近年来多旋翼这种气动布局的飞行器大量应用于消费级无人机和一些特殊行业应用。这使很多人把能悬停的飞行器和多旋翼直接画上了等号，而忽略了其他可以悬停的气动布局的潜力。我并不是否定市场的选择，而是希望无人机不仅仅只有一种形态，针对不同的用途灵活选择气动布局。 在此背景下，我们研发了一款共轴双桨的无人机Tdrone，并将其开源。希望大家能够根据我们完整的技术方案，了解这类飞行器，甚至自己亲手做出一个这样的飞行器！

In recent years, multi-rotor aerodynamic aircraft have been widely used in consumer UAVs and some special industries. Mention of hovering aircraft, the first thing we have in mind is multi-rotor, which ignoring the potential of other hovering aerodynamic configurations. There is no denying the fact that multi-rotor occupied most of the market share, while UAVs should not only has one form. It is necessary that a flexible choice of pneumatic layout for different applications and scenarios.
In this context, we have developed a coaxial two-propeller UAV Tdrone. This article provides a complete information and an open source solution to share this. I hope you are interested in  this kind of aircraft，even make one by yourself!Why Coaxial drone？

共轴双桨气动布局的飞行器其飞行原理类似于我们常见的直升机。与直升机不同的是，共轴双桨气动布局取消了直升机上常见的尾桨，使用了两个直径相同共轴布置的螺旋桨。与直升机相同的是，都使用了倾斜盘作为变距机构，来控制飞行器的俯仰和横滚自由度。下面的视频介绍了倾斜盘的工作原理：

The flight principle of coaxial twin-propeller aerodynamic configuration aircraft is similar to that of our common helicopter. Unlike helicopters, the coaxial twin-propeller aerodynamic configuration cancels the common tail rotor on helicopters and uses two propellers with the same diameter and coaxial arrangement. Like helicopters, tilting discs are used as pitch-changing mechanisms to control the pitch and roll degrees of freedom of aircraft. The following video describes how the tilting disk works:

• youtube直升机斜盘原理视频
• bilibili直升机斜盘原理视频

对于小型共轴双桨气动布局的飞行器，通常采用单层变距的结构，就是说上下两层旋翼只有一个旋翼可以变距，而另一个旋翼则为定距。这样布局的好处是最大限度简化机械结构，利于飞行器的制造和后期维护。 当然如果追求更好的性能也可以设计更为复杂的双层变距结构，来使飞行器获得更强的飞行性能。

For a small coaxial twin-propeller aerodynamic configuration, a single-layer pitch-changeable structure is usually adopted, that is to say, only one rotor can be pitched in the upper and lower layers, while the other is fixed-pitch. The advantage of this layout is to simplify the mechanical structure to the greatest extent, which is conducive to the manufacture and later maintenance of aircraft. Of course, if we pursue better performance, we can also design more complex double-layer variable-pitch structure to achieve better flight performance.

共轴双桨相对于多旋翼飞行器的优点有：

• 1.在相同的工作尺寸下（飞行中） 共轴双桨飞行器拥有更大的旋翼面积进而拥有更高的飞行效率；
• 2.在相同的工作尺寸下（飞行中） 共轴双桨飞行器拥有更大的有效载荷；
• 3.在相同有效载荷下，其旋翼转速低于多旋翼，进而产生的噪音更小，拥有较好的静音性；
• 4.其产生俯仰和横滚控制力矩时不需要频繁使主旋翼加减速，减少了能量的损耗，尤其在飞行器尺寸较大的情况下，这种相对于多旋翼的优势就会更明显；
• 5.其螺旋桨可以方便的折叠收纳，没有多旋翼飞行器较为复杂的机臂折叠锁定机构，折叠起来机身更为规整，便于携带与运输；

The advantages of coaxial twin-propeller over multi-rotor aircraft are as follows:

• 1. Coaxial twin-propeller aircraft has larger rotor area and higher flight efficiency under the same working size (in flight).
• 2. The coaxial twin-propeller vehicle has larger payload under the same working size (in flight).
• 3. Under the same payload, the rotor speed is lower than that of multi-rotor, which results in less noise and better silence.
• 4. When generating pitch and roll control moments, the main rotor does not need to be accelerated or decelerated frequently, which reduces the energy loss. Especially in the case of large aircraft size, this advantage over multi-rotor will be more obvious.
• 5. The propeller can be folded and accepted conveniently without the complicated folding and locking mechanism of the multi-rotor aircraft arm. The folded fuselage is more regular and easy to carry and transport.

共轴双桨相对于多旋翼飞行器的缺点有：

• 1.相较于多旋翼飞行器，共轴双桨飞行器的机械结构相对复杂，导致在制造成本与可维护性上不如多旋翼飞行器；
• 2.飞行模态相对多旋翼复杂一些，在飞控设计方面有一定的挑战；

The disadvantages of coaxial twin-propeller compared with multi-rotor aircraft are as follows:

• 1. Comparing with multi-rotor aircraft, the mechanical structure of coaxial twin-propeller aircraft is relatively complex, resulting in lower manufacturing cost and maintainability than multi-rotor aircraft.
• 2. Flight mode is more complex than multi-rotor, which has some challenges in flight control design.

任何飞行器都是面向于目标用途和使用环境设计的，各种气动布局之间没有绝对的好坏之分。不仅在地球上如此，在其他星球上我们的理论依然适用～

Any aircraft is designed for target use and use environment. There is no absolute difference between different aerodynamic layouts. Not only on Earth, but on other planets our theory still holds true

• NASA共轴飞行器

在莱特兄弟使用固定翼飞行器完成人类第一次载人飞行的100多年后，我们有望见证人类首次在除地球以外的星球上使用无人飞行器，而这个无人飞行器正是共轴双桨无人 机！

More than 100 years after the Wright brothers completed their first manned flight using fixed-wing aircraft, we are hopeful to witness the first use of UAVs on planets other than Earth, which is a coaxial drone!

Tdrone无人机是从2015年10月开始研发的，到2016年4月第一代Tdrone具备了初步飞行能力，就如视频中展示的那样（连接）。Tdrone使用了两个经过改装的1806无刷电机作为动力，两个舵机用来控制斜盘，偏航使用差速控制。飞控使用了CC3D飞控。其搭载了两轴稳定的云台和运动相机。续航时间在10分钟左右。

The Tdrone UAV was developed in October 2015, and by April 2016 the first generation of Tdrone had initial flight capabilities, as shown in the video. Tdrone uses two modified 1806 brushless motors as power, two steering motors to control the swashplate and differential control for yaw. Flight control uses CC3D flight control. It is equipped with a two-axis stable platform and a motion camera. The duration is about 10 minutes.

Tdrone实物：

Tdrone使用了CC3D飞控。CC3D飞控原生即支持该种类型的飞行器，但需要一些特殊的设置。这是我使用的配置文件（连接）。 你可以直接使用该配置文件，但遥控器 的设置需要根据你使用的遥控器的情况进行重新设置。这一步与多旋翼是一致的，参考多旋翼的部分即可。 地面站固件版本为 15.02.02。 我们会在此不断完善飞控的设置教程，请关注后续的更新。

Tdrone uses CC3D flight control. CC3D flight control native supports this type of aircraft, but requires some special settings. This is the configuration file I use. You can use the configuration file directly, but the remote control settings need to be reset according to the situation of the remote control you use. This step is consistent with the multi-rotor system. Refer to the multi-rotor system. At the same time, the ground station firmware version is 15.02.02 . We will continue to improve the flight control setup tutorial here, please pay attention to the follow-up updates.

Tdrone整机采用3D打印技术制造，所有零件都进行了3D打印优化，可以直接打印，打印材料使用了普通的ABS塑料。**核心部分使用了铝管。98%的零件都使用了螺丝固定，方便后期维修更换。

Tdrone is manufactured by 3D printing technology. All parts are optimized for 3D printing, which can be printed directly. The printing materials are made of ordinary ABS plastics. Aluminum tubes are used in the central core. 98% of the parts are fixed by screw, which is convenient for later maintenance and replacement.

我十分理解大家想尽快制造出属于自己的飞行器的急迫心情。但在一切开始之前，你需要弄清楚以下几点：

• 1.所有的零件尺寸都是按照我的3D打印机公差精度优化的，可能它并不适合你所使用的3D打印机。你需要根据你自己的打印机适当的调整零件。你可以先打印出一些需要配合的零件来测试。
• 2.所使用的电机与舵机尽量使用与我们建议或相近似的型号，不要偏差过多。
• 3.该飞行器的制造需要一定的动手能力，虽然打印机完成了大部分的工作，但仍需要你手工处理一些金属零件布线及调整电机等。

I fully understand your urgency to build your own aircraft as soon as possible. But before everything starts, you need to figure out the following points:

• 1. All part sizes are optimized according to the tolerance accuracy of my 3D printer. Maybe it is not suitable for your 3D printer. You need to adjust the parts appropriately according to your own printer. You can print out some parts that need to be matched to test.
• 2. Use the motor and steering gear as much as possible, and do not deviate too much from the model we recommend or approximate.
• 3. The manufacture of the aircraft needs a certain practical ability. Although the printer has completed most of the work, you still need to manually process some metal parts wiring and adjust the motor.

点击YouTube，bilibili视频链接来观看Tdrone的实际飞行视频.

• YouTube飞行视频
• bilibili飞行视频

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