Tail Booms

All the flight control surfaces are on the tail booms, which are mounted to the wingtips and pivot with the aft wing sections when the feather is deployed. Each tail boom has a vertical stabilizer and horizontal stabilizer.

Upper and lower rudders are mounted at the back of each vertical stabilizer for yaw control. Pitch and roll is controlled by elevons that are attached to the trailing edges of the outward extending horizontal stabilizers. The fiberglass construction of the elevon skin gives radio transparency for antennas. For control during supersonic flight, the entire horizontal stabilizer on each tail boom pivots.

Minor modifications were made to the tail booms during flight testing. To resolve an aerodynamic problem, the distance from tip to root of the horizontal stabilizers was increased by 16 inches (41 centimeters). Also, a triangular strake was added in front of each horizontal stabilizer, and a flow fence was added midspan on each horizontal stabilizer.

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Fig. 4.15. Critical to the safe return from space, the feather had only two positions, all up or all down. Redundant pneumatic actuators raised and lowered the feather. While retracted, the feather was held in place by a redundant locking system. However, only the force from the pressurized

actuators was needed to keep the feather fully extended. Mojave Aerospace Ventures LLC, photograph by David M. Moore

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Fig. 4.16. During reentry and with the feather extended at an angle of about 65 degrees, SpaceShipOne descended nearly level on its belly. It did not drop straight down, though, but instead moved forward as it fell. The diagram shows the angle of attack at 60 degrees, which is a measure of the direction of motion with reference to the position of the wing.

James Linehan

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