The drag of Zeppelin airships

This report is a discussion of the results of tests with Zeppelin airships, in which the propellers were stopped as quickly as possible while the airship was in full flight. In this paper the author refers to the theory involved in these tests and calls attention to one scientifically interesting fact which can be derived from the tests and which has not yet been noted. The most important question concerning the tests is, of course: does the negative acceleration of an airship with stopped propellers supply proper data for determining the drag of the airship when in uniform flight? This can not be absolutely answered, however, except that in this particular case the agreement is sufficient and that the data obtained from the test are the true quantities, or, at least, the approximate quantities wanted.