水平尾翼對整架
大型航天模型來說,也是一個很重要的問題。我們有必要先搞清常規(guī)布局飛機的氣動配平原理。
The horizontal tail is also a very important problem for the entire large aerospace model. It is necessary for us to understand the aerodynamic trim principle of conventional aircraft first.
形象地講,飛機在空中的氣動平衡就像一個人挑水。肩膀是飛機升力的總焦點,就是前面的水桶,水平尾翼就是后面的水桶。
Visually, the aerodynamic balance of an aircraft in the air is like a person carrying water. The shoulder is the overall focus of the aircraft's lift, the center of gravity is the bucket in front, and the horizontal tail is the bucket in rear.
升力的總焦點不隨飛機迎角的變化而變化,永遠固定在一個點上。,是在升力總焦點的前部,所以它起的作用是起低頭力矩。
The total focus of lift does not change with the change of aircraft angle of attack, and is always fixed at a point. First of all, the center of gravity is in front of the total focus of lift, so its role is to lower the head torque.
由此可知,水平尾翼和機翼的功能恰恰相反,它是用來產(chǎn)生負升力的,所以它起的作用是抬頭力矩,以達到飛機配平的目的。
It can be seen that the function of the horizontal tail and the wing is the opposite. It is used to generate negative lift, so its function is to lift the moment to achieve the purpose of aircraft trim.
由此可知,水平尾翼只能采用雙凸對稱翼型和平板翼型,不能采用有升力平凸翼型。水平尾翼的面積應(yīng)為機翼面積的20-25%。
It can be seen that the horizontal tail can only use the biconvex symmetric airfoil and the flat airfoil, and cannot use the lift planoconvex airfoil. The area of the horizontal tail should be 20-25% of the wing area.
選定22%,計算后得出水平尾翼的面積為89100平方毫米。同時要注意,水平尾翼的寬度約等于0.7個機翼的弦長。
Select 22%, and the area of the horizontal tail is 89100 square mm after calculation. Also note that the width of the horizontal tail is approximately equal to the chord length of 0.7 wings.
此外還要了解好確定水平尾翼的安裝位置,從機翼前緣到水平尾翼之間的距離(就是尾力臂的長度),大致等于翼弦長的3倍。此距離短時,操縱時反應(yīng)靈敏,但是俯仰不精確。此距離長時,操縱反應(yīng)稍慢,但俯仰較精確。垂直尾翼、水平尾翼和尾力臂這三個要素合起來,就是“尾容量”。尾容量的大小,是說它對飛機的穩(wěn)定和姿態(tài)變化貢獻的大小。
In addition, it is also necessary to understand and determine the installation position of the horizontal tail. The distance from the leading edge of the wing to the horizontal tail (that is, the length of the tail arm) is approximately equal to 3 times the chord length of the wing. This distance is short, and the response is sensitive when operating, but the pitch is inaccurate. When the distance is long, the control response is slightly slow, but the pitch is more accurate. The three elements of vertical tail, horizontal tail and tail arm are combined to form "tail capacity". The size of tail capacity refers to its contribution to aircraft stability and attitude change.
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