飛行器設計學習筆記(一)

Mon Lapin,

想給你看我做的飛機，可限於時間，我只能慢慢學，一點點更新了。

————————————————正文——————————————————————

我們先忽略起飛和著陸的部分，然後來觀察飛機的主體部分，我們把它叫做機艙(cruise)。

當飛機以一定的速度直線飛行時，主要有四種力作用在飛機上：重力，浮力，阻力和推力。

1.重力是由地球引力造成的，地球引力會將飛機向地心拖拽。為了讓飛機飛行，第二種力必須作用在飛機上，讓它向上升起。我們把這個力稱作浮力。

?重力就像我們的愛，會沉沉地把我拉向你一樣：這個時候你是地球，而我就是飛機。

可我若想向上飛行，則需要自己努力才可以夠到天空。

2.浮力是當飛機飛行在空氣中造成的，主要是由機翼產生的。機翼有一個特殊的形狀，稱作翼面。機翼上這樣特殊的形狀會讓上方流動的空氣比下方流動的速度要快。在機翼下方緩慢流動的空氣會產生更高的氣壓，這樣產生的浮力能讓飛機上升，同時平衡重力。

?如果你的愛太沉重了，我就需要用我的愛來平衡我自己了:)不要太愛我啦(?? 3(???c)

3.阻力同樣也是由飛機在空氣中飛行而產生的。當物體在流體（像空氣和水）中運動時，流體會產生一種力來阻礙物體的運動，這就是阻力。為了讓飛機保持一定的速度向前運動，我們需要另外一種力來克服阻力，就是推力。

?就好像外界對我們同樣有阻力一樣，只要我們生活在這個社會中，就不可避免的要受到制約。為了好好在一起，我們需要共同克服阻力。

4.推力是由飛機引擎產生的。推力可以讓飛機向前運動同時克服阻力。引擎通常是用螺旋槳或推進器或加速氣流產生的。螺旋槳有許多扇頁，這些扇頁通過旋轉形成氣流產生推力。每個扇頁都有特殊的翼型切面，就像機翼一樣，可以產生浮力。

噴氣引擎通常有許多風扇，它們會加速氣流。氣流的速度比飛機要快，但它們的質量比飛機更輕。而飛機的動量可以平衡氣流的動量，這樣就會產生推力。(p = mv，動量=質量*速度 )

?我們可以通過精神和身體來產生推力，這會讓我們距離更近，來平衡阻力:)

你說我們誰的動量更大呢？笑，愛你:)

Well ignore the take-off and landing for now and look at the main segment of the flight, called ``cruise".

During this time, the plane is flying in a straight line at a constant speed. And there are four main forces acting on the plane, Weight, Lift, Drag and Thrust.

1. Weight is the force produced by gravity pulling the plane towards the ground. In order for the plane to fly, a second force must be acting on the plane to pull it upwards. We call this force Lift.

2. Lift is produced by the plane as it travels through air, mostly by the planes wings. A planes wings have a special shape, called an airfoil, which forces air to flow over the top surface of the wing quicker than the bottom surface. The slow moving air beneath the wing puts more pressure on the bottom of the wing than the fast moving air on top, resulting in a force that pulls the plane up and balances the weight force.

3. Drag is also produced by the plane travelling through air. When objects move through fluids, like air and water, the fluid produces a force that opposes their motion. To keep a plane moving forwards at a constant speed, another force is needed to overcome drag.

4. Thrust is the force produced by the planes engines.This force pulls the plane forward through the air and overcomes the drag force produced by the air. The engines usually produce thrust by turning a propeller or accelerating a stream of air. Propellers have a number of blades that rotate and create forces to pull the plane through the air. Each blade has an airfoil cross-section, like a wing, and generates a lift force. Jet engines often have fans that act like propellers, but they also accelerate a narrow stream of air. The air moves much faster than the plane, but it has a lower mass. The momentum added to the stream of air is balanced by momentum added to the plane, which provides the thrust force.

參考資料來自《Model aircraft design》by Jon D