Edge of Knife (oz12309)

About this Plan

Edge of Knife. Hyperbatic funfly model, for .19 to .25 engines.

Quote: "You say you're looking for a red-hot sport aerobatic machine, one that can do it all, including knife-edge loops? Look no further! You'll find all the performance you can handle and then some in Tyrone Parker's Edge of Knife.

If you're interested in dampening the verbose a bit or just want to have a good time and make the other fellows jealous - this is the machine that is capable. The vertical winglets above and below the CG (disguised as a canopy and an air scoop) enable this plane to effortlessly sustain knife-edge flight and perform the legendary knife-edge loop with ease. The disguised winglets also keep it up on axis as it rolls. It will flat turn round and round like a control liner - flat spin upright or inverted, and snap and tumble (lomcevak) like crazy. Keep it light, install a suitable engine (Fox .19 BB, Picco .21, and Super-Tigre .25 recommended) and it's guaranteed to blow the balsa dust out of your brain.

With the exception of wire-to-wood, where I use five-minute epoxy, cyanoacrylate adhesives are used. Regular CA to tack things together, followed by a coat of thin CA.

Begin construction with the wing. Cut spar halves from tough, springy 1/B-inch balsa and join with CA. Cut joiners from similar 1/16 stock, taper ends as shown on plan and CA to spar center section. Drill 7/64-inch ID control cable housing holes. Measure and mark rib locations. Cut light 1 x 1/4-inch trailing edge to fit as shown on plan and join with CA. CA 1/8-inch balsa joiner to T.E. Mark rib locations on T.E. Bevel sub-trailing edge so that it's 3/8 at the front surface and 1/4 at the aft surface. Trim ends as shown and mark rib locations. Cut sub-leading edge from 1/8 balsa and mark rib locations. Cut leading edge halves from 1/4-inch balsa. Cut W-1 ribs from 1/8 balsa and remaining ribs from 1/16 balsa as shown. Drill control cable housing holes in ribs W-1 through W-4.

Glue aft halves of W-1 and W-4 to back of spar, taking care to keep them square. Glue trailing edge in place keeping it parallel with spar center and square. Add W-2 and W-3. CA W-7 to spar and add sub-trailing edge. Add W-5 and W-6 and 1/8-inch balsa brace at aft W-4. CA forward sections of W-1 and W-7 to front of spar and add sub-leading edge. CA forward W-2 through W-6 in place. Cut ends of 1-1/4 inch wide 1/16 balsa to fit around TE joiner as shown and CA in place. Cut out at aileron wells. CA 1-inch wide 1/16 balsa leading edge sheeting in place. CA remaining center section sheeting between W-1 and W-2 in place. Add 1/16x 3/16-inch cap strips over ribs and 1/16 balsa fillets at inside corners. CA leading edge in place, trim, carve to shape, and sand. Cut ailerons from light 1-1/2x 3/8-inch TE stock as shown. Sand front of tip section square and CA to sub-TE at tip. Bevel front of ailerons as shown on plan detail and check for nice fit in wells. Drill control horn mount holes. Add 1/4-inch light balsa wing tips then sand finished wing cornpletelysmooth. I've enjoyed good results by shaping lightly with #B0 sandpaper, smoothing with #220 and polishing with #600.

Cut fuselage sides from light 3/16 balsa. Trim wing openings to fit. This is one of the most tedious parts of the entire project but get them close so you won't need any excess glue or filler (and weight). When satisfied, slide sides back off wing and mark landing gear mount position inside sides. CA 1/2-inch balsa triangle longerons in place from back of LG mount aft and from front of LG mount forward. If you've failed to select light enough stock you'll probably have to soak the triangles in ammonia, bend them and pin them to a board to dry somewhere before you can make the curve at the fuselage front. Using light triangular stock, or the old soak and dry technique, CA the top longerons in place. Sand outside fuselage sides smooth, slide back onto wing and CA in place..."

Direct submission to Outerzone.

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