Since the trim angle is measured at full inflation  and at equilibrium a change in the lift coefficient must be  accompanied by a corresponding change in the car load to  maintain equilibrium.  Therefoxe, when the lift is greater,  the load will also be greater, and the ship will trim at a  greater nose dovm angle.  A difference between the  su~ner  and winter trim angles may be observed because of this factor.  At less than full inflation the trim of the ship is  affected by the above factors, and also by the relative  inflation of the ballonets.  The dynamic lift of an airship is the lift which de› pends upon the forward motion and the angle of attack of the  ship with respect to the air.  See Fig. III for dynamic lift  at various forward speeds.  The curves plotted in Fig.  IV  show the variation of the  minimum length of the take-off run of model K-airships with  heaviness and head wind.  The assumptions on which the curves are based are  n~ither  exact nor invariable, but they are on the safe side,  giving an over estimate rather than an under estimate of  the required length of the take-off run.  The suspension system and the car structure of the K- airship are designed for a total car load of 16,000 lbs.  The  minimum factors of safety at this load are 3.00 for the car  structure and 4.00 for the car suspension.  (4)  Factors of Safety  -12- (3) Dynamic Lift 