| Abstract | It la felt that for the 400 m.p.h. 5000 lb. load bush aircraft, propellers are the optimum means of propulsion. Further, although it is realized that the turboprop has a better specific consumption than the tip Jet propeller, the latter may well lead to a more economic aircraft design, owing to the mechanical simplicity of tilting a Jet-driven propeller rather than a complete turboprop engine, or even a complete wing. This note examines current propeller practice, and concludes that it would be possible to duct sufficient compressor delivery air through a normal propeller blade to feed a small combustion chamber on the tip, or to fill an unreheated tip nozzle. Further, it seems that an 8-bladed (4 plus 4) contraprop is a reasonable proposition as a wing-tip unit, and that one such unit on each wing tip should be reasonable for an aircraft of the size specified, with tip combustion for take-off and without for cruising. This is of course subject to fuller calculation of cycle performance. |
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