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What all lies between DTFB and full balsa builds?

#1
Okay, the title says my question. As my builds get bigger and I crash less, what are some building techniques between folding DTFB and doing full winter builds in ply and balsa?
 

Hai-Lee

Old and Bold RC PILOT
#2
Okay, the title says my question. As my builds get bigger and I crash less, what are some building techniques between folding DTFB and doing full winter builds in ply and balsa?
Not sure what you are envisioning but here is a link to a Balsa AND FB build. The bird is still in my hanger, it hasn't warped and it was still flying the same as originally just about a month ago, (last time out).

The link: https://forum.flitetest.com/index.php?threads/balsa-foamboard-test-build-ft-spitfire.32734/

The LE and the like work equally well using the master series curved skins rather than the standard FB folds.

Have fun!
 

Bricks

Well-known member
#5
Biggest difference to me is when building balsa scratch builds much less forgiving in the measurements and cuts. The newer laser cut kits, are much better then the older die cut kits. The first run of the die cut kits were pretty good but as the dies would wear on later kits more time had to be taken to fit parts correctly., edges would crush instead of a nice clean cut.
 
#6
I'm wondering about other alternatives to balsa. I know when you start getting into really big stuff glass and plywood become dominant. I wonder if anyone has built something out of plywood and monocoat?
 

Tench745

Well-known member
#8
Almost the entire realm of RC lies between DTFB and balsa, depending on how you define "balsa builds."
Cut and fold foam board planes blend easily into paperless foam sheet builds. This is not far from built-up foam construction like wilmracer's giant P-40 build, or carved foam like my new Dumod build.
And foam fuselage plugs for fiberglass builds can be made the same way. Pitts Challenger III Build
Or you can do a balsa and DTFB build like Hai-Lee mentioned, or use carved foam to replace balsa blocks in a traditional balsa plan. Or combine the techniques.
Do a DTFB fuselage, balsa wing, sectional foam cowlings, etc etc.
 

Tench745

Well-known member
#9
I'm wondering about other alternatives to balsa. I know when you start getting into really big stuff glass and plywood become dominant. I wonder if anyone has built something out of plywood and monocoat?
Plywood and monocoat would be needlessly heavy.
Plywood should not be used as a majority material in aircraft building (<=personal bias), particulary in smaller planes like we fly which can't take the excess weight (<=fact).
In a well built airplane, balsa will do just about anything plywood will do and be lighter while doing so. What balsa won't do, another hardwood can often still be a better structural choice than plywood, particularly when weight is factored in.
Plywood has become popular because it's easier to source, is easily laser-cut, and allows for simple/fast tab-and-slot construction of factory kits.
 
#10
I have no problem with precision cuts as I have a laser but I don't like balsa due to it being a pita to source.
You must live somewhere totally remote (I feel sorry for you), I initially thought: " I can't buy balsa because it is super expensive and I need a lot " turns out that balsa in Germany is not expensive at all and available in different qualities and quantities (also very easy to work with).
I recently tried hotwirecutting which is kinda easy as well but you need a suitable space (for bigger wingspan) and a more sophisticated infrastructure.

Plywood has become popular because it's easier to source, is easily laser-cut, and allows for simple/fast tab-and-slot construction of factory kits.
I agree and the fuselage is often the only place where plywood makes senses.
 

localfiend

I like 3D printers...
Mentor
#11
3D printing. Way more complex shapes, flight characteristics closer to balsa (not bad necessarily, but planes have momentum), lower drag, and great resistance to moisture.

You'll have to be more careful on landings, so they're good for when you've stopped normally crashing, and only have mistakes when you're pushing the limits.

Also, assembly time is way, way shorter. Print times on some models can be high, but that doesn't really count as you don't have to watch your machine. I start prints at night, and then again the next morning before heading to work. I live in the middle of nowhere, so I can generally print a plane out faster than ground shipping would get a plane to me.

Also, if you feel like it, you can sand parts down, and paint them. The test section below was actually less work for me than fiberglass over foam. Though there are some bubbles in the paint, this rattle can was at the end of its life.

Paint.png
 
#12
Almost the entire realm of RC lies between DTFB and balsa, depending on how you define "balsa builds."
Cut and fold foam board planes blend easily into paperless foam sheet builds. This is not far from built-up foam construction like wilmracer's giant P-40 build, or carved foam like my new Dumod build.
And foam fuselage plugs for fiberglass builds can be made the same way. Pitts Challenger III Build
Or you can do a balsa and DTFB build like Hai-Lee mentioned, or use carved foam to replace balsa blocks in a traditional balsa plan. Or combine the techniques.
Do a DTFB fuselage, balsa wing, sectional foam cowlings, etc etc.
This is the reply I was looking for. Thank you!
 
#13
Plywood and monocoat would be needlessly heavy.
Plywood should not be used as a majority material in aircraft building (<=personal bias), particulary in smaller planes like we fly which can't take the excess weight (<=fact).
I don't share your personal bias there as I once owned a full-sized plane that was almost entirely plywood and fabric. The best plane I ever owned.
As to needlessly heavy, you might be right, I just don't know, when you use a stronger material you can use less of it.

Plywood has become popular because it's easier to source, is easily laser-cut, and allows for simple/fast tab-and-slot construction of factory kits.
Exactly the advantages I see. The question is simply how much is too much and where should I go other routes?
 
#15
3D printing. Way more complex shapes, flight characteristics closer to balsa (not bad necessarily, but planes have momentum), lower drag, and great resistance to moisture.

You'll have to be more careful on landings, so they're good for when you've stopped normally crashing, and only have mistakes when you're pushing the limits.

Also, assembly time is way, way shorter. Print times on some models can be high, but that doesn't really count as you don't have to watch your machine. I start prints at night, and then again the next morning before heading to work. I live in the middle of nowhere, so I can generally print a plane out faster than ground shipping would get a plane to me.

Also, if you feel like it, you can sand parts down, and paint them. The test section below was actually less work for me than fiberglass over foam. Though there are some bubbles in the paint, this rattle can was at the end of its life.

View attachment 148959
I also have a 3d printer and parts make perfect sense to me but the whole aircraft doesn't. I have seen some hybrids that make perfect sense. Carbon or hardwood spares, printed ribs, and cowlings, monocote covering.

Thanx I'll check out your links
 

localfiend

I like 3D printers...
Mentor
#16
I also have a 3d printer and parts make perfect sense to me but the whole aircraft doesn't. I have seen some hybrids that make perfect sense. Carbon or hardwood spares, printed ribs, and cowlings, monocote covering.

Thanx I'll check out your links
Yeah, depends on how they're designed, and some models wouldn't be worth it.

This one here however is pretty well optimized.


You could certainly combine foam and 3D printing, I've done it before. More work, but that's not always a bad thing if you can get the result you want.
 
#17
I am in a weird way. East of the Mississippi is supposed to be not remote but I don't have a single hobby shop within a two-hour drive!
Simply order online. A 1mm balsa sheet costs 0.99Euro plus 5bucks shipping (10bucks for longer carbonrods) from the Hobbystore, 2,20Euro from the local hobbyshop and 3,50Euro from the DIY warehouse.

Have you tried Papercovering over foam or balsa ? It's a lot of fun and surpringly strong.
 

Hai-Lee

Old and Bold RC PILOT
#19
Just one more comment or thought for you. The shape of the structure is what flies and the weight should only be adequate to maintaining the shape. You can build a plane out of almost anything but the real trick is to build the structure strong enough and light enough.

many people tend to be sort of stuck in a single technique or 2 and have their own material preferences. With the modern range of available materials the planes we fly should be engineering marvels but sadly they tend to be built full of compromises and often far too much material and hence weight.

Using the properties of the various materials and selecting the material, for each and every part, in relation to its strength and weight requirements would be the best approach. Balsa has great compression and tension resistance in one plane but is very weak in the other planes. FB has good tension properties but fails in compression. Plywood has great tension and compression properties in multiply directions but is really a little heavy as it often carries laminations that are set at angles, (by the construction), that are not load bearing and only provide a degree of support against deformation.

Other materials have better properties but tend to be rather brittle and lack resilience.

On other concern in material selection is the jointing or materials. Balsa tends to rip or splinter around its glue joints of even fail well away from the joint by splintering. Plywood not only breaks but its also tends to delaminate at the point of failure. FB crushes and tears whereas FGlass, CF, and 3D printed plastics seem to shatter. My current work into structures is to improve the security of the material joints, stress transfer from the joints and joint security under impact forces through material selection and design.

Simply put you can build out of anything! The best build will use a multitude of different materials each selected as best for purpose. (Purpose can include price, availability, and tooling requirements). There is NO superior material but rather each material should be seen as having advantages and disadvantages. You chose based upon maximizing the advantages and minimizing the disadvantages.

I still build using FB BUT by using many other materials I now build at about half the weight and with far greater strength/durability.

Just a few thoughts!

Have fun!
 
#20
Just one more comment or thought for you. The shape of the structure is what flies and the weight should only be adequate to maintaining the shape. You can build a plane out of almost anything but the real trick is to build the structure strong enough and light enough.

many people tend to be sort of stuck in a single technique or 2 and have their own material preferences. With the modern range of available materials the planes we fly should be engineering marvels but sadly they tend to be built full of compromises and often far too much material and hence weight.

Using the properties of the various materials and selecting the material, for each and every part, in relation to its strength and weight requirements would be the best approach. Balsa has great compression and tension resistance in one plane but is very weak in the other planes. FB has good tension properties but fails in compression. Plywood has great tension and compression properties in multiply directions but is really a little heavy as it often carries laminations that are set at angles, (by the construction), that are not load bearing and only provide a degree of support against deformation.

Other materials have better properties but tend to be rather brittle and lack resilience.

On other concern in material selection is the jointing or materials. Balsa tends to rip or splinter around its glue joints of even fail well away from the joint by splintering. Plywood not only breaks but its also tends to delaminate at the point of failure. FB crushes and tears whereas FGlass, CF, and 3D printed plastics seem to shatter. My current work into structures is to improve the security of the material joints, stress transfer from the joints and joint security under impact forces through material selection and design.

Simply put you can build out of anything! The best build will use a multitude of different materials each selected as best for purpose. (Purpose can include price, availability, and tooling requirements). There is NO superior material but rather each material should be seen as having advantages and disadvantages. You chose based upon maximizing the advantages and minimizing the disadvantages.

I still build using FB BUT by using many other materials I now build at about half the weight and with far greater strength/durability.

Just a few thoughts!

Have fun!
This should be pinned somewhere. Nothing I didn’t know but stated with a certain clarity.