There are many similarities between the names of various parts of the propeller and the wing. The blade is equivalent to the wing surface of the wing, the blade also has leading edge and trailing edge, and the profile shape of the blade is similar to that of the wing. However, when the model aircraft flies, the propeller rotates to generate tension and moves forward with the aircraft, so its working condition is much more complex than that of the wing.

1、右旋螺旋槳和左旋螺旋槳

1. Right hand propeller and left hand propeller

當我們站在螺旋槳后面（相當于飛機駕駛員的位置）來觀察螺旋槳旋轉。如果看到螺旋槳是順時針方向旋轉，這種螺旋槳稱為右旋螺旋槳，反之稱為左旋螺旋槳。

When we stand behind the propeller (equivalent to the position of the aircraft pilot) to observe the rotation of the propeller. If you see that the propeller rotates clockwise, this propeller is called a right-hand propeller, and vice versa.

對于大多數活塞發動都采用右旋螺旋槳，這是因為使用的螺釘和螺紋都是右旋的居多，這樣螺旋槳就不會松脫了，由于慣性，螺旋槳會變得很緊，保證了。

For most piston engines, right-handed propellers are used because most of the screws and threads used are right-handed, so the propeller will not loose. Due to inertia, the propeller will become very tight to ensure safety.

2、螺旋槳的旋轉面

2. Rotating surface of propeller

螺旋槳旋轉時，通過螺旋槳上一點并且垂直與旋轉軸的一個假想的平面。

When the propeller rotates, it passes through a point on the propeller and is perpendicular to the axis of rotation.

3、螺旋槳直徑

3. Propeller diameter

螺旋槳兩個槳尖之間的距離。也可以認為是螺旋槳旋轉時更大旋轉面的直徑。

The distance between the two tips of a propeller. It can also be considered as the diameter of the maximum rotating surface when the propeller rotates.

4、槳葉角

4. Blade angle

槳葉剖面的弦線與旋轉平面之間的夾角稱為槳葉角。

The angle between the chord of the blade section and the rotation plane is called the blade angle.

從定義上看，螺旋槳的槳葉角與機翼的安裝角相似。不過機翼裝在機身上的安裝角一般沿機翼翼展都是相同的，只有少數模型的機翼安裝角在翼尖部分小，靠一根部分大?？墒锹菪龢臉~卻完全不同了：越靠近旋轉軸，剖面的槳葉角越大；越接近槳尖，剖面的槳葉角越小。制作正確的螺旋槳，從槳尖到槳根，槳葉角的扭狀程度是逐漸增大的。

By definition, the blade angle of a propeller is similar to the installation angle of a wing. However, the installation angle of the wing mounted on the fuselage is generally the same along the wing span. Only a few models have a small wing installation angle at the wing tip and a large one at one end. However, the blades of the propeller are completely different: the closer to the rotating shaft, the greater the blade angle of the section; The closer to the tip, the smaller the blade angle of the section. When making the correct propeller, the twist degree of blade angle increases gradually from the tip to the root.

圖1－38  作用在螺旋槳上的空氣動力

Figure 1-38 aerodynamic force acting on propeller

5、旋轉速度

5. Rotation speed

螺旋槳旋轉時槳葉上任一剖面延圓周切線方向的旋轉線速度。

When the propeller rotates, the linear speed of any section of the blade along the tangential direction of the circumference.

為螺旋槳每分鐘的旋轉圈數，為槳葉上任一剖面到旋轉軸的距離。

Is the number of revolutions per minute of the propeller, and is the distance from any section of the blade to the rotation axis.

由于螺旋槳槳葉各剖面到旋轉軸的距離都不相等，所以螺旋槳旋轉時，各個剖面所經歷的路程也不相等。越靠近槳尖，半徑越大，旋轉速度也就越大。螺旋槳旋轉所引起的習慣力對氣流的速度就等于螺旋槳的旋轉速度。

Because the distance from each section of the propeller blade to the rotation axis is not equal, the distance experienced by each section is not equal when the propeller rotates. The closer to the tip, the greater the radius and the greater the rotation speed. The speed of the habitual force caused by the rotation of the propeller to the air flow is equal to the rotation speed of the propeller.

6、前進速度

6. Forward speed

模型飛機飛行時，由于槳葉隨著模型一起運動，所以螺旋槳的前進速度等于模型飛機的飛行速度。

When the model aircraft flies, because the blades move with the model, the forward speed of the propeller is equal to the flight speed of the model aircraft.

7、合速度

7. Closing speed

螺旋槳旋轉時產生拉力，使模型向前飛行。這是，真正作用在槳葉上的氣流是螺旋槳旋轉引起的相對氣流速度和模型前進作用在槳葉上的相對氣流的速度之矢量和。它稱為合速度。

When the propeller rotates, it generates tension to make the model fly forward. This is that the real air flow acting on the blade is the vector sum of the relative air flow velocity caused by the rotation of the propeller and the relative air flow velocity acting on the blade forward of the model. It is called combined velocity.

8、槳葉迎角

8. Blade angle of attack

槳葉剖面的弦線與合速度方向之間的夾角稱為槳葉迎角。如果模型沒有前進速度，那么槳葉角就等于槳葉迎角。所以一般情況，槳葉迎角總是小于槳葉角的。

The angle between the chord of the blade profile and the direction of resultant velocity is called the blade angle of attack. If the model has no forward speed, the blade angle is equal to the blade angle of attack. Therefore, in general, the blade angle of attack is always less than the blade angle.

與機翼情況相似，這個角度的大小，決定了槳葉剖面產生的拉力大小。

Similar to the wing, this angle determines the pull generated by the blade profile.

9、氣流角

9. Air flow angle

合速度與旋轉速度之間的夾角稱為氣流角。

The angle between the closing speed and the rotating speed is called the air flow angle.

顯然，由于槳葉各剖面處的旋轉速度都不相同，所以越靠近槳尖氣流角越小。

Obviously, because the rotation speed at each section of the blade is different, the closer the blade tip is, the smaller the air flow angle is.

10、幾何螺距和實際螺距

10. Geometric pitch and actual pitch

如果螺旋槳翼面旋轉一面前進，親近的方向是沿著槳葉剖面的翼弦方向，也就是說槳葉迎角為0度，那么每旋轉一圈，剖面前進的距離稱為幾何螺距。

If the propeller surface rotates and moves forward, the close direction is along the chord direction of the blade section, that is, the blade angle of attack is 0 degrees, then the forward distance of the section is called geometric pitch for each revolution.

圖1－39  幾何螺距與實際螺距

Figure 1-39 geometric pitch and actual pitch

但是與機翼的情況相似，要使螺旋槳產生足夠的拉力，槳葉與相對氣流一定要呈某個迎角，所以在實際飛行中槳葉應當是沿著氣流的方向并帶著某個迎角前進，而不是沿槳葉剖面翼弦方向前進。螺旋槳槳葉沿著相對氣流方向旋轉一周，剖面前進的距離稱為實際螺距，也就是說，幾何螺距使槳葉迎角為0度時的實際螺距。如果把螺旋槳旋轉一圈時槳葉剖面經過的軌跡加以展開，從圖上可以看到實際螺距一定比幾何螺距小。如果槳葉迎角越大，這個差別也越大。

However, similar to the case of the wing, to make the propeller produce sufficient tension, the blade must have an angle of attack with the relative air flow. Therefore, in actual flight, the blade should advance along the direction of the air flow and with a certain angle of attack, rather than along the chord direction of the blade section. The propeller blade rotates one circle along the relative air flow direction, and the forward distance of the profile is called the actual pitch, that is, the geometric pitch makes the actual pitch when the blade angle of attack is 0 degrees. If the trajectory of the blade profile when the propeller rotates one circle is expanded, it can be seen from the figure that the actual pitch must be smaller than the geometric pitch. The greater the blade angle of attack, the greater the difference.

螺距太大而飛行速度不夠快，則攻角太大而失速，這種情形在這里叫螺旋槳打滑，螺距太小而飛行速度太快，則攻角太小，效率則很差，所以結論是高速飛機用小槳大螺距，低速飛機用大槳小螺距。以前在萊特兄弟時代，飛機做好以后要拉一個綁在樹上磅秤來測拉力，現在在航模飛行場上偶而也有人這么做，現在我們知道這是多余的，測得的拉力因沒有飛機前進的速度，只是靜拉力，所以只有在飛機靜止時有效，飛機有了速度后就不準了。

If the pitch is too large and the flight speed is not fast enough, the angle of attack is too large and stall. This situation is called propeller slip here. If the pitch is too small and the flight speed is too fast, the angle of attack is too small and the efficiency is very poor. Therefore, the conclusion is that high-speed aircraft use small propeller with large pitch and low-speed aircraft use large propeller with small pitch. In the past, in the Wright brothers' era, when the plane was ready, it was necessary to pull a scale tied to a tree to measure the tension. Now some people occasionally do this on the model flight field. Now we know that this is redundant. The measured tension is only static tension because it does not have the forward speed of the aircraft, so it is only effective when the aircraft is stationary, and it is not allowed when the aircraft has speed.