A logistics and potential hazard study of propellant systems for a Saturn 5 derived heavy lift (three-stage core) launch vehicle

The Bush Administration has directed NASA to prepare for a return to the Moon and on to Mars - the Space Exploration Initiative. To meet this directive, powerful rocket boosters will be required in order to lift payloads that may reach the half-million pound range into low earth orbit. In this report an analysis is presented on logistics and potential hazards of the propellant systems envisioned for future Saturn 5 derived heavy lift launch vehicles. In discussing propellant logistics, particular attention has been given to possible problems associated with procurement, transportation, and storage of RP-1, HL2, and LOX, the heavy lift launch vehicle propellants. Current LOX producing facilities will need to be expanded and propellant storage and some support facilities will require relocation if current Launch Pads 39A and/or 39B are to be used for future heavy noise-abatement measures. Included in the report is a discussion of suggested additional studies, primarily economic and environmental, which should be undertaken in support of the goals of the Space Exploration Initiative

Design and control of remote manipulators

Results of investigations on vibrational modes of manipulators revealed: (1) any arbitrary manipulator may be analyzed for its small motion compliances; (2) a simulation of the Martin-Marietta shuttle boom with a 65,000 lb. payload attached, indicated three natural frequencies; and (3) simulations can be made of rigid limbs and flexible joints as well as for flexible limbs and locked joints and combinations thereof. Trajectories for arms were determined so that some integral criterion such as integral of kinetic energy or control torque magnitude is minimized over a motion of the arm. Experiments performed to evaluate various TV displays in conjunction with manipulator control modes showed that when mounted directly to the manipulator control arm and arranged to look approximately along the arm to the hand the operator could perform the task almost as quickly as when viewing the task directly

Improving outcomes in outsourced product development: a joint consultant-client perspective

Although firms increasingly outsource front end product development activities to production suppliers or design consultants, this practice has received little scholarly attention. The few existing academic studies report high failure rates but generally present only the client firms’ view of the causes. Our first results from in-depth interviews of both clients and consultants give a richer picture of enablers of success and causes of failure. We confirm some previous findings(internal divisions within the client, “poor communication” between parties),identify new ones (inadequate client capabilities, failure to transfer design intent), and combine them into a comprehensive model of outsourced product development that includes negotiating project scope, continuously managing expectations, and carefully re-integrating the design output into the client’s operations. Finally, we classify several types of client dependency (need for new ideas, extra capacity, or specific technical expertise) and highlight the particular hazards associated with each

Environmental effects on polymeric matrix composites

Current epoxy resins utilized in high performance structural composites absorb moisture from high humidity environments. Such moisture absorption causes plasticization of the resin to occur with concurrent swelling and lowering of the glass transition temperature. Similar effects are observed in composites. Data are presented showing the effects of absorbed moisture on Hercules AS/3501-5 graphite/epoxy composites. Prediction of moisture content and distribution in composites, along with reduction in mechanical properties, are discussed

The effectiveness of a double-stem injection valve in controlling combustion in a compression-ignition engine

An investigation was made to determine to what extent the rates of combustion in a compression-ignition engine can be controlled by varying the rates of fuel injection. The tests showed that the double-stem valve operated satisfactorily under all normal injection conditions; the rate of injection has a definite effect on the rate of combustion; the engine performance with the double-stem valve was inferior to that obtained with a single-stem valve; and the control of injection rates permitted by an injection valve of two stages of discharge is not sufficient to effect the desired rates of combustion

Degree Correlations and Motifs in Technological Networks

Recent network research has sought to characterize complex systems with a number of statistical metrics, such as power law exponent (if any), clustering coefficient, community behavior, and degree correlation. A larger goal of such research is to obtain insight into the systems’ functions by means of these and similar analyses. In this paper we examine network models of mechanical assemblies. Such systems are well understood functionally. We show that they have both rich and varied community structure as well as negative degree correlations (disassortative mixing), and show that this can be explained by additional powerful constraints that arise from identifiable first principles. In addition, we note that their main “motif” is closed loops (as it is for electric and electronic circuits), a pattern that conventional network analysis does not detect but which is used by software designed to aid in the design of such systems. The implication is that functional understanding of complex systems requires considerable domain knowledge beyond what typical network analysis tools employ