Weissinger and Maass 



r - • " ' ' Radial coordinate 



r„(x) Mean camber line 



T Thrust 



Tp .V- Propeller thrust v- , .. :. . 



Tg, T^, . . . , T^, ... Basic integral operators of ring-airfoil theory 



t (^) Nondimensional thickness distribution 



[thickness = c • t ( ,f )] • . .. 



u, V, w Axial, radial, and azimuthal induced velocity 



V .'/j.i><^- }-', Free -stream velocity -:^r ;. 



v^ Normal component of free-stream velocity at profile 



X Axial coordinate 



Xp Axial propeller location 



a Angle of attack 



a (^) Local angle of attack 



r,r(r) Circulation of propeller blades 



7 Ring vortex distribution 



7^, 7^ Axial and azimuthal components of helical vortices 



Ap Pressure jump at propeller disk and slipstream sur- 



face 



v - ^(^- ^') = (x- x')/R Argument of kernels in ring-airfoil theory (also 



T] = x/R, see Fig. 5) 



B "Glauert variable," ^ = -cos 



\ = c/(2R) Chord-diameter ratio of duct 



ij. - R /R^ Propeller tip clearance with respect to reference 



cylinder 



^- 2x/c Nondimensional axial coordinate; ^= -l( + l): lead- 



ing (trailing) edge 



p Mass density 



pj^^) - 2r_^(x)/c Nondimensional mean camber line 



1248 



