REDUCTION OF MOMENTS INDUCED ON THE COILING HUB OF A BOOM DEPLOYMENT MECHANISM

Abstract

Reduction of Moments induced on the Coiling Hub of a Boom Deployment Mechanism Many deployable systems feature booms that are flattened and consequently, collectively coiled onto one hub. These coilable booms are often attached tangentially to their respective coiling hub. This attachment leads to the implication of a moment of torque around the axis of deployment, whenever the booms face axial load (compression), which is one of their principal design tasks. It is desired to reduce this kind of moments, as it does not only work against the deployment motor, but there is also no inherent way to counter them without adding additional friction within the moving system. The theoretical way to reduce moments, tangentially induced on a cylinder, as is the case for a coiling hub, is to reduce its diameter. Storage of the booms requires the coiling hub to have a certain minimum diameter, however. Therefore this paper examines the possibility of integrating the root of the booms closer to the axis of rotation of the coiling hub, while still maintaining a larger diameter for coiling. To achieve this, consideration is given to the option of coiling the boom, tighter than its elastic strain would allow for full storage, but only locally, by creating a cavity within the coiling hub. Additionally this cavity can be used to insert a locking mechanism, holding the coiling hub in place, once deployment is completed. This locking mechanism and its potential to be functionally integrated into a guiding system for the boom tip are also parts of this paper. The effects on the root of booms on long time durability and load carrying capability of this option will need to be examined further.