Rockoon

A rockoon (from rocket and balloon) is a solid fuel sounding rocket that, rather than being immediately lit while on the ground, is first carried into the upper atmosphere by a gas-filled balloon, then separated from the balloon and ignited. This allows the rocket to achieve a higher altitude, as the rocket does not have to move under power through the lower and thicker layers of the atmosphere.

The original concept was developed by Cmdr. Lee Lewis, Cmdr. G. Halvorson, S. F. Singer, and James A. Van Allen during the Aerobee rocket firing cruise of the U.S.S. Norton Sound on March 1, 1949.

A serious disadvantage is that balloons cannot be steered and consequently neither the direction the launched rocket moves in nor the region where it will fall is easily adjustable. Therefore, a large area for the fall of the rocket is required for safety reasons.

TIME magazine reported in 1959: "Van Allen's 'Rockoons' could not be fired in Iowa for fear that the spent rockets would strike an Iowan or his house." So Van Allen convinced the U.S. Coast Guard to let him fire his rockoons from the icebreaker Eastwind that was bound for Greenland. "The first balloon rose properly to 70,000 ft., but the rocket hanging under it did not fire. The second Rockoon behaved in the same maddening way. On the theory that extreme cold at high altitude might have stopped the clockwork supposed to ignite the rockets, Van Allen heated cans of orange juice, snuggled them into the third Rockoon's gondola, and wrapped the whole business in insulation. The rocket fired."

The Office of Naval Research (USA ONR) used the Loki in some of its Rockoon launches, lofting the Loki to high altitudes on a helium balloon before firing, for upper atmosphere research. The first Rockoon launch of the Loki I occurred on Jul 1 1955 from shipboard off the coast of Greenland.

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Wikipedia