Is foamboard really too heavy?

[quorneng]

The original Depron is no longer made even by Depron. They now make a EPS sheet that is softer and rather more flexible like the stuff you get from Hobby King and others but it is still available.
My latest alternative is 5 mm XPS sheet that is used as an underlay for laminate flooring. Light, rather soft yet a bit brittle so not a direct substitute for FT foamboard. Readily available and fairly cheap in DIY stores but you have to buy a pack of 20 sheets so you end up building a lot of planes but if you get good using it the sky is the limit.
My latest is a 34" span Hawker Hunter F6 with a 50 mm EDF.

No balsa or carbon in it at all although the duct and nose cone are printed. The canopy is the battery hatch.
It is so light (for an EDF) it hand launches with ease and belly landing on grass is no problem either.

 

[Hondo76251]

The original Depron is no longer made even by Depron. They now make a EPS sheet that is softer and rather more flexible like the stuff you get from Hobby King and others but it is still available.

Thats more or less what i came up with in my investigation. I have a sheet or two of very thin(3mm?) very firm/stiff (if somewhat brittle) stuff that i got a long time ago. If i could ever find a good substitute for that id be thrilled but it doesn't seem to be in the cards.

No point in sourcing rare material for a build, Not much fun in sharing a plane made of un-obtainium. Looks like the hotwire cutting is gaining popularity, should probably focus on that i suppose.

 

[SSgt Duramax]

Its really weird, because when I show up to my club with a foamboard scratchbuilt aircraft, all the oldies marvel at how some kid has made a what seems to be similar to an aircraft, and can fly.... usually. I am known at the club as the kid that shows up with the most jankiest aircraft, and they are genuinely interested, and often end up giving me a lot of their stuff, even though I don't really need it or want it. I mean some of them occasionally try to say a few thing which they think will help me, but they are usually what somebody else was saying about making it over complicated, for example: "Oh maybe you should have used some wood for a spar instead of foam" and "its a good idea to double the esc amps becuase that gives you more room to breath" stuff like that, its just over complicted and adds weight. Foamboard is a light building material, and also decently strong if you build right, so you don't need all of this super strong stuff to make it heavier.


Did anyone read all of this or am I alone right now..... probably?

Don't worry, I read it. There was some talk on RCG last night about people hating on 3D printed planes. The real question you need to ask, is who are you building for? Are you building to impress onlookers and other old fogies at the club, or are you doing it for yourself? Now, I would say foam board building has a lot of positives over a 3D printed plane. Printed planes get a bad rap, because depending on how they are printed and constructed, they can shatter when they hit the ground, and they can be heavy, and they can be tough to put together or print out.

No one has really perfected it yet. I have one that doesn't shatter when it hits the ground, but it is on the porky side, and doesn't fly that great unless it is booking it. My model D flew fine, but a less than stellar motor mount broke, and the plane tipstalled and lawndarted about 6 feet off the ground, the fuselage shattered and was trash (the absurdly overbuilt wing survived just fine). I have a 3D printlab plane I have yet to fly, and it may be on the fragile side, but it looks great.

So there are lots of pros and cons, and I typically try not to overbuild my planes too. My big ole nightfury doesn't have a wooden spar, and flies just fine and doesn't break. I have only snapped one wing, and it was a tiny trainer wing on a heavier pusher plane. That one little strip of packing tape just didn't do it, and the hot glue let go at the seam.

I've only fried one ESC, and that was a 20a ESC trying to run a 6045 prop on a 1806 and 3S AKA something stupid I knew better than to do. It isn't completely fried, but the motor will cut out everytime you get off the throttle and need a restart.

Thats more or less what i came up with in my investigation. I have a sheet or two of very thin(3mm?) very firm/stiff (if somewhat brittle) stuff that i got a long time ago. If i could ever find a good substitute for that id be thrilled but it doesn't seem to be in the cards.

No point in sourcing rare material for a build, Not much fun in sharing a plane made of un-obtainium. Looks like the hotwire cutting is gaining popularity, should probably focus on that i suppose.

I need to get on the hotwire thing. I don't need anymore crap in my garage, the best solution would be a bigger garage, but I don't have the land for that right now.

 

[Hondo76251]

Ive got a printer, have yet to set it up. Been too busy (for over a year now i guess 🤦‍♂️) but its not really my style so i haven't felt compelled yet. I can, however, envision a plane made of foamboard with 3d printed spars, formers, and key reinforcement that would be bad@$$. A perfect combination of techniques by by estimation. (Maybe a hotwire cut and sanded nose cose and wingtips 😉)

Beauty of the hotwire thing is that it looks like it shouldn't have to to take up a ton of space if done carefully.

Can i do carefully?

Clearly not...

 

[SSgt Duramax]

Ive got a printer, have yet to set it up. Been too busy (for over a year now i guess 🤦‍♂️) but its not really my style so i haven't felt compelled yet. I can, however, envision a plane made of foamboard with 3d printed spars, formers, and key reinforcement that would be bad@$$. A perfect combination of techniques by by estimation. (Maybe a hotwire cut and sanded nose cose and wingtips 😉)

Beauty of the hotwire thing is that it looks like it shouldn't have to to take up a ton of space if done carefully.

Can i do carefully?

Clearly not...

I was thinking the same about the 3D print hybrid. Perfect formers, 3d print all the curvy parts, the rest of the straighter stuff with foam. I think if done well it could actually be pretty modular.

 

[Bo123]

Yeah about depron I still have trouble finding it, as hobbyking don't sell their 5mm stuff anymore, and the 3mm stuff is too thin. I still do like depron, however when building the plane still gets a little damaged just from moving around.

 

[Bo123]

I was thinking the same about the 3D print hybrid. Perfect formers, 3d print all the curvy parts, the rest of the straighter stuff with foam. I think if done well it could actually be pretty modular.

Andrew Newton made a Macchi with 3D printed formers and using depron strips to sheet it like a boat, then sanding down a little and still getting that nice curved shape.

 

[Hondo76251]

As was mentioned "depron" is a brand, like how we refer ro Kleenex.

How much different is DTFB or FTFB when stripped of paper to "depron" as its commonly referred? 🤔

 

[Bo123]

Depron is much less dense than FB when stripped of the paper, at least for the FTFB.

 

[Hondo76251]

Depron is much less dense than FB when stripped of the paper, at least for the FTFB.

Thats what i was wondering. Ive had other "depron" i had ordered and i was not sure what to do with it really. I just stuck with FB. Whatever this really thin stuff i have is, I'd like more of it but it sure doesn't seem to be what most are referring to as typical "depron"

 

[quorneng]

This 3 mm sheet and printed formers do work well.
A printed former is so stiff it only needs to be a 'ring' so the fuselage ends up substantially hollow.

The fuselage of the Antonov AN2 in my avatar is done that way.

When the 3 mm foam skin is complete it provides all the strength and stiffness.
Of course the AN2 is a good subject for this type of construction as it has a big fuselage.

 

[Mr NCT]

This 3 mm sheet and printed formers do work well.
A printed former is so stiff it only needs to be a 'ring' so the fuselage ends up substantially hollow.
View attachment 224892
The fuselage of the Antonov AN2 in my avatar is done that way.
View attachment 224893 Lo
When the 3 mm foam skin is complete it provides all the strength and stiffness.
Of course the AN2 is a good subject for this type of construction as it has a big fuselage.

Love the AN2! Saw one on the ground in Detroit. It made the Cessnas parked next to it look like toys.

 

[Buzzardmodels]

As was mentioned "depron" is a brand, like how we refer ro Kleenex.

Yes, absolutely, Depron is a registered trademark. Greg Tanous of rcdepron.com in Texas imports the stuff directly from Germany and sells it by the case and partial case. Depron was once imported by the now defunct rcfoam.com, and was available in two different types; standard "Depron", and "Depron AERO".

For a while, HobbyKing sold various thicknesses of "Aero-modelling Foam Board" It was not Depron. It was complete garbage, super brittle, and impossible to bend.

The current Depron is different than the old stuff, it weighs the same, but the mechanical properties are a bit different. It is slightly more flexible, and way more durable. In my opinion it is a good tradeoff, and closer to an ideal building material. Kind of a cross between the "old" stuff and EPP.

Here is a list of the densities of the "old" vs. "new" Depron.

 

[Hondo76251]

Yes, absolutely, Depron is a registered trademark. Greg Tanous of rcdepron.com in Texas imports the stuff directly from Germany and sells it by the case and partial case. Depron was once imported by the now defunct rcfoam.com, and was available in two different types; standard "Depron", and "Depron AERO".

For a while, HobbyKing sold various thicknesses of "Aero-modelling Foam Board" It was not Depron. It was complete garbage, super brittle, and impossible to bend.

The current Depron is different than the old stuff, it weighs the same, but the mechanical properties are a bit different. It is slightly more flexible, and way more durable. In my opinion it is a good tradeoff, and closer to an ideal building material. Kind of a cross between the "old" stuff and EPP.

Here is a list of the densities of the "old" vs. "new" Depron.
View attachment 224920

good info!

I may have to look into that 🤔

 

[Foam Folder]

Don't see that foamboard is heavy, I always reinforce with 3/16" square spruce strips, landing gear to motor mount and cab. Lighter than a Timber, about the same weight as a Fun Cub. I like 60" for the Cub wing span. Takes off in about 4' also lands much slower than a Timber.