0.8 

 0.7 



n — I — I — r 



Rj = 2.5 (10)^ 



— PARENT 



O O LARGE BULB 

 A A SMALL BULB 



L = 0.0484 » 

 (3.13 + adeg) 



C, = 0.0498 



(3.25 + a deg) 



-2-4 2 4 6 

 ANGLE OF ATTACK a (deg) 



10 



Figure 27 - Lift Coefficient as a Function of Angle 

 of Attack — Bulbous Tip Foils 



predicted comparable lift curve slopes since the only difference was the spanwise 



22 

 thickness distribution. In addition, wingtip bulbs are known to behave similarly 



to endplates which retard the rollup process, resulting in an effective increase in 

 the lift curve slope. The bulb drag data are given in Figure 28 and show a 6.9 and 

 13.2 percent increase in drag at the design C for the small and large bulb respec- 

 tively. The larger drag increases for larger C reflects the change in the lift 

 curve slope. These observed drag increases are significant and are apparently 

 related to both the increased bulb surface area and the profile drag. 



The cavitation characteristics of the bulbous tip foils are shown in Figure 29. 

 As seen. Equation (1) fits the data quite well, e.g., the large bulb data indicate 

 k - 9.9, which corresponds to a 33 percent increase in the TVC speed as compared to 



39 



