0.05 — 



0.04 — 



t 0.03 — 



0.01 — 



-0.2 



Rg = 5 (10)® 



PARENT 



O LARGE BULB 



^ SMALL BULB 



V - 



_ \ 



'^OA O^/^ 



0^2l_q.°'^ 



o^/ 



<^ 



V 



V 



2/ 



/ 

 / 



0.1 0.2 0.3 



LIFT COEFFICIENT C, 



0.6 



Figure 28 - Drag Coefficient as a Function of Lift 

 Coefficient — Bulbous Tip Foils 



the parent. The small bulb is somewhat less effective. The appearance of the bulb 

 TVC was similar to that of the parent; however, the location was different (as dis- 

 cussed above and shown in Figure 17). 



For the parent foil, the cavitation data were limited for the low a values due 

 to tunnel saturation conditions. However, this was not the case for the bulbous 

 tips. Here, the lowest a value for each bulb represented a threshold above which 

 TVC was not observed. Also shown in Figure 29, the bulbs did induce some local sur- 

 face cavitation — back bubble cavitation — which was attributed to the relatively large 

 thiekness/chord ratios of the bulb sections made necessary by the short chord lengths 

 at the foil tip. 



40 



