Low Cost Autonomous Attack
System (LOCAAS)
Investigators
R. Tramel and N. Suhs, Micro Craft, Inc.
Application Overview
Define the unsteady aerodynamics that characterize the deployment flight profile of the Low Cost Autonomous Attack System ( LOCAAS). The LOCAAS deployment sequence includes ejection from a dispenser, inflation of a ballute for speed reduction and flight stabilization, and deployment of wings and fins for autonomous controlled glide to intended targets. Computational analysis is being employed to reduce costs and risks associated with anticipated flight test requirements.
Methodology
Overset structured grids are used to discretize the LOCAAS geometry. The approach is ideally suited to the LOCAAS flight profile. Grid components conform to the shape of the LOCAAS, facilitating resolution of the viscous boundary layer and important off body aerodynamics. Grid components are allowed to move with six-degrees-of-freedom in response to applied and aerodynamic loads without the need for re-gridding. A scalable version of the OVERFLOW-D1 code has been developed under the CHSSI CFD CTA and is being used to accomplish project objectives.
Results (8/31/97)
An initial simulation result has been completed for a solitary LOCAAS (stowed configuration) in stable level flight. The computation was run using 48 nodes of an IBM SP. The grid system is composed of 15 grid components and 4.76 million grid points.
Significance
This effort has dual
objectives that involve evaluation of scalable CHSSI software and the aerodynamic
performance of the Low Cost Autonomous Attack System. The LOCAAS is in the advanced
development phase at Wright Laboratory Armament Directorate. It is designed to provide the
technology base for future low-cost laser radar sensor submunitions. This sensor
technology provides increased cost per kill efficiencies through the ability of the sensor
to detect, extract, and classify a
variety of ground mobile and fixed targets.
References
1. Wissink, A. and Meakin, R., "On
Parallel Implementations of Dynamic Overset Grid Methods,"
SC97: High Performance Networking and Computing, San Jose, CA, November 1997.
2. Meakin, R., "Composite Overset Structured Grids," in Handbook of Grid
Generation, ed.
J. Thompson, N. Weatherill, and B. Soni, CRC Press, Inc., Boca Raton, FL, 1997.
Oblique View
Front View
Top
Side
Top View
Figure 1. LOCAAS
surface geometry definition.
Figure 2. Selected surfaces from near-body volume grids.
Mach Field
Surface Pressure Coefficient
Figure 3. Computed Mach and surface pressure fields.
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