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Hi All, I'm new to the Rocketry Forum and had a question

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Rktman

Eric
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Hi All, I'm new to the Rocketry Forum and had a question: has anyone tried foamcore (aka Foam Board) for fins or glider wings (especially the delta shaped models) and if so, how does it compare to balsa in terms of its strength/weight ratio for low-power rockets (A, B, or C engines)? It's plentiful in 1/2" and 3/16" thicknesses at hobby and art stores, there's no wood grain to sand and finish, and is easily cut, shaped, and painted.
 

gpoehlein

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Yes - a number of people have used both foam core and depron sheets (from Midwest - think of foamcore without the paper) for both. More for wings and even centering rings. The main problem is finding foamcore that isn't warped. Too often there will be a distinct curl to the sheets. This seems to be worse (from my experience) if the board is stored standing on its edge. Also, it isn't quite as stif as balsa or ply, and larger fins and wings can flutter a lot. Slower launching gliders can work, but as fins for any rocket large enough to use the thicker fins, it could lead to fin shredding. There are a few builders who have built large fleets of radio controlled rocket gliders from foam core and depron (AstronMike comes to mind immediately).
 

Incongruent

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Hi All, I'm new to the Rocketry Forum and had a question: has anyone tried foamcore (aka Foam Board) for fins or glider wings (especially the delta shaped models) and if so, how does it compare to balsa in terms of its strength/weight ratio for low-power rockets (A, B, or C engines)? It's plentiful in 1/2" and 3/16" thicknesses at hobby and art stores, there's no wood grain to sand and finish, and is easily cut, shaped, and painted.
I haven't used it for glider wings or fins, but it is weaker than balsa. I know that foam core is used for lightweight centering rings, but they're weaker as well as lighter. I'm not sure how strong they would be if the weight were matched, though.

If you want to eliminate wood grain, you can paper the balsa. A tutorial can be found here:
http://www.rocketryforum.com/showthread.php?65628-Papering-balsa-ply-Fins-A-foolproof-method
 

Rktman

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Yes - a number of people have used both foam core and depron sheets (from Midwest - think of foamcore without the paper) for both. More for wings and even centering rings. The main problem is finding foamcore that isn't warped. Too often there will be a distinct curl to the sheets. This seems to be worse (from my experience) if the board is stored standing on its edge. Also, it isn't quite as stif as balsa or ply, and larger fins and wings can flutter a lot. Slower launching gliders can work, but as fins for any rocket large enough to use the thicker fins, it could lead to fin shredding. There are a few builders who have built large fleets of radio controlled rocket gliders from foam core and depron (AstronMike comes to mind immediately).

gpoehlein Appreciate the feedback gpoehlein. Looks like the model aircraft builders use the thicker depron foam stuff reinforced with wood and carbon fiber, but a rocket--even a smaller one--is subject to more G-force stress and weight is more of a consideration for getting enough height for proper recovery deployment. Guess I'll stick with balsa and basswood for the most part, but may experiment with foam for the smaller delta wing variety of gliders that utilize the mini motors.
 

Rktman

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Thanks for the tip Incongruent. I've tried the glue stick method for attaching tissue over balsa as well as using a very thin (squeegeed almost dry) layer of white glue like Elmer's and it works ridiculously well. The article you referred gave me an even better method to get balsa and paper together. No worries about trying to align precut paper shapes and their edges with the fin edges, just lay the glue down on the penned in outline on a sheet of paper (and you can get as messy as you want now) and press your fin onto it. (Slap forehead) why didn't I think of that? No more concerns about misaligned paper/balsa edges and glue smears where you don't want it. Just trim your fin out and do the same to the other side. All nice and tidy. Sure beats the tedious multiple coats of filler and sanding and having to inhale those fumes.
 

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There's a guy who flys at METRA and CATO who uses foam board from a box store to make his entire rocket. I think his preferred adhesive is duct tape. A couple of years ago I called it "Foamy" because it didn't have a name. He's found the speed of foam (a fast I) and does some really cool H flights. Can't wait to see when he starts doing some of the slow J's.
 

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I've used foam core on quite a few of my rockets with larger than normal fins. That said , I always have a balsa or bass leading and trailing edge as well as the tip. Big wood fins can weigh a lot compared to foam and you can gain a cg advantage with foam. The problem comes with the fin shape. The more swept the fin the better and thus less flutter. At least in my experience, a swept trailing edge is preferred. As far as a delta wing is concerned, they are not really prone to flutter(as long as the airfoil is true). Tip flutter may be a concern but the wood leading, trailing , and tip should be stiff enough to take care of that problem. I'm currently in the design process of a large F-106 with that build technique.--H
 

Rktman

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That's really encouraging, thanks for the feedback cbrarick (and yes, although duct tape is the butt of a lot of jokes, it's actually pretty amazing stuff. It's tough and the fabric reinforcing makes it pretty much bulletproof. I've seen it used for RC planes and rocket glider hinges really successfully).
 
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Rktman

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I've used foam core on quite a few of my rockets with larger than normal fins. That said , I always have a balsa or bass leading and trailing edge as well as the tip. Big wood fins can weigh a lot compared to foam and you can gain a cg advantage with foam. The problem comes with the fin shape. The more swept the fin the better and thus less flutter. At least in my experience, a swept trailing edge is preferred. As far as a delta wing is concerned, they are not really prone to flutter(as long as the airfoil is true). Tip flutter may be a concern but the wood leading, trailing , and tip should be stiff enough to take care of that problem. I'm currently in the design process of a large F-106 with that build technique.--H
Those are good points to know and keep in mind thanks. I was thinking of using it for smaller scale delta wing rocket gliders that wouldn't experience the same kind of G force stress that thin wings would. I began thinking about foamcore while scratch building a tube finned rocket and seeing how far back the CG shifted with the weight of both the 1/8" balsa support struts and tube ring together. Would enjoy seeing how your F-106 turns out!
 

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Ho Heck Yes!
Foam Core has been used in Mod-Roc Gliders for decades. If memory serves the first time I saw it used was in the early 1990's a thing called " The Space Camel" a D12 powered boost glider. As I recall it didn't fly well for me but that's because I'm an awful Glider builder! Others seemed to have no trouble getting the thing to glide.

Robert Edmonds (Edmonds Aerospace) has built quite a few experimental Large wing area gliders using 1/8" and 3/16" FoamCore. Most worked pretty well in testing.

I used 3/16" FoamCore for the wings of a Micro T4 (.488") body DownScale SkyDart trying to get the overall Mass down for single MMX-II power. Still flew much better when Boosted on a Chad Staged 13mm Oop A10-0T booster motor LOL!

Lots of TFR's Glider experts use Foam Core for the entire gliders. Check out the Scratch built forum for more info.

142-sm_Space Camel D BG (NO-Good)_10-03-93.jpg


240b1-sm_MM BoosterStages13-6mm Staged MM Skydart_09-06-06.jpg
 

Rktman

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I love this forum! Appreciate all the feedback and advice Micromeister. Given your experience I now want to try larger glider models using the thicker carvable foam sheets that I see RC plane builders using. Maybe incorporate spruce or carbon fiber reinforcing in key areas. And thanks for the tip about the scratch built forum, I wasn't aware there was one (I've only had about an hour's worth of time to poke around this site -- there's so much here that I haven't seen yet).
 

aerostadt

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You need to scroll down to Rocket Boosted Gliders and look at Frank Burke's posts. He has built a small company DynaSoar Rocketry and sold over 200 kits based on rocket gliders using 6 mm depron and the E6 motor. The long burn and low thrust of the E6 motors allows the rocket gliders to withstand the boost phase quite well.
 

Rktman

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Thanks dr wogz that's a new one to me, never heard of that product before. How's it compare in weight to foamcore, and can CA be used on it without melting/damaging the coroplast?
 

Rktman

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You need to scroll down to Rocket Boosted Gliders and look at Frank Burke's posts. He has built a small company DynaSoar Rocketry and sold over 200 kits based on rocket gliders using 6 mm depron and the E6 motor. The long burn and low thrust of the E6 motors allows the rocket gliders to withstand the boost phase quite well.
Thanks aerostadt, just bookmarked the site. Really good to know that the material can successfully be used with the right design and engine combo!
 

dr wogz

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Thanks dr wogz that's a new one to me, never heard of that product before. How's it compare in weight to foamcore, and can CA be used on it without melting/damaging the coroplast?
Although I have a SPAD kit, I have not yet built it.

weight, I think they're pretty equal.. Coroplast is relatively hollow. Strength wise, it's pretty durable, until you 'force' a bend into it along the flutes. And yes, you can glue it (CA) but 'they' recommend you 'flash' it to remove the shine. (They suggest a very quick blast from a torch, like a Benzo type thing use d for plumbing, to get rid of the shiny surface film)

read up a bit on the page, and you should find the assembly tips..


And yes, usually after an election, the stuff is "free"!! (I've seen a "master card" plane at a local meet, as well as one for a lost candidate..)
 

gpoehlein

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Thanks dr wogz that's a new one to me, never heard of that product before. How's it compare in weight to foamcore, and can CA be used on it without melting/damaging the coroplast?
As to what it is, think of corrigated cardboard but made from polyethylene instead. Most coroplast I've seen does seem to be made from polyethylene (the stuff milk bottles are made from) and have a "slick" feel to them. PE can be tough to glue and to paint because there aren't a lot of things that really like to stick to it well. I've never built anything with it, so I don't know what glues and paints to use.
 

Rktman

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Thanks man, appreciate the feedback. Don't think I can wait for the free stuff, but I'll keep that in mind in 4 years haha.dr wogz
 

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