跟住睇番啲Trimming Guide, 發現咗一段Footnote, 解釋咗我之前嘅疑惑... Symmetric翼型嘅設計, 果然係要加少少Up Elevator, 去保持整體上攻角, 抵消地心吸力... In order to maintain level upright flight, the wing of a plane with a symmetrical airfoil wing needs to have a positive Angle of Attack (AOA, usually less than 1 degree). This positive angle provides the lift required to cause the plane to fly level. If the plane is balanced slightly to the nose heavy side (required for pitch stability), it will require a slight up elevator trim to hold level flight. A plane with a zero/ zero wing to elevator angle will also need a slight amount of up elevator trim to hold level flight. Therefore, a plane trimmed in this manner will have a tendency to pull to the canopy on a straight, thumbs off, down line because the elevator is controlling the AOA of the wing.
食完晚飯開盒影相...
