Posted by Dan.Cummins |
Dec 27, 2009 @ 12:39 AM | 9,929 Views
**** UPDATE ****
Post maiden tuning has resulted in a a CG location at 36% MAC (61mm) in order to achieve good dive test, inverted flight test, and axial roll results. A heck of a lot further back than I would have thought, but that's where it flies best. New version R1 updated the camber compensation from 1mm per % camber to 1.5mm per % camber.
I wanted to document my TWF wing build progress/process, and encourage more RCG and SD builders to go for it, and build a TWF for themselves.
After some thought, I realized that the tried and true build process documented by Sleddriver (Jay Decker) on slopeflyer.com (http://www.slopeflyer.com/soaring/ol....com-site.html) is difficult to improve on, so I won't. Jay's process is well documented, and produces a solid TWF wing.
What I did find, is there is not one single source for calculating the wing tube location for a TWF. The process is straight forward once you know what to calculate.
The wing tube should be located on the aerodynamic center (AC) of the your wing. The AC is the aerodynamic neutral point of the wing. Adam from Wyowindworks illustrates what AC is nicely in these three graphics in the ZMAX build thread: