cg location depends on a bunch of things, but for the purposes of modelers the best idea is to make a lot of simplifying assumptions, use a shorthand formula, and then adjust by flight trimming. Howard Chevalier offers a workable rule of thumb (Model Aerodynamics, p. 109) neutral point = location of wing aero center + tail volume * (1-4/AR) where AR = the wing's aspect ratio, and tail volume = (stab area/wing area)*(TM / C) where TM = distance from wing a.c. to stab a.c. and C = wing's mean aerodynamic chord after you figure the neutral point, locate the c.g. about 20% of the wing's mean aerodynamic chord forward of that point. Then trim to taste. This formula gives results that usually (though not always) are within striking distance of the correct value as computed with all the relevant variables. The DA program written by Helmut Lelke, found at http://www.charlesriverrc.org/articles/design/helmutlelkedesignanalysis.htm will give you estimates of the TM and C I have a spreadsheet that will do the complete computation, but it is undocumented and unruly -- a one-man dog. --- Bill Johns <[EMAIL PROTECTED]> wrote: > Greetings! > > A couple of questions about cg's. > __________________________________________________ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail - only $35 a year! http://personal.mail.yahoo.com/ RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
