The Aerodynamics of Sails 



h-^,-^- ,. (B8) 



With these two requirements, the solution of Eq. (B6) is 





* * * 



DISCUSSION 



; Hans Thieme '■• 



Institut fiir Schiffbau der Universitdt Hamburg 

 -; Hamburg, Germany 



I think Professor Milgram's lecture here is a long step forward in theoreti- 

 cal calculation of sail forces. Hoping he will proceed in his work, I may only add 

 some additional information on experimental work. 



At the Shipbuilding Institute of the University of Hamburg a lot of wind- 

 tunnel tests are performed. Most of the results are not published yet, but it is 

 possible to have the reports open for your future use. A list of the reports is 

 given below. They comprise our investigations on single sails of different pro- 

 file and shape, fundamental sail combinations, and complete rigs for three types 

 of vessels. The best results for the cruiser yacht, 7KR- YACHT, the oldtime 

 four-masted barque, PAMIR, and the six-masted square-rigger, 6M-DYNA, de- 

 veloped by Mr. PrQlss of Hamburg, are compared in the figure here (Fig. Dl). 

 I think the figure also shows quite clearly the possibility of increasing the ef- 

 ficiency of sail propulsion. The last report in the list comprises some informa- 

 tion on the blockage effect of large sail areas and other superstructure lateral 

 areas on the forces measured in the wind tunnel by means of so-called "silhou- 

 ette tests." 



REPORTS OF THE INSTITUT FUR SCHIFFBAU 

 DER UNIVERSITAT HAMBURG 



No. 107 (1962). Wagner, B.: Preliminary wind-tunnel tests with full-rigged 

 masts. 



No. 122 (1964). Wagner, B.: Wind-tvinnel tests with cambered plate section 

 sails on a square-rigger mast of elliptic cross section and new cantilever 

 design. 



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