Expanding Foam with Molds?

[Snelson5254]

Hello All,
I am relatively new to the hobby and I have yet to scratch build my first plane. I want to investigate the feasibility of using expanding foam from a can (brand name "Great Stuff") as a construction material for an RC plane, assuming I had suitable molds (which I plan on 3D printing). I looked around and found only limited examples of its use in the hobby, so I wonder what you all think. Thanks

 

[Piotrsko]

If you use molds for skins, maybe ok, but expanding foam is really pricey and not very dense so not very strong. If you are printing skins just make them a bit thicker

 

[Hai-Lee]

Hello All,
I am relatively new to the hobby and I have yet to scratch build my first plane. I want to investigate the feasibility of using expanding foam from a can (brand name "Great Stuff") as a construction material for an RC plane, assuming I had suitable molds (which I plan on 3D printing). I looked around and found only limited examples of its use in the hobby, so I wonder what you all think. Thanks

Sadly the expanding foam has a few known issues. First it can be quite heavy or if used sparingly the structure is quite weak. Unfortunately the expanded foam does not have uniform density and so occasionally the trapped gas pockets can be quite large without any surface indication.

You can use it but as a outer finish over an internal framework or the like. if you do use it make sure you test your mold release agent is effective because sticking to the mold is quite common!

Otherwise go for it!

Have fun!

 

[Snelson5254]

Sadly the expanding foam has a few known issues. First it can be quite heavy or if used sparingly the structure is quite weak. Unfortunately the expanded foam does not have uniform density and so occasionally the trapped gas pockets can be quite large without any surface indication.

You can use it but as a outer finish over an internal framework or the like. if you do use it make sure you test your mold release agent is effective because sticking to the mold is quite common!

Otherwise go for it!

Have fun!

This is very good to know, and it will change how I approach this project. Thank you very much!

 

[The Hangar]

You can use it for filling in gaps in your airframe to make it more durable for combat, but other than that it probably won’t make much of a difference other than add weight.

 

[Merv]

If you are going to the trouble to make 3D molds, you should consider fiberglass or carbon fiber.

 

[bracesport]

the 3D printed parts I have made in PLA work well with a 1mm wall section (no foam) - there are so many techniques that can be mixed and matched - there is nothing wrong with experimenting!