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Author Topic: Flapper foam types?  (Read 409 times)
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mWang12324161
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8th grader from North Carolina interested in F1N.



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« on: July 22, 2019, 01:20:02 PM »

Hello!
I am trying to build a small-scale flapper glider with a wingspan less than 30 cm. I have heard of a few types of foams (Depron, pro formance, durobatics), but can anybody tell me which is the best for flapper gliders and how thin I should sand the foam to? Many thanks.
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Max Wang
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« Reply #1 on: July 23, 2019, 07:50:20 AM »

Durobatic if you can find it. 
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mWang12324161
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8th grader from North Carolina interested in F1N.



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« Reply #2 on: July 23, 2019, 08:22:45 AM »

Thanks!
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Max Wang
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« Reply #3 on: July 23, 2019, 10:02:56 AM »

The best foam I know of right now is Dollar Tree foam board. It has a paper backing both sides that must be removed. Either soaking in water or spraying with rubbing alcohol will loosen the paper (I can't remember which).

It's about 3/16" thick so it will require a lot of sanding. I would go for about .030" at the flap joint and taper to .020" at the trailing edge.

I would look for some plans for SO gliders that meet the rules. Here's the one I designed for the first year that gliders were flown. There was no minimum weight that year so everything on this plan could be scaled up in weight to meet whatever the rules say. With heavier wood you can leave off all of the diagonal carbon tow and possibly the spanwise tow as well.
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Re: Flapper foam types?
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spr
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« Reply #4 on: August 06, 2019, 05:00:38 AM »

Graupner's  Vector Board is an interesting new foam.  https://www.graupner.com/Accessories/Construction-Materials/Vector-Boards/

We have built several 300 mm indoor CLGs with 0,5 mm VB flaps and it seems to work well. No sanding neccessary, can be glued with standard cyano.  I guess JHaerospace has used it VB too in their glider kits.
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Olbill
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« Reply #5 on: August 06, 2019, 09:34:36 AM »

I haven't tried VB yet but it looks promising. Gluing with CA is a plus but I would probably go with UV glue b/c of the easy alignment.
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bjt4888
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« Reply #6 on: October 09, 2019, 01:50:57 PM »

Spr,

I’ve seen some European catapult glider designs indicating 1 mm vector board. You mention 0.5 mm for 300 mm span.

In your experience, is the 1 mm flexible enough for flaps? Are people sanding the 1 mm to lighten and make more flexible on these designs? Or, is unsanded 0.5 mm better?

Brian T.
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spr
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« Reply #7 on: October 09, 2019, 04:05:09 PM »

Brian,
I do not have any experience of 1 mm Vector board, I have just 0,5 mm stuff.

 VB material cannot be sanded, it is kind of rubberish and does not sand at all. I think 1 mm stuff might be better for F1N, but for smaller clg flaps I suppose 1 mm is a bit too stiff.

My best time in Cat II hall with 300 mm span, 3 gram CLG with 0.5 mm VB flaps is 48 seconds. Bunts nicely to glide so I suppose the flaps function as they should.

Simo
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bjt4888
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« Reply #8 on: October 09, 2019, 07:21:14 PM »

Simo,

Thanks very much for the additional info. I’m thinking that I’ve seen vector board and just didn’t realize it. I believe that J&H Aerospace uses this foam on their Science Olympiad catapult glider.

I’m considering graupner for gliders for middle school students in order to hopefully avoid sanding. I’m still undecided though as I have been getting very good results sanding 1 mm Great Planes ProFormance foam. It is about 40 minutes of sanding though.

Brian T
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SyLa-20871
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« Reply #9 on: October 09, 2019, 10:53:00 PM »

Simo,

Thanks very much for the additional info. I’m thinking that I’ve seen vector board and just didn’t realize it. I believe that J&H Aerospace uses this foam on their Science Olympiad catapult glider.

I’m considering graupner for gliders for middle school students in order to hopefully avoid sanding. I’m still undecided though as I have been getting very good results sanding 1 mm Great Planes ProFormance foam. It is about 40 minutes of sanding though.

Brian T




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