Apr 18, 2002, 11:21 PM Registered User London Ont. Canada Joined Sep 2001 64 Posts I need to find the CG for a swept wing I have made a new flying wing and I need to find the CG. The wing is as follows Tip: 4.75 Root:11.25 Wing span:40" total height18" height to trailing edge 6.75 I hope this makes sense Where is Sparky Paul when you need him? Any help you have would be great.
 Apr 19, 2002, 07:33 AM Registered User kingston Ont, Canada. Joined Nov 2000 33 Posts Might be a little hard to explain, but here goes. Take the root chord , add it to the tip leading edge. Take the tip chord, add it to the root trailing edge. Cross all 4 corners with a line. Where they cross in the middle is the mean aerodynamic chord or MAC. This is where you measure the CG from. On a flying wing the CG is between 15 and 20% from the leading edge. Hop this helps. If it needs more explaination let me know.
 Apr 19, 2002, 10:08 AM Ascended Master Palmdale, CA Joined Oct 2000 13,621 Posts http://home.earthlink.net/~pjburke1/cg.htm This locates the mac. . And I can't believe you haven't bookmarked the site! For shame!
Apr 19, 2002, 10:12 AM
God is good
Banjul
Joined Jan 2001
4,246 Posts
Quote:
 Originally posted by Sparky Paul . . . . For shame!
OK, it's bookmarked. BTW, most useful . . . . thanx

VP
 Apr 19, 2002, 11:30 AM Registered User Northern New Mexico Joined May 2001 140 Posts Here's one that you can use in Excel. It will also help in calculating the twist (or washout) for stable flight. http://members.webpathway.com/patrul...ng_calc_1a.zip
 Apr 19, 2002, 11:46 AM Registered User London Ont. Canada Joined Sep 2001 64 Posts Thank you All SP I know, I know. You have have all been a great help! Now do you include the control surfaces in these dimensions? I haven't made them yet, still working out if I want them to taper to the inside, or the outside? Any advice? Last edited by D.FLinn; Apr 19, 2002 at 11:52 AM.
 Apr 19, 2002, 02:10 PM Registered User Joined Feb 2002 3 Posts I suggest going to http://www.b2streamlines.com/Panknin.html and downloading the Panknin twist spreadsheet. It'll tell you the twist and CG for a desired static margin among other things. Make sure you read the usage caveats. BTW, in a flying wing control surfaces are always included as part of the wing dimensions. Elevons extending far inboard aren't nearly as effective as elevons that remain outboard. The inboard element makes the roll response sloppy. However, for ease of control surface hookup to the servo the surfaces are extended inboard so that the servo can be placed ahead of the CG. As you get nearer the tip the control surface should be a larger percentage of the chord. Last edited by coffey; Apr 19, 2002 at 02:16 PM.