GPHS motion studies for heat pulse intervals of reentries from gravity-assist trajectories. Aerospace Nuclear Safety Program

Technical Report · Thu Mar 01 04:00:00 EST 1990

DOI:https://doi.org/10.2172/10149710· OSTI ID:10149710

Lucero, E F; Sharbaugh, R C

Motion studies of the General Purpose Heat Source Module, GPHS, were conducted in the heat pulse interval associated with entries from earth gravity assist trajectories. The APL six-degree-of-freedom reentry program designated TMAGRA6C was used. The objectives of the studies were to (1) determine the effect of ablation on GPHS motion, and (2) determine whether the GPHS module entering the earth`s atmosphere from an earth-gravity-assist trajectory has a preferred orientation during the heat pulse phase of reentry. The results are given in summary form for easy visualization of the initial conditions investigated and to provide a quick-look of the resulting motion. Detail of the motion is also given for the parameters of interest for each case studied. Selected values of initial pitch rate, roll rate, and combinations of these within the range 0{degree} to 1000{degrees}/sec were investigated for initial reentry angles of -7{degrees} (shallow) and -90{degrees} (steep) and initial angles of attack of 0{degree} (broadface to the wind) and 90{degrees}. Although the studies are not exhaustive, a sufficient number of reentry conditions (initial altitude, reentry angle, angle of attack, rotational motion) have been investigated to deduce certain trends. The results also provide information on additional reentry conditions that need to be investigated. The present results show four GPHS orientations that predominate - all with some pitch oscillations and rolling motion. These are: angles of attack, {alpha}{sub R} of 0{degree}, 30{degrees}, 90{degrees} and tumbling. It should be assumed that all these orientations are equally probable because only combinations of two initial reentry angles, {gamma}{sub 0}, and two values of {alpha}{sub R}. have been investigated. Further the probability for any given initial rate on orientation is not known.

• Research Organization: Johns Hopkins Univ., Laurel, MD (United States). Applied Physics Lab.
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AI01-88NE32140
• OSTI ID: 10149710
• Report Number(s): DOE/NE/32140--21; JHU/APL-ANSP-M--21; ON: DE93013817
• Country of Publication: United States
• Language: English

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