Intelligent programming aid:
If you wish to set up multiple tasks in order to move the wheel doors to several positions, it should
be obvious that the new task’s initial positional value and start time are determined by the previous
position and time for the servo concerned. This is carried out automatically, helping to speed up the
programming procedure, and eliminates the need for you to note down the servo’s previous position
and stop time.
A similar situation applies when you set the retract process DOWN » UP. When you set up the extend
process UP » DOWN, the positional values for Start and Stop for that servo are already entered as
Stop and Start.
The following example demonstrates how one wheel door opens half-way when the transmitter
switch is operated, pauses for a while, then runs to its end-point. When the switch is reversed, the
door returns to its original position in a single movement lasting three seconds.
UP » DOWN means undercarriage extension. Out-
put 3 of the door sequencer has been selected.
The servo runs from its initial value of 1100
µs (right
servo end-point) to the stop value of 1500
µs (servo
centre).
The servo only starts moving 1.0 seconds after the
switch is operated, and the period is 3.0 seconds
(4.0 s – 1.0 s).
Task 1 has now completed its course.
After a pause lasting 2.0 seconds at servo centre,
the servo starts moving in the direction of 1800
µs
(left servo end-point). The movement period is 2.0
seconds (8.0 s – 6.0 s).
Task 2 has completed its course.
DOWN » UP means undercarriage retraction. In this
example, when the switch is operated, the servo im-
mediately starts running slowly from the left to the
right servo end-point (Start time 0.0 s).
The positional values vary according to your linkages, and must be adjusted to suit your indivi-
dual model. Clearly it is important to avoid your wheel doors jamming (striking their mechanical
end-stops). The timing values shown here should also be set to suit your requirements. The task
numbering does not need to coincide with the timed sequence; for example, Task 5 could be set to
run before Task 2.
Our example clearly shows how the function is built up. Additional movements or intermediate stops
when the doors open or close can be added at any time; all you need is to set up a new free task.
Viewed overall, there is now no reason at all why the retraction and extension of the undercarriage
in the model should not exactly emulate that of the full-size aircraft. In other words: you can give
free rein to your imagination.
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