Balsa substitute

[Ara Dedekian]

       Kerdi Board is a waterproof backing for phony-stone shower panels. It's an extruded polystyrene foam with a .025 film on each side giving it a stiffness and, according to Sparky's density calculator, my 1/2" thick piece came out to 6.22lb/cu ft. It comes in thicknesses from 3/16" to 1" thick.

       The 6lb/cu ft is what got my attention. Can it be used for our purposes? Maybe a geodesic profile fuselage faced with balsa? Just wondering.

      Ara

     

[Ken Culbertson]

I have often wondered about 1/2' aluminum honeycomb core for profile fuselages.  Covered with 1/64" plywood or .5mm CF they should be quite stiff and light.  Anybody tried that?  I would also think 1/8" should work for flaps and stabs.  With the price of balsa as high as it is I would think this might be a viable option...or not.

Ken

[Steve Berry]

Assuming you can find it, Depron is a pretty good substitute. Use it for ribs with spruce spars and sheet the wing with the thinnest version of it, and you're ready for glass and finishing epoxy.

Steve

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[Ken Culbertson]

Assuming you can find it, Depron is a pretty good substitute. Use it for ribs with spruce spars and sheet the wing with the thinnest version of it, and you're ready for glass and finishing epoxy.

Steve

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[Tim Wescott]

Maybe a geodesic profile fuselage faced with balsa?

It would probably be better to strip off the fiber part -- which probably doesn't add much strength and will certainly add weight -- then face with balsa.

I think folks have published notes on foam-core profile fuselages with balsa or carbon-fiber facing.  There's also folks building all-composite stunt aircraft.

I don't have any old price sheets lying around, but is balsa really more expensive in real terms, or is it just inflating in price along with everything else?  If you take the price of a sheet of 1/8" contest balsa from 1962 and adjust it for inflation, how does it compare to a sheet of 1/8" contest balsa today?

[Steve Berry]

I don't have any old price sheets lying around, but is balsa really more expensive in real terms, or is it just inflating in price along with everything else?  If you take the price of a sheet of 1/8" contest balsa from 1962 and adjust it for inflation, how does it compare to a sheet of 1/8" contest balsa today?

Now that is what is really needed. We keep wanting balsa prices to be the same as 20+ years ago, even though everything else has gone up in price.

Steve

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[Paul Wescott]

I don't have any old price sheets lying around, but is balsa really more expensive in real terms, or is it just inflating in price along with everything else?  If you take the price of a sheet of 1/8" contest balsa from 1962 and adjust it for inflation, how does it compare to a sheet of 1/8" contest balsa today?

Balsa doesn’t grow on trees ya know…

[Steve Berry]

Balsa doesn’t grow on trees ya know…

Technically, that is correct.

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[john e. holliday]

I have 2 planes I built using foam board on one of them.  They are the Big Snapper with LA 25.  the one with foam board has only the ply wood parts and a balsa piece for leading edge.  Ready to fly there is only 6 ounces difference.  Have not posted picture of them as I want to see how they fly first.

[Paul Wescott]

I have 2 planes I built using foam board on one of them.  They are the Big Snapper with LA 25.  the one with foam board has only the ply wood parts and a balsa piece for leading edge.  Ready to fly there is only 6 ounces difference.  Have not posted picture of them as I want to see how they fly first.

Interested in the build!  Also, which one is 6oz lighter?

[Paul Wescott]

Maybe a geodesic profile fuselage faced with balsa? Just wondering.

Ara

If you have a flat plank of Kerdiboard, faced/skinned with balsa, where does the “geodesic” come in?

[Mike Alimov]

I've vacuum bagged 1.6 oz glass on both sides of a 1/2" white bead polystyrene foam board (hot wired to desired thickness from discarded TV packaging), and it made for a light and stiff profile fuselage.

[Ara Dedekian]

If you have a flat plank of Kerdiboard, faced/skinned with balsa, where does the “geodesic” come in?

     Hello Paul,

          Below is a portion of Brodak's plan for a 1/2A Pathfinder. The diagonally framed and sheet covered profile fuselage shown in the plan is what I meant by, 'geodesic'. Triangular spaces or holes could be cut out of the Kerdiboard before skinning to save weight.

   Ara

[Dan McEntee]

    This thread is simply mis-titled. There is NO substitute for balsa wood! What is being discussed are alternative construction methods and materials. Look at what all you have to do to replace one sheet of balsa. If it were that attractive, easy and cost effective, I would think that the cottage kit makers would have been using something else a long time ago, even if we are only talking about profile models. Some interested party should build a few profile models with these methods and put them in regular service to see how well they hold up to use with internal combustion engines. That would tell the tale.
  Type at you later,
   Dan McEntee

[Dave_Trible]

This would also be my concern.  Several times including once recently I had to go back and fiberglass profile fuselages built with solid 1/2” balsa but softer/ lighter than about 12 lb. wood due to vibration issues.  Once encased in cloth and epoxy they eliminated poor engine run issues.  I also had the same problem with one of the built up- sheet covered profile kit fuselages.  I can’t imagine trying this with foam as a structural component.  I too sweat paying the balsa bill these days but not sure how you’d ever compare structures or costs.  Composites are far more expensive considering supplies, molds and time for very little net gain other than the fun of trying new things.  I think most builders these days don’t build more than one or two new airplanes a year.  That considered and compared to many other endeavors it’s not that bad.  (Says me)

Dave

[kevin king]

Balsa doesn’t grow on trees ya know…

Fortunately i know a guy. 

[944_Jim]

Fortunately i know a guy.

Steven Tyler says "dude looks like a lady."

[Dave Hull]

The Pailet Skylark--which is a beautiful plane--used 3/32" sitka spruce for the fuse sides and a lot of balsa for everything else....

Looks like they graded the balsa billets for weight, based on the end markings. Sure would be nice to have a pallet of the good stuff!

[Steve Berry]

Steven Tyler says "dude looks like a lady."

 
Along those lines....Home Depot has a bunch of pine 2x4s that identify as contest grade balsa.

[Robert Whitley]

That was a great day trip with Kevin and Rosalie and yes the lifts of balsa blanks are colour coded for weight.
I loaded up much goodly with nice balsa so I’m good for quite a while.

Thanks to Kevin and John for helping out with my addiction.

[kevin king]

That was one of 20 pallets of balsa.

[Rusty]

Why doesn't somebody make a control line model using the technique Lanier used in the 70s?  They made a plastic shell fuselage and foam wings covered with some sort of paper.  They were not competition level models, but they flew.  Some flew pretty good. 

[Gerald Arana]

Fortunately i know a guy.

OMG! I fail to see a shortage of Balsa Wood................  OBTW: You can mortgage/sell your house and have a pallet load! 

Jerry

[Gerald Arana]

Why doesn't somebody make a control line model using the technique Lanier used in the 70s?  They made a plastic shell fuselage and foam wings covered with some sort of paper.  They were not competition level models, but they flew.  Some flew pretty good.

I learned to fly RC with a low wing trike gear Lanier model. I can't remember which one it was. It's been too long ago.

Jerry

[Paul Wescott]

Foam board seems to be a pretty good substitute…

Flite Test Round-nose Bent-wing Corsair out of Foam-board:
https://www.flitetest.com/articles/ft-corsair-release

Photo of some random guy on social media making large scratch-build foam-board wings (below)

[john e. holliday]

Interested in the build!  Also, which one is 6oz lighter?

The balsa one naturally.

[kevin king]

.

[Istvan Travnik]

Dear Friends,
Why don't you state the titel: "Balsa substitute material + its technology?
If you afford my advise, there is a wonderful long road before every open minded comrade. Visit and follow a 11years old topic of mine: "The bluefoam model, or how to build a stunt plane without a bit of balsa?"
I promise every help, all tricks, every know-how, skills,  etc. just ask me!
Materials are close to you, at a fragment price...
Just start and won't get wrong, my friends!
Istvan 

[Steve Helmick]

Fortunately i know a guy.

Are you sure that's a guy, Kev? Well, to be fair, these days you never know, and if he decides he's a she, then you have to take his/her word for it or risk being called a facist or something offensive like that.  Steve

[Curare]

Assuming you can find it, Depron is a pretty good substitute. Use it for ribs with spruce spars and sheet the wing with the thinnest version of it, and you're ready for glass and finishing epoxy.

Steve

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Steve, I have a lot of 1/8" depron left over from my foamy RC days, and I've built wings using the depron as wing sheeting, but how do you go about making it for a stunt ship?

[Steve Berry]

Steve, I have a lot of 1/8" depron left over from my foamy RC days, and I've built wings using the depron as wing sheeting, but how do you go about making it for a stunt ship?

Here's a great step by step tutorial. Granted, it's for RC, but can be adapted to CL easy enough.

Steve

[Curare]

Here's a great step by step tutorial. Granted, it's for RC, but can be adapted to CL easy enough.

Steve

yep, pretty m,uch the exact same way I did the Staudacher below.

[Rusty]

Just wondering why can't we grow Balsa in America?  I see acres and acres of landscaping tree farms in my area, so why can't somebody start growing Balsa here?

[Dave_Trible]

Just wondering why can't we grow Balsa in America?  I see acres and acres of landscaping tree farms in my area, so why can't somebody start growing Balsa here?

In short,  climate.  It may grow other places but there are really only two places on earth where the climate is perfect for growing quality balsa.  Those are Ecuador and New Guinea.  These are different varieties of balsa but basically the same other than the New Guinea wood is more yellow in color.  Balsa grows faster and has huge leaves.  It provides shade for other sprouting vegetation.  It also requires a huge amount of water.  There isn’t really a balsa shortage,  it just goes to the highest bidder.  At times that’s been US Navy ship builders and more recently blades for windmills.  For sure if we stop using much of it the supplies for our use will dry up.  BUY BALSA.

Dave

[Dan McEntee]

Just wondering why can't we grow Balsa in America?  I see acres and acres of landscaping tree farms in my area, so why can't somebody start growing Balsa here?

      You need a tropical climate, like what is found along the Equator, and even that is not a guarantee of successful growth. It takes a specific cross pollination for a balsa tree to grow. That was one reason for a previous shortage balsa out of Ecuador, that a surge in moonshine production that used a certain flower as part of it's recipe stunted the growth of balsa trees for a while.. In the areas around New Zealand, they have been able to successfully grow balsa on plantations but I think it is different than what we want for models. Look at some of the R/C ARFs that come out of China and examine the balsa that these are made from. it's almost clear with no grain, from what I have seen. From what I have read, most of the plantation grown product goes to industrial and other uses for the wood. Wood for model use is just a tiny fraction of the consumption of balsa wood and has been that was  for a long, long time.
   Type at you later,
    Dan McEntee

[Steve Glass]

https://www.rcdepron.com/depron/7168566362297/usa

[Steve Helmick]

My shower was refurbished using that Kerdi Board stuff on the floor pan and 3 walls. It seems like fairly dense foamboard with a waterproof layer on both sides, near as I can tell. The guy doing the remodelling said it was the way to go, but it costs more than cement board or 'blue board'. There's tile on walls and floors over it, and so far, so good. I'm sure it will outlive me.  Steve

[PerttiMe]

Foam board seems to be a pretty good substitute…

Flite Test Round-nose Bent-wing Corsair out of Foam-board:
https://www.flitetest.com/articles/ft-corsair-release

Photo of some random guy on social media making large scratch-build foam-board wings (below)

I believe they use Dollar Tree Foam Board. Something like: https://www.dollartree.com/readi-board-white-foam-boards/809955
Foam core with paper on both sides. Remove the paper, or not, depending on structural needs.

[fred cesquim]

Now that is what is really needed. We keep wanting balsa prices to be the same as 20+ years ago, even though everything else has gone up in price.

Steve

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how much a balsa sheet cost in USA to jeopardize one´s life to build a plane each 2 year?
here in brazil cost the same as USA + 100% o import tax x 5 wich is our cambio rate. i am pretty sure our cost is about 8 times more
you can build without balsa? yes. will it perform the same? no
does it worth the performance and looks deterioration? i don´t think so