Hi John, On Feb 6, 2007, at 2:33 PM, John Denker wrote: >> CGoffset = D - (F*L) / W [1] ???? >> >> where D is the distance between the front wheel and the main wheel, F >> is the weight of the front wheel, >> L is the distance between the nose and the main wheel, and W is the >> total weight of the aircraft. > > That's a misquotation or misinterpretation of the relevant > formula, as you can easily see by considering the case > where F=0, i.e. all the weight on the main wheels, in which > case the center-of-mass is located at the main wheels.
Sharp!! It was my misquotation. D = distance between the main wheel and the nose tip. L = distance between the main wheel and the front wheel. When F = 0, CGoffset = D, which means all the weight is on the main wheel as CGOffset is equal to the distance between the nose tip and the main wheel. > In that case, equation [1] reduces to > > CGoffset = D [2] ???? > > or in my notation > > (Xs - Xc) = (Xf - Xm) [3] ???? > or > (Xs - Xc) = (Xf - Xc) (since Xc = Xm) > > which will not be true except in some exceedingly unusual > special case. > > Here the subscripts have the following meaning: > s stands for spinner > c stands for center-of-mass > f stands for front wheel > m stands for main wheels > > For details, including some of the algebra worked out > correctly, see > http://www.av8n.com/physics/cm-calc.htm With the correct quotation, The formula that I used shows exactly the same point as the (7) at the URL above does. (Xs - Xc) = (Xs-Xm) + (Xf−Xm) Wf / W (7) # I used Xs instead of D to avoid confusion. In the formula I've quoted, CGoffset = (Xs - Xc), D = Xs-Xm, L = (Xf -Xm), F=Wf Anyway, the actual calculation was made in this formula without misquotation. :-) Tat ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier. Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
