Alternative Building Material

[Mike Griffin]

I know of one person who is currently building with alternative materials and using innovative building techniques to accommodate those materials.

Has anyone seriously looked at this as a mainstream alternative due to the horrendous increases in balsa?  I was looking at some kit pricing on RSM's website and the price of most kits have doubled.   At some point if this continues, the cost is going to become prohibitive to a lot of people.  Kit manufacturers are simply trying to cover their costs and make some profit but this is getting crazy.

Mike

[50+AirYears]

Well, we've ALREADY been using alternatives for building part of or complete models for YEARS.  Fiberglass, foam, boron and carbon fiber, spruce, kraft paper, all kinds of alternatives.  Ever see plans for wartime models from parts of Europe, see the wing ribs looking like Swiss Cheese?  Thin plywood with lightening holes cut in.  The Joe Ott line of kits, maybe some Comet and Guillow kits of the time used cardboard and even reed for parts.  Model Aircraft of the time showed lots of hints on alternative materials for almost EVERY part of model aircraft.   We've done it before, we can do it again.  And we have MANY better alternative materials materials today.  See it as a creative challenge!

[Motorman]

Mike, what materials are you talking about?

[Mike Griffin]

Mike, what materials are you talking about?

Hi Walter,

The last time I talked with Eric Rule, he was building a model using two methods of construction.  He was going to build one the traditional way using balsa as the main component.  The other was going to be built from a plywood subframe and covered with a thin wood veneer, foam and a heavy paper.  I was not sure how each of these materials were going to be used.   I have not been able to talk with him recently to see what progress he had made but the way he explained it to me, it sounded like a viable alternative and very cost effective.  Maybe if he sees this post he will let us know what progress he has made. 

Mike

[phil c]

Probably the biggest issue in building with alternative materials is the adhesives.

Glues such as Polyurethane Gorilla glue can add multiple ounces because they are the same final density as epoxy.  They require the same usage tricks to keep the  weight down-  small dabs instead of globs.  If possible apply it in a thin layer.
White glue and Carpenter's glue cure by evaporation.  Make sure any joint has open air or wood to transfer the water out.  If not, these glues can literally take years to dry as they mildew.
Cyano-Acrylate- aka Hot Stuff(tm) cures to type of solid acrylic acid polymer.  If you've ever picked up a piece of plexiglas it is lighter than glass, but much denser than balsa.  Use the absolute minimums.  Plus it is a very expensive substitute for dope.
Contact cements- 3M 77 is common.  It can be effective with very light coats.  Makes iron-on glass reinforcing, do it yourself iron on film.
Lite Ply saves about 1/2 the weight of same thickness birch ply.  It's not terribly rugged because it is brittle.  But it's easy to glue back together.  The RC'er use it(ARF's and kits') by cutting out lots of panels out of, say, a fuselage side.  Using a very open structure like that, with proper design, is plenty strong for ordinary flying.  It does crack here and there in hard landings though, which can be hard to spot.
Carbon matte, carbon fiber cloth- all require careful molding, preferably vacuum molding and/or application to keep the weight down.  Excess/Meager resin can cause spots that will fail.

There are lots of "tricks" building "foam" wings for various planes.  If you want to learn see how the design/construction has changed over the years.  The most common method changed from16/-3/32 balsa epoxied to blue styrofoam.  It pretty quickly change to the white bead board which about half the density and comes all the way down to .8lb/cuft.
The latest tricks are using the foam as an inner mold and then removing all/most of it after the outer surface has healed.
There are a lot of different ways of mounting landing gear, retracts, internal fittings, hinges, etc.  Some are over kill, others fragile.

[Brent Williams]

There are lots of good alternative methods and materials to make functional airplanes.  Making beautifully finished, 15-20 appearance point airplanes with alternative materials and methods is much more difficult for the average person.  Balsa, dope, ect are proven methods that the community understands.  Anything else is a grand experiment that may be a risk of time and effort. 

[Istvan Travnik]

Hallo Mike,
I suggest you to get acquainted with my complete technology based on blue Styrofoam.
You can find here the topic "The bluefoam model, or how to... "
There is a link to a 220 pictures' gallery, and the conversation deserves to read carefully.
If I need to summarize briefly, the key is the proper quality (high energy) laminating Epoxy e. g. CIBA / Huntsman  LY 5052.
This resin can be soluble by Methanol, and will be hardened even in very-very thin layer to next day. Most epoxies cannot do that: they remain sticky.
Istvan

[CircuitFlyer]

I agree with Phil, alternative materials require alternative adhesives and coverings.  It also opens the door for alternative methods of fabrication as well.

Case in point, here is a 1/2a electric trainer I just built for the club.  No balsa or ply used.  The materials for the complete airframe cost less than $3.  The foam board parts are cut out using a needle cutter attachment on my DIY CNC router.  All of the other bits and bobs are made on a 3D printer.  Assembled using hot glue.  5oz RTF.

Paul

[john e. holliday]

Well I'm working on two identical planes.  One with usual construction and not going for the lightest balsa.  The other using foam board.  Both have ply in the critical areas,  balsa leading edge and wing tips on the foam one.   With out weighing I can say the foam one will not be a contender but would make a good sport plane because of weight difference.  Pictures will be coming when the lower half of the body lets me.

[Dave Moritz]

One has to wonder whether alternative materials, as useful as they are, might still be a tough sell when it comes to a kits? Expectations and all that. Perhaps balsa kit prices would need to become prohibitively high before potential kit buyers would consider these alternate materials in kit form. 

Dave Mo...

PS: I use such materials every chance I get.

DM...

[Dave Hull]

This theme has been explored in many ways. One example is given in the article in Model Aviation by Charles Schobloher back in July of 1977 when "...the cost of balsa, like coffee [was] sky high." It is worth reading from the AMA archives (Mold It--The Easy Way) for anyone who is looking for alternatives.

He described it as a lost foam molding technique to make parts or entire airframes. I think the attraction then, and I see recurring in this thread, is that it doesn't use any(?) conventional model building supplies in the basic airframe. The lure of making an equivalent--or even improved--airframe using readily available, cheaper substitutes appears to be nearly universal among modelers.

Remember that this was also in the era of one-off foam-fiberglass airplane construction as popularized by Burt Rutan. And yes, you can add a ton more technology and get better results. But that sort of defeats the idea that there is an "Everyman's Solution" to costly traditional construction. Don't want to make an expensive (either dollars or labor hours, your choice) female mold? Then you need a one-off plug. Don't want to pay for carbon fiber, or even fiberglass? Ok, then read Charles' article.

Personally, I'm not a fan of cardboard airplanes, or exposed foam airplanes. I could put a ton of work into them, and they still look like, well, cardboard and foam....

The Divot

[Motorman]

Those molds are allot less work the second time you use them.


Motorman

[john e. holliday]

In reality I think the scratch builder will get more benefit from using materials not normally used in model air craft.  Read an article about a POW camp that let those that wanted to to use a hardwood to make free flight planes to fly.  but when one was flew out of site the program was shut down.

Also look at what was used during the WW II.

[Dave_Trible]

I have to agree the cost of balsa is way up from a few years ago.  I’ll just stick with it.  There isn’t much else to really replace it in most ways and even the windmills ensure they will keep planting the trees and sending it.  Eventually the supply will meet demand and price will stabilize.  Our whole hobby/sport costs a lot more than it used to- like everything else.  It’s still far less expensive than most other things grown men do: golf, racing, sports betting, girlfriends.....

Dave

[Motorman]

If it has wheels or a skirt you can't afford it.   I'll stick with balsa too but I'll just build smaller planes.


Motorman

[Mike Griffin]

I have to agree the cost of balsa is way up from a few years ago.  I’ll just stick with it.  There isn’t much else to really replace it in most ways and even the windmills ensure they will keep planting the trees and sending it.  Eventually the supply will meet demand and price will stabilize.  Our whole hobby/sport costs a lot more than it used to- like everything else.  It’s still far less expensive than most other things grown men do: golf, racing, sports betting, girlfriends.....

Dave

Yeah, dont you just love these things

[Dan McEntee]

Yeah, dont you just love these things

    I've seen photos before of these things with the generator pod burning before, but this one looks like it a blade burning. Once the fire is out, they just leave the damn thing there for the rest of us to enjoy. They are not worth repairing or removing them as an eyesore.

  Type at you later,
    Dan McEntee

[Paul Wescott]

There is a TON of work being done with balsa-alternatives.

Larry Renger designed and with the help of Eric Rule’s laser cutting expertise built several nearly indestructible CL trainers to replace the nearly extinct Cox PT-19’s the club had been using.  Not really in line with precision stunt competition but I bet the leap could be made.

There’s really just too much to be said here but below is a taste, and I did not include 3D Printing.  But you can visit Aerofred.com and find scores of 3D printed designs.

I also did not include the basic hot-wire cut foam wings that everyone probably has a passing understanding of and are proven performers in RC Pattern and High Performance RC Gliders.  Cut out the airfoil.  Smooth the surface a bit.  Coat it with one of various goops, or paints, or fiberglass, or Kraft paper, or shrink-film / doculam, none of which are balsa or balsa-adjacent.  Anybody remember the “Ukey”; it had a film-covered foam wing with pine dowels as stub-spars (still not balsa).

S.P.A.D. - Simple Plastic Aircraft Design

        https://en.m.wikipedia.org/wiki/Simple_Plastic_Airplane_Design

        https://www.spadtothebone.net/

Foam Board / Foam Core (Dollar Store)

        https://www.flitetest.com/articles/an-alternative-foam-board-build-method

Andres the high school student uses mad skills (CAD and 3D Surfacing) to create flat patterns that are laser cut out of dollar store foam board and folded up into a full fuselage and 8-foot wing:
https://www.solidsmack.com/prototyping/make-a-massive-8-foot-a-10-warthog-from-dollar-store-foam-board/

Paper Mache

        https://www.flitetest.com/articles/foam-board-and-paper-mache-for-strength

Enjoy...

[Bob Hunt]

Yup, the balsa issue, problem, dilemma, dare I say Pandemic is real, and it isn't going to be solved for quite a while. Even if the wind prop makers stop using balsa it will be a long time before the supply is replenished. That's not the real problem long term for balsa...

The reality is that we as a group are shrinking (I know, Captain Obvious stuff...). There are not enough young people coming along who have the love of the hobby/sport to replace those of us who are aging out. Model airplanes, for several reasons, are just not something on which the next generations will focus. Sure, modeling will still be around for years to come, but with an ever diminishing audience. We never did account for a huge marketplace for balsa, but in the future we will be even less of a marketplace for that amazing substance.

We can wring our hands and lament constantly about the ever-closer demise of the hobby/sport, or we can vow to enjoy what is left of it for our lifetimes. I am choosing to do the latter.

I posted a thread a while back on Stunt Hangar entitled "Balsa: Changing the paradigm." (Here's the link to that piece:https://stunthanger.com/smf/open-forum/balsa-changing-the-paradigm/) Basically I wrote about the fact that we all grew up using certain thicknesses of balsa for specific parts of our models, and that we could change that paradigm by using thinner, denser balsa and achieve even stronger and lighter - or at least as light - models as we achieved with the traditional sizes.

I also have posted threads here that explain what I call the "Lost-Sheeting" method of making sport and test-bed models. In that method a foam core is covered with .2 ounce/square yard carbon mat that is applied using water thinned Titebond II glue. I used that method in a thread about a small electric twin model that I am building. That thread is on the All Amped Up section of the forum (here's the link:https://stunthanger.com/smf/gettin-all-amp'ed-up!/new-small-electric-twin-question/).

I have to get to work, but I have a lot more to say about this subject. I'm sure there will be comments about what I have posted here, and I will respond to them as I get the time. In the meantime, I'm attaching here a few photos of models built using the Lost-Sheeting method.

Later - Bob Hunt

[Dennis Saydak]

Here's an example of what can be done using alternative materials. Although this is an R.C model there is no reason this approach couldn't be used in C/L. There isn't a scrap of balsa in this model. Cedar, foam board and cardboard are the materials used. The cowl was formed using paper mache. I was the pilot for this and several other great flying models models built by a good friend who is no longer with us.

[Mike Griffin]

I started this thread to generate some good discussion and I want to thank everyone for their input.  Everyone has posted some really good information on this.  Bob Hunt's comments were especially pertinent as they always are.  For those of you who posted pictures of alternative building methods and materials, that is a great help.  Eric Rule and I have had several discussions about this and I think he was building two Toreadors, one using the traditional materials and methods using balsa and the other one with alternative type materials.  I need to get back to him and see how that is progressing. 

Bob's point about the shrinking market due to attrition is especially interesting because there is not much that can be done to correct that but I certainly agree with him on his point of enjoy it while it lasts. 

Mike

[Avaiojet]

I started this thread to generate some good discussion and I want to thank everyone for their input.  Everyone has posted some really good information on this.  Bob Hunt's comments were especially pertinent as they always are.  For those of you who posted pictures of alternative building methods and materials, that is a great help.  Eric Rule and I have had several discussions about this and I think he was building two Toreadors, one using the traditional materials and methods using balsa and the other one with alternative type materials.  I need to get back to him and see how that is progressing. 

Bob's point about the shrinking market due to attrition is especially interesting because there is not much that can be done to correct that but I certainly agree with him on his point of enjoy it while it lasts. 

Mike

Mike,

Did you read the entire Thread replies.

You left out Istvan Travnik, he's the go to guy for building without balsa and ply, has been for quite some time, AND he has participated in the Forum with much information and photo.s

Plus, he actually flies his models! 



Check his work out and you'll need nothing else. Do what Istvan Travnik does.

Take the proven road.

CB