Coaxial ROTOR Drive Systems

Perfect "Coaxial Helicopters" for Everybody?

The 1950's American Dream of Flying to Work is still a dream of today?

The Gyro's“Rotor Drive System” was invented some 100 years ago in "1923" by Mr. De la Cierva of Spain with an aim to eliminate the risk of airplane STALL after he witnessed his best friend's plane crash dead due an unexpected STALL

“1923年” 百年前,西班牙的 De la Cierva 飛機工程師,親眼目睹了自己最好的朋友因飛機失速意外而墜毀,為了讓飛機能免於失速的風險,他發明了“旋翼轉子升力系統”。100 年前,西班牙的 De la Cierva 於 1923 年發明了“轉子驅動升力系統”,其目的是消除飛機失速的風險,因為他最好的朋友因意外飛機失速而墜毀身亡。

The "2023" marks the 100th Anniversary of the Helicopter Invention!  Thanks to the De la Cierva's invention of the Rotor System, helicopters have undergone the 100 years time tested value to become the Perfect Helicopters for Everybody!  What he had accomplished in 1923 was a type of articulated rotor system which the world's has seen until today that shaped like the picture below called the C.4 C.4 that will never stall! 

Today, the airplanes with Rotor Blades are known as Gyroplanes, Autogiros, or Gyrocopters.  The most distinctive SAFETY feature of a Gyroplane or Helicopter is that it won't STALL and fall from the sky!As once it's airborne fly, it can always auto-rotate, even without power, and land SAFELY! In aviation, it is believed proven technology is essential for safety, and it is better to choose RELIABILITY over NOVELTY.


Understanding COUNTER-ROTATING Coaxial Rotor Design

Coaxial rotor designs have been used on military helicopters for the better since last 75 years. A coaxial rotor eliminates the need for a tail rotor and creates a safer, more stable machine.  To understand how coaxial design outperforms other helicopters, let's examine the physics.

The physics of helicopters

For single-rotor helicopters, lift is generated through the main rotor rotating. This rotation generates torque about the main helicopter, causing the main fuselage to spin around in the opposite direction.

Early engineers designed the tail rotor to counter this torque and keep helicopters stable. Tail rotors are generally much smaller rotors mounted on a perpendicular axis to the main rotor.

By controlling the speed of the tail rotor, the pilot can stabilize the craft as well as control the direction of the helicopter.

Slowing the tail rotor would cause the helicopter body to rotate in the opposite direction of the main rotor due to excess torque in that direction.

Speeding up the tail rotor would do the opposite. Along with direction, helicopter pilots can control the yaw of the craft by adjusting the angle of the tail rotor. By pitching the tail rotor slightly up or down, the pilot creates a moment arm through the helicopter, which in turn adjusts the yaw of the craft.

Why a coaxial design is better ?

Now that we understand the basic mechanics of single-rotor helicopters, we can begin to see why coaxial rotors might present some advantages.

By placing two rotors on a single axis and rotating them in opposite directions, a net-zero torque around the main body of the helicopter is created, keeping it very stable.

Through both mechanical means and electronic means, each rotor is perfectly timed and controlled to cancel out the net torque of the other rotor in real-time. This allows the coaxial craft to achieve rather significant hovering capabilities when compared to their single-rotor brethren.

When you think of helicopters, you think of vertical takeoff and the ability to hover. Remove those aspects, and the helicopter functions identically to a plane.

As a side note, vertical takeoff isn't exclusive to rotorcraft.  However, planes that harness the ability without rotors – mainly the harrier jet – accomplish the task with much less efficiency and stability.

A helicopter's ability to hover and be stable is synonymous with its quality of being a helicopter.

In coaxial designs, the improved ability to hover and maintain stable flight ultimately makes for better helicopters. Better helicopters mean that they are easier to control and much safer for the occupants.

Theoretically, if one rotor broke in a coaxial system, the craft could still be landed safely.

Lastly, the application of coaxial rotors means that there is no inherent need for the craft to have a gyroscope to provide stability. The rotational effects of both rotors provide for a near-perfect gyroscope, improving the stability of the craft once more.

So why we don't see more coaxial helicopters? 

Issues with coaxial helicopters

The first main fault is that the timing of the two rotor blades needs to be near perfect. Speed and directional changes need to be achieved together. Even the slightest fault in calibration essentially makes the aircraft unstable and impossible to fly. 

A fault in calibration is worse than you probably think for the craft's ability to fly.  If the timing is off enough, coaxial helicopters won't produce enough lift to even leave the ground and end up just spinning on the tarmac.

On top of the need for accuracy in the tuning of the rotors, these rotors tend not to be as responsive as a single-axial rotorcraft. When you make an aircraft more stable, you generally make precise movements harder to achieve – it's a constant tradeoff in aerospace engineering.

While coaxial helicopters are safe and efficient, they are not well suited for applications where pilots need fine maneuverability.

They are, however, perfect for applications where precise hovering is needed.

The coaxial rotor design is one of the most prominent helicopter designs to date.

While it has its inefficiencies; it won't be going away anytime soon.

The stability of the design is popular within the hobbyist community and even many military and

rescue helicopters to date. 

So if you were designing a helicopter, which design would you choose?

Yoshine CDS:Coaxial Drive Systems

In 2003, the world's first "unmanned" coaxial helicopter with a payload up to 100kg was successfully developed and lift off in Taichung, Taiwan, by YOSHINE HELICOPTERS using a patented "CDS" technology!

2003年,祐祥載重100公斤的『共軸無人直升機 』在台中『漢翔公司』協助在漢翔園區起飛!



2003 CDS Shown at Duxford UK Helitech 2003
英國展出 創造了歷史 

4 cds 

2005年,美國的PM科技雜誌報導, “EZYCOPTER by Yoshine Helicopters of Taiwan 為全球第一架「無尾旋翼」個人休閒運動「雙主旋翼」共軸直升機,未來也有國防軍事用途發展潛力。

2 TechWatch

CDS 解決了直升機「反扭力」問題,提供直升機『自動平衡』或『自動排檔』的能力!

2004年全球第一架 “CDS” 技術研製成功

傳統直升機《手排》飛控方式 vs. 共軸直升機《自排》解決方案








2009Paris -061

 "CDS":新一代無扭力直升機的飛控系統 專業廠商



瑞士 直升機試飛飛行員(上左) / 韓國直升機客戶(上右)



(2)無人直升機 載重遠距飛行的無人直升機,供「農、漁、牧」及「國防軍事」用途。 

cds1 parts

The Hybrid Coaxial Air Taxi

The Coaxial Helicopter of the Next Generation

One Step Closer to Zero Emission



Safe and Reliable Electric Vertical Take Off & Landing.  Affordable and Sustainable solution.  New Electro-Hybrid drive, Long Range Electric Flight

Fast Employment for Air Mobility and Surveillance Solutions, Civil or Defense.

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Proven Coaxial Technology, to certify under FAA Far Part 27:成熟的共軸直升機技術  

Goal for Future Zero Emission:未來的零碳排放目標

Renewable and Sustainable Energy:可再生和可持續的能源

Speed up to 280 Km/h:最高時速可達 280 公里

Autorotation Capability:「自轉安全降落」著陸能力

Electric Drive with Range Extender:電動直升機 + 增程器發電機

eVTOL - Low Noise Level with 8 rotor blades:電動起降 / 八旋翼低噪音水平

Stable and Agile even in Strong Wind:強風中也能穩定敏捷飛行

Less Mechanical parts than Multi-Copter:機械零件比多軸直升機還少

Lower Operating Costs:較低的營運成本

Long Endurance (Generator/Range Extender):長續航力 (發電機/增程器)

Three Passengers + One pilot:3名乘客 + 1名飛行員

CoaxCopter from Charles Lin:“共軸直升機”:世界直升機的趨勢

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