Application of Spring Tabs to Elevator Controls

William H. Phillips

1944 оны 1-р сар · NACA

Энэ электрон номын тухай

Summary: Equations are presented for calculating the stick-force characteristics obtained with a spring-tab type of elevator control. The main problems encountered in the design of a satisfactory elevator spring tab are to provide stick forces in the desired range, to maintain the force per g sufficiently constant throughout the speed range, to avoid undesirable "feel" of the control in ground handling, and to prevent flutter. Examples are presented to show the design features of spring tabs required to solve these problems for airplanes of various sizes. It appears possible to provide satisfactory elevator control-force characteristics over a large center-of-gravity range on airplanes weighing from about 16,000 to 300,000 pounds. On airplanes weighing less than 16,000 pounds, some difficulty may be encountered in obtaining sufficiently heavy stick forces for rapid movements of the control stick. Some special tab designs, including geared and preloaded spring tabs, are discussed. The geared spring tab is shown to offer a means of obtaining satisfactory ground control without introducing excessive variation of force per g with speed. By the use of spring tabs on elevators, the control forces may be made more closely predictable and the variation of stick-force characteristics among different airplanes of the same type may be greatly reduced. One of the principal objections to the use of spring tabs is the amount of weight required for mass balance to prevent flutter.