Nov 03, 2012, 09:58 PM
Registered User
United States, OH, Troy
Joined Jan 2008
77 Posts
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Wing Shear, Bending and Spar Spreadsheet

I've been wondering how to calculate the shear loading and bending moments of a canteliever wing for a while, so I decided to look it up. I found a good paper and a helpful wikipedia article. I decided to make a spreadsheet to do the calculations for me. It determines the Limit Shear and Bending moments using the Schrenk elliptical approximation, then on the next spreadsheet you can design an I-beam spar using the data. I also included several common building material strengths and had the spreadsheet determine if these materials were strong enough in bending moment for the spar at the given section points.

Its has some limitations mostly that you cannot tell what will happen when you use different materials for the spar caps and shear web. Also it doesn't determine if the spar is strong enough in shear, but it is my assumption that if it is strong enough in bending it should be strong enough in shear.

Use:
Place your aircraft information into the purple boxes. Go to the next spreadsheet and design your spar by changing the data in the purple boxes making sure the material you wish to build with can handle the stress.

Paper: http://www.lightaircraftassociation....roximation.pdf
Wikipedia: http://en.wikipedia.org/wiki/Second_...l_axis_theorem

Scott

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 Nov 09, 2012, 05:56 PM Cheese eating monkey. France, Bretagne, Rennes Joined Jul 2011 258 Posts Thank you for posting this, unfortunately, I am not used to imperial units so didn't really inderstand the nitty gritty of the spreadsheet but the paper looks clear and concise. Last edited by Panoramix; Nov 10, 2012 at 06:45 AM.
 Nov 09, 2012, 09:58 PM greg somerset, nj Joined Feb 2005 377 Posts collection of info on spar construction http://ciurpita.tripod.com/rc/notes/compositeSpar.html
Nov 21, 2012, 10:59 PM
TEAM FUTABA TEAM DURALITE
Joined Nov 2004
749 Posts
I threw a little something t'gether a few years ago....

takes the planform, applies Schrenks, calculates the moment at multiple locations along the span, calculates the shear, calculates the shear web thickness based on material properties.. as well as spar cap thickness...

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