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Michael A. Brown
Advances in Space Research,Volume 48, Issue 11,December 2011
Abstract
The purpose of this paper is to introduce a new deployable mast design that may provide a means to scale up solar sails to very large dimensions. The paper describes the basic analytical approach for truss beams, compares this new design with the state-of-art truss used in NASA’s solar sail development work, and provides analyses of novel applications enabled by the mast design.
Additional information:
The truss described here was developed at the US Naval Research Laboratory (NRL) to address the requirements of masts of extreme L/D ratios used in column and/or cantilever loading. The structure has several novelties:
- External “roll-up” stowage. This provides large bend radius for longerons, allowing use of highest elastic modulus graphite available and also unrestrained mast diameter, the two combining for high bend stiffness.
- Mechanical deployment. This means constant deployment force, independent of mast length, as well as the ability to stow and deploy the mast integral with power cables, sensor and control devices, etc., all along its length.
- Reformable lonngerons. Solid rod graphite longerons can be replaced by thin graphite ribbons of the same mass that upon deployment curl up to to a U-shape to increate moment of inertia of the longerons, and thus the bending strength of the mast, by an order of magnitude. At deployment the longeron nodes are locked to the battens and diagonals, to resist increases in waviness when the longerons are compressed. These innovations address the problem of waviness in high L/D masts that can result in local buckling of longerons.
- Advanced design. If the ribbon longerons increase in thickness and width from a cantilever’s mast tip to its root, both local and global moment of inertia increase, making the equivalent of a tapered beam for combined column and cantilever loading. The deployment mechanisms are linear actuators that grasp the mast’s nodes and pull them from stowage. After deployment these mechanisms can be separated and, equipped with solar panels, controls, etc., walk along the deployed mast to perform repairs or to integrate it into a larger system.
I am looking for opportunities for space applications of this design.
Mike Brown
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