Well, first and foremost I would think the CG is a bit too far back for your ability. You need more forward CG for relaxed un-powered flight. The prop stalled will act less as a fin than when rotating - if you fly your plane propeller-less the differencies are even bigger. One thing you could try is to slope it motorless, as that moves the CG forward quite a bit! You need to retrim the elevons, too, of course! The can guess reason the elevons look like they do is that the designer (hi Jerry!) wanted most of the control surface near the tips for optimum rolling and elevator power. As wing thickness and width, CG and inertia factors also affect the design, you don't want thick, heavy servos at the tips, where they probably would be more effective! On swept-wing jet aircraft ailerons and elevons often taper in width towards the wing tip, as the one thing that true high-speed design must avoid is flutter. The hydraulic ram, operating the surface, sits near the inner end, where the width of the control surface is widest, thus stiffest. Usually the ram power and movement limits are varied with speed, as the controls become stiffer to move with speed and less efficient! Sometimes there are two sets of ailerons, where the outer is only used at low speed, as to avoid flutter problems. If the control surface's width, compared to the wing's, increases in percent as we go towards the tip, as on a Zagi, the wing rolls more efficiently than one where the width (in percent) decreases toward the tip. Gliders (full-size) of the 50's often had ailerons that disappeared to nothing towards the tip, spelling out two facts: torsional stiffness of the wing nor the aileron wasn't that good, and the aircraft were no aerobatic masters! On a flying wing these problems are further accentuated! At the same time most wings will not stand a maximum control surface movement at high subsonic speed (efficiency drops off over Mach 1), so most likely slower movements but more. If unpowered the limits are set by the pilot's strength, if powered a limiter is often incorporated. The Zagi - hardly transsonic - solves this with VERY flexible elevons - at low speed the outer ends move all the way, while at high speed the airloads bend the surfaces to an amazing degree! Thus a force limiter built-in! Thus there is less risk for overloading, if built as designed. Build stiffer elevons and you might need to beef up all the other parts too, change to more expensive servos, install more spars and reinforcements, et cetera! Often just changing motor to something slightly more powerful leads to other changes - as the structure proves to be too weak for the increased loads and speeds, or the plane look decidedly haggard after a short while! Or you end up with a molded Zagi, with CF elevons, that will stand a lot before it breaks to pieces. But it is then another kind of aircraft! And not according to the Slope Combat rules! Tord S Eriksson www.tord.nu RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
