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Project 006 – Aileron Servo Fairings for Radian Pro Glider
This project
is to create fairings to protect the aileron and flap servos from damage when
the glider runs along a grassy runway during landing.
When
the Radian Pro glider lands on the grassy runway at my local flying club, the
servo horns controlling the ailerons and flaps run across the top of the
grass. The horns can be grabbed by the grass and cause the horns to be
wrenched with a force that can turn them on the shaft of the servo, jumping
over teeth on the spline! The glider spins around instead of gliding along the
ground in a straight line and when the glider stops, the aileron is not at
the neutral position where it should be. This has happened to my glider and
to radian pros of a few friends as well. The solution is to make fairings to
protect the servos.
Making the Moulds
The first
mould is made from pine wood on a three ply base. Holes are drilled along the
internal corners to ensure the HIPS sheet is drawn right into the corner. The
mould is coated with a thin layer of wood filler and sanded to make a smooth surface.
A cavity is made underneath the mould so the holes drilled through to the
base can connect with the holes in the top of the vacuum forming box.
 
Making the Fairings
The fairing is
made from 0.5mm HIPS. After the first was made, I made three more moulds by
pouring ‘plaster of paris’ into a form.
Each form makes
two fairings by cutting the form in half. With four moulds in total I can
make eight fairings from one HIPS sheet.
Attaching the Fairings
The fairings are
attached with double sided foam tape on the underneath of the fairing flange.
Alternatively, reinforced tape can be used on the top of the flange.
 
In these
photos below, it can be seen that the tip of the servo horn is only about 5mm
above the line from the wing tip to the bottom of the fuselage. This is why
the grass can grab the servo horn. With the fairing installed, it acts like a
skid and lifts the wing above the grass and conceals the servo horn safely
inside.
 
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I put fairings
over the flaps servos as well.
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These
fairings have proven to be useful on other types of gliders which have been
supplied without servo fairings. At the time of publishing this page, I have
made seventy of these fairings for other members of my flying club.
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