Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

Footage shows the night vertical takeoff of the Viking Hollan hot air balloon. The crew is shown participating in survival
technique training, boarding the plane to depart to Canada, and preparing for the vertical takeoff in the hot air balloon across the
Atlantic Ocean. Scenes also include the making of the capsule for the balloon, some flight activities, and the landing of the balloon.
CASI
Vertical Takeoff; Balloon Flight; Vertical Flight; Climbing Flight; Vertical Landing; Crash Landing
20000064110 NASA Glenn Research Center, Cleveland, OH USA
Issues and Effects of Atomic Oxygen Interactions With Silicone Contamination on Spacecraft in Low Earth Orbit
Banks, Bruce, NASA Glenn Research Center, USA; Rutledge, Sharon, NASA Glenn Research Center, USA; Sechkar, Edward,
DYNACS Engineering Co., Inc., USA; Stueber, Thomas, DYNACS Engineering Co., Inc., USA; Snyder, Aaron, NASA Glenn
Research Center, USA; deGroh, Kim, NASA Glenn Research Center, USA; Haytas, Christy, Cleveland State Univ., USA; Brinker,
David, NASA Glenn Research Center, USA; May 2000; 14p; In English; 8th; 5th; Materials in a Space Environment, 4-9 Jun.
2000, Arcachon, Arcachon, France, France; Sponsored by Centre National d’Etudes Spatiales, France
Contract(s)/Grant(s): RTOP 632-6A-1E
Report No.(s): NASA/TM-2000-210056; E-12258; NAS 1.15:210056; No Copyright; Avail: CASI; A03, Hardcopy; A01, Microfiche
The continued presence and use of silicones on spacecraft in low Earth orbit (LEO) has been found to cause the deposition
of contaminant films on surfaces which are also exposed to atomic oxygen. The composition and optical properties of the resulting
SiO(x)- based (where x is near 2) contaminant films may be dependent upon the relative rates of arrival of atomic oxygen, silicone
contaminant and hydrocarbons. This paper presents results of in-space silicone contamination tests, ground laboratory simulation
tests and analytical modeling to identify controlling processes that affect contaminant characteristics.
Author
Oxygen Atoms; Silicones; Contaminants; Mathematical Models
20000064622 Virginia Polytechnic Inst. and State Univ., Multidisciplinary Analysis and Design (MAD) Center for Advanced
Vehicles, Blacksburg, VA USA
Study of a Global Design Space Exploration Method for Aerospace Vehicles
Baker, Chuck A., Virginia Polytechnic Inst. and State Univ., USA; Watson, Layne T., Virginia Polytechnic Inst. and State Univ.,
USA; Grossman, Bernard, Virginia Polytechnic Inst. and State Univ., USA; Mason, William H., Virginia Polytechnic Inst. and
State Univ., USA; Cox, Steven E., Florida Univ., USA; Haftka, Raphael T., Florida Univ., USA; February 2000; In English; See
also 20000064579; No Copyright; Abstract Only; Available from CASI only as part of the entire parent document
In the early stages of the design process of aerospace vehicles, the search for optimal configurations is wide open, and the
use of local optimization tools may risk missing the best designs. Therefore, global optimization methods are attractive for the
early design stage. Unfortunately, global design optimization usually requires the evaluation of a very large number of designs,
a formidable computational challenge. The present work demonstrates the use of massively parallel computers for handling this
computational challenge. A variety of load balancing methods are used to ensure efficient utilization of the computer nodes.
Global optimization was applied to the High Speed Civil Transport (HSCT) aerospace configuration design problem with 28
design variables and 68 nonlinear constraints in a multidisciplinary design optimization (MDO) environment. Even with the use
of simple engineering analyses, a thorough design space search is computationally expensive due to the large number of designs
that need to be evaluated. The more expensive constraints, such as range and takeoff distances, are performance related. Previous
work with this design problem has shown that the design space contains disconnected islands of feasible points, representing different
available design concepts. These complexities make it difficult for an optimizer to successfully find the global optimum.
The global optimization method used is a Lipschitz algorithm that (essentially) uses all possible values of the Lipschitz constant.
By using all possible values of the constant, equal emphasis is placed on local and global search by the optimizer. This causes the
optimizer to continue searching globally for the islands of feasible space, while converging on designs in the promising regions
that have already been discovered. For each optimization cycle in the algorithm, a large set of new designs that need to be evaluated
is generated. Since the objective function and constraint evaluations for each design can be computed independently, parallel computers
can be easily used to concurrently evaluate all of the new designs. When there is enough variance in the evaluation time
of these designs it is beneficial to have some form of dynamic load balancing. The load balancing schemes investigated for this
study are: static load balancing, dynamic load balancing with a master-slave processor organization, fully distributed dynamic
load balancing, and fully distributed dynamic load balancing via threads. The parallel optimization runs were conducted for a fixed
number of iterations of the modified Lipschitzian algorithm on an SGI Origin 2000. Around 10,000 aircraft designs were evaluated
in the design space exploration before finding the global optimum, with the optimizer sampling many of the promising regions
of the design space in the process. The variation in the evaluation times of the designs investigated was small. The parallel efficien-
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