is symmetrical about the x-z plane while [8] is satisfied by 

 positioning the center of weight-in-water below the towpoint. 



With respect to yaw, the principal destablizing elements 

 of the configuration are the vertical struts connecting the 

 main wing panels and, since both the wing struts and vertical 

 stabilizers are symmetrically disposed, we may write for 

 Equation [9]: 



d? ^2 ^z) - ^s ^s ^s ^ - ^v % ^v ^t 



where subscript s denotes the forward struts and v the verti- 

 cal stabilizers. The tail efficiency factor, <5^/q* must be 

 considered since the span of the vertical stabilizer passes 

 through the wake of the lower wing„ Since the gap-to-chord 

 ratios of both wing and vertical stabilizer struts are large, 

 and since each is effectively end-plated by the wing and hori- 

 zontal stabilizer, we may assume, ^■s ~ ^^ ~ ^o* ^®^ assuming 

 q./q = 0.8, we need only require 0.8 S x > S x . From 

 Table 1, S = 4.5 sq ft; s =3.77 ft; S^ = 1.37 sq ft; 

 and X = 0.51 ft, A more refined estimate of stability in 

 yaw would include the contributions of the horizontal lifting 

 surfaces, the bulbous housings, and the remaining parts of 

 the structure. But this appears to be unnecessary. 



74 



