Improved optimum design of DEWAR supports

Abstract

A number of struts or straps support a rigid, delicate mass (dewar) which must be successfully launched and maintained in orbit for a long time at a very low temperature. The support system must be designed so that the heat flow into the mass is minimized subject to constraints on minimum allowable natural frequency of the mass during launch, minimum natural frequency of the mass in orbit, maximum allowable stress in any support member during launch, and no buckling or slackening of any support member during launch. A user-friendly system of computer programs called DEWAR is described by means of which optimum designs can be obtained for a support system consisting of simple tension straps or simple tubes, or support systems with a passive thermal disconnect feature through which the thermal conductance is greatly reduced during the transition from the launch condition to the orbital condition. Most of the present paper consists of a sample case in which DEWAR is used in the tutorial mode.