AmSHIP AERODYNAMICS  TM 1-320  48  the amount of load at that frame.  The shear in figure 27 was com› puted in this manner.  (1) For instance, the load at station 0 is -1,000 pounds.  Then  the shear between stations 0 and 10 equals -1,000 pounds.  At station  10 the load is  +  2,000 pounds.  Hence the shear between stations 10  and 20 is -1,000 pounds  +  2,000 pounds, or  +  1,000 pounds.  (2) For an airship in static equilibrium, when centers of buoyancy  and gravity are vertically disposed, areas under the shear curve must  add algebraically to zero.  This should be checked before proceeding  to computation of bending moments.  f.  For calculation of bending moments, all loads between ends of  the airship and any frame are considered as supported by cantilever  action from that frame.  In the case illustrated by figure 27 starting  at station 0, the bending moment for- (1) Station 0= 0.  (2) Station 10= - 1,000 X 10= -10,000 meter-pounds.  (3) Station 20= ( -l,OOOX20)  +  (2,000X 10) =0.  g.  An easier method of computing bE ding moments is to sum up  the areas under the shear curve.  Thus in figure 27, for station 20,  the bending moment= 10,000- 10,000= 0.  For an airship  in  static  equilibrium, when the center of gravity is vertically below the center  of  buoyancy, the bend-ing moment c_urve returns to zero at both ends  of the airship, since the summations of positive and negative areas  under the shear curve are numerically equal.  h.  Table IV, extracted from "Airship Design," by C. P. Burgess,  of the Bureau of Aeronautics, United States Navy, shows loads, shear,  and bending moments on the  ZR- 1,  computed in accordance with  the method described therein.  i. In computing aerodynamic loads, shear, and bending moments, a  method. somewhat similar to that described above is employed.  (1) Upturning dynamic forces on the hull are computed, using the  Munk formula.  This formula is omitted here as it involves mathe› matical computation beyond the scope of this manual.  The forces  so determined are distributed to the frames as concentrated loads.  (2) Excess static weight or buoyancy is then distributed to the  frames in proportion to the cross-sectional area at the frames, unless  known eccentric loading shows this distribution to be greatly in error.  (3) Dynamic force on surfaces is then distributed to proper frames.  This force, as shown in paragraph 39c, is given by the relation- F=  (Vol)  v 2 [a(kz - k$_{1}$ )  sin  28  63 