Sheet Balsa Leading edge, OH NOOOO!

[Balsa Pilot]

Greetings to all!

I found a really old kit, (Monocoupe 24") in a sales lot from an old hobby store. Construction is formers for the fuselage and the wings are normal with ribs and upper and lower spars, BUT, the screw in the mix is the plans call for sheeting the upper leading edge of the wing with 1/32nd" sheet balsa. I have the sheet of balsa, all I need to know are tips on how to attach it so it's smooth. Having never done this before I'm a little concerned on how to get this right because the chances of me finding a kit like this are slim (I'm guessing).

The questions that occur to me are:
1. Should the sheet be wet for flexibility?
2. Does CA glue work with wet balsa?
3. Is a different kind of glue more appropriate?
4. Am I better to cover in sections or do the whole leading edge,(there is a dihedral/centre section/dihedral)
5. Once the L/E is sheeted, should it be doped to cover, or, will it go all wavy if it's doped?

Any hints and/or insights would be most helpful and appreciated greatly.
Thanks again to all, HAPPY SPRING!!!
Henry

[tom arnold]

I'd wet the sheet, wrap it around the LE and let it dry over night----trying to glue it wet will screw it up big time as the wood will shrink and wrinkle. Once dry, do not use Duco-type cement as it shrinks as it drys. My choice would be Elmers wood glue sparingly (as you don't want to swell the wood up again) brushed on the ribs and the now-curved sheet slipped into place and held down with flat sticks pinned around the edges. Very carefully set aside and let dry again overnight.

There is no reason to dope it if it is going to be covered by tissue but if you do, I'd forgo dope and use Krylon (Clear) as different types of dope shrink differing amounts. Krylon shrinks the least of any sealer. Needless to say do not use any water-based acrylic or you will have a swollen, wavy sheet that may or may not return to normal as it dries again.

[dirk gently]

Is the wing construction similar to this:
http://pfmrc.eu/index.php?/topic/50857- ... ntry538961
?

If the balsa sheet doesn't go around the leading edge and is only on the top of the wing, it doesn't need to be wet while being glued on.

[Chris A.]

Hopefully your 1/32 balsa sheet has the grain running straight down the length of the sheet. It is easier to bend down the length of the grain rather than across or at an angle with leading edge sheeting. With a straight grain sheet, you lessen the chance of warping. Make sure the sheet is thoroughly wet as you want to avoid splitting at the tightest bend. Once dry and initially glued, check for warps. If everything lines up, I then suggest going underneath and making sure you have the sheet glued well to the ribs and leading edge. If the plans call for it, don't forget to build in trailing edge washout. The end result is a very strong yet still light wing that will hold its shape. Works best with straight leading edge wings.

[NcGunny]

Are all the wing ribs the same size? If they are..stack em all together and sand em all at once. 1/32 balsa doesnt need to be wet for LE. Also, does it use sheeting under the wing also..to form your LE's edge? You might even be able to not sheet it...fish mouth ur ribs insert square stock and sand to shape for the LE

[Balsa Pilot]

thanks to all for replying,

the leading edge sheet only covers the top "third" of the top of the wing, with the bottom being the usual rib to leading edge, covered by tissue affair. I should have mentioned that the wing is already assembled to the point of applying the sheet covering. The sheet of balsa I have does have the grain running lengthwise

I assume then that the sheet won't have to be wet, but should conform to the rib shape, with simple wood glue like Elmer's ?? I have no problem using Elmer's type glue, what do you all think of using a CA glue in this application(only asked as a time saving alternative).
I will use Krylon, as it is a standard on my bench, and now I won't try doping the sheet balsa after it's on the wing.

Thanks again for your help and experience
Best as always
Henry

[tom arnold]

CA will work fine and you can press the sheet into place and run drops along the rib-sheet junction from the bottom with the wing upside down. I'd very carefully fit and pin it in place before gluing as any misalignment and it is there forever.

[davidchoate]

The ribs and LE must be 1/32" smaller where the sheeting goes, and I use 1/32" a lot even where it calls for 1/16" to reduce weight. You do not have a lot of room for sanding. Adhering it I would wet it, and a trick I got from this forum is using an ace bandage to hold it in place because water based glues take a while to cure. CA sets too Quick and is hard to sand away if You dfo not get it 1st time. If the wing is too fragile for Ace bandage then weights and finger pressure. Use the bathroom first so You got a couple hrs. to give it undivided attention til it sets. Also if a Flying plane. Pay attention to any washout or dihedral settings cause once sheeted even if just the LE the wing becomes much more rigid and hard to twist and bend. And sometimes You can infill between the ribs, or if the top and bottom spars are located at the same place on the ribs you can add whats called shear webbing between them. Sorry I do not have any photos handy. But You do not have to stick precisely to a 80 yr. old plan. research the alternatives and use whats best for the purpose as these are "multi-purpose Kits" to Quote Mitch again.

[David Lewis]

The trick is to use as little glue as possible because this type of wing construction adds up to a lot of gluing area. I wouldn't even glue the whole length of the rib. Just a drop on the front (LE) and a drop on the back (spar). On a 24" span strut braced wing, sheeting is not needed.

[Balsa Pilot]

thanks again to all for the helpful hints,
I never considered how much extra gluing area this method involved, so a drop here and a drop there worked very nicely!
This method sure involves a lot of sanding, but the result (now that its finished) sure looks cool.
Will start the covering today, however the wife has had the spring cleaning itch for the last couple of days, so there will be a short delay.

Going to dry cover and spray later after the experience with the "VAL" and its super flimsy paper. I will see if I can get some pics of both onto a subsequent posting. The "Val" turned out spectacularly, while the "Monocoupe" is a constant challenge-having to go back and redo or rebuild certain issues. The modellers of the past must have been very, very, talented individuals, or, I'm still far down on the talent curve. The carving and sanding on this bird are extremely tough. It was designed and flown by a guy named TOM STARK. This guy was an artist with sandpaper.

OH! Does anyone have any ideas about what to use for gap filler or putty?

Thanks again to all of you for the helpful input

Henry