FOAM WING CONSTRUCTION CONTINUED
Tempoarily install all control surfaces and hinges. You want to get a straight line
gap of about 1/16in. Cap the surfaces again with whatever thickness you need to
acheive the right lines and gaps. This can be done quickly with CA and the T bad
and 80 paper.
Check the plans and take measurements for retract location. Assemble the gear
with the wheels and lay them in place. Mark the retract location on the sheeting.
See picture below for making gear mount plates out of 1/4 ply. It should stick out
about 1 in. all around the retract, make 2 exactly alike and make sure the gear go
in and out of the plate easily. Now put the plates in place on the sheeting and
draw around them with a pen. Use a flat blade screwdriver to pop out the balsa.
Use a 2in. square bent wire held by a vice grip pliers and heat with a Bunson
torch. When the gear is retracted the strut should be about level with the bottom
sheeting. Also the struts should cant forward enough to place the axle under the
leading edge of the wing to make for an easy taxiing plane that wont tip over in
grass. Using these parameters start cutting out the foam with the hot wire a
little at a time. Keep test fitting the plate and retracts. If you cut out too much
you can shim it back up with balsa. Now with the gear in place start to retract
the strut and mark cut out lines for the strut and wheel. Go slowly and remove a
little at a time. Once satisfied with the fit, epoxy the plate in with epoxy
thickened with talc powder. Once dry drill a 5/16 hole in each corner of the plate
through to the top sheeting, be carefull not to go through the top sheeting. Test
fit hardwood dowels and cut each to fit. Mix up some epoxy and talc and glue in
the dowels so they are flush with the gear plates.
Set the retract in place and draw a line around the frame on the gearplate. Use
balsa wood and thickened epoxy to fair in the gearplates up to the outlines, when
dry,sand flush with sheeting. Recheck gear fit and adjust as nescessary.
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