High-torque apparatus and method using composite materials for

Abstract

An apparatus for deploying an umbrella-type structure such as an antenna reflector is provided. The umbrella-type structure includes a plurality of rib members movable from a stowed configuration to a deployed configuration. The deployment apparatus comprises a movable deployment tube and a hub pivotally attached to the plurality of rib members and slidably attached to the deployment tube. The hub is adapted to move along the deployment tube. The deployment apparatus further includes a plurality of rib deployment straps connecting the deployment tube to the rib members and a mechanism for moving the deployment tube in order to tension the rib deployment straps which in turn pull the rib members into the deployed configuration. The apparatus includes structural members made of composite materials, having a low (near zero) coefficient of thermal expansion, low density, and high strength. A method of deployment in accordance with the invention transitions through three distinct phases of deployment, continually providing high deployment torque consistent with the requirements for moving the inner rib members through nearly 90 degrees of travel, thereby permitting unassisted deployment of a large structure in a 1-G environment.