stunthanger.com

Building Tips and technical articles. => Building techniques => Topic started by: Avaiojet on December 10, 2017, 05:30:02 PM

Title: Sheeted Foam Wing reenforcement?
Post by: Avaiojet on December 10, 2017, 05:30:02 PM

My sheeted foam wing halves are now joined at the center.

I know what we did in R/C pattern with fiberglass and resin to reinforce the center joint. Probably a bit overkill for CL.

I was thinking a couple of layers of .75 oz. glass cloth about an inch on each wing half?

Soooooooo, What are you guys doing to reinforce the center joint of a sheeted foam wing.

Thanks in advance.

CB

Title: Re: Sheeted Foam Wing reenforcement?
Post by: john e. holliday on December 10, 2017, 09:28:40 PM

Maybe not for CL as the CL plane will turn quicker and sharper.   If you browse some of the build posts you will see how some do it.  Myself I just put a strip of glass and epoxy top and bottom a little wider than the fuselage.   

Title: Re: Sheeted Foam Wing reenforcement?
Post by: Howard Rush on December 11, 2017, 12:44:41 AM

Quote from: Avaiojet on December 10, 2017, 05:30:02 PM

What are you guys doing to reinforce the center joint of a sheeted foam wing.

I think most guys do what you suggested. Had you asked what makes sense to do structurally, my answer would be different. See the recent thread here on the same subject, or, better yet, give some thought to where the loads go. Note also that stunt plane structural requirements differ from combat plane structural requirements.

Title: Re: Sheeted Foam Wing reenforcement?
Post by: RandySmith on December 11, 2017, 01:25:48 AM

Quote from: Avaiojet on December 10, 2017, 05:30:02 PM

My sheeted foam wing halves are now joined at the center.

I know what we did in R/C pattern with fiberglass and resin to reinforce the center joint. Probably a bit overkill for CL.

I was thinking a couple of layers of .75 oz. glass cloth about an inch on each wing half?

Soooooooo, What are you guys doing to reinforce the center joint of a sheeted foam wing.

Thanks in advance.

CB

I use a strip of 1 to 1.5 inch glass  around the center joint, and  cut  2, .5 ounce  fiber glass  ellipse about the size of a football, one  top one  bottom, attached  with finish resin, long direction going toward tips,  I also  overlap the  silk span  in the middle,  take  care  to  NEVER  sand the fillets too deep, as  you will go thru, and into the sheeting, this will create  a  stress point and the wing will snap off at that point.  I also put light thin fillet around the  inside, this makes it very strong, helps to fuel proof  it  and Prevents  fillet cracks


Randy

Title: Re: Sheeted Foam Wing reenforcement?
Post by: Avaiojet on December 13, 2017, 05:52:26 PM

Quote from: RandySmith on December 11, 2017, 01:25:48 AM

I use a strip of 1 to 1.5 inch glass  around the center joint, and  cut  2, .5 ounce  fiber glass  ellipse about the size of a football, one  top one  bottom, attached  with finish resin, long direction going toward tips,  I also  overlap the  silk span  in the middle,  take  care  to  NEVER  sand the fillets too deep, as  you will go thru, and into the sheeting, this will create  a  stress point and the wing will snap off at that point.  I also put light thin fillet around the  inside, this makes it very strong, helps to fuel proof  it  and Prevents  fillet cracks


Randy

I understand what you did. I didn't have any .5 oz. cloth so I used .75 oz. two layers with finish epoxy. I miss working with polyester resin.

I'll be using silk on the sheeted wing and will also overlap in the center.

Now I can start working on the top wing.

Thanks for the reply.

Charles

Title: Re: Sheeted Foam Wing reenforcement?
Post by: Crist Rigotti on December 14, 2017, 08:28:14 AM

Post #45 and #46.  Same procedure for a foam wing without landing and a lite-ply spar.

https://stunthanger.com/smf/gettin-all-amp'ed-up!/legacy-40-electric-a-build-log/msg385715/#msg385715