THE EVOLUTION OF A 



FULLY CAVITATING PROPELLER FOR A 



HIGH-SPEED HYDROFOIL SHIP 



B.V. Davis 



The De Havilland Aircraft of Canada Limited 



Ontario, Canada 



and V- 



J.W. English 

 Ship Division, National Physical Laboratory 

 Feltham, England ■■■-■ 



SUMMARY 



A description is given of the work that has been conducted in producing the 

 main, foilborne, fully cavitating propellers for the 200-ton Canadian Armed 

 Forces hydrofoil ship HMCS Bras d'Or. 



Designed for an all-weather antisubmarine role in the Atlantic, severe 

 thrust loadings are experienced by the screws in both the takeoff and flying con- 

 ditions, and model testing was essential to aid in design and confirm the pre- 

 dicted performance. The high thrust loadings produce difficult structural prob- 

 lems, and some testing was conducted to clarify this aspect of design. 



The joint programme of work was sponsored by the De Havilland Aircraft 

 of Canada, the prime contractors in designing and building the vessel. Broadly, 

 the hydrodynamic design and water-tunnel testing were conducted at Ship Divi- 

 sion NPL, while the structural analysis and testing were conducted at De Havil- 

 land, Canada. The programme has evolved a fully-cavitating propeller design 

 with good hydrodynamic and structural characteristics over a wide range of 

 speeds and thrusts. Water -tunnel testing is continuing for the purpose of fur- 

 ther developing the design. 



A brief review of some future alternative methods of propulsion is included 

 in the paper, together with a resume of future development prospects for fully 

 cavitating and ventilated propellers. 



INTRODUCTION 



The HMCS Bras d'Or hydrofoil ship, designated FHE 400 by the Canadian 

 Armed Forces, represents the fruition of a long Canadian Navy interest in such 

 craft, an interest dating back as far as 1911. It was in 1960, however, following 

 a review of the Naval Research Establishment's (now DREA) proposals, that the 



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