Manufacture Of Propellants Research Articles

The manufacture of bronze propellers from a metallurgical point of view

A brief review is given of the copper-based casting alloys, suitable for the manufacture of ship’s propellers. Some specific properties of these alloys are illustrated. The moulding, melting and casting techniques employed in the production of high-q

Évolution récente de la technique des jaugeages industriels aux moulinets dans les écoulements en charge

Current meters have been in use for flow gauging purposes for a very long time. They are subject of stringent requirements, especially when used as a check on hydraulic machine performance. The very principle of their operation, however, is a source of uncertainty, consisting as it does in the use of a current meter calibrated in calm water in a flume to measure discharge in turbulent flow in an enclosed space. Methods of use based on sound experience have managed to keep this margin of error within reasonab1y close limits. The increasingly wide range of use of these instruments and the wish to achieve greater accuracy have been followed by intensified research, which has centred around the two most important effects discovered in previous research, namely (i) an 'interference' effect between the current meters and their supports and (ii) the effect of flow turbulence. This research has now progressed so far that it should soon be possible to reduce these effects, for example by a careful reappraisal and choice among existing equipment. On the current meter data output side, improvements have been made to the impulse emission system and to velocity and discharge calculation methods. Technological progress has also been made with ball-bearing and propeller manufacture, with the result that it should now be possible to cut down considerably on calibration operations, which would be replaced by simple propeller geometry and bearing opposing torque checks. Finally, two gauging methods for convergent streamline flow are mentioned, which tend to improve measurement accuracy in this field and which have recently been compared.

Economic implications of extracting propellants from the moon.

Lunar propellant extraction is analyzed to obtain a preliminary evaluation of its potential for reducing operational costs of space activities. Expressions are derived for the cost of propellant manufacture and deployment throughout earth-moon space using both expendable and reusable tankers for propellants manufactured both on the earth and on the moon, where the lunar extraction cost per pound of propellant is a parameter. Comparisons show that expendable tankers always are preferable for earth propellants and that reusable tankers are essentially always preferable for lunar propellants. The economic advantages of lunar propellants increase with increasing distance from earth and are evident particularly for deployment and refueling in lunar orbit. The results show that, for some values of extraction costs, significant operational cost savings are possible through use of lunar propellants. Speculative estimates indicate these values may be achievable, but that considerable ranges can be estimated within the present uncertainty about technical feasibility of extraction methods. The results are essentially independent of earth launch costs, foreseeable advances in propulsion technology, and other lunar activity. Further study of this concept and its mission applications clearly seems justified, especially to determine more precisely the characteristics of the required lunar equipment and operations.

MARE ISLAND'S ACCURATE METHOD OF PROPELLER MANUFACTURE.

MARE ISLAND'S ACCURATE METHOD OF PROPELLER MANUFACTURE.

SCREW PROPELLER MANUFACTURE

SCREW PROPELLER MANUFACTURE