What are the CDS advantages?

The EZYCOPTER is a new generation of personal recreational coaxial helicopter "kits" designed for maximum safety and affordability. The EZYCOPTER employs a new Coaxial Drive System (CDS) that can be powered with one or two small turbine, rotary, or piston aircraft engines. 

CDS kits come with a symmetrical articulated rotor system, four rotor blades, and a 3-in-1 swashplate system, integrating collective and cyclic controls with a differential pitch mechanism for yaw maneuverings. 

On January 18, 2005, an EZYCOPTER demonstrator was successfully flown with a computer on board while remotely controlled by our pilot. The EZYCOPTER unmanned prototype made its maiden flight with data collected confirming that a coaxial helicopter can become a reality at an affordable price. 

The EZYCOPTER is the first capable of accepting either a single or twin engines. Because there is no tail rotor to rob away some engine power, engines with smaller horsepower and lighter weight can be used, resulting the possibility to install two engines in a smaller helicopter footprint. Twin engines provide not just flight safety, improved engine life, they also eliminate the concern for constant focus attention for auto-rotation.  Reduced horsepower also contributes to reduced noise, allowing more acceptable neighbor friendly hovering and flying!

The coaxial utilizes four shorter main blades instead of two long ones, which further saves engine power while adding stability and further reduce noise due absence of a tail rotor. These distinctive features enable the EZYCOPTER to be built lighter in weight, smaller in size, making home-built coaxial possible and home-based operation acceptable. Point to point vertical personal transportation
with no runway and airport suddenly become feasible with the EZYCOPTER.

The EZYCOPTER features:

NO TAIL ROTOR COAXIAL DRIVE SYSTEM - Stable, easy, and safer to fly than conventional helicopters.

TWIN-ENGINE CAPABILITY - Two smaller engines may be installed to work simultaneously and independently. When one engine fails, the other will allow safe landing, eliminating concern for auto-rotation.

AFFORDABILITY ˇV With the elimination of a tail rotor and the symmetrical nature of the CDS, cost of an EZYCOPTER will be comparable to a high-end sports car and much less than a "comparable" conventional helicopter.

COMPACT SIZE ˇV Diameter of the main rotor blade is only 6M (19.68ft.), EZYCOPTER can be stored in compact spaces such as automotive garages, making ˇ§home based" operation feasible.

The EZYCOPTER CDS features:

1. Ultimate Compactness:

The EZYCOPTER presents the ultimate in compactness and demonstrates its capability in operating with a high payload while requiring a minimum amount of power. Under the same payload condition, the EZYCOPTER is smaller and lighter than either a single rotor or tandem rotor configuration. This reduces, significantly, the amount of space required for vehicle storage and permits operations from anywhere where there is a small takeoff and landing area available.

2. Higher Useful Load:

With the absence of a tail rotor, the EZYCOPTER allows all of its engine power for lift. Therefore, in comparison with a tail rotor configuration, the useful load of the no tail rotor EZYCOPTER is higher, with a similar power rating. Also the lower weight of the coaxial design and the less power loss due to shorter shaft power transmission provide the EZYCOPTER a higher useful load advantage over the tandem or any other multi-rotor configuration.

3. Safer VTOL Characteristics:

In cross winds, or on a rolling pitching takeoff, or when landing, the control of the EZYCOPTER is much easier due to the following:

(a) The inherent torque neutralization characteristics of the coaxial rotor system eliminate dangerous inertia and torque and cross wind effects during takeoff and landing;

(b) The use of the collective, cyclic, and yaw controls makes precision flight controls possible;

(c) The use of the correlation between the throttle and the collective makes automatic flight control easier and safer.

4. Lower Empty Weight:

The design of the fuselage is strictly functional and independent of the lifting system. Accordingly, it can be made smaller in size than other designs resulting in lower fuselage weight. Consider other weight savings:

(a) The weight of the coaxial transmission system for a given horsepower is lighter than the total weight of the two or more transmission systems utilized in either the anti-torque tail rotor or tandem rotor configurations;

(b) The total blade area of the coaxial rotor is essentially equal to the blade areas of the main rotor of a comparable single rotor. The area is more when compared to other multi-rotor high-disk loading systems.

(c) The total combined weight of the fuselage, transmission, and rotor system of the coaxial rotor helicopter is lower than that of a tail rotor configuration with an equivalent power source, yet substantially lower than that of the tandem or other multi-rotor configurations.

5. Complete Symmetrical Rotor System:

The symmetry of the EZYCOPTER coaxial rotor system permits the same aerodynamic efficiency and control for flight in any direction; a feature found only in true coaxial helicopters with precision collective, cyclic, and yaw controls.

6. Freedom from control cross-coupling:

Control cross coupling exists in all other rotor configurations, causing control complexity and unexpected vibration. Lack of control cross coupling in the EZYCOPTER yields the following advantages:

(a) Only ONE control is required for transnational flight along any axis;

(b) Control along each axis is powerful, symmetrical, and unaffected by the controls along the other axes;

(c) Comparable transitional accelerations in all directions are obtainable;

(d) Precision handling ability with excellent control; even under adverse cross wind conditions and;

(e) Exact and excellent hovering positioning is excellent due to the symmetry of the coaxial rotor system.

7. Lower Manufacturing Cost:

The EZYCOPTER coaxial has an advantage over the other configurations because of its lower empty weight; the following two features further amplify this advantage:

(a) The symmetry of the rotor system and the transmission reduces approximately by one half the numbers of critical individual components as compared to single rotor configuration;

(b) The freedom of torque reactions of the fuselage allows for simpler fuselage structural design.

8. Optimal Transmission Design:

In a coaxial configuration, the inherent feature of splitting the power input into two paths results in a transmission design internally balanced, compact and capable of handling greater horsepower per engine input than other configurations. This design is naturally suited for multi-engine inputs without creating external torque reaction problems.

This unique feature of the coaxial transmission achieves greater significance as the size of engines can be increased as required.

 9. Modular Construction:

The torque-free coaxial rotor system eliminates torque reactions to the fuselage, making the fuselage independent from the rotor-transmission-engine combination.

And in the case of the EZYCOPTER, all four controls - longitudinal and lateral cyclic controls, collective and directional yaw controls - are fully independent and wholly incorporated and integrated into the lifting mechanism.

This feature makes it possible to consider the engine, transmission, rotors, and their controls as a major subassembly package, yielding the following advantages:

(a) Design and Manufacturing Flexibility

(b) Lower Structural Weight

(c) Growth Potential

(d) Modular Construction

10. Growth Potential

This is an area that the coaxial helicopter promises the most. As stated above, the fuselage of the coaxial system is purely functional and independent to the lifting system. Therefore, an increase in size of one of the major sub-assemblies does not affect the other. The coaxial transmission is suited, naturally, for multi-engine operations, as stated previously, without creating external torque reaction problems.

Also, there is, only, a small weight increase per additional engine. This feature permits various other helicopter designs to be considered when using the YOSHINE CDS without major modifications or runaway associated costs. It is believed that this unique feature will encourage many helicopter enthusiasts to seek out the YOSHINE CDS as a component part of their own helicopter development program.

11. Reduction & Elimination of Common Helicopter Flight Hazards

The U.S. Department of Transportation has published a ˇ§Basic Helicopter Handbookˇ¨. One of the chapters in it is titled, ˇ§Some Hazards of Helicopter Flightˇ¨. Ten items of hazards have been listed to indicate that a typical single rotor helicopter has to deal with. The unique EZYCOPTER coaxial design either reduces or eliminates these hazards. The following list indicates which:

1. Settling with power


2. Retreating blade stall


3. Ground resonance


4. Low-frequency vibrations


5. Medium frequency vibrations


6. High frequency vibrations


7. Transition from powered flight to autorotation


8. Anti torque system failure in forward flight


9. Anti torque system failure while hovering


10. Height-Velocity Curve


The reduction and elimination of these hazards are the most significant features of the EZYCOPTER from a safety stand point and substantiates YOSHINE objective to deliver a coaxial helicopter that is easier to build, easier to fly, and reasonably affordable.