American Kitefliers Association

I *love* my spar chart and use the heck out of it.  I posted this over at Kitebuilder and am happy to share/discuss it here:

http://cid-ba417f98ade07865.office.live … a=25040449

That link takes you to my "skydrive" on MSN/Hotmail.  If you hover over the line item for the spreadsheet with your mouse, a little "i" icon in a circle will appear to the right side of that line.  Click that "i" button, and a menu will appear in the right hand margin, and "Download" will be an option.

At least, that's how it shows on my screen.

Check it out, feel free to post or email any comments or questions.  If you have trouble picking it off of SkyDrive, let me know and I'll email it to you.

Regards,

Maybe you could provide some explanation of that chart? I"m not sure what "scale factor" and some of the other column headings mean. But it looks like a good tool otherwise.

Sure thing Phil!  I'm about to hit the road - I'll come back to this this evening or some such.

Ok.  Some 'splainin on the chart.

The main thing that I use the chart for is to use the "Scale Factor" column.

Say I've got a kite framed in FL370 fiberglass, and I want to change it out for carbon to shave some weight.  I hit the button on FL370 to make it the reference spar, then start scanning the "Scale Factor" column in the carbon section to find the tube with the scale factor closest to 1.00

Or, let's say I'm looking at a kite plan that calls for 0.2100 carbon spars - but I want to make the kite 1.5 times larger.  So, I hit the button on the .2100 carbon and find the spar with a scale factor closest to 1.5

That's what I use it the most for - that sort of thing.

Some links to the engineering and derivations of the information:

Scroll down to the headings of "stiffness vs. Flexibility" and "David Lord's Scale Factor"
http://www.kites.tug.com/Specs/cokecan.html

The mathematical and engineering derivation of the Scale Factor:
http://gamma.nic.fi/~sos/spars/scalefac.htm

Some more information about tubes and moments of inertia (bike related, but the principles apply)
http://mnhpva.org/tech/frame_tubes.html

The beam bending equations used to make some of the calculations on the sheet
http://www.engineersedge.com/beam_bendi … nding2.htm

That sounds like a very hand tool that I had no knowledge of before your post. I have had issues before needing just that type of information and now I know the easy way to look it up. Before it was jsut a try it and see if it works system. Thanks for the post and the full explanation.

Simon Crafts wrote:

If you have trouble picking it off of SkyDrive, let me know and I'll email it to you.

I'm on a Mac right now so that's correct Simon, I have the same issue with my free website http://www.rmka.info it's a Microsoft Office Live hosted site. I only paid to register "rmka.info" domain name. But I have to wait for my Stepson to go to sleep by morning sometime and get off of the Dell laptop with Windows 7 so I can go there to update our website or see this Spar Chart file.

Robin
RD7

Both Open Office (free) and Numbers (cheap from Apple) will read and write most Excel files and run on Macs. There may be some fancy features (and it sounds like Simon may have used them) that won't work with one or the other of these programs, but for most purposes they work fine. Don't know what would help with managing the website, tho.