stunthanger.com

Building Tips and technical articles. => Building techniques => Topic started by: Allan Perret on March 03, 2010, 12:14:44 PM

Title: Foam Wing weight.
Post by: Allan Perret on March 03, 2010, 12:14:44 PM: About what is the best weight you could expect, using proper techniques, on a 60 size (~675 sq in) foam wing ?
Just the cores and skins epoxied and LE & TE installed, not including tips, flaps and controls.
Title: Re: Foam Wing weight.
Post by: Alan Buck on March 03, 2010, 01:26:56 PM: Hi, Allan I'm using a foam wing for a SV22 I did 83/4ozs cores sheeted wiht 1/16 and epoxy. complete with tips, controls, flaps,silkspaned with 4 coats of dope and 1/2 oz of tip weight built in 14.25ozs. Hope this helps you. wing is 670 sq in
Title: Re: Foam Wing weight.
Post by: Steve Fitton on March 03, 2010, 02:00:47 PM: Yikes! My Dreadnought wing with flaps, etc, silkspan and 3 coats of dope weighs 18 ounces. My plane will never fly, I might as well start over... HB~>
Title: Re: Foam Wing weight.
Post by: RandySmith on March 03, 2010, 03:39:19 PM: Quote from: Steve Fitton on March 03, 2010, 02:00:47 PM
Yikes! My Dreadnought wing with flaps, etc, silkspan and 3 coats of dope weighs 18 ounces. My plane will never fly, I might as well start over... HB~>

My Foam Dreadnought wing weighed 14.5 with flaps tips controls tip box leadouts bellcranks paper and 2 coats of dope
My XL 675 sq in weighed 13.5 with all the above ready to glue in to the fuse

Panels should weigh 4 to 4.5 ounces each, unless you have gear of heavy spars in them, The biggest thing to add weight is the technique you use of glueing the skins...the best way I have ever found is to sand the inside of the sheeting and coat it with one coat of thick dope...sand this smooth when you put on the epoxy it will take about 1\3 of an ounce to coat the whole surface...if you use punk wood and do not seal it it will take as much as 2 ounces to make the sheeting look wet...and over 3 if you use certain types of thick cement
Some people also use hairspray to seal the wood grain prior to glueing

Randy
Title: Re: Foam Wing weight.
Post by: Jim Pollock on March 03, 2010, 09:23:07 PM: Gee,

I thought my SV-11 Wing was heavy at 16 ounces with bellcrank, pushrod, Flap Horn, Tip Weight Box, and the Flaps.

I guess it ain't so heavy now?

Jim Pollock H^^
Title: Re: Foam Wing weight.
Post by: Steve Fitton on March 04, 2010, 02:57:17 PM: I checked my notes just now. The inboard (larger) wing core, sheeted with leading edge and trailing edge weighed 4.3 ounces.

The 18 oz figure included the fact that the completed wing had not only clear over the silkspan but also filler, also the flaps are rigid 8 to 9 pound C grain. The wing without flaps weighs 15.3 ounces with the filler sanded out.