Using foam for fillet  
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Using foam for fillet - 12/11/2007 8:27:14 PM   
Skypoint



Posts: 140
Joined: 6/18/2002
From: Plano, TX, USA
Status: offline 		Hi Gang,

I'm building a Wendell Hostetler 29% Gee Bee Zee from plans, and he's calling for urethane foam for the wing fillets, then covering them in 1/16th balsa. I've not used foam of any type before, (the Zee has very large fillets) and would like to know what's best to use, along with how to best shape and attatch the stuff.

Thanks for your help!

Jim

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RE: Using foam for fillet - 12/12/2007 2:30:43 PM   
Deadeye



Posts: 3630
Joined: 7/16/2002
From: Conrad, MT, USA
Status: offline 		Urethane foam is the stuff they use for insulation in the spray cans. It expands after it is sprayed. Shape with a razor, and sand. You might get better answers posting this in the scale forum. Good luck.

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RE: Using foam for fillet - 12/12/2007 3:19:30 PM   
OldScaleGuy



Posts: 752
Joined: 12/19/2005
From: Seymour, IN, USA
Status: offline 		With large fillets, I would use balsa blocks. I would be concerned that the foam would be easily damaged just from handling the plane even with 1/16 sheeting over it.

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RE: Using foam for fillet - 12/12/2007 3:24:05 PM   
LesUyeda



Posts: 927
Joined: 10/10/2002
From: San Diego, CA, USA
Status: offline 		That spray can foam is really pretty tough stuff, but it continues to expand for a considerable time. I filled the insides of a vacuum formed pilot bust with it, and a month later it was starting to come apart at the seams.

Les

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RE: Using foam for fillet - 12/15/2007 3:33:00 PM   
Skypoint



Posts: 140
Joined: 6/18/2002
From: Plano, TX, USA
Status: offline 		Thanks for your help guys! I found out about a product called Superfil from Stits. It's light, doesn't shrink, and sands easy so they say.

Jim

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RE: Using foam for fillet - 1/5/2008 1:51:48 PM   
beenie



Posts: 376
Joined: 10/16/2002
From: Baton Rouge , LA, USA
Status: offline 		I have used styrene foam for fillets in smaller planes with no problems. I usually just fiberglass over it and it has been fine. Covering in balsa and then fiberglassing will most likely insure you from any reasonable handling damage.

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RE: Using foam for fillet - 1/15/2008 6:18:21 PM   
deckerv



Posts: 796
Joined: 5/16/2002
From: Wellsville, NY, USA
Status: offline 		Wonder if he's referring to this stuff...
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXBH62&P=0

Would think a large dowel wrapped in sandpaper would help shape it well, though I've yet to use this stuff.


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RE: Using foam for fillet - 3/9/2008 3:30:25 AM   
Texan



Posts: 468
Joined: 12/20/2001
From: Georgetown, TX, USA
Status: offline 		Jim,

I used green "floral" foam from the craft shop to shape fillets for my Pitts Super Stinker. It is very easy to work with, just harden the material with thin CA and kicker. I follow-up with a thinned mixture of epoxy and milled fiberglass. Sand the high spots then fill as usual.

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< Message edited by Texan -- 3/9/2008 3:33:05 AM >

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RE: Using foam for fillet - 3/9/2008 2:57:50 PM   
Campy



Posts: 3372
Joined: 1/2/2002
From: Baltic, CT, USA
Status: offline 		The floral foam (green) or the pink or blue sheet foam (Home Depot, Lowes) will work quite well. It is easy to cut and sands well.

I agree about the 1/16" balsa sheeting and the possible lack of protection for the foam. I suggest 1/32" ply to sheet the filets with. If the filets get damaged with the ply on them, the filets are going to be the least of your problems.

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RE: Using foam for fillet - 3/9/2008 3:22:11 PM   
Texan



Posts: 468
Joined: 12/20/2001
From: Georgetown, TX, USA
Status: offline 		This is my first time using green foam to shape fillets. It was amazingly easy to shape but very delicate until treated with thin CA. Just allow the thin CA to soak in and LIGHTLY spray it with kicker. This stuff will handle the CA, kicker, and chemical "heat" without any problems. Just make sure you like the shape BEFORE using the CA. It gets rock hard and requires aggressive sanding after treatment.

I don't believe covering with balsa is needed for extra strength. However, it's cheap enough to try for yourself, just a couple of bucks at the local craft store and test it before using it on the plane.

I'll post more pictures later today.

< Message edited by Texan -- 3/9/2008 3:37:14 PM >

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RE: Using foam for fillet - 3/10/2008 4:03:41 AM   
Texan



Posts: 468
Joined: 12/20/2001
From: Georgetown, TX, USA
Status: offline 		Foam fillet after filling the low spots and blending.

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RE: Using foam for fillet - 3/11/2008 1:42:24 AM   
Broken Wings



Posts: 455
Joined: 1/15/2003
From: Port Saint John, FL, USA
Status: offline 		Have you ever tried Leather Fillets? Old control line stunt model makers trick.

Bill Sawyer sells them and he can be found on the Stuka Stunt Works forum. They come in many different sizes (widths) and they CA in place. You just buy them buy the foot. They're like belt leather only they've been cut to fit in a corner.

They work EXCELLENT and you can paint them.



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RE: Using foam for fillet - 3/11/2008 2:44:21 AM   
Texan



Posts: 468
Joined: 12/20/2001
From: Georgetown, TX, USA
Status: offline 		That's a new one on me... and I've been around for a while.

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RE: Using foam for fillet - 3/11/2008 4:04:28 AM   
TommyWatson



Posts: 971
Joined: 3/28/2002
From: Pendle HillNSW, AUSTRALIA
Status: offline 		Superfil is the very best, Easy to shape and easy to sand.

You can smooth it out befor it completly sets with a wet finger.


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