The pilot commands longitudinal vehicle response mainly through control column inputs. Hence it is found that the characteristics of the control system

Fig. 12.15 Effect of stick force and stick movement per g on pilot opinion (from ref. 12.15).

influence the handling qualities of the vehicle. An otherwise satisfactory – vehicle can he rated as poor due to a control system that does not “feel” right to the pilot. Figure 12.15 shows the manner in which pilot rating varied with stick movement per g and stick force per g in an aircraft with an irre­versible control system. It is seen that there is only a relatively small region where a satisfactory rating is achieved, indicating the importance of the proper selection of control system characteristics. The studies which produced these results also determined that pilots do not object to break-out or frictional forces if they are not large when compared to the stick force per g.