SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 6 - March 24, 2006

18 SPACECRAFT DESIGN, TESTING AND PERFORMANCE
Includes satellites; space platforms; space stations; spacecraft systems and components such as thermal and environmental controls; and spacecraft control and stability characteristics.

For life support systems see 54 Man/System Technology and Life Support.

For related information see also 05 Aircraft Design, Testing and Performance; 39 Structural Mechanics; and 16 Space Transportation and Safety.

20060008916 NASA Langley Research Center, Hampton, VA, USA

Truss Performance and Packaging Metrics

Mikulas, Martin M.; Collins, Timothy J.; Doggett, William; Dorsey, John; Watson, Judith; [2006]; 10 pp.; In English; Space Technology and Applications International Forum (STAIF-2006), 12-16 Feb. 2006, Albuquerque, NM, USA; Original contains color and black and white illustrations Contract(s)/Grant(s): 612-20-00-11 Report No.(s): Paper-036; Copyright; Avail.: CASI: A02, Hardcopy

In the present paper a set of performance metrics are derived from first principals to assess the efficiency of competing space truss structural concepts in terms of mass, stiffness, and strength, for designs that are constrained by packaging. The use of these performance metrics provides unique insight into the primary drivers for lowering structural mass and packaging volume as well as enabling quantitative concept performance evaluation and comparison. To demonstrate the use of these performance metrics, data for existing structural concepts are plotted and discussed. Structural performance data is presented for various mechanical deployable concepts, for erectable structures, and for rigidizable structures. Author

Structural Design; Trusses; Space Erectable Structures; Mechanical Properties; Fabrication; Packaging

20060008942 NASA Ames Research Center, Moffett Field, CA, USA, Raytheon Information Technology and Scientific Services, Moffett Field, CA, USA

The Apollo Capsule Optimization for Improved Stability and Computational/Experimental Data Comparisons

Cliff, Susan E.; Thomas, Scott D.; May 2005; 68 pp.; In English Contract(s)/Grant(s): WBS 21-982-10-20 Report No.(s): NASA/TM-2005-213457; A-0513777; No Copyright; Avail.: CASI: A04, Hardcopy

Numerical optimization was employed on the Apollo Command Module to modify its external shape. The Apollo Command Module (CM) that was used on all NASA human space flights during the Apollo Space Program is stable and trimmed in an apex forward (alpha of approximately 40 to 80 degrees) position. This poses a safety risk if the CM separates from the launch tower during abort. Optimization was employed on the Apollo CM to remedy the undesirable stability characteristics of the configuration. Geometric shape changes were limited to axisymmetric modifications that altered the radius of the apex (R(sub A)), base radius (R(sub O)), corner radius (R(sub C)), and the cone half angle (theta), while the maximum diameter of the CM was held constant. The results of multipoint optimization on the CM indicated that the cross-range performance can be improved while maintaining robust apex-aft stability with a single trim point. Navier-Stokes computations were performed on the baseline and optimized configurations and confirmed the Euler-based optimization results. Euler Analysis of ten alternative CM vehicles with different values of the above four parameters are compared with the published experimental results of numerous wind tunnel tests during the late 1960's. These comparisons cover a wide Mach number range and a full 180-degree pitch range and show that the Euler methods are capable of fairly accurate force and moment computations and can separate the vehicle characteristics of these ten alternative configurations. Author

Space Capsules; Apollo Spacecraft; Command Modules; Shape Optimization; Navier-Stokes Equation; Euler Equations of Motion

Source: NASA