Kako covek napreduje u svom letenju tako je sve zahtevniji po pitanju preciznosti i utrimovanosti svog modela. Na pocetku sve to jednostavno promakne posto je kolicina krvi u adrenalinu relativno mala. Evo jednog teksta koji mi je zazvucao apsolutno logican i ispravan pa bih me zanimalo i vase misljenje.
When a glider is nose heavy it has up elevator trimmed in to pull the nose up when it is flying slowly. This is desirable in small doses because it provides positive stability. As the model slows, the nose drops (elevator trim has less force on the tail) , the speed increases and a stall is avoided. If the model nose drops, the speed increases, elevator trim has more force on the tail and the plane levels out.
When the CG is moved back and back, less and less up elevator trim is required to maintain level flight. The positive stability is reduced until it is neutral. At neutral the model will not pull out of a shallow dive on its own. A tail heavy model will increase the steepness of a shalow dive if left alone.
What to do:
Step1: Dive test the Ion. Trim the model for level flight. Move the CG back until the model slowly recovers from a 30/45 degree dive on its own. Ideally it should take about two seconds for the model to level out from the dive with hands off the sticks.
Step2: Now the CG is in the right place for gliding, lets get the motor right. Turning on the mortor increases the speed (like a dive does) and makes elevator up trim push harder on the tail. If the CG (hence elevator trim) is near neutral then the increased speed with motor should not cause the model to climb into a loop on its own. If it does climb (or dive) when the motor is turned on, you have two choices:
A) add some down (or up) thrust angle to the motor with washers at the motor mount.
B) Mix some elevator compensation to the motor in your computer radio. If you use this option be careful to only mix a few percent of down. Many people do not like this option because they fear that, sometimes when turning on the motor at low altitude, the model may get pointed at the ground first!
I have an Ion that is trimmed near neautral glide. It still noses up with motor. I mixed slight down elevator to the "motor on" switch. With this, when I turn on the motor the model stays level. I then pull up elevator. When I release the elevator the Ion maintains it climb at the angle I left it in. At the top of the climb I blip some down elevator before releasing the motor switch.
poz
