How Cyclic and Collective Pitch Works on RC Helicopters-遥控直升机的原理

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原文内容链接：http://www.rchelicopter.com/2008/04/23/cyclic-collective-pitch-rc-helicopter/

遥控直升机的循环螺距和总螺距是如何工作的。

Cyclic collective pitch is used by RC helicopters to control flight. In a previous article, fixed pitch helicopters were explained. Fixed pitch helicopters change their direction and altitude by changing the rate at which their rotors spin, and sometimes by using a tail rotor. Finer control can be achieved by changing the pitch of the rotor blades. By changing the pitch of the blades, the airflow from them can be changed, moving the helicopter in different directions. Changing the pitch of the blades is more efficient than just increasing the speed of the blades. In this article, the mechanics of variable pitch helicopters will be explained.

遥控直升机通过循环螺距控制来控制飞行。(In a previous article, fixed pitch helicopters were explained 这个链接解释了什么是固定螺距直升机)固定螺距直升机通过改变旋翼旋转的速率来改变飞行的方向和高度，有些有用到尾旋翼。更好的控制方法是改变旋翼的螺距。通过改变旋翼的螺距，来改变飞行方向。这比只用改变旋翼的转速更有效。

How The Swashplate Works on RC Helicopters
十字盘(倾斜盘)是如何工作的



In order for the rotor blades of an RC helicopter to change pitch, there must be a way to transform the linear motion of a servo arm into the rotating motion required by the rotor blades; this is accomplished by using a swashplate. The swashplate is a mechanical device, consisting of two plates mounted to the main rotor shaft. One of these plates is attached to the servo controls and the helicopter body, and the other rotates with the helicopter rotors. As can be seen in the picture, the swashplate transforms the motion of the servo arms into motion of the upper plate. Each rotor is connected to the upper disk of the swashplate, and so they will move as the bottom disk moves. The horizontal rods visible in the picture represent where the servo arms would connect, the number of rods included depends upon the individual helicopter. Every RC helicopter that can change the pitch of its rotor blades will have a swashplate attached to its main axial. There are many different implementations of swashplates, but each follows the same basic design shown in the image. In a conventional RC helicopter, two servos are used to control the swashplate. One servo is used to control the horizontal motion (bank) and the other is used to control the forward and aft motion (pitch).

为了能够改变直升机的旋翼螺距，必须要有一种方法把舵机摇臂的线性运动转变为旋翼要求的回转运动。这就由十字盘来实现。
十字盘是一个机械部件，由2个固定在主轴上的盘组成。其中一个盘靠直升机机体上的舵机控制，另一个则与旋翼一起转动。正如你在图片中看到的，十字盘把舵机摇臂的动作从下盘传递到上盘。上盘连接着每个旋翼，所以旋翼随着下盘一起运动。图片中水平方向的那些杆代表连接舵机摇臂，有多少杆由不同的直升机决定。每个可以改变旋翼螺距遥控直升机主轴上都有十字盘。有很多不同的十字盘，但是每种都是基于图片中相同的基本设计。一个常见的遥控直升机有两个舵机控制十字盘，一个用于控制水平(副翼)，另一个控制前进和后退(俯仰)。

RC Helicopter Collective Pitch – Climbing and Descending
遥控直升机的总螺距-爬升和下降

When a RC helicopter needs to climb or descend, it uses collective pitch. When the command is given for the helicopter to climb, the servos push the entire swashplate upwards. This has the effect of simultaneously increasing the pitch of all the rotor blades. When the pitch is increased, the rotors grab more air as they move, and so lift produced is increased. This increase in lift occurs evenly, so the helicopter does not turn. When the helicopter needs to descend, the swashplate is lowered in the same way. This will decrease the amount of lift produced from the rotor blades.

直升机需要爬升或者下降时要使用总螺距。当收爬升指令后，舵机推动整个十字盘向上。这会影响到所有旋翼螺距同时增加。当螺距增加后，升力便提升了。因为所有旋翼的升力增加是一致的，所以直升机没有没有发生翻转。直升机需要下降时，十字盘向下运动。这将使整个旋翼总升力下降。

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RC Helicopter Cyclic Pitch – Attitude Control
遥控直升机的循环螺距-姿态控制

Changing the bank and pitch of the helicopter requires the swashplate to tilt. This is accomplished by tilting the lower disk of the swashplate. When the lower disk is tilted, the upper disk will also tilt, while it is spinning. The main rotors, which are attached to the upper swashplate will also tilt. In order for this to happen however, each rotor must be given time to “fly up”, or “fly down” to the location where it needs to be. This is accomplished by using pitch links, which provide each rotor with the information of where it needs to go, before it has to be there. The net effect is that the blades move cyclically, and tilt the motion of each rotor in one direction. The swashplate can be tilted in any direction, so the helicopter can change its pitch and bank in proportion to the commands given by the transmitter.

改变直升机的倾斜(副翼)和俯仰，需要倾斜十字盘，倾斜十字盘的下盘来实现。当下盘倾斜后，上盘也跟着倾斜，并旋转着。主旋翼也随着上盘一起倾斜，因此每一个旋翼在一定的时间和位置升力增加或者减少，由链接上盘到旋翼的连杆实现控制。这就是旋翼循环运动的效果，而且每个旋翼的倾斜方向是一致的。十字盘可以向任意方向倾斜，因此直升机可以通过发射机给出的指令的对应比例改变俯仰和倾斜。

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RC Helicopter Cyclic Collective Pitch Mixing (CCPM)
遥控直升机循环/总螺距混控-CCPM混控

Model RC helicopters can use more than two servos in combination to control the motion of the swashplate. Software running on the rc transmitter (radio) tells each servo how much to move to achieve the desired motion of the RC helicopter. Each linkage to a servo is represented by a silver rod in the above picture. All of these rods are placed equidistant from each other. A swashplate mix refers to the number of linkages attached. For example: a two linkage swashplate would be controlled by two servo rods, placed 180 degrees apart from each other. A three linkage swashplate would use a 120 degree swash plate mix. The swash plate in the picture above has 6 control rods, and so it would use a 60 degree swash plate mix. Most RC helicopters will use a swashplate with between two or four control rods. The largest RC Helicopters use 4 control rods, because of the extra strength they give the swashplate mechanism.

模型遥控直升机能使用超过2个舵机来组成十字盘的运动控制。发射机上运行的软件告诉每一个舵机的运动量，实现要求的动作。每个舵机通过图片中银色的杆连接。所有杆之间的距离相等。十字盘混控与十字盘上的球头连接点数量有关。例如：两个球头的十字盘由两个舵机控制，两个球头180度放置。3个球头的十字盘要用120度十字盘混控(3个球头120度分布)。图片上的十字盘有6个球头，所以用到60度十字盘混控。大多数的遥控直升机用到2至4个舵机控制，最大的遥控直升机用4个舵机控制，提供额外的力量。

rxjzzs

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ming112

感谢分享。。。。。。。