Monday, January 14, 2008

Le wings

Been bz building and hoping to complete the fish soon for a slope trip, its nearly complete so a quick update. After shaping the fuselage, i proceed to work on the wings.

Electronics going into the fish. HS85mg x 4 , CC Berg 4 rx and 4xAA eneloop pack

Tape the alierons on and cut away the excess length.

Measure aileron servo location. Mark out location.

Dremel out the foam. Use a piece of masking tape as depth indicator.

Pot in the servos with epoxy and cling wrap.


Before taping up the wings, its time to toughen up the epp. The best way i learned from RCGroups is to apply thinned goop(TG) . TG to epp is like epoxy to wood, it adds a rubbery like coating that bonds the epp beads together making it much stronger. My first time trying this out and found out that it really works, the epp is much tougher, yet remain flexible and bounce back to shape. Apply too much however will add weight.

Here's what needed, Goop, Goop-off which acts as a solvent for goop, glass jar and foam brush.

Squeeze some goop into the glass jar, pour the solvent and start mixing till u get syrup like consistency.

Apply to the epp with foam brush. Solvent in jar will evaporate off quickly so add more solvent to maintain consistency. The fumes are not so good for the body, do it in well ventilated area.

See the film of thinned goop when i tried to peel off the masking tape. It sticks to epp really well. Add more coats for strength.

To keep the weight down, i applied 2 coats TG only to the leading edge and wing tips. It takes about a day or two to dry completely.

Taping the wings

At this point, its time to tape the wings.

Been looking for bi directional FG tape, finally found it at Its about SGD20 a roll and free delivery!, definitely much stronger than the normal unidirection filament tape.

3M 77 is first sprayed over area before taping. Tape is layered on smoothly and not stretched so that wing will not warp. I m quite concerned about adding too much weight so only keep the taping to key areas.

First taped a layer length wise top and bottom across the center to cover the spar area. Then a whole piece over the LE. Then also at the TE. Center the servos and goop them in and slice a path for the servo leads. Tape over the sliced paths.

Tape up the wing tips.

Add some X strips.
At this point, the wings still feels abit flexible around the center so added a few more pieces of tape.

Top of wing

Finish up with another coat of TG. The whitish parts are the TG areas after its dried. Wings feel stiff now span wise, but torsional stiffness still not as good. It should better after its covered.

A thicker layer applied at the tips to fill up the gaps.

Wings done, tackle the fuse next.

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