We have a lot to do in
this one module, I need to cut out a portion of the plywood to accommodate
the larger instrument panel, while mounting the actuators for both the
gear and gear doors in the remaining space. I started by
building the retract mechanism:
I want this to be strong, so I backed
up the servo with a 3.5mm mounting plate. The shaft is 10mm, and
I machined Delrin bushings to pass through the plywood. The
plywood was treated with a mixture of West System 24 hour epoxy,
thinned with acetone, so it soaked into the wood. While still
wet, I built fillets using West System Epoxy and West System 404 Hi
I decided to disassemble,
paint the plywood, then reassemble after all the cuts were made.
Painting the wheel wells after assembly would be a lot more
difficult... Maybe this way I can make a later task a bit easier!
It took a while, but I finally
got the geometry correct... When fully extended, the connecting rod is in-line
with the servo arm, so any load is taken up by the servo mount, rather than
borne by the servo's mechanism:
When there is no
power to the retract servo, since the arm is just over-center, a load on
the gear will cause the servo arm to rotate upwards, against a Delrin
stop that I attached to the assembly. This gives the gear a
positive mechanical lock without power.
The actuators for
the landing gear doors use the arms from the aileron actuators of a
T-Rex 600. I had to make a bunch of parts on the lathe to get this
just right, but it works like butter!
To complete the assembly,
I ran Gold-N-Rod flexible cables to the Gear Door actuator arms.
This allowed me to move the gear door servo to an area of the fuselage
where I have more room. This is good, as there is not
a square centimeter to spare! There is a servo mount in the kit for
a throttle servo (which I certainly do not need, being electric), so I am