The rigid airship in its modern form is a German conception, but the nature of the strength calculations employed by the Germans has been a carefully guarded secret. When the U.S. Navy undertook the construction of rigid airships it was arranged to have one ship designed and built in the United States, the ZR. 1, and one ship designed and built in England, R.38 (ZR.2). Lacking practical information and experience, fundamental theory had to be resorted to in undertaking the design of ZR.i, and all available information had to be analysed,, compared and, so far as possible, tested. After the unfortunate loss of R.38 the calculations for ZR. 1 were reviewed and additional calculations and investigations undertaken.

The authors of this paper, under the direction of Rear-Admiral W. A. Moffett, Chief of the Bureau of Aeronautics, U.S. Navy Department, have been charged with the design of ZR.i and have had in the course of duty to make, or cause to be made, such studies and investigations as would assist in analysing and simplifying the problem as much as was possible in advance of full-scale experiments in flight.