Improved Empirical Model For Base Drag Prediction On Missile Configurations Based On New Wind Tunnel Data
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Improved Empirical Model for Base Drag Prediction on Missile Configurations Based on New Wind Tunnel Data
"New wind tunnel data have been taken, and a new empirical model has beed developed for predicting base drag on missile configurations. The new wind tunnel data were taken at NASA/LaRC in the Unitary Plan Wind Tunnel at Mach numbers from 2.0 to 4.5, angles of attack to 16 degree, fin control deflections up to 20 degrees, fin thickness-to-chord (t/c) ration of 0.05 to 0.15, and fin locations flush with the base to two chord lengths upstream of the base. The newly developed empirical model uses these data along with previous wind tunnel data. It estimates base drag as a function of all the above variables along with boattail and power-on or power-off effects. In comparing the new empirical model to the used in the former aeroprediction code, the new model gives improved accuracy over wind tunnel data. The new model also is more robust due to inclusion of additional variables. On the other hand, additional wind tunnel data are needed to validate or modify the current empirical model in areas where data are not available."--Report documentation page.
Improved Empirical Model for Base Drag Prediction on Missile Configurations Based on New Wind Tunnel Data
New wind tunnel data have been taken, and a new empirical model has been developed for predicting base drag on missile configurations. The new wind tunnel data were taken at NASA/LaRC in the Unitary Plan Wind Tunnel at Mach numbers from 2.0 to 4.5, angles of attack to 16 deg, fin control deflections up to 20 deg, fin thickness-to-chord (t/c) ratio of 0.05 to 0.15, and fin locations flush with the base to two chord lengths upstream of the base. The newly developed empirical model uses these data along with previous wind tunnel data. It estimates base drag as a function of all the above variables along with boattail and power-on or power-off effects. In comparing the new empirical model to that used in the former aeroprediction code, the new model gives improved accuracy over wind tunnel data. The new model also is more robust due to inclusion of additional variables. On the other hand, additional wind tunnel data are needed to validate or modify the current empirical model in areas where data are not available ... Empirical model, Missile configuration, Wind tunnel, Base drag prediction.
Improved Power-on, Base Drag Methodology for the Aeroprediction Code
Improved methods for base pressure prediction under base bleed and rocket motor-on conditions have been developed. The base bleed method makes several refinements to the method developed by Danberg at the Army Research Laboratory in Aberdeen, Maryland. The improved rocket motor-on, base pressure prediction improves upon the method developed at the Army Missile Command in Huntsville, Alabama by Brazzel and some of his colleagues. The major refinement to the base bleed method of Danberg was to estimate the power-off value of base pressure empirically based on an extensive data base, as opposed to using computational fluid dynamics codes to predict this term. The major modifications to the power-on base pressure prediction method of Brazzel was to extend its range of applicability to high values of thrust coefficient, to Mach numbers less than 1.5, and to different afterbody shapes. In comparing the improved methods for power-on base drag prediction to experiment, it was seen that both methods gave reasonable agreement to most experimental data bases. However, more validation is needed, particularly for the combined effects of angle of attack, fins, and power-on conditions.