In applications where the required downforce is small 

 -(less than 1000 pounds) and the speed low, it is generally- 

 conceded that downforce can best be produced by the use of 

 weight alone. There are exceptiors to this: in a helicopter- 

 towed system, weight becomes a critical factor. The con- 

 figuration considered herein requires a downforce of 4450 

 pounds at a design speed of 7,2 knots, users of oceano- 

 graphic equipment were asked for comment on the shipboard- 

 handling problem of such a heavy body and were unanimously 

 of the opinion that the maximum practicable weight, for ease 

 of handling aboard most oceanographic vessels, should not 

 exceed 1000 pounds. They also concurred in citing a maximum 

 acceptable linear dimension of seven feet. 



In view of this unanimity of opinion, our configuration 

 was designed to achieve the required downforce by a combina- 

 tion of weight and dynamic depression. An arbitrary weight 

 of 1000 pounds in water was assumed, and calculations were 

 made (see Appendix I) to determine the wing and tail cpnfigur- 

 ations needed to produce the additional 3450 pounds of down 

 force at a towing speed of 7.2 knots. A biplane configura- 

 tion was selected to keep the span small for easier handling. 

 With the calculated necessary effective hydrodynamic lifting 

 area of 39,75 square feet distributed equally, each wing, 

 and the tail, has an area of about 13 square feet. The re- 

 sulting configuration is shown in Figure 3, 



26 



