it has worked great. The cuts are very smooth. I guess that I am happy with the results. I cut these wings for one of our club members. Also cut the stab for his senior telemaster.

I use this method too.

Using both sorgum and the Scotch 77 product, I've had delamination of the skin from the core.

A few tips.

1) Sand the skins after edge joining them (the side to be adhered). Any irregularities will prevent an intimate bonding. Also cut the skins to allow a 1/4 inch edge all the way around.
2) vacuum clean both the skins and the foam... many times!
3) I apply the adhesive to both the skins and the cores.
4) Make sure you get the Z-Poxy finishing resin. (Part#Pt-40) www.franktiano.com/ZapFrameset-3.htm
5) By using this product, the foam cores become "safe" to use polyester resin on the wing exteriors.
6) Make sure the resin is room temp. Escalating the resin to 80 degrees might shorten working time too much.
7) Balsa and obechi ply can be adhered equally well.
8) By using the resin that hardens, it reduces flexibility in the finished wings.
9) Using high temp films to cover the wings can be frustrating. Stick with moderate to low temp films.

Definitely set the cores in the shucks onto as flat a surface as possible. Top this with a single piece of plywood and equally distribute a hundred pounds across the ply.

Bill Evans, who used to make and kit Scimitar tailless airplanes, always used double sided tape of some kind. Either the carpet tape or dressmakers tape.

I have never used it myself. I have used 3M spray adhesive.

billrad

i still have a desparado 60 one of bill evans designs also have the plans for the desparado 3000 around here some place, and yes he used some kind of double stick tape to stick the skin to the cores as a side note he used 1/64 plywood for the skin

Don't mean to rain on your parade but did you check your math? Last time I checked, a gallon of water weighed about 8 lbs. Multiply that by 5 = 40 times 4 bottles equals 160 lbs. That's about half what your weight is unless the bottles each weigh over 8 lbs on top of it.

Concrete blocks are another good and relatively inexpensive weight source and you don't have to worry about spills or leaks anywhere.

Ive been using the slow cure epoxy for years. I use Pro Build, mainly due to its what I use when doing layups from molds. Its thin and spreads easily. Any other brand will do.

First thing I do is get the sheeting together and tap together enough to cover each side. Then, I fold the taped joint back so the bare balsa is showing and I use wood glue to glue in that joint. Fold it back down and then do each joint that way. Reason is, wood glue is easier to sand than epoxy If you didnt do this step, epoxy would uzzz out the seam and then you get a hard seam surrounded by soft balsa. When you sand it, the seam will show when you cover it. Just a trick I learned over the years.

Then do as the othes say. Lay the sheeting in the shuck, tape side away from wing core lol. Then coat with epoxy, add the core, then epoxy and then the other sheet, then top it off with the skin. I use a couple of 2 x 10's and 3 large car batteries for weight. The epoxy gives you time to arrange the skins before it sets, the weight holds it all in place so you dont get any warpage. Also, the epoxy makes the wing ...solid...It will never peal off or get an air bubble under it.

Thats my contribution All the above means are perfectly fine for skinning cores. Just pick the one that you feel comfortable with and go with it.

WBG

That 3M 77 Spray glue usually attacks the foam. Unless you put a very thin layer of the 3M 77 contact cement on the foam wing, it will dissolve the foam. In my experiences, the 3M 77 spray glue usually seperates after a while. Using too much will ruin the foam, using a thin layer usually doesn't adhere well.

Dave Brown does not make sorgum glue anymore. Sig makes a great contact cement, but it is very expensive. But in my opinion, is the best contact adhesive anywhere.

I find that Elmers Carpenters wood glue is great for attaching balsa to foam wings. It is just as strong as epoxy and less than half the weight.

Any of the methods will work, some better some worse. One key thing nobody mentioned is weight build up. Some methods will build heavier than others

A couple things to consider: water containing glues could warp the panels unless great care is used to select the same weight and type balsa for top and bottom. Contact glues have to be water based to work with foam. 3M77 has changed its formula and now it attacks polystyrene foam in all colors. In last month's Model Aviation, Bob Hunt describes a different product that worked well with PS foam.

Gorilla glue doesn't really need water to be spritzed; humidity in the air is usually enough to kick it off. Except, gorilla glue or Pro Bond or other Polyuretahne glue will likely kick off in about 25-30 minutes...it may not be enough time to lay down an even coat on a 50" panel, top and bottom skins. And if you wanted to do both panels at the same time, you are staring a time constraint in the face. Many guys use this method but you have to work fast

I have tried the above methods over a period spanning 43 years of model building. Have also tried the double sided tape method. It's heavy but also adds the strength of the carrier tape. You have got to be very careful and remove all dust from the foam and balsa with a tack cloth. Actually a tack cloth is very good to use for epoxy or gorilla glues as well. You need a dust free surface to produce the best bond possible

Over the past 25 years or so, I've used slow cure laminating epoxy to sheet wings. I have a pot life of 75 minutes with the stuff I use (Pro Set, 125 resin 229 hardener). I've found it to be the easiest and lightest method yet.

The easiest way to apply epoxy (and gorilla) is with a small paint foam roller from Home Depot. The rollers have a smooth surface and once lightly loaded with the glue you can do a sheet in short order. Take the roller just before layup and run it all over the foam surface. This will do two important things: removes any final bits of sanding dust from the surface and also deposits ever so slight amount of the foam, which makes the surface more receptive to the sheeting. The sheeting should look practically dry after you apply the epoxy. You don't want any puddles

Weighing down the panels in their shucks is the old tried and true approach to a finished wing. I suggest that you make sure the panels are flat during the cure. Measure the height from your surface to the panel center line.

Other method of holding sheeting against foam that I've played with: designed and built a press that compressed the panels during the cure. This worked well and required no heavy lifting. But the best and easiest method yet is vacuum bagging the panels, except this is a more advanced technique, where one uses the absolute minimum amount of glue. For your first wing, weights is the simplest way to proceed

Good luck

Over the years,I've used most methods, latex,sorgum and epoxy. By far the easiest and the best is the method originally used by Bill Evans of Bishop, California. Simitar Hobbies.This is double sided tape about 2" wide with backing. You completely cover the wings in strips. remove the backing and all that is left is a thin layer of glue. It sticks great and adds very little weight,clean and east to use and does not require weight as it sticks instantly.. One roll of the tape would cover about 2 normal size wings.
I am not sure, but last time I heard Bill Evans was not well and may have left us and Simitar may no longer be in business. The original product was of US manufacture but has since been replaced by a Japanese product
If Simitar no longer sells the product, it is available here in Australia and I can get you in contact with the supplier.

quote:

ORIGINAL: littlera

I use a thin coat of West Epoxy on the balsa skins, and clamp it all together. Works great. I do the work in a spot in my garage on the concrete floor where I have determined the floor is absolutely flat. For the top, I use a piece of 30mm granite from a sink cut-out I saved from a kitchen remodel. This stone is heavy and flat to a very high degree. After placing the granite, I set four 5 gallon full water bottles on top of that. This adds about 330 lbs. to the 75 lbs. or so for the stone.

Sufficient clamping force and flat surfaces are critical for having wings set up without warps!


Don't mean to rain on your parade but did you check your math? Last time I checked, a gallon of water weighed about 8 lbs. Multiply that by 5 = 40 times 4 bottles equals 160 lbs. That's about half what your weight is unless the bottles each weigh over 8 lbs on top of it.

Concrete blocks are another good and relatively inexpensive weight source and you don't have to worry about spills or leaks anywhere.

[quote]

Yes, John, my math was flawed. I am an engineer, and can usually handle such complex calculations. but this time did it in my head on the fly. I multiplied 8 (as you noted, 8 lb./gal.) times four bottles to get the significant number 32, upped this to 320, and added five lbs. for the bottle weights. I knew it was wrong almost as soon as I hit the OK button to publish.

What is the best foam to use. White, pink or blue for the wings. I have been using the pink and it seems to cut really smooth. The white that I tried seemed to have very small ridges in it. Maybe I had the wire to hot. I have several club members that want me to cut some foam wings and turtle decks. I am new at the foam cutting but getting better I think.

I guess one other question. Are you putting the LE and TE on before you sheet the wing?

You can do that but have to be careful to shape the edges accurately without gouging the foam. Or add the LE and TE caps after; that's what most people do. To preserve the balsa sheeting during the sanding process, add a piece of 2" wide masking tape aft of the caps directly on the balsa sheet for protection. You still will need to use care

A better method is to feather cut the TE and run the balsa to the edge; a small 1/8" cap may be used and feathered. Ailerons are cut from the wing, preserving accuracy of the airfoil and producing the best flying possible

The LE could be done similarly but that's a more advanced technique where a balsa sheet is first molded around the LE to shape it, then sheeting could be done as usual. What you want most is accuracy between the two panels so that the plane could fly the best it can

Gorish, Put the leading edge and trailing edge on after the balsa skins are bonded to the foam. This will help to shape them properly. Also, use a flat block of 320 sandpaper to level out any imperfections in the foam prior to applying the epoxy and do this carefully not to distort the airfoil. Dan

For most of my wing cutting, I use a program called Profili. It is specifically designed for the modeler. I design my wing and ribs on it. When I print out my templetes, I cut them out of 1/8 ply. Now, here is another trick Ive learned over the years

After you sand the temps smooth around the edges. I take use small piano wire, around .010 works good, and glue it to the edge the cutting wire rides on. This will stop the rough "lines" you see and feel in the foam. Anything that will cause the cutting wire to catch for a brief moment, will generate a flaw in the surface of the foam. The smoother your temp is, the better

I also leave a flat area where the leading and trailing edge go on as my run off and on area for the wire. Leading edges are not that bad, but a thin trailing edge can be tricky. Your cutting wire will stretch and drag leaving a ..bowwed...effect on trailing edge. Not many will come out perfect all the way across. so I just figure a 1/4 thick trailing edge and add balsa to finish it out. Same with elading edge.

Once again, all the above ways is legitimate. This is just the way I do mine and it works for me. I dont like spray adhesives cause I had bad luck on a build that I did years ago. after the model was finished, it set in the sun and the skin started seperating from foam. Was a mess. Ive never tried the double sided tape. I will some time just to see how it does I just find, dont get in a hury, use epoxy so you have time to make sure everything is lined up, and let it set overnight. It never goes wrong and last longer than the airplane will in my experience LMAO.

here is a picture of some panels I did on one of my DC3's. Foam core with balsa covering. I used wood glue to glue the sheets together before putting them on the core. See how well the seams sanded out.

Good luck with your sheeting Im sure you will do just fine. Its really not that hard. We all went through a learning curve and we all do it the way it works best for each.

WBG

Warbirdguy
Do you have a link for the profill program that you are using. I tried a search but no joy.

I too liked Dave Browns stuff.. but since you cant get it. I have been using the methond found on the WOW planes website The trick is to keep the 3M 77 spray moving. Dont stay to long in one place.. I have also sound found that going over the foam 3-5 layers of light spray works great!

I have not used the gorilla glue.. with that I would think of a super thin layer on the form and a like mist of water on the sheet would work well.

Gorilla glue.

I saw that too, was looking for the article. It was basically a honeycomb job, without removing the foam and making it fragile.

Gorilla Glue. I've done this 4 times with great success.

Here is the info you requested. I have had nothing but good things to say about him. Every time contacted him, he always contacted me right back. I have a slow connection speed so when I purchased the full program, he was kind enough to mail it to me. Now, get this, it got here within a week lol. Ive had people from one state over mail me stuff that took longer. The man knows his stuff and support is unquestionable.

Stefano Duranti
via della Casazza 43/b
32032 - Foen di Feltre (BL) - Italy
Tel. 0439310326
E-mail [email protected] - [email protected]


The site address is www.profili2.com

I think I might try the gorrila glue method. Never heard of it before but like I said before, willing to give any a try at least once

WBG

I've been in construction for 30 years and I have NEVER seen a concrete floor that was perfectly level. I recommend this resource for info on skinning wings http://jackdevinemodels.com/foam_bldg_technology.htm very good information. Good luck with whatever method you choose.

Before cutting any foam other than white beaded foam with a hot wire, get expert advice that doing so is safe and wont produce toxic fumes.

Glue the skins together.

Sand smooth.

Spray hairspray on the glue side of the sheeting to seal the wood. It will not get absorbed into the wood this way and you will save weight.

I'd use finishing resin. I'd apply it to the skins mixed in a large syringe in 1 inch squares (I don't want it to spread more than 1/4" in width once the sheeting is set with weight.
Line joining areas with glue.
No, the entire surface will not be spread with glue.


Finishing resin gives you more time to work.

You could cut out lattice work in the foam core, but the foam is VERY light and not as much weight savings by cutting the foam as when you use this glue method.

Brian

Ok, you had me up till you said you dont want the entire area to be covered in glue. the whole reason for doing it that way is to keep it from rising up after its finished. Also, hairspray???? LOL. the main reason for using epoxy is because epoxy will penatrate the balsa a tiny bit to get a hold on it to ...hold it down...does not make any sense to keep the epoxy from sticking to the wood to save weight. I do 52" wing panels. I use a total of maybe 2 oz of epoxy to do both top and bottom. That would be 4 oz of resin for 108" of wing. I doubt weight would be an issue in the context. I know the original poster is not doing a plane that big, but, even if he did one at 60", that would still be only a tad over 2 oz of resin. So I got to say, I dont know where you got that idea, but, I believe your over engineering and going on flawed data to support your idea. Hairspray??? LOL really??? Im sorry man. Im just setting here laughing at that one.

Stick with tried and true. Epoxy, spread thin as you can. Weight it down on a flat surface, you got your wing sheeting done the best it can be done.

WBG