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Blue Scout Junior




Written and Edited by Cliff Lethbridge

Classification: Research Rocket

Length: 40 feet, 5 inches

Diameter: 2 feet, 7 inches

Finspan: To Be Updated


The Blue Scout Junior, designated XRM-91, represented a major revision of previous Scout rockets. It was introduced to support smaller, more streamlined scientific research activities of the U.S. Air Force.

The Castor second stage and Antares third stage used on Scout, Blue Scout I and Blue Scout II rockets were adapted to become the first and second stages, respectively, of the Blue Scout Junior.

Each of these stages was modified to carry four fixed, triangular fins at their aft ends. These fins provided stabilization during flight.

A new third stage, called Alcor, was introduced. It burned for 30 seconds and could produce 8,000 pounds of thrust. A new fourth stage, called Cetus, could produce a maximum thrust of 900 pounds.

The rocket, which did not carry any guidance equipment, was launched from a beam used previously for U.S. Army Sergeant missiles. The Blue Scout Junior was spin-stabilized from launch.

Spin rockets on the second stage were fired at launch and stabilized the Blue Scout Junior at three revolutions per second. This motion was sufficient to keep the third and fourth stages on course following burnout of the first two stages.

Launches of all classes of Scout rockets from Cape Canaveral ceased in 1966. However, both the U.S. Air Force and NASA continued to refine the vehicle. The U.S. Air Force introduced the XRM-92, called the Air Force Scout, a four-stage rocket similar to the original NASA Scout.

NASA continues to use a modern version of the Scout for launching lightweight scientific payloads, although all of these launches are conducted from Vandenberg Air Force Base, California.

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