Accession Number : AD0267471

Title :   ATMOSPHERE ENTRIES WITH VEHICLE LIFT-DRAG RATIO MODULATED TO LIMIT DECELERATION AND RATE OF DECELERATION-VEHICLES WITH MAXIMUM LIFT-DRAG RATIO OF 0.5

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON D C

Personal Author(s) : KATZEN,ELLIOTT D. ; LEVY,LIONEL L. JR.

Report Date : DEC 1961

Pagination or Media Count : 1

Abstract : An analysis has been made of atmosphere entries for which the vehicle lift-drag ratio was modulated to maintain specified maximum decelerations and/or maximum deceleration rates. The part of the vehicle drag polar used during modulation was from maximum lift coefficient to minimum drag coefficient. The entries were at parabolic velocity and the vehicle maximum lift-drag ratio was 0.5. Two-dimensional trajectory calculations were made for a nonrotating, spherical earth with an exponential atmosphere. The results of the analysis indicate that for a given initial flight-path angle, modulation generally resulted in a reduction of the maximum deceleration to 60% of the unmodulated value or a reduction of maximum deceleration rate to less than 50% of the unmodulated rate. These results were equivalent, for a maximum deceleration of 10g, to lowering the undershoot boundary 24 miles with a resulting decrease in total convective heating to the stagnation point of 22%. The maximum convective heating rate was increased 18%. (Author)

Descriptors :   AERODYNAMIC HEATING, ATMOSPHERE ENTRY, DECELERATION, DRAG, FLIGHT PATHS, HEAT TRANSFER, HYPERSONIC VEHICLES, LIFT, MANNED, MATHEMATICAL ANALYSIS, MODULATION, REENTRY VEHICLES, SPACECRAFT

Distribution Statement : APPROVED FOR PUBLIC RELEASE