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Old Nov 13, 2003, 01:52 PM
Mighty Dingus is offline
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Balsa vs. Depron weight...


How much heavier is Balsa than Depron (zepron, FFF, etc...)?

I have a Potensky Eagle that had the control horns pull out of both the elevator and rudder. Both were white foam (similar to FFF). It was suprisingly stiff, but kept cracking no matter how many times I glued the horns back in.

I replaced them both with 3/16" balsa, but now the plane is very tail heavy. I moved the battery (2s2p Etec 1200's) 2" forward, but it's still tail heave. Obviously, the balsa is much heavier.

My question is: If I find the standard blue fan fold foam, is it going to be as heavy as the Balsa? Will it be stiff enough to work as large surface Elevator and Rudder? Obviously, I have no experience with Bluecore, FFF, Depron, etc.


Any suggestions will be greaty appeciated.


Blackwood
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Old Nov 13, 2003, 02:02 PM
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i would go for 3mm depron, for its weight is very stiff and weighs much less than balsa. look at the 'mini gee bee' in door prop hanger with really big control serfaces made from 3mm depron.

t.n
Old Nov 13, 2003, 02:20 PM
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Use the Depron. Balsa of all grades is usually heavier, but it depends upon the balsa sheet thickness. Thinner balsa sheets tends to be more dense than thicker sheets.
Old Nov 13, 2003, 03:22 PM
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Now the trick is finding Depron tonight. I hate having a plane sitting there waiting for me to fly it... All it needs is about 10 mintues of work to get the new Tail feathers on it, if I can find Depron locally.

Thanks for the help.


Blackwood
Old Nov 13, 2003, 03:29 PM
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I have a question about Depron.

Does the material react to CA glues or anything else that I need to be wary of? I'm planning on building a EDF Jet out of the stuff (6mm for structural and 3mm for wings and skin) and I'd like to know if you can bend it with heat - I.E. a hair dryer. ANY Help you can provide will be greatly appreciated!!!
Old Nov 13, 2003, 03:50 PM
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being a sheet metal worker i made some metal formers and made some wing and fusalage sections, all i did was trap the depron between the metal formers the put it in the oven on its lowest setting for 5 min. going to experiment more as soon as i have finnished building my back log of models
so it can be done but not with a hair dryer i think as the shape needs holding long enought for it to cool to a temp where it will hold its shape.
also an electric oven is best as the heat is more even.
heres my trial fusalage section.

when are they going to include spell check
Last edited by t.nollett; Nov 13, 2003 at 03:53 PM.
Old Nov 13, 2003, 03:51 PM
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and a wing skin
Old Nov 13, 2003, 06:56 PM
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RcParkflyer,normal CA will not work on depron,FFF or any other form of EPS.You will need "odorless" CA, Gorilla Glue, white "school" glue, or epoxy.

As far as heat forming it,a hair dryer will probably not get hot enough.A heat gun, like for stripping paint or for monokote will work.Doing it by hand can be a challenge,though. I build and sell a bipeplane made from depron,and heat form the wings and the curved parts of the fuselage in the oven. I made forms much like t.nollett does. I bake mine at 200-225 for about 10 -15 mins,Then pop them right out of the hot molds,no need for cooling the molds.Hope this helps.

Len
Old Nov 13, 2003, 07:50 PM
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Blackwood, you might consider making a small doubler for your control horn to control surface joint. A doubler will spread out the point loads of the horn to a larger area of the foam, making it all stronger.

A small square of 1/64" plywood glued to the cracked area of the control surface, with the horn glued to a hole in the plywood would fix all your problems.

This would be a good idea even if you make new Depron control surfaces.
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Old Nov 13, 2003, 07:54 PM
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Hey Dingus, I have alot of 3mm Depron... Could probably hook you up with some.

BC
Old Nov 13, 2003, 09:46 PM
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I picked up a sheet of Sturdy Board. It seems pretty light and stiff, and more importantly, it's the only thing I could find.

BCripe1, I work in Lake Forest and live in Huntington Beach. What would be a good time to get together? Give me a call if you can anytime at 714 404-7710. I'd like to use Depron and do it right.


Thanks.


Blackwood
Old Nov 14, 2003, 01:08 AM
Mikey C. is offline
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Noob question: Is Depron the same material that styrofoam plates are made from? I've used the styro plate material for control surfaces and tail feathers for some of my bashed-together models, and it seems to work fine.

-Mike
Old Nov 14, 2003, 06:43 AM
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Mikey: Basically, it's the same. The Depron, SturdiBoard, Zepron or Fan Fold usually does not have the hardened skin like the plates and other vacuum formed finished goods do. If you bake it in a form, as mentioned above, it will skin over and become much stronger (and brittlle).
Old Nov 14, 2003, 10:44 AM
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I don't know how much everyone else does this, but when I make a wing using the core of sturdy board (kind of like depron) I just cut a top and bottom piece and create a spar out of 1cm balsa. I taper it at the tips and sand the edges of the leading and trailing edges that will be on the inside of the wing. Next I just place tape on the outward facing side of each wing side (top and bottom) and bend a little by hand. All you have to do then is glue the spar in place on the bottom, and glue the two wing halves together. If you look for Tyson in the foamies or parkflyer sections then you can see it all step-by-step on a Fiddler's green Spitfire he had done.

RG
Old Nov 15, 2003, 02:57 AM
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Thanks, Gene. That answers my question perfectly.


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