Grotto 2

Doug's Tsbuami (Swallow) Build

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Last update 22MAY2006

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YS 61FR : Cut a small circular notch in firewall to clear Header. File header flange about 2 degrees to increase it's angle.

Use epoxy to apply fibreglass inside firewall across gear mount area and back up the inside of the second former (the one with the wing pin holes). After the epoxy has cured, don't forget to drill the epoxy/glass out of the wing pin holes.
Reinforce wing butt joint with glass and epoxy, approximately 1" wide.
Doug moved his throttle servo to the gear mount plate as shown in the photos.
Replace the wimpy  elevator pushrod with carbon fiber aeroshaft or similar.
The horns supplied will not allow you to align the pivot hole with the hinge line. Replace them with some that will.
Beef up the wing mount bolt plate attachment to fuselage with epoxy and fiberglass.
Replace stock hinges. Doug used Radio South hinges.
Replace the tailwheel assembly. Doug made his own as follows:
1- A brass tube with a washer soldered to one end is inserted into the rudder post balsa. Choose a tube size appropiate to your tailwheel wire.
2- Bend tailwheel wire as shown to form a bearing surface with a wheel collar.
3- In place of a set screw, use a length of threaded rod fabricated from a long bolt with the head removed. This will act as a tiller arm.
4- Cover the tiller with a piece of fuel tubing.
5- The entire assembly is held to the rudder using a wire loop or flat stock formed into a loop and inserted into the bottom of the rudder.

Reinforcement must be added where the long tips of the cowl are screwed to the fuselage. Doug used nylon inserts CA'd into the balsa to hold the screws.

After a few flights, Doug noticed the cowling had worn a hole through the first layer of covering, trapping oil in a small bubble between the layers. A few strips of thin rubber on the cowl edge will prevent this or stop further damage, however Doug says it was not possible for him to get the oil out once seepage began.

Doug's CG: 6.75" from leading edge at fuselage side.

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