Front Gear Assembly

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 density filler.


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 still on-track!


Here is the completed assembly in action:


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