Development 



I 

 The detailed design considerations involved in attain- 

 ment of the objectives stated above are given in Appendix I 

 of (2) . On the basis of the work reported therein, a proto- 

 type design was executed and a full-scale depressor fabri- 

 cated and tested (Figure 3) . 



■The depressor was test- towed from the No. 2 carriage at 

 the David Taylor Model Basin. Towline tension and the cable 

 angle at the depressor, relative to the horizontal , were 

 measured and recorded as a function of tow speed. The first 

 test demonstrated the depressor to be hydrodynamically un- 

 stable in pitch, thus making it impossible to control the 

 dynamic downforce. For the second test, the effectiveness 

 of the horizontal stabilizers was increased by adding stabi- 

 lizer area and tip plates. In this condition, the depressor 

 was towed at speeds to seven knots and found to be stable 

 and responsive to trim adjustments. The results (6) were 

 corrected to standard sea conditions for design trim and are 

 given in Figures I-l, 1-2, and 1-3 vniiich show, respectively, 

 cable tension at the depressor as a function of tow speed, 

 towstaff angle as a function of tow speed, and cable ten- 

 sion at 7% knots as a function of horizontal trim tab setting. 



1.3 



