lml@lancaironline.net Mailing List Archive

<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> Yes Ian I can see whereYou can be confused because in the thread no one has defined the mean aerodynamic chord,MAC. In the simplified case of a rectangular wing such as a pre-1969 Piper Cherokee the MAC could be approximated as the chord length most any where along the wing;however ,with a tapered wing You can graphically locate the position of the MAC by drawing diagonals from the corners of the tip rib to the root rib. Where the diagonals cross ,draw a line perpendicular to the spar. This chord line then approximates the MAC. Let's assume this chord line was 30" 11% of 30" would give You 3.3" back from the leading edge as Your most forward C.G. limit. 29% of 30" would give You 8.7" back from the leading edge as Your most rearward C.G. limit. A mathematical way of determining the length of the MAC would be to divide the wing area by the wingspan. If You drew lines parallel to the spar from the 3.3" and 8.7" points to the wing root You would then have Your allowable C.G. range. Measuring the distance of these 2 points to some convenient reference point such as the firewall would give You a repeatable check on Your C.G. George Choi 27368 Royalton Road Columbia Station,Ohio 44028 440-236-8800 Have a good day >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML website: http://www.olsusa.com/Users/Mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please send your photos and drawings to marvkaye@olsusa.com. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>