[smoknrv4]

What are some pros and cons with these types of foams for indoor flying, I've only ever built with Depron, but I notice the EPP foam is much cheaper, I know the grain structure is more "open" like regular Styrofoam, so its probably lighter. Some input would be appreciated on this subject, from someone with experience with both.
Thanks

[philipa_240sx]

Pros:

- EPP is lighter but the additional weight for bracing negates some of that. Attached is a chart comparing various foam densities (courtesy Gene Bond on RCG)

- It bounces like a Nerf ball upon impact with little to no damage. Hence why it's popular for 3D indoor planes.

- Generally unaffected by the solvents in most glues.

Con's

- EPP is more flexible than almost any other type of foam and requires bracing to make it flyable. It's not enough to simply convert a Depron model to EPP... the entire design must be thought out in terms of CG, foam thickness, etc

- Paint doesn't stick quite as well

- EPP cannot be sanded... it just fuzzes up.

- It absorbs water so it will become heavy if submerged. Not a problem indoors unless you've figured out how to float fly from a pool!


Those points aside, working with both types of foam is similar.

[foamball]

I like the EPP better than Depron... It is more resiliant to bumps and grinds, and a porable hotmelt glue gun is the only thing I need, if the goof was bad enough..
Have built Nutballs, Darts, Discs and what have you from EPP and it's my choice of materials.... Yes, some downfalls, but the bouncy resilance to it makes up for the "Cracking Depron"...
My thoughts anyway....

[philipa_240sx]

I agree foamball,

Built properly, EPP can be fun to fly and it takes a beating. Hot melt glue makes for fast (but heavy) repairs.

The trouble sometimes is finding EPP. There is only one LHS near me that carries it. Ordering from the US is sometimes too expensive when you only need 2-3 sheets.

[smoknrv4]

I guess trussing the fuse and carbon spars are the way to go if using EPP for indoor.

[philipa_240sx]

Originally Posted by smoknrv4

I guess trussing the fuse and carbon spars are the way to go if using EPP for indoor.

Pretty much. The trick is adding just enough bracing to the right places. These models are good examples.

'The Nasty'

http://www.rcgroups.com/forums/showthread.php?t=390003

'Slofly'

http://www.wattflyer.com/forums/showthread.php?t=2601

[LuvEvolution7]

I'm new to the whole Depron scene, so I have a question that's in line with the thread...........where do you buy Depron from? is there a place to buy it in bulk in southern Ontario, or are you stuck buying in small quantities at a LHS? bulk would obviously be much better and cheaper than the LHS route. thanks for any info.

Rich

[smoknrv4]

I have bought from RCFoam a couple of times and its fairly reasonable for boxes of 10 sheets, they also sell CF rods and other building supplies also.

http://www.rcfoam.com/?gclid=CN3lnrrQq5ECFQUalgodiGEodw

[j3_av8r]

Originally Posted by philipa_240sx

I agree foamball,

Built properly, EPP can be fun to fly and it takes a beating. Hot melt glue makes for fast (but heavy) repairs.

The trouble sometimes is finding EPP. There is only one LHS near me that carries it. Ordering from the US is sometimes too expensive when you only need 2-3 sheets.

I agree that EPP is remarkable stuff. A few of us at work have been combat flying Superflies for the last few years. And we don't use streamers. It was all physical contact. We are so rough on them. And once in a while you would break out a big chunk. But just hot glue it back together and keep going. I don't think I have ever laughed so hard while flying.

A few years ago I purchased a big block (something on the order of 3ft x 5 ft x 6 in thick) of EPP from Morval in Kitchener. http://www.morval.com/. If you have access to a foam cutter, you can make a lot of sheets out of a block like that!

[herbiehoss]

The Germans have developed a special adhesive for hobby materials (balsa, plastic, hardwood, plywood, film, metal, Depron etc.). Is incredibly good.