Linkage Design Inputs

Linkage Design inputs are numeric values that describe the geometry of the servo and control surface arrangement. There is also an input for airspeed so that servo torque can be approximately calculated.

The inputs are made using the little up/down arrows. These incrementally adjust the value. A single click makes a small change. If you hold the arrow down, the value changes quickly.

The typical process is to start by making a guess at all the values (a preliminary setup) and then refining the setup using the plots and output blocks. The data entry arrows work especially well in the fine-tuning phase.

The input values are quantified simultaneously in English and metric units - the arrows adjust both at the same time.

Input for Long Pushrod

Input for Long Pushrod is easy. Just define the servo and control horn setup so that the program can figure out the control surface motion. Also define the control surface dimensions and airspeed so that the program can estimate servo torque.

It is a convention of the program that the control surface is faired (zero deflection) when the servo deflection is zero. This way it is easy to set up for equal deflection (elevator) or asymmetric deflection (flaps) or some combination (flaperons).

Input for Short Pushrod

Input for the Short Pushrod setup is nearly the same as for the Long Pushrod setup except that now the program needs to know where the servo is relative to the control surface. These values are reflected immediately in the picture of the arrangement.

The program uses this extra information to make a precise calculation of the control surface location, taking into account the variation in pushrod angle that arises from the proximity of the servo and control surface.

Input to Perpendicular Axis Pushrod

These inputs are again in the same format as Long Pushrod except that inputs are required to define the relative location of servo.

Rotary

The inputs for the Rotary arrangement are different from the others, but the same in concept.

An additional input is the drive wire length and diameter. This is an important consideration for this arrangement in that it strongly influences the rigidity of the system. The program calculates the approximate flexure of the drive wire and the resultant control surface offset as a result of aerodynamic load. This helps the designer determine the wire diameter.