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The Ground Effect on Lifting Propellers

Albert Betz

出版	National Advisory Commitee for Aeronautics, 1937
URL	http://books.google.com.hk/books?id=4NRCAQAAIAAJ&hl=&source=gbs_api

註釋

In what follows an estimate will be made of the magnitude of the ground effect. For the two cases where the distance a of the propeller from the ground is very small, and very large, respectively, in comparison with the propeller radius r(sub o) the relations may be simply expressed. We consider first the effect of the ground, assuming that the thrust is held constant, as may be done by a suitable change in the propeller speed.