Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/327

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THE SCREW PROPELLER.
§ 210

regarded to a certain extent as an open question. The same query has arisen in the case of the aerofoil, but the objections in that case are partly concerned with aerodromic and other considerations.
Fig. 130.
Should future experience show that flattening of the section (compare § 191) and diminution of pressure towards the extremities is advantageous from the aerodynamic point of view, the whole matter will require to be thoroughly reinvestigated before we can regard the theory of peripteral motion as complete.

§ 210. The Peripteral Zone.—Before we are in a position to discuss the conditions that regulate the number of blades

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