VI-B-4 TWO STAGE BALLISTIC LAUNCH VEHICLE G. Launey and W. Richards Engineering Analysis Division The Launch Analysis Section of the Engineering Analysis Division has initiated a study to determine the requirements for a two stage reusable ballistic entry launch vehicle to deliver the SPS into a 50 x 270 nautical mile (92.6 x 500 KM) insertion orbit. The vehicles were sized to deliver one and two million pound payloads into the insertion orbit when launched due east from ETR (Eastern Test Range). The performance capability of these vehicles was then determined when launched due east from a launch site latitude of 7 degrees. All trajectories for this analysis were computed using a 3 degree-of- freedom trajectory program integrating the equations of motion of a particle moving over a rotating oblate spheroid planet under the influence of gravity, thrust, and aerodynamic forces. During first stage flight, the vehicle flew a vertical rise for 16 seconds and then pitched over a constant inertial pitch rate for 10 seconds. The vehicle then flew a gravity turn trajectory to staging. A 4 second coast period was allowed for stage separation. During second stage flight the vehicle was flown using a near optimum linear-tangent steering law to injection. The second stage flight used an exoatmospheric simulation. All vehicle stages were sized using a set of weight scaling equations. The coefficients for these weight scaling equations were derived from Saturn V weight and geometry data obtained from Mr. W. Heineman of the Spacecraft Design Division. The S-IC stage weight and geometry data was used to generate weight scaling coefficients for body structure and miscellaneous item weights for the booster stages. The S-II stage data was used for the second stage body structure and miscellaneous item weights. The entry thermal protection and recovery system weight coefficients for both stages were obtained from Sigma Corporation. The rocket engine propulsion system weight scaling and performance data was obtained from Mr. M. F. Lausten of the Propulsion and Power Division. Saturn V aerodynamic data was used for all configurations. The reference areas used in conjunction with the aerodynamic data were calculated based on the cross sectional area of the base diameter of the vehicles investigated in this analysis. The stage propellant tanks and skirts are constructed of the same aluminum alloy used on the Saturn V S-IC and S-II stages. The exposed surfaces of these tanks and skirts are coated with a super Koropon primer film to protect the aluminum material from salt water as recommended by Mr. Don Medlock of Structures and Mechanics Division. The recovery system includes a parachute/retrorocket combination used to decelerate the stages to a terminal velocity of 150 fps (45.7 MPS)
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