>could someone explain to me the balancing method and tools >used to place a CG to 0.5mm accuracy?
To measure the CG: I turn the assembled glider over on its back, and find the level-balance point by supporting it on a wood-pencil eraser which is slightly rounded. I might add some tape to a wingtip if necessary to get perfect lateral balance, so the eraser point can stay exactly on the centerline. I mark the eraser (CG) position on the wing, and measure its distance from the LE using a ruler which has a balsa stick taped onto its end to make an "L". The balsa stick rests against the LE while the ruler is held parallel to the wing bottom or the chordline to make the measurement. The recommended 3.6" CG position is what I measured off my Supra in this way. It's a relatively far-aft position, which is just on the verge of tuck-in in a steep dive test. It recovers very slowly in a shallow dive test. The best CG and hook positions may depend somewhat on the chosen dihedral. To measure the hook location: I tape a short balsa stick or dowel into the hook, parallel to the wing. I then place a drafting triangle against the bottom of the wing, and touch it to the stick. This gives the hook position on the wing chord, measured perpendicular to the wing bottom surface. The recommended 3.8" hook location is what I measured off my Supra this way. This is rather far aft hook position which requires special action during launch. On my Evo program the left slider is an elevator (speed) trim with a small gain. For the launch throw I push the slider all the way forward which feeds in a slight amount of down-elevator. Once the glider rotates and settles down in the climb, I pull the slider back to its normal center position for maximum load just short of stall. I have 100% Ail.Diff and lots of Ail->Rud coupling during launch, so I can steer with might right thumb, leaving the left thumb free to work the slider. PS I've done some sims of the initial pitch dynamics immediately after the throw. There is a very significant CL overshoot at the end of the initial nose-up rotation. So if you trim the glider for maximum pull during the climb and zoom, and throw with this trim, then you are guaranteed to stall at the top of the nose-up rotation. So for maximum launch performance, it is necessary to add some initial nose-down trim to safely get past the initial pitch transients after the throw. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
