A survey of impulsive trajectories Final report

Literature survey of astrodynamics problems on intercept, transfer, and rendezvous trajectorie

Study of future world markets for agricultural aircraft

The future world market for US-manufactured agricultural aircraft was studied and the technology needs for foreign markets were identified. Special emphasis was placed on the developing country market, but the developed countries and the communist group were also included in the forecasts. Aircraft needs were projected to the year 2000 by a method which accounted for field size, crop production, treated area, productivity, and attrition of the fleet. A special scenario involving a significant shift toward aerial fertilization was also considered. An operations analysis was conducted to compare the relative application costs of various existing and hypothetical future aircraft. A case study was made of Colombia as an example of a developing country in which aviation is emerging as an important industry

Cost/benefit trade-offs for reducing the energy consumption of commercial air transportation (RECAT)

A study has been performed to evaluate the opportunities for reducing the energy requirements of the U.S. domestic air passenger transport system through improved operational techniques, modified in-service aircraft, derivatives of current production models, or new aircraft using either current or advanced technology. Each of the fuel-conserving alternatives has been investigated individually to test its potential for fuel conservation relative to a hypothetical baseline case in which current, in-production aircraft types are assumed to operate, without modification and with current operational techniques, into the future out to the year 2000

Father role identity : An exploration of the construct and its measurement

There is relatively little research in respect of father’s and their post-divorce contact with their children. Preliminary research suggests father’s identification with the parent role may play an influential role in this contact. Though the Self Perceptions of the Parental Role Questionnaire (SPPE) has been utilised to measure father’s identification with the parent role, the psychometric properties of this instrument have yet to be systemically investigated. The lack of psychometric information about the SPPR seriously limits this instruments utility. The aim of the current study was twofold. Firstly, to determine the psychometric properties of a formal measure of parent role identity, the Self-perceptions of the Parental Role questionnaire (SPPR). Secondly, to explore the constructs father role and father role identity. Seventy four fathers completed the SPPR. From a sub sample of twenty five fathers the reliability of the SPR satisfaction scale was found to be acceptable for research and clinical application (Cronbach’s alpha .73, r=.82). The reliability of the Integration scale was low and could not be recommended for either research or clinical use (Cronbach’s alpha .68, r=.65). Reliability of the SPPR’s other two scales, competence and investment, was not clearly established because their Cronbach’s alphas and test-retest reliabilities did not produce commensurate results. An exploratory principle components factor analysis did not support the factorial structure of the SPPR. Feedback suggested participants found the instructions and some items of the SPPR difficult to understand. The outcome of a qualitative analysis of interviews of a sub group of fathers (n = 27) was consistent with previous research and identity theory that fathers identified sub roles which make up the father role. These sub roles were the traditional, teacher, and shared experience and participation. Item analysis revealed the SPPR does not inquire about these sub roles. The qualitative data also revealed the importance of father’s perceptions of the parent role, rewards of parenting, sacrifices, confidence/competence, and sources of help and advice in the father role. Item analysis revealed the SPPR inquires only about rewards and costs and sources of advice. The qualitative data suggests the SPPR could be improved by adding items which inquire about perceptions of father sub roles, confidence/competency in these roles and sacrifices made to complete these roles

Mission Capabilities of Ion Engines. Phase II

Payloads and mission times were calculated for space vehicles propelled by ion rockets using nuclear power supplies having specific weights from 10 t o 50 lb/kw. Included in the study were five missions: low-altitude lunar satellite, low-altitude Venus satellite, solar probe, Saturn probe, and a Jupiter satellite with a circular orbit at the altitude of Jupiter's fourth moon. The variation of payload with the ration of power supply weight to gross weight was studied and the optimum power levels thereby determined. The ion rocket payload capabilities were compared with those of high-thrust vehicles using hydrogen-oxygen rockets and tungsten-core nuclear rockets; in addition the performance of high- and low-thrust systems staged in combination has been investigated. Launch vehicles considered in this study were the Atlas-Centaur, the Saturn C-1, and the Saturn C-5

Applications of advanced transport aircraft in developing countries

Four representative market scenarios were studied to evaluate the relative performance of air-and surface-based transportation systems in meeting the needs of two developing contries, Brazil and Indonesia, which were selected for detailed case studies. The market scenarios were: remote mining, low-density transport, tropical forestry, and large cargo aircraft serving processing centers in resource-rich, remote areas. The long-term potential of various aircraft types, together with fleet requirements and necessary technology advances, is determined for each application

Mission Capabilities of Ion Engines Using SNAP-8 Power Supplies

Mission performance capabilities of ion engines powered by the 30 kw and 60 kw SNAP-8 power supplies are compared for the following missions: a 24-hr equatorial satellite, a 100 n mi lunar satellite, a 500 n mi Mars satellite, a Mercury probe, and an out-of-the-ecliptic probe. The capabilities of arc- jet engines and chemical engines for the same missions are compared with those of the ion engines. The majority of the comparisons are for 8500-lb spacecraft which are boosted into a 300 n mi orbit by the Atlas-Centaur. Variations in initial orbit altitude, the use of actual launch dates rather than dates based on simplifying assumptions, and the combined use of chemical and electrical propulsion systems were also evaluated in terms of their effect on mission performance