1167. Cone Angle and Diameter Optimization for Outer Planet Probes
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Paper
Abstract
Outer planet atmospheric entry probes are science instrument delivery and data return vehicles that must provide protection against the entry heating and erosive effects of uncertainly defined atmospheres. Entry probe design requires careful attention and early emphasis by weight engineers because weight is a major determination of the launch propulsion , in transit maneuvering and planetary encounter control system requirements. If follows that mass properties engineering can be the keystone to select the combination of design which maximize the scientific return, maximize mission confidence, and minimize overall costs. For example, elimination of active stabilization and control systems by
Achieving inherent (passive) stability throughout all flight phases will significantly improve mission confidence and science value at lower program costs. To realize the probe system benefits of this example, the weight engineer must define solutions that consider all the weight affecting design parameters and satisfy the following requirements: (1) the maximum principal axis must be coincident with the spin axis, and (2) the center of gravity (c.g.) must be far enough forward to provide adequate stability during entry and descent into the atmosphere.
The analytical mass properties technique described in this paper was developed to guide the probe baseline configuration toward the most efficient design. This technique was automated to permit accurate evaluation of the interaction among the following parameters affecting weight:
A. fore body cone angle
B. probe diameter
C. equipment density
D. total equipment weight
E. heat shield requirements
F. stability requirements
G. ballistic parameter
H. mission constraints which relate communication time available, maximum probe mass and depth of atmospheric penetration
I. science payload
A detail mass properties analysis of the reference probe for Jupiter (150kg, 330lb) was used to validate the mass properties generated by the program. While the specific software developed for the outer planets probe is limited to sphere/cone and conic entry probes, the general approach is adaptable to many preliminary design activities.
