-Rocket Engines

Inventory Number


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