34 research outputs found

    Optimal reusable-tug and expendable-kickstage trajectories for high-energy planetary missions including correction for nodal precession

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    Equations are derived by using branched trajectory optimization techniques and the maximum principle to maximize the payload capability of a reusable tug/expendable kickstage vehicle configuration for planetary missions. The two stages and the payload are launched into a low earth orbit by a single space shuttle. The analysis includes correction for precession of the orbit. This correction is done by the tug. The tug propels the payload and the kickstage to an energy beyond earth escape and returns within a specified time to the precessed orbit. After separating from the tug, the kickstage accelerates the payload to the required injection conditions. Planetary injection conditions are specified by the mission energy and a fixed declination and right ascension of the outgoing asymptote. The multipoint boundary value problem resulting from the analysis is solved by a Newton-Raphson iteration technique. Partial derivatives of the boundary conditions are obtained by perturbing the initial conditions one at a time, integrating the trajectory and adjoint equations, and observing the changes in boundary conditions. Maximum payload capability is derived for two typical mission energies. In addition, the variations of several mission and stage parameters are also examined

    Thrust vector control requirements for launch vehicles using a 260-inch solid rocket first stage

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    Gimbaled nozzle and liquid injection thrust vector control requirements for solid rocket two stage launch vehicle

    Comparative evaluation of existing expendable upper stages for space shuttle

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    The use of existing expendable upper stages in the space shuttle during its early years of operation is evaluated. The Burner 2, Scout, Delta, Agena, Transtage, and Centaur were each studied under contract by their respective manufacturers to determine the extent and cost of the minimum modifications necessary to integrate the stage with the shuttle orbiter. A comparative economic analysis of thirty-five different families of these stages is discussed. Results show that the overall transportation system cost differences between many of the families are quite small. However, by considering several factors in addition to cost, it is possible to select one family as being representative of the capability of the minimum modification existing stage approach. The selected family meets all of the specified mission requirements during the early years of shuttle operation

    The critical care management of poor-grade subarachnoid haemorrhage

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    Additional Data for "Haptoglobin genotype and aneurysmal subarachnoid haemorrhage: individual patient data analysis"

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    This is the additional data for article &#39;Haptoglobin genotype and aneurysmal subarachnoid haemorrhage: individual patient data analysis&#39;.This supplemental data as original submitted is also available on request. Minor changes to the accompanying text were made between the two versions.</span
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