How to build a balsa sheeted foam core wing.
 

What is the technique in balsa sheeting foam core wings. I have read the manual recomending to use the Zap Finishing Resin or the Hobbypoxy Smooth n Easy Finishing Resin. Is these glues just regular epoxy? I have read at other places here on RCU that one could mix 50/50 white glue and water and use a brush to put it on the foam core. Also if I would like to lighten the struckture is it wise to remove some of the foam by cutting out holes on the foam core? What other ways is there to lighten? Changing the balsa sheets for lighter ones?

RE: How to build a balsa sheeted foam core wing.
 

As to choice of adhesive, there are a few ways to go, epoxy for one (look for laminating epoxy), aliphatic another, polyurethane (foams up as it cures) seems to be the new favorite. Here's one website with good photos & text: http://www.mackrc.net/patternwings2/index.htm

As to removing foam pieces from the cores before sheeting, it can be done, but is rather laborious. It also creates problems as to just where to remove and where to leave for structural integrity. It is a process best left to those willing to accept unsuccessful experiments. A lot of bother for not much weight saving, in my humble opinion.

As to weight of the finished wing, two areas to focus on are the amount of glue used and the weight of the balsa skins. Use the least amount of glue that will give good bonding from balsa to foam core. I would think aliphatic would be the lightest of the glue choices, but have yet to experiment with that myself. I like the polyurethane. Its foaming action creeps into voids, and its viscosity is thin enough that it can readily be spread out for a very thin coating. Also it has a very strong bond. Keep it off your skin (human skin). Not toxic (that I know of), but sticks good and doesn't wear off for days.

I weighed the balsa sheet pack that came with a quarter-scale kit a few days ago and calculated the wood is nearly 14 pounds per cubic foot. Contest balsa, if you can find any, would be less than half that. I figured if I used the wood in the kit, it would cost me close to two pounds in the finished weight as compared to contest balsa. That's a lot of heavy wood--more than a 10% weight penalty. Having been unsuccessful in finding any truly contest grade wood I decided to take a chance on a quantity of AAA grade balsa, which with a little luck might come out around 8-9 lbs/cu ft. We'll see when it gets here. I will sort the pieces out and use the very lightest for sheeting the tail parts, next lightest for sheeting fuselage parts aft of CG, then the rest for wings and forward fuselage.

RE: How to build a balsa sheeted foam core wing.
 

Great feedback. I have 2 days ago ordered a 1/4 scale myself, the Lanier Extra 300S 72".

Where can I find the polyurethane glue? Is it difficult to use or is it mearly using a brush spreading it out like regular glue? What is the price of contest balsa? If using contest should I go for the same thickness as stock or could one even try slightly thinner to save even more oz? How much sheeting are you replacing and what is it costing you? Where are you buying your balsa? is it worth buying contest balsa online or should one go to a store and inspect each sheet?

I had a chat with another guy here on RCU that said the fuz sides are of poor and very heavy and brittle ply. That there is a good idea to swap them for 1/8 lite ply instead to save several oz. He also meantioned the contest balsa as you did. Needless to say, I will try to lighten this fram and changing some wood for better one sounds not to difficult. In addition I will try to chose good equipment and hardware. Have for instance ordered CF wingtube and are looking into CG gear. Did order the fiberglass cowl and wheel pants option together with my kit.

....hmm, I can see that I came up with loads of questions on this on. :) However I have never sheeted foam core wings before and I want it to be done good as well as ligt weight.

Regards,

C.

RE: How to build a balsa sheeted foam core wing.
 

Polyurethane glue is available in several different brands. Gorilla Glue is in our local hobby shop, ProBond is at the hardware store, pretty much the same stuff I think. Dribble out a small bead and spread it as thin as you can, roller works best for me.

http://www.lonestar-models.com/ for prices.

Thickness: I ordered 3/32" thick so I can sand without fear of sanding all the way through. If I were more careful I could use 1/16", but I'd rather work in my usual casual style and suffer the consequences. Master builder I am not. I think I ordered 100 sheets of 3" x 42" for considerably less than $100. That's more than I need, but I'll use it over the next few projects, then evaluate. If I could go to a store and weigh each sheet I would do that, but the local hobby shop sells the same stuff that comes in the kits.

It would be great if you could find a set or two of cheap foam cores and practice once or twice before doing your project. I learned that in art class years ago. (Our teacher would say, If you're not sure how it will work, and the whole class would join in: Make a model! She did not mean model airplane, but a throwaway before screwing up your masterpiece.)

CF substitutions for aluminum will help on wing tube and landing gear. On a plane this size I think titanium axles are worth the cost. On our grass fields I find the typical Dubro axles don't stand up well to even soft landings, and if you go to 1/4" for more strength they get very heavy, but the 3/16" titanium is light and stands up well. I believe they're a PSP product, available from Don's Hobby, Troy Built and others.

RE: How to build a balsa sheeted foam core wing.
 

Hmm titanium wheel axels sounds expensive and very nice. I ordered the NMP Light Weight Aluminum wheel axels from Central Hobbies, together with their 3/16 carbonrods with 3 mm titanium fittings and Dave Brown Treaded Lite Flite Wheels. I also ordered a Tru Turn Light backplate Spinner, eventhough I know it is not as light weight as a plastic one. I would like to have a CF spinner but are unsure if I can use a starter on it?

http://www.centralhobbies.com/landing_gear/Axles.html

As soon as the kit arrives I will check out the wood and see what balsa and ply I need to replace. Not meantioning where to find high quality ply and balsa here in Sweden. Eventhough I know that pretty much every hobby store is keeping AAA balsa in stock I am unsure about the contest. I will only buy the quantity needed for this kit so I suppose it will not be too expensive.

Another way of reducing weight, as I have been told, is to replace all the fuzdoubler with contest balsa. Claiming that contest is strong dispite its weight and in a sandwich construction as double it will be sufficent. Also to replace some ply formers in the fuz with contest balsa... Sounds a bit flimsy to me but then I don't have much experience. The only build I have done before was the GP Extra 300S .60 kit. However I manage to complete that one to me very satisfying.

As said, I am planing to replace the included ABS turtle deck and conopy hatch by foam/balsa construction. However I am a bit conserned the balsa structure to be too fragile. I would like it to withstand some handling without getting brused with nicks too soon.

What quarter scale kit are you working with?

C.

RE: How to build a balsa sheeted foam core wing.
 

A bit prematurely I know, but I am leaning towards this colour scheme.

RE: How to build a balsa sheeted foam core wing.
 

My project is the Lanier CAP 232 81" wingspan. We must have bought from the same clearance sale. I have yet to be greatly impressed with any Lanier product, but I can't resist deep discounts, so I figured this would be a good exercise in rehabilitating a cheap kit.

I have seen suggestions along the line of replacing fuselage ply doublers with balsa (but not contest balsa!). Since I will most likely be powering with gas, I will wait until I actually start gluing up before I decide about wood for the forward fuselage. I am not looking to make a high-performance model here, just trying to avoid producing a flying pig.

RE: How to build a balsa sheeted foam core wing.
 

Or worse yet, a screaming pig running at full throttle to stay aloft. I actually are hoping my OS 120 FS will power this thing allright for traditional aerobatics. lets see how this stunt will turn out. Still, it is fun and motivating to set goals before a build and if this means that I actually shaved off 1,5 lbs when it is done then I suppose it all was worth it. Dispite needing to buy a YS 140 for it.
Do you have other weight reduction tricks in that bag of yours?

Is contest balsa as strong but lighter weight than regular AAA balsa?

RE: How to build a balsa sheeted foam core wing.
 

I built a kit way back when from the SIG models company called a "Kommnander" It was a sheeted foam core wing. Sig sold (and hopefully still sells for your sake) a glue that was called something like CORE-Bond??? Anyhow, it would not eat the PS foam and was easy to apply. My advice is spend extra time pre-building the skins as an entire sheet the entire chord of the wing. I used a razor plane to shave the edge of each 3"x36" plank square. I then butted individual planks together on top of waxpaper on a flat worksurface. I used wood glue to edge join the sheets until I had a single composite piece big enough to cover, lets say, the top left half of the wing. I would then apply the entire sheet as one application, being careful to roll the piece on from leading edge to trailing edge and not just plop it down (avoid risk of a warp or bubble) ONCE THE GLUE TOUCHES, ITS A KEEPER!!! So line things up, get you a good helper. Also the seams where the individual sheets a butt spliced requires only enough glue to hold them while installing. The real strength of the wing is in the foam/balsa sandwaich. I say this because, you need to use the wood glue sparingly to prevent ugly glue edge lines from peeking thru that gorgeous monokote film you are going to cover the sheeting with. If you use CA, the hardened CA will not sand out and your sheeting will look crudy under the monokote. By the way, I crashed my plane 5 yrs ago from a stupid move at full throttle and the wing only had a ding where it caved in the fuselage. They no longer make that kit, but I did keep that wing as a memento of some sort. Best of luck with the build, you should have a gorgeous wing that can take all sorts of G-loads without any problems whatsover.

RE: How to build a balsa sheeted foam core wing.
 

robotronski,

Thank you for sharing this. As you gather, I have never sheeted a foam wing before so I need all help I can get. I was actually planing in using CA for joining the sheets but remember now, after you meantioned it, that it is difficult to sand over a seam where it has been glued together. I agree that a better alternative is to use wood glue.

RE: How to build a balsa sheeted foam core wing.
 

Perhaps the following thread will answer your initial question. By the way, ACP Composites has a great system for $100 that allows the vacuum bagging technique.

http://www.rcuniverse.com/forum/m_38...tm.htm#3818590

RE: How to build a balsa sheeted foam core wing.
 

It does. Boy is that serious or what... Way out of my league. [:o]

RE: How to build a balsa sheeted foam core wing.
 

Latex-based contact adhesive works well, if not after the high-strength of epoxy resin. This is probably what Robo' was referring to. DEFINITELY prepare the sheets into skins big enough to cover whole top or bottom surface, and PRE-SAND the wood so you don't have to do it on the wing - causes flat spots. Aliphatic resin, used sparingly, is a good sandable glue for joining the sheets.

When you do it, sheet top and bottom in one go, and weigh the lot down to dry in the foam cores' "beds" they were cut from.

It's actually pretty easy - practise on foam tailplanes first if possible!

Cam

RE: How to build a balsa sheeted foam core wing.
 

Camdyson, good point to practice on the tail plane first. Will do that.

Well I swinged by the boatstore and picked up epoxy resin and very fine cell rollers for this job. On the instructions for the resin it says that it will be dry to handle in 8 hrs and to fully cure in 24 hrs. I plan to use the smallest amount of this stuff to keep the weight down. Lets see how it will turn out.

RE: How to build a balsa sheeted foam core wing.
 

Before you go any further, take a look at the video (free) at this site.. http://www.rcgroups.com/links/index.php?id=4901 ..Jim shows how much - virtually all - of the epoxy can be removed if you are vacuum bagging, even with his low tech system. This is a major benefit of any sort of vacuum bagging - it allows the use of the minimum amount of resin, glue, etc. so that the resulting structure is strong and yet as light as possible.

By the way, Jim is a friend of mine and he may be using Gorilla Glue for the vacuum bagging now instead of epoxy, since I did the experiments and then my wings, tail feathers, etc. with Gorilla Glue and the ACP system.

You will also notice in the video that with the vacuum bagging system we don't need to worry about what glue to use to edge glue the balsa sheeting (and how easily is will sand smooth) since we don't edge glue at all.

RE: How to build a balsa sheeted foam core wing.
 

I cant find a vacum system and really cant justify such a purchase for just 1 set of wings either. I guess I will just go don the traditional route. As I understood, the vacum system is simulating a very large weight on the construction. That I can do too by putting a table upside down over the foam and loads of weight on top of that.

RE: How to build a balsa sheeted foam core wing.
 

Actually, to simulate the vacuum's 'weight' you would need to have a large car (not just a SAAB) on top of the parts being joined, and have to ensure that all sides of the parts (shucks) were being held together by the exact same weight - as a vacuum produces. Didn't you look at the video? Jim uses - very successfully - a $50 food saver vacuum system.

RE: How to build a balsa sheeted foam core wing.
 

I did watch the video and it looks like a great technique producing a awesome result, but I dont even know where to buy such a vaccum machine. Then it is the aspect that I am just doing one set of wings and after that not in need of the machine anymore. I think I will just follow the techinqes discribed to me initially and keep it low tech. I have however found the compound for the job, epoxy resin 24 hrs cure time, at my local boat store (the one hobby store I asked for it directed my to the boat place).

RE: How to build a balsa sheeted foam core wing.
 

If you have an air compressor, a vacuum pump can be made fairly cheap. Check out:

http://www.joewoodworker.com/veneering/welcome.htm

Mike

RE: How to build a balsa sheeted foam core wing.
 

Good tip but I don't have a compressor either. Justy basic tools, glue, table, and a desire to build something nice.

RE: How to build a balsa sheeted foam core wing.
 

Seems like you are in good shape, especially by getting the proper type of resin - for lamination, not for adhesive uses. Remember to use only enough resin to do the job - any more and you are just adding unnecessary weight.

Hey - lots of wings were successfully sheeted before folks started vacuum bagging! Good Luck.

RE: How to build a balsa sheeted foam core wing.
 

Newc,

I will have that in mind when going thru this building step. Thank you.
However, I will keep my eyes open for a vaccum machine. If unsucessfull finding one I will do it the traditional way.

RE: How to build a balsa sheeted foam core wing.
 

Just a follow-up note on my AAA balsa sheets, which came in today, 100 sheets averaging 10.24 lbs/cu.ft. This was described on their website as '8 lbs and up'. So that is better than the almost 14 lbs/cu.ft. sheeting that came in the kit, but a long way from contest balsa. Other than being a bit heavier than I was hoping for, it's nice wood, clear, regular grain. I'm sure it will all find a good use somewhere. Now I have to find a little gram scale somewhere to weigh and sort the individual sheets.

RE: How to build a balsa sheeted foam core wing.
 

majortom,

Myself took the extra expense of ordering contest balsa for all the sheeting and AAA for all the leading edges. Lite ply to replace the fuz sides. I will have to dig up a digital scale myself to see if it was worth the extra cost and to play the matching game. ;)

What was the materials weight that you are going to swap, and what is the all up weight of the new material. Hence what is the weight gain going to be on you flier?

RE: How to build a balsa sheeted foam core wing.
 

Those are sensible questions, to which I don't have much in the way of real answers at the moment. I have already forgotten the cost of the new wood, but let's say somewhere around $.70 US per sheet. Let's say I use 30 sheets to do my model, so cost is $21. Let's say I use the 30 lightest sheets, which will all be less than the average weight in the package. Let's say they weigh 9 lbs/cu.ft, compared to the 13.8 lbs/cu.ft. that came with the kit. So I'm saving 4.8 lbs/cu.ft., with a net usage after trimming and sanding of maybe .15 cu.ft. that will actually end up flying on the plane. So .15 x 4.8 = .72 lbs or about 12 ounces. That's nothing to sneeze at on a plane that might finish out around 15 pounds. I consider that to be money well spent.

Of course the wood I will not have used, that will now be available for a future model or two, will be heavier... so I will be going backwards in my career, which has been the story of my life for some time now. It's tough getting old.

RE: How to build a balsa sheeted foam core wing.
 

majortom,

That is a great weight reduction for mearly 20 bucks. I hope I could achive the same weight reduction eventhough it will be on a smaller plane than yours. However, as you know, I spent even more money [:'(] to get the conest grade (4-6 lbs sq.ft) instead. I really feel motivated to find a digital scale now... The balsa was shipped today and I expect my order to arr in a week or so. Lets hope one can trust online purchase for balsa and that they are actually inspecting the goods, as they claim, before they ship it away. I guess I will find out soon.

RE: How to build a balsa sheeted foam core wing.
 

Having weighed & sorted every sheet, I'm happy to report that the lighter half of the 100 sheets averages 8.7 pounds/cu ft. The distribution of weight is definitely humped to the light side, with a relatively small number of individually heavy sheets tailing out on the top end of the distribution. So I have a small number of sheets that I can use where I need wood strength, and I can get good value out of pretty much the whole pack. So yes, I would do that again.

RE: How to build a balsa sheeted foam core wing.
 

When sheeting a foam wing, you need to sand the mating edges of all the balsa sheets. This will assure that all the edges are perfectly straight. Then, when you glue the edges together--you are gluing a straight edge to another straight edge. Trying to glue balsa skins together without sanding them will lead to wrinkles and then bumps and warps in the finished product.

I got a piece of 3" aluminum angle at least 1 meter long. Secure it to the workbench and use sandpaper with adhesvie back along the vertical edge. Now, you lay the balsa sheet flat and slowly and carefully sand it back and forth a few strokes untill the entire edge is perfectly straight. Do this on BOTH side of EVERY sheet.

I like to pre-fab all my skins. It usually takes 4 or 5 pieces of balsa for each side of each wing panel. So, get 5 sheets and lay them out flat on the bench. Place them on top of wax paper. Push each piece up to the next piece and assure that the mating surfaces are going to line up perfectly without any wrinkles or warps.

Now use masking tape to secure all the sheets together. Just use a piece of masking tape along the glue joint between all the sheets of balsa. If your using 5 sheets of balsa, then you'll have 4 joints to tape. Run a strip of tape down each joint and tape all the sheets together to make 1 large skin.

Now pick it up and flip it over. Tape on the bottom.

Now you just slide the sheets over to the edge of the table and let the joint flex open a little bit. Run a bead of glue into each joint. You can do 2 joints and then spin the sheet around and do the other 2 joints.

I like to use regular carpenters wood glue for glueing the edges together. After you put glue on all the joints, slide the skin back on the bench and allow any excess glue to squeeze out. Wipe it off with a wet paper towel. Allow the glue joints to dry for several hours.

Paint images attached.

RE: How to build a balsa sheeted foam core wing.
 

Majortom,
You got a good batch.

Rcpilet,
I think I will use true edge and an exacto blade for the sake of simplicity and because I dont have 1 m long angle to use. What grade paper are you using for this purpos and for the sake of smoothing out the skin?

RE: How to build a balsa sheeted foam core wing.
 

I use 80 grit paper on the angle.

Okay--you have skins now. Leave the masking tape on one side. This is going to be the OUTSIDE of the skins. This is going to be the surface that you will see when your done.

Sand the glue off the joints with 100 grit. Be careful. Just a little bit. There should not be that much sanding if you wipes off the excess glue witha wet towel.

Now you need to trim your skins to shape. I trim mine to overlap the leading edge by about 6mm or 8mm. You will not wrap the skin over the leading edge. Just let the excess hang out over the front of the wing. I trim the trailing edge to overhang about 6mm. Trim the length of the skins to overhang the root and tip by about 8mm.

Now you need to prep your foam:
Use a cloth to wipe off any dust. A tach cloth works well.

Lay the foam wing panel down in the bottom core. Line it up perfect and tape it to the bottom core with masking tape. The top core is left aside for now, so that you can apply the balsa skin to the top of the wing panel.

If your using glue, such as epoxy you'll need to apply glue to the foam AND the balsa skin.

Apply your glue to the balsa skins and wipe off as much of it as you can get. I use an old credit card to squeeze off as much glue as possible. The balsa skin should just look wet. That is all. You should not have pooled up glue or be able to see any puddles of glue. Wet the entire skin well and spread the glue around liberally, then squeeze off as much as possible with a credit card.

Now use the same technique on the foam.

If your going to use contact cement, you'll need to use this same method to apply the cement to both the skins and the foam.

If your using a polyurethane glue--you only need to apply the glue to the foam. But, I use a spray bottle and mist my balsa skins lightly with water.

When you are finished applying the glue, set the skin on top of the foam and line it up as best you can. Now put the top foam core on top of the skin and prepare to compress it. Use a LOT of weight and distribute it evenly. A couple hundred pounds of weight is a minimum. Minimum 100 kilos. Better off with 150--200 kilos.

Allow the glue to cure for 24hrs--36hrs.

RE: How to build a balsa sheeted foam core wing.
 

Okay, you got 1 skin on. Some guys will do both skins at once--but I've screwed it up before, so I just do 1 at a time now. I'm not the best builder either.

Just pull the wing panel out of the cores and do the same thing on the other side.

When you have both sides sheeted, now you can sand off the excess on the root, tip and leading edge. Stand the wing up on the leading edge and sand it back and forth across a long piece of sand paper. Sand SLOW. Sand EVENLY. Don't get in a hurry.

If you do not want to stand the wing up on the leading edge to sand it--it will be fine to use a sanding block. But just remember to use a very long sanding block. At least 12" (30cm). If you get a sanding block much lionger than 18" (45cm) it will be cumbersome and hard to handle well.

SMALL SANDING BLOCKS ARE USELESS. ALL THEY DO IS SAND RIPPLES AND WAVES INTO BALSA. NO SMALL SANDING BLOCKS

Use a large sanding block to sand the excess off the root and tip.

Then glue on the leading edge balsa block. Shape the leading edge balsa with a razor plane or sanding block with 60 grit paper. When you get close--drop down to 80 grit and then 120 grit.

How you shape the leading edge is up to you. Some people try and shape them uniformly across the leading edge and gradually taper the curve to match the thickness of the wing as it tapers down and gets thinner near the tip. I prefer a very blunt and fat root section and an almost razor sharp tip. This helps snaps and stall.

RE: How to build a balsa sheeted foam core wing.
 

Rcpilet,
Thank you for this, great how to contibution to this thread.

RE: How to build a balsa sheeted foam core wing.
 

Here is an example of how I like to shape my leading edges on aerobatic models.

RE: How to build a balsa sheeted foam core wing.
 

I assume to simulate the wash-out the full scale planes has? However, this not so for the aerobatics as you do want an aerobat to easy go into a spinn (I am a full scale pilot since 10 yrs.). Another reason it to simulate a laminated wing profile to achive less drag (read fuel efficency).

One of the skydivers at the skydiving club, where I am one of the pilots, is a aeroplane mechanic teacher by trade and has access to all the gadgets in the school where he teaches. He promised me today that he is going to try to help me to laminate/balsa sheet my foam core wings using the new vaccum technique. :)

RE: How to build a balsa sheeted foam core wing.
 

No. There is no washout in an aerobatic model like an Extra. Thats not why I do it.

I shape the tips sharper to make them STALL faster than the root. The sharper angle of the leading edge at the tip will make the wingtip stall sooner.

You WANT an aerobatic plane to stall sometimes. You need the wing to stop flying in order to perform certain maneuvers--like snaps.

With a leading edge that is uniformly shaped and just gradually tapered--sometimes the wing will not want to stall for a VERY LONG time. When it finally DOES stall--it is very violent. It tends to make the plane twist up in a ball and go very deep into a snap or tumble.

With the sharply tapered tip--the wings will stall sooner--but less violently. You don't always WANT the most violent snaps that a plane will produce. This is especially true in IMAC or Pattern type flying. You want SMOOTH. Not erratic and violent.

It depends on the plane too. I have built enough kits and flown enough different types of airframes, that I kind of know how much to taper the leading edges. If this is your first big kit--you may want to just sand the leading edges uniformly. Have fun flying the plane and build a few more kits. Experiment slowly with the leading edge shapes and see how it effects different wings of different planes.

RE: How to build a balsa sheeted foam core wing.
 

"I shape the tips sharper to make them STALL faster than the root"

This is the same purpose as the wing washout on full scale planes (not on aerobatics because of stated reason)

"If this is your first big kit--you may want to just sand the leading edges uniformly."

I will most likley follow your advise = stick to original drawing = uniform LE's. Obviously I don't want to risk my first 1/4 scale kit, and will instead concentrate on a light weight and best build I can come up with, and not manipulating too much with the aerodynamics of the construction. All the wing profiles (of a well designed rc model) uses well established wing profiles that has been developed by many engineers (in the 50's) that took into account Raynolds number together with other importaint aspects. The result ended up as several finished wing profile (that a model mfg choises when design their planes) that has a lot of work into em wich I will not take the risk of destroying. Obviously, with experience and knowing what to achive altering a profile there is no prop. However, with my limited building experience I rather not go that route.

RE: How to build a balsa sheeted foam core wing.
 

If vacuum bagging, the taping of the individual sheets together and cutting to shape are the only things that are necessary before the actual core to sheeting bagging. The epoxy resin (laminating) or Gorilla Glue will hold the individual pieces of sheeting down to the foam core (and the edgeas will be percfectly held down - without the need to edge glue the sheets together and this therefore eliminates one sanding step.

The above is shown in Jim Young's video referenced earlier as well as the video from ACP Composites that comes when you get one of their vacuum bagging set-ups.

RE: How to build a balsa sheeted foam core wing.
 

Ok, quick update.

My kit is finaly here and so is the contest balsa I ordered to replace the stock sheeting in order to save weight.

Needless to say I was very curious to see if this stunt would save around 10 oz as expected or not, so I found my sweet little digital scale (acurate to +/- 1 gram=0,035oz) and went to action...

The weight of all stock balsa sheets: 598gram=21,09oz
Weight of the contest balsa to replace the stock: 311gram=10,97oz
------------------------------------------------------------------
Weight reduced by replacing the stock sheeting for contest grade is 10,12oz or 0,63 lbs if you like. Same as slashing the weight of the sheeting by 50%.
Now some scrap and cutting some of the material off is expected while building the kit, so a total of approx 0,5 lbs will be saved on this model by this stunt alone.


I have hooked myself up with one of the Skydivers at my Skydiving club to help me out vaccum sheet the wings. This guy is a aeroplane technician instructor with the keys to the school where he works at (access 24/7). He said they have a 2000 liter airtank at the school used for the students laminating classes. We are planing to laminate my wings on a weekend. Hopefully this will work out without any snags and hopefully I will get myself a set of super lite wings with a minimum amount of resin used. *fingers crossed*

RE: How to build a balsa sheeted foam core wing.
 

Though I've not built a foam wing in many years, I've cut many cores and sheeted them with both balsa and 1/64 ply. Prepared the skins in large sheets as has been outlined but used 3M spray adhesive. Spray very lightly both the core and sheeting and let dry to touch. Using venition blind strips, locate the sheeting on the wing and remove in order.

The bond is permanent, and light as long as discipline is used to spray lightly... it doesn't take much.

RE: How to build a balsa sheeted foam core wing.
 

Hello AA5BY

"Using venition blind strips, locate the sheeting on the wing and remove in order." ??? What is venition blind strips??? Can you please explain this in other words please. Being a forigner I didn't understand that last sentence.

So if understand you corr, one can do as normal, core back into its sleefs after sheeting is in place and weight it down to dry, but use 3M spray instead?

Have you tried the epoxy resin way of doing it as well? Why did you prefere your method, what is the name of the 3M spray? Loads of questions I know, but I am trying to find the best, esiest, and lightest way of doing this as I am about to sheet my first set of wings.

Regards,