I agree, I used this film way back in the 80's when i could not afford solar film or mono-cote for large 1/4 scale models. I found a whole roll of this at 4' wide thrown away by a school and it lasted me like forever. It worked just as good if not better than standard covering in my opinion. And yes it will take a lot of heat and can warp even balsa structure if you keep shrinking it. I even spray painted mine and it did not peal.
Instead of hot glue use gliden gripper foam safe paint, wayyyyyy stronger and permanent bond. The stuff is insanely strong and amazing and unlike hot glue is not heat sensitive. Gliden Gripper cannot be build apart, the foam will fail first behind the glue joint!
For larger wings take into account to add a thin layer of CFK rovings (not expensive) on lower and upper sides of the spars; these will take lots of load during (aerobatic) flying ! Have done that for numerous models and works perfectly !
Im thinking about just adding ribs on top of a flat dallor tree foam board to prevent the wristing ( rather than just adding KF)..Use newspaper. postcard paper or whatever to skin the top so I can paint it. I have big sheets of drawing paper...it's slightly thinner than regular writing paper. There's so much stuff you can use if you dont have to worry about NITRO...I been collecting clear plastic (#2 plastic) from cakes...A couple more cakes..I'll have enough plastic to skin a 40' wing..lmao I'll have to experiment with full symmetrical ( fat rigs)...basically a foam board for the center,( sort of like KF4) So it'll have to make ribs for top and bottom. If it works...Im going to cut lighting holes in the center board..starting from the outter bays. For a 30 " - 40" 3d park fliers..it should be okay. Not going to burn holes in the sky...Just make the model twist and turn in a tight space. I need to make it 550 grams or less for a 36" 3D type models. it's recommended in the plans..Sort of like that grass hopper.lmao. That particular model has a flat bottom air foil ...basically I want to make something like the something extra scale down.lmao...They just have different air foils...that's all...Air frame, wing span..ect are all pretty much the same...just cosmetic If it works...I'll just use packing tape to skin it...Just put strips of postcard paper on top of the ribs..so the tape will have a smoother surface to stick to. hmmmm....maybe use heffy trash bags to skin it.lmao
you can do a foam CF or FB sandwhich panel, but you need high density foam. The resins used for CF/FB are very strong and may leak through the styrofoam pores. The spar could be any material, balsa would suffice and will adhere with the hot glue just fine. If you have the money for CF why not =)
I've never done a comparison but I take it balsa is heavier than DTFB ? If I were to apply this method to, say, a FT design, could I expect any weight savings from building the wing this way vs. the normal "fold over" type of construction? I suspect I already know the answer, but I am not familiar with the characteristics of doculam. Great video! Love your builds!
It really depends on the size. Smaller wings will more than likely weight the same. What you can expect is that you will have a more efficient airfoil over FT designs and use of this technique will lend itself in building balsa airplanes too. Paper on DTFB is heavy. This allows you to use foam without the paper and make a more scale airplane that will fly better than use of FT build techniques.
Shear webs are placed in between the upper and lower spars forming an "]["-beam type construction just like they use in the construction industry of buildings. Aiding in minimizing certain specific forces and/or stresses being applied on the wing, as much as possible, while in flight is a paramount function of shear webs.
If I put that much into a wing, I would give it a coat of west systems epoxy rather than a laminating film. I would want to add some structural strength, and the weight is not an issue like a thick coat of gel coat would be. This is because I know that within 10 min after take off I would hit a goose head on or something and all that work would be fluttering down from the sky. The epoxy would give it a flying chance, at least save some of the structure rather than total destruction. That and I would be using those Estes rocket engines to get it off the ground and up to altitude fast, then they drop like spare fuel cannisters when the parachute charge goes off.
Thanks for the video - really helpful. I presume you could create any airfoil you wish by just cutting the ribs to the right airfoil profile? I'm looking to create a Newman airfoil.
Sure! I've done this with numerous types of foils, semi and fully symmetrical. Undercambered would work well too though it may be more tricky to cover. For quick and dirty panels to try, you could simply how wire a foam core using templates and then spend the time on a built up wing like this. Lots of fun ways o approach it.
Hi Josh, excellent tutorial. Thank you for taking the time to help those who want to be informed. Doculam is an interesting material, will have to try that. On a separate note, I wonder if a thin strip of balsa, over the edges, to allow the use of other films. The weight penalty verses ease of other films ??? Also wonder if it is possible to use ribs from a balsa model as templates for the foam ribs ? Looking forward to your future build videos.
"I wonder if a thin strip of balsa, over the edges, to allow the use of other films. The weight penalty verses ease of other films ???" Balso is pretty light, and thin strips would be especially light. Other materials for covering (like tissue) would be much lighter than the office stuff (I think). It's a good idea (with the balsa edges) composite construction, but a lot of fucking around, that's all.
Justwantahover Yes, tissue would be lighter. But not as strong. The film does act like a stiffener (torsionally). You sure could do balsa cap strips to use other films that use a higher temp. I would reserve this for much larger wings though. The balsa would greatly contribute to increased weigh with wood AND glue. The added strength would be great. The idea is not to make a wing that is overly strong. Just strong enough to get the job done. Obviously I'm not a proponent of over building models.
Another glue of you don't have a glue gun or just want to use something else that is very good with styrofoam is Gorilla Glue. Best glue I've encountered for styrofoam and you use very little since it expands 3 times it's size. Just moisten the surfaces and apply a thin film and I mean thin. The glue basically turns into foam itself it seems, and it's very strong and won't burn you either which is great if you're a kid. My glue gun only has high temperature so melts foam before it cools, that ain't cool!
Hi my friend. So, Its sturdy enough to fly??? I REALLY loved this type of wing you teach, but please, Im a beginner, so what do you suggest for me to add more strengh to the wing?? How wolud I do that?? Thanks for the video!! :D
Sure is! My SE5a uses this construction method and it works well. See that video on my channel. You can add strength by adding sheeting (foam or balsa) to the leading edge or add carbon fiber within the foam spar. Even thin ply would go a long way here.
Great set of tips, thanks for sharing. How do you cut your ribs? I'm thinking hot wire cutter?? The covering didn't look the tight in the video, can you get that material tighter? Thanks for sharing :)
In this video, they were simply cut by hand. The new video I did cut them with a wire cutter but it's a bit different overall from this approach. The covering I used in this video did not shrink all that much because it is doculam... a document lamination film. Ultracoat or Monokote will indeed shrink more and tighten up more.
I'm really not sure. I've never built one but I suppose if you reinforced the "hook area in the wing properly it would do fairly well. Use of kevlar, CF or glass as a skin would certainly help strengthen the peg.
Did you hand cut those ribs, or can you buy them pre-cut? I don't know how much load you're going to have, Would it be smart to use carbon rod in the middle as well as the foam ones?
BennyCFD Yes, hand cut. Its far easier to cut foam over balsa. If you remove any film or paper than it is even easier. Yes, carbon would be good but depending on your application balsa or foam spars with shear webbing will be sufficient.
I dont want to flame nor troll but...Does this have any particular reason to do ribbed wing out of foam ? If you put so much effort into it...like cutting out ribs manually...isnt it better to use balsa instead ? Is it so much lighter ?
It can be! The advantage is that its cheaper, faster, and sometimes lighter to build. If you mess up you really do not care because of the cost and time invested is not significant. You can cut out one rib in less than a minute whereas with balsa it takes several minutes to cut and sand to proper shape. You sheet of balsa will be about $5 for a 24x4" sheet where with this foam you can go to a dollar store and pick up a 20x30" sheet for a dollar. You can use that same foam for sheeting the wing as well. Its just a very versatile build medium. Thank you for having a look!
I think weight is dependent on your design. Balsa is better if your worried about a nice plane. But for experimental planes this is the better route for cost reasons. Foam Board does a good job either way.
The foam wing would be lighter (a lot lighter) than the balsa wing even if you made the ribs thicker. I would NOT use foam spars, though, not even if this were for indoor rubber. While foam ribs would probably be OK for electric I would NOT do this for a glow powered model, it'd fall apart pretty quickly because foam has little compression strength. If you want to use foam for a glow powered plane you'd have to go with sheeted wire-cut foam cores rather than foam ribs (this is usually heavier than a similar sized balsa framework wing but is very strong and stiff).
Ailerons can be attached with any hinge material. You can insert a small piece of balsa on the inside of the wing if you have fears of it pulling free. I personally love to use old floppy disk material. Sand it a litte and any glue will hold it and it flexes nice too.
It absolutely can be glassed. You have to be strategic about what cloth you use and where you use what weight of cloth. I frequently use 0.75oz cloth and waterbased polyurethane (WBPU) as a surface finish that is more paintable and gives a very smooth finish. Epoxy will give strength at more of a weight penalty. Perhaps I should do a video on my glassing techniques.
My experience with covering films on foam at this point tells me that you really can use any of them but they are far more sensitive to temperature fluctuations. Do a test patch on some crap foam before you apply to the model and you'll be just fine.
First, you got screwed paying 10 bucks for a couple of yards of Doculam (laminating film). It is available everywhere online for about 20 bucks per 250 foot roll. Second, that film will shrink a ton. You just never got it hot enough and left the covering slack. Laminating film will take more heat than MonoCoat or any other purpose-sold model covering film. Using it over foam ribs might not be the best useage for that very reason.
You could use it to shrink it but it depends on the covering. In this case, doculam does not shrink all that much. Other coverings can be more forgiving but usually require a hotter iron... something that will melt the foam too.
Joshua Orchard I found an approach that works quite well: massive overkill. The wet rag didn’t produce much change, so I put a sheet in the shower, turned the water to full hot, and let it run for few minutes. That made it easier to peel the paper away. Having achieved some success, I applied More’s law: “If a little’s good, More’s better, and too much is just right”. I put a sheet in the shower and flooded it, adding a second sheet trapping water between them. I let them soak, reapplying water. After about an hour the paper wrinkled, and peeled off in one piece. I was left with a bare sheet of clean foam, with no effort. The paper has a slick finish and it takes heat, time and water to dissolve the adhesive. I realize this is a long post, but I hope this will help others. Let’s be careful out there.
Depends on the airfoil you want. You can readily use an online airfoil generator but if you are trying to design a whole panel you are looking at purchasing profili or compufoil.
felipe j. Garzon flitetest.com/articles/how-to-make-inexpensive-hot-wire-templates See the links to the airfoil generators linked in that article. They will generate basic NACA 5 and 4 digit series airfoils.
I was wondering because I build wings from very thin A grain balsa and tissue covering and can get 1 meter wings as light as 28 grams, and I thought that maybe by some miracle this method could be lighter than mine. Super lightweight techniques interest me because I am always trying to make the slowest flying aircraft that I can....and cause my flying field is small, so if I like keeping my planes around they'd better be slow...
Nice concept but the covering looked like crap leaving all those wrinkles. I would have to cover it with a thin sheet of balsa to hide that hideous looking covering.
Agreed, however in this video I was using doculam, which has very minimal shrink. Low temp coverings would work better. You can get the idea from the video that you CAN cover it but yes, 1/16 balsa sheet would also work very well.
Joshua Orchard I was thinking of doing just what you have done, except for a 1/8 inch x 3/8 inch balsa spar directly above and below the foam spar, plus 1/8 inch balsa at the leading and trailing edges. Then use (4) slabs of 1/8 inch foam for sheeting between the balsa members so its all flush. The foam spar would really be part of the shear webbing in that case.
Joshua Orchard If your wing needed to be tapered you could hotwire a much shorter version of the wing in the conventional way, but then cut it into slabs to use for your ribs.
Yes, this is good thinking. Really all that we are looking at here is using foam as a different medium in balsa construction technique. It is easier to cut, less expensive, and has potential for very light aircraft without sacrificing too much strength.
I do not have the time right now to do a video of it but perhaps in the future. I'm currently building a plane with this design so maybe after that. Basically you want to enlarge the leading edge to create a lip for the skin foam to butt up against. Apply glue to the ribs and tape the sheet in place that will be the skin. You may have to remove a portion of the ribs to account for the skin thickness. It will add a lot of rigidity and strength.
FYI for you and others that have asked, see the following build log for sheeting with foam. forum.flitetest.com/showthread.php?11337-FFVS-J-22-Scratchbuild
I have never used foam or plastic film (and never will) but when covering balsa wings, we never used to stick it to the ribs or spars. Just the edges. Les warpage when you shrink it.
Yes but the strength gained is so small that it is worth losing in exchange for the exponentially decreased risk of terrible wing warpaing. Trust me, I've made the mistake of sticking tissue covering to the inner members of a balsa frame and shrinking it. That wing never flew...
My SE5a used this exact method: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-dWLQHr-Sv2Q.html Build details here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-gSLBSyRZFyI.html My built-up funder and lightning used it similarly but I sheeted the ribs with more foam: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-_VN7ZkBuxqA.html
In this case I used Doculam. It is a film material designed for laminating documents at a low heat setting. It is also thinner than the higher heat laminating material.