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Symmetrical Ultralight Intermeshing & Interleaving Helicopters

Primary Objectives:

    1. It is easier to fly then existing helicopters.
    2. It is safer to fly then existing helicopters.
    3. It complies with; European - JAR - VLR , Britain - BCAR-S, and future modified US - SP/LSA.

Personal Arial Rotorcraft (PAR) wish list;


For a larger version, click on the drawing; then click on the magnifying mouse pointer.



Power-train ~ with dual engine & transmission

Rotor - Hub ~ 3-blade - Constant Velocity Joint w/ Hub Spring


For 3-blade CVJ+HS rotor and single engine, the general arrangement of the power-train will probably be a compact unit similar to the above 60-year old Flettner Fl 282.

Overview of Objectives:

Easier to fly:

Symmetrical handling characteristics:

The symmetry of the two counter-rotating rotor disks eliminates the need for a tail rotor. This reduces the demands on the pilot in coordinating the cyclic, collective and pedal. The yaw function should be similar to that of a plane. In 1948 the symmetrical Kaman K-125 was flown by a housewife with only 2 hours of ground instruction and 36 minutes of dual instruction.

Moment Coupling between the Rotors and the Fuselage:

The hub springs provide a coupling between the rotors and fuselage so that there is greater safety during a low G flight condition.

The constant velocity joint and hub springs minimize the pilot's off-axis compensation, caused by cross-coupling. In addition, it results in rapid and positive responses to the pilot's control inputs.


To eliminate low rotor speed. This is the second highest cause of fatalities. The highest is wire strikes.

Incorporates a rotor governor (not an engine governor) which provides;

Automatic entry into autorotation

Simple single stick control (if desired); with the cyclic grip controlling the throttle.

Safer to fly:

Engine Reliability: 

The 3-cylinder inline engine, with water-cooling and fuel injection, is significantly derated for greater reliability then other 2-stroke engines.

Redundancy and Gradual Deterioration: 

Where possible, components should be designed for gradual and observable deterioration thereby minimizing catastrophic failure.

Low disk loading & relatively large tip weights:  

To allow for a slower entry into autorotation, a slower descent rate in autorotation and more stored energy for use in the flare. Also, there is the high likelihood of being able to do autorotative landings without any forward airspeed.

Movable rear surfaces:   Maybe or partially

A ruddervator or stabilator assists with yaw and autorotation; thereby off-loading some of the control demands placed upon the rotor-disks. Either ruddervator or stabilator rotate downward to maintain a downward airflow on the tail surfaces, and yaw control, during autorotation. Pitch and/or roll assistance might be considered for incorporation later.


The intent is to add low rpm warning, low fuel warning plus other electronic flight and power train sensors.

Regulation Compliant;

United States ~ Sport Pilot / Light Sport Aircraft: Not yet accepting helicopters.

Pilot: The piloting of the SynchroLite should be easier than gyrocopters and airplanes, which are compliant.

Aircraft: The SynchroLite should not be much more complex than gyrocopters and airplanes, which are compliant.

European - JAR - VLR (Very Light Rotorcraft)

Britain - BCAR-S (Britain's Civil Airworthiness Requirements Section S-Small Light Airplanes)


Related to two blades per rotor only: The helicopter is small and transportable within a van or trailer. The blades can be pivoted so that they are all parallel and pointing forward or aft during storage or ground transportation. The two rear legs and the tailboom detach. The rigidity of the rotor necessitates that the helicopter be stronger then helicopters with teetering rotors, therefore it will be more adaptable to ground transportation.

Three blade rotors: To be considered.


The maintenance should be quite comparable with the existing Light Sport Aircraft.

Commercial Viability:

A prototype of the SynchroLite will be built. Any subsequent commercialization must be by others.

Other things that might reduce the costs of the craft and make it more viable are:

Primary Grouping:


SynchroLite Overview

Concerns & Tasks


Potential electric drives: Electrotor


Power Train ~ w/ 2 motors

Control - Flight


Power Train ~ w/ 1 engine

Weight & Balance

Landing Gear

Power Train ~ w/ 2 engines

Dimension, Area & Drag



Trim, Stability & Control



Vibration Analysis

Control - Power Train


Special Tool



Intermeshing Information


Flight Dynamics

Helicopters - Outside



Helicopters - Inside



Rotor Concepts:

CNC Workstation

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Last Revised: July 14, 2010

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