BrokenSpoke

It's been many, many, years since I built a plane from a kit and to the life of me, I cannot remember the best way to sheet the wings. I am building a Stik using a short kit from LazerWorks and the leading and trailing edges of the wing are sheeted. What is the current, best, method for applying balsa sheeting?

Thanks!

BrokenSpoke

What I'm asking is what is the best method for holding the balsa sheet in place? Pins?

kenh3497

I have to assume this is a rib and spar wood wing. I have not used the method but saw a wing for a modern pattern ship being skinned. It actually had a "bed" made out of the negative side of the ribs. The sheet was laid in the bed and the ribs were laid in and glued. I think both sides were done at the same time. The foaming polyurethane glue (gorilla glue) was used. This would be hard to do without the negative ribs.

A twist on that would be to support the training edge of the wing after the ribs are glued to the spar. I would raise the trailing edge so the wing was about "level". I would use the polyurethane glue and glue the top half of the sheeting on. When dry, flip the wing and do the bottom side. This should give you a pretty strait wing. Use magazines to weight down the sheeting while it drys.

If it is a foam wing. I still like the poly glue. It really penetrates the foam for an EXCELLENT bond. Spread the poly glue on the sheeting so the wood just looks damp. If it is shiny, you have to much glue. Both sides of the wing can be done at once or separate. Which ever you feel comfortable with. Stack back in the shucks and weight down with as much weight as you can. I like to use a 60# bag or two of softener salt.


The wing sheets should be made up first. Straiten the edges of the sheeting by cutting off the crooked part with a strait edge. Some even will make up a long sanding tool with a chunk of aluminum or steel angle. Some 80 grit sandpaper is glued to one side and the sheeting is further straitened by sanding the edge. Light sand the sheet after the glue is dry, before attaching to the wing. To edge glue the sheeting I would use yellow wood glue and keep the glue to a minimum, only enough to bond the edges. A strip of masking tape down the seam will keep the seam tight. and allow you to open it up to apply your glue. Go here for a very good tutorial on making skins. http://www.airfieldmodels.com/inform...kins/index.htm In fact this whole site is a wealth of knowledge.

Good luck on your build and welcome back!!!

Ken

CK1

My Feedback: (60)

If you are using alphatic resin (wood glue ) pins are hard to beat for simplicity .

BrokenSpoke

Thank you both for your replies. kenh3497 you are correct in that it is a rib and spar wing vs a foam core wing. Your suggestion about using magazines is new to me and I may give is a try. CK1, interesting to see that pin and glue is still a popular build method. The last wing I covered was close to 20 years ago so I figured that something had replaced that method.

Thanks again for the suggestions and help!

kenh3497

If using pins, I have some little round plastic discs that have a hole in the middle. The pin is a tight fit in the hole and helps the pin hold the wood down. I have no idea if they are even available any more or not. I bought them 20+ years ago. I think they were called "pin clamps"????? Sorry no photos.

A quick Google says they were made by Rocket City. Here is a link to a supplier. May be available at your LHS also. http://www.shortysbasement.com/index...&productId=198

Ken

saramos

If you are using carpenters glue (alphatic or PVA), you could try the iron on method. Apply glue to the ribs and place the skin on and then remove. This will transfer some glue to the skin. Re-apply glue to the ribs and any dry spots on the skin that will contact the ribs/stringers. Let dry for about an hour. Now place the skin in position and using a covering iron, iron over the skin and ribs. The heat will reactivate the glue and give an almost instant bond. This works particularly well if there is a sub leading edge to support the front edge of the skin.

CafeenMan

Ken is right about pin clamps. They are excellent for holding down sheeting as the provide a clamping surface much larger than the pin shaft. If you can't find any you can make them yourself from 1/32" plywood.

You can use a pin to drill the holes in them but that will get tedious and probably painful pretty quickly. If you have some small number drills it will be much easier. Figure out what size drill gives the pins you use a snug fit in the plywood.

You can drill the holes first or after you punch out the disks. Use a small hand-held hole punch to punch out the disks. They do a good job on thin plywood.

As I understand it you're sheeting the leading edge and trailing edge, not the entire wing, correct? Are there cap strips on the ribs between the sheeting?

kdc

Make the sheets up first joining to make a large sheet. Joining is done by applying masking tape when the sheets are butted tightly together than turning over and allowing joint to 'hinge' open, apply glue and then use more masking tape to hold flat.
PVA glue and pins is the way I do it plus some masking tape to hold it down if required. If it's a steeply curved LE then maybe glue to the LE first and when glue is dry pull it back down to glue to the ribs. Maybe use cyano for this.
T pins are much better than normal pins. They can be inserted at an angle, alternating every other pin ( ie dovetail fashion ) to hold the balsa down. Also map pins are useful because they are very sharp & the plastic head can go right down onto the balsa instead of the 'clamps' mentioned above.

If you should want to drill holes in lots of tiny bits of ply etc, of course you drill all the holes whilst its still a big piece of ply and then cut up after!
For holding down spars to the building board I use chipboard screws into the board ( I use plasterboard / sheet rock as a building board ) with ply pieces to grip the spar.

kdc

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kdc

Building board from plasterboard and clips for spar fixing. Also showing method of making clips in one long strip which is cut into pieces after glueing & drilling - much easier!

kdc

This photo shows dovetail method of using T pins. T pins can be removed with pliers. Dont use glass headed pins which can shatter & pierce your thumb whilts inserting!. Also shows a typical map pin inserted up to head to hold balsa.

guamflyer

I gotta tell ya , the old school methods work really well.. it's just adding a slight twist with modern glues and tools..
I still build by hand ...the glue is still stuck to it....


SLOPE FAST - SOAR DEEP

guamflyer

badger5964

My Feedback: (6)

I think these are the pin clamps for use described above

[link=http://www.a2zcorp.us/store/Category.asp?Cguid={682DDB36-84EB-4782-8F33-FFF4318DCABF}&Category=ModelTools:Pins]Peck Polymers pin clamps[/link]