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Maximum Attainable Drag Limits for Atmospheric Entry via Supersonic Retropropulsion

Summary: Maximum Attainable Drag Limits for
Atmospheric Entry via Supersonic Retropropulsion
Nošel M. Bakhtian
Stanford University, Stanford, CA, 94305
Michael J. Aftosmis
NASA Ames Research Center, Moffett Field, CA, 94035
This study explores augmentation of the decelerative forces experienced during Mars
entry through a flow control approach which increases aerodynamic drag, based on SRP
jet manipulation of the bow shock. We develop analytic drag models based upon attainable
shock physics seen in high-fidelity simulations of SRP jets. These flow models use SRP jets
to recover shock losses normally associated with the strong high-Mach number bow shock
on the entry vehicle. Partial recovery of stagnation pressure allows for significant decelera-
tion at comparatively high altitudes without the burden of increased fuel mass, increasing
both the mass of deliverable payloads and the payload mass fraction. To quantify achiev-
able benefits, an analytical study determines the maximum possible drag coefficients for
cascading shock structures (oblique shocks followed by a normal shock) at values ranging
from 1.2 to 1.4. A trajectory study then quantifies the potential gains in drag during entry,
along with estimates of total vehicle mass and payload mass fraction, revealing a tremen-
dous potential for aerodynamic drag which is substantial even if only a modicum of the
stagnation pressure losses can be recovered through SRP flow control. Finally, a strategy


Source: Alonso, Juan J. - Department of Aeronautics and Astronautics, Stanford University


Collections: Engineering