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Mike, The picture of this honeycombed wing shows a spar along the back of the wing between the honeycomb and aileron line that is not shown on the wing plan that you sent me a pdf file of. Is this optional or should it be added to reinforce the honeycombed tip? If I need to add it, what material should I use- spruce, balsa or lite ply?, and can you give the the length measurement.? Thanks,
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Joined: 10/27/2002 From: Woodstock, GA, USA Status: offline
It's optional, but I use it anyway. It can be just a piece of 1/8"x1/4" balsa, but I like to sandwich .007" carbon between 2 pieces of 1/16" balsa and make the 1/8" x 1/4" spars from that. The length is 16".
I'm about to get neck deep in this build thread......
-Mike
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ok let's roll......
Capping the cores
First, trim the LEs of the wings, stabs and fin down fairly close to the core. Sand this flush using either a block sander or long, stiff bar sander. be careful to keep it all straight and true, and don't sand too much.
Cut out a piece of capping for each core. The Wing and Fin LEs are made from 1/2" contest balsa, and the stabs are capped with 3/8" contest balsa. Cut these a little oversized so you can trim them back.
Glue the LE caps in place with polyurethane glue. All you need is a thin film, just enough to be damp. Anything more is dead weight. Spread it on with a finger and then go over it with a paper towel. if it's just damp, it's perfect.
Tape the LEs in place with masking tape in numerous locations. Pull the tape snug so there is no gap.
Let the cores sit for 6-8 hours before trimming.
-M
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After a few hours, you can remove the tape from the LEs.
Trim and sand the tips flush at this point. Take care to keep the tip face at a right angle to the center line of the wing. Rough sand the roots flush as well. DO NOT final sand these, just get them close.
Make marks at the center of the LE capping where the core meets the capping, and one mark at the center of the TE capping. Using a straight edge, make a mark on the face of the LE capping at the root and the tip.
Use a straight edge to make a line donw the center of the LE using the reference marks. This will give you a reference to sand to.
Now prepare the tips. the wing tips are made from 2" contest balsa blocks, hollowed as much as possible. Roughly trim it to shape.
The Stab tips are made from 1" contest balsa.
On the fin tip, I normally stack 2 pieces of 1" contest balsa, and sandwich a piece of .007" carbon between them. This stands up vertically and gives this piece a lot of stiffness.
Using the same method as the TE with the polyurethane glue, attach the tips and tape firmly in place with masking tape.
Let all of this cure overnight.
-M
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After the caps have cured overnight, it's time to sand them to shape.
I suggest a 14" sanding block (or so) with fresh 80 grit sticky back paper. This takes a lot of the work out of this step.
Start by sanding the tips flush with the wing panel. be CAREFUL that you don't sand into the skin here. Block control is critital. Just take your time and pay attention to the angle of the block. If in doubt, apply some masking tape to the skins and that will "warn" you if you're getting out of shape.
On the leading edges, first sand the LEs flush to the wing or stab or whatever, at about the same angle. Again be very careful here.
After The LEs are "blocked" to the contour of the core, start turning the corner, a little at a time, toward the center line. Keep it round.
Once you have achieved a roughing in of these shapes, STOP. Don't do any more until completion of the plane.
-M
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Now we need to mark and cut out the control surfaces.
The best way to do this, starting with the wing, is to make a poster board template. If you just free hand it, you're less likely to get it equal.
Mark out the cut lines, the relief lines for all of the capping, and the servo boxes.
It's critical to extend the wing capping into the wing about 2 1/4" or so.
Make all of your marks on the bottom and leave the cores in the top shuck for cutting.
The best tool for this job is a band saw. You can cut it out by hand if you mark both sides and trim/sand to the lines, but a band saw makes this job painless.
Make certain your band saw table is 90 degrees to the cutting blade. begin your cut carefully and cut about 1/8" away from the actual outline. This will allow you to sand to final position for a perfect fit.
Cut out the ailerons, and then trim away the excess material.
-M
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Lastly (for now) we need to finish capping the wings and ailerons.
Make the wing capping out of 1/4" contest balsa, and the LE of the aileron from 3/8" contest balsa. Make sure that the aileron capping is well oversized.
Using the same glueing methods outlined earlier, glue and tape the capping in place.
Place the ailerons down face first on a table. if you lay them on thier sides, they could possibly warp. Adjust your tape so they stay straight.
After a couple of hours, sand the ends flush and install the end caps on the ailerons and wing. These are made from 1/8" contest balsa.
-M
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Got kinda sidetracked. Close, very close. It's built, not painted yet.
I'll get back to this thread when things die down a bit. I said that before didn't I? Soon anyway. I won't go into any gory details but let's just say it has been an interesting 6 months or so. I've learned a lot. Actually I would do quite a few things differently now, and I'll share them with you all soon. Nothing critical, just argueably better, lighter, more simple.
-Mike
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quote:
ORIGINAL: Aussie_Knife_Edge
G'day Mike,
What Balsa sheet weights should I be selecting for the VF3E?
-36 pieces 1/16x4x36" contest balsa (LIGHT!) 12 grams or less -2-3 pieces of 1/16x4x48" contest balsa (LIGHT) 16 grams or thereabouts, not as critical -3 pieces 1/8x4x36" contest balsa (LIGHT) 24 grams or less -2 pieces 1/4x4x36" contest balsa (LIGHT!!!!) 50 grams or less -2 pieces 3/8x4x36" contest balsa (you get the idea) less than 70 grams -1 piece 1/2x4x36" contest balsa (ditto) less than 100 grams -1 piece 1x4x36" contest balsa (getting the picture?) 200 or less -1 piece 2x4x36" contest balsa (this one can make or break ya) less than 400...the lighter the better BTW how's my kit coming along? -Ship
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RE: Black Magic VF3 E build thread! - 
