Item 1536

OTHER: Helicopter - Inside - Single Rotor - Simple Electric Ultralight


Proposed Methods of Implementing Collective and Cyclic control:

Method 6: Tractor motor+prop and pusher motor+prop.

Do sketch also and show flexible hub-bar to blade coupling.


~ The propellers in the following sketches should be located behind the rotor blade so that folding blades may be used. ~

Method 1: Speed - Pitch coupling between the motor+prop and the blade; resulting from the gyroscopic precession on the motor.



Method 2: Torque - Pitch coupling between motor and blade; resulting from the torque tube. There may also be some Speed - Pitch coupling between the propeller and the blade; resulting from the gyroscopic precession on the propeller. A Torque - Pitch coupling will result in a faster response to control changes than a Speed - Pitch coupling will, and this will particularly important for the proposed method of electrical flight control.

For correct direction of rotation move the gear on the prop shaft to the blade's trailing edge.

Method 3: The motor frame is mounted on 'bearings' that allow limited rotation about the shaft's axis or rotation. Torque - Pitch coupling between motor and blade; resulting from the torque tube. There will also be Speed - Pitch coupling between the motor+propeller and the blade, resulting from the gyroscopic precession.

Method 4: Servo flap - Pitch coupling that is produced by limited rotation of the frame of the motor about the shaft's axis or rotation. There may also be some Speed - Pitch coupling between the propeller and the blade; resulting from the gyroscopic precession on the propeller. There is also the possibility of mounting the servo flap on the leading edge of the blade.

Could the flap be utilized to counter any negative effect of perturbations?

Method 5?: Similar to #2, How about a motor at the blade's root driving a shaft to a 3-gear set of miter gears that drive a leading edge prop and a trailing edge prop in the opposite directions?

General Specifications:



Flight Control: (electrical control circuits)

Power Control: (electrical power circuits)

Flight Options:

    1. Power is provided buy a small battery pack and flight duration is limited to a few minutes. Additional battery packs and a charger can be utilized to provided a number of short flights.
    2. Power is provided by a 100-200 ft long cable, which is attached to 2 or 3 house circuits or to a Gen-set.
    3. A combining of options 1 and 2. The cable is used to obtain elevation, then disconnected and the small battery pack is used for a few additional minutes.
    4. A large, perhaps 100-lb, battery pack is located where the reciprocating engine would normally be located. Currently, this battery pack would be very expensive, however, the price and efficiency of batteries will continue to improve. Options 1, 2 and 3 could be used during the time required for construction, flight testing and training.

Specifications and Required Power:


Safety and Reliability:


    1. If one of the two electrical circuits (one for each blade) breaks down then the other circuits must shut down instantly so that the craft can go into autorotation.
    2. There is no flight control if the circuits are shut down.

Both circuits must be given full redundancy. Not required for Method 5?

Additional Power and Control:


Previous Craft:


To produce maximum thrust at full power the tip speed should fall between .88 and .92 mach. Note that if this represents the mean tip speed then the tip of the blade when pointed to the mast will be less and when pointed away from the mast will be higher.

It might be necessary to use two motors and propellers on a common axis. One would be a tractor and the other a pusher. The tractor will not be able to fold. Look into counter-rotation versus same rotation, in respect to aerodynamics and gyroscopic precession.

Related Outside Information:

Additional Notes not yet assimilated into the above.

Method 5:

Method 6: Posted to Rotary Wing Forum September 24, 2006


A teetering rotor assembly that bolts to the rotational bearing on the top of the gyrocopter cyclic control system.

Cyclic control is by conventional gyrocopter flight controls.

Collective, from autorotation pitch to maximum pitch, is by power from an electric motor.


There is a single high-speed electric motor and the center of the rotor, with the centerline of the motor aligned with the blade pitch axis.

Both the motor's rotor (armature) and the motor's frame (stator) rotate, and they rotate in opposite directions.


A folding propeller is mounted behind the trailing edge of both blades.

Its axis of rotation is slightly below the blades feathering axis. This is done so that increasing the motor's power will increase the pitch of both blades. (torque-pitch coupling)

The blade rotates inside down. The propeller's blades will be experiencing a much faster inflow airspeed when they are pointing outward, away from the mast, then when they are pointing inward, toward the mast. This problem exists when the craft is at hover or in transitional flight. It also exists when the propeller is on the advancing side and on the retreating side.

It is located as far out the rotor blade as is possible, to minimize the aerodynamic differential between when the propeller blade pointing toward the hub and when it is pointing toward the rotor blade's tip.

Power Transmission:

Behind the propeller is a 90 miter-gear set.

One gear is attached to the propeller shaft and the other gear is attached to a torque-tube, which runs from the motor to this gear.

One torque-tube attaches to the motor's shaft and the other torque-tube is attached to the motor's frame.

The torque tube is manufactured from carbon composite and it will flex with the blade but it is rigid in torsion.


Direction of Propeller Rotation:

    • From the prospective of propeller rotational drag moments I believe that the may be more efficient if it is rotating CCW, when viewed from the rear. This is because when the blades are nearest to the mast they are experiencing a slower free-air speed then when they are nearest to the rotor blade's tip. If the blade pitch is determined by the mean free-air speed then the blade when closest to the mast will be imparting the greatest rotational speed to the air and it would be best to have this paddle like thrust to be downward and providing lift.

Forward Speed:

  • Blade mounted propulsors appear to be limited to hover and slow transitional flight.
    • As the forward velocity of the craft increases the airflow over the advancing blade will increase. This mean that the propeller's rpm (and tip Mach number) must be higher.
    • When the propeller is on the retreating side, its thrust is in opposition to the direction that the craft is moving.

A possible means of overcoming this concern might be some idea similar to; OTHER: Miscellaneous - Thoughtless Ideas - Root Turbofan Rotor

For more on this subject see:

Rotary Wing Forum ~ Theory of Flight ~ A Helicopter for the Price of a Gyrocopter.


Related Pages:

Introduction Page | SynchroLite Home Page | Electrotor Home Page | UniCopter Home Page | Nemesis Home Page | AeroVantage Home Page:

Initially displayed: September 18, 2006 ~ Last Revised: June 25, 2009