This is the most common helicopter design that has a main and a small tail rotor, made famous by Sikorsky & Bell by selling thousands to the U.S. Government.

This design has two rotors mounted one on top the other on a single axis and rotating in opposite directions. Both Peter Papadakos of the U.S., and Kamov Design Bureau of Russia perfected this design primarily for military applications. Russian Kamov KA-50 was produced as a counter force for the U.S. Apache with this design.

This design also has two rotors, one in the front and one in the rear of the aircraft. This designed was pursued by Frank Piasecki and finally purchased by and made famous by the Boeing Aircraft Company.

This design also has two rotors arranged side-by-side and V-12 was built in early Russia. Not much is known what happened to the aircraft but many similar aircraft seemed to have been designed around the concept.

This design utilizes two intermeshing rotors, one located on each side of the aircraft. Charlie Kaman of Kamax Corporation was the pioneer for this design.  His aerial trucks have been sold around the world.

Advantages of the Yoshine Coaxial Configuration

Yoshine's EzyCopter incorporates the best features for a small coaxial design with distinct innovations by it's engineers as described below:

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 to be used by the coaxial rotor system for lifting purposes. Therefore, in comparison with a tail rotor configuration, the useful load of the EzyCopter is much higher. Also the substantially lower weight of the coaxial design and the shorter shaft power transmission loss 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 single coaxial rotor system eliminate dangerous inertia and torque and cross wind effects during takeoff and landing;

(b) The use of the collective and the cyclic 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 is 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 an equivalent engine required to power a tail rotor configuration and substantially lower than that of the tandem or other multi-rotor configurations.

5. Complete Symmetrical Rotor System:

The symmetry of the EzyCopter's 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 and cyclic 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 coaxial helicopter 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 Typical EzyCopter Symmetrical Rotor System

(a)  The symmetry of the rotor system and the transmission reduces approximately by one half the number 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.

 A Typical Coaxial Transmission

9. Modular Construction:

The torque-balanced 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, collective and directional control) are fully independent and wholly incorporated into the lifting mechanism. This feature makes it possible to consider the engine, transmission, rotor and its 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 subassemblies 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 coaxial transmission system and without any major modifications or associated costs. It is believed that this unique feature will encourage many helicopter enthusiasts to seek out the Yoshine Coaxial Design System 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 “Basic Helicopter Handbook”. One of the chapters in it is titled, “Some Hazards of Helicopter Flight”. 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:

The reduction and elimination of these hazards are the most significant features of the EzyCopter from a safety stand point and substantiates Yoshine’s promise to deliver a highly efficient and safer vertical air vehicle that is easier to build, easier to fly, and reasonably affordable.

Some Team Members