1524

Item 1524

DESIGN: Electrotor-SloMo ~ Motor - Axial Flux - Miscellaneous - Blade Pitch Control

The following covers the use of a single rotor, not the current tandem rotor idea. Perhaps both ideas should be explained here until one wins out.

The idea of a Torque-pitch coupling may be flawed. This is because if the blade experiences a mild downdraft, the drag will decrease and this will cause the pitch to decrease. Or alternatively, a large downdraft on thw plan view area of the blade may cause the pitch to increase. I believe that this may be a fatal flaw. Conversely, and updraft would have the same effect but in reverse, in that the pitch will increase. Any damping (delaying) of the pitch response will slow down the cyclic speed.

Could the above concern be eliminated by the inclusion of a damper?

The leading and lagging of the individual blades may well create an inplane vibration and move the center of lift about the axis of the mast.

Notes:

Each of the two aerodynamic rotors has two blades and one motor. Each of the motors has two stators. Therefore the blade to stator ratio is one-to-one.

The idea is to allow the stators to rotate slightly about the mast, but a spring and damper limits this rotation. In addition, the idea is to have a 'pitch link' type of connection between a blade and a stator. If one of the two stators receives more current than the other it will rotationally advance in respect to the rotor. This precession will cause the linked blade to have its pitch increased. If the other stator receives less current then it will rotationally retard in respect to the rotor. This recession will cause the linked blade to have its pitch decreased. If the stators have their power increased when their blade is on the retreating side and have their power decreased when their blade is on the advancing side then this will cause the rotor disk to tip down at the front.

The hope is that this rotation will not be detrimental to the electrical powering of the motor.

Could the rotation of a stator, in respect to the mast and rotor, cause an outer ring on the stator to rise up. Around the outer cicumfrance of the ring is a groove. In this grove rides a cam follower, which is on the end of the blade's pitch link. The lifting of the ring will result in an increasing of the pitch of the blade. Will the mass be too great for 1P cycling?

Quotes from Design and 'Development of a High-Speed Axial-Flux Permanent-Magnet Machine': File in computers; [Disk Motor.pdf]

Is this statement relevant? "If the windings are connected in series, then one stator may be rotated over a certain angle with respect to the other which results in reduced cogging torque and space harmonic components [37]." ~ DESIGN AND DEVELOPMENT OF A HIGH-SPEED AXIAL-FLUX PERMANENT-MAGNET MACHINE, page 27

See section 4.15 'Effect of the stator offset' in 'Development of a High-Speed Axial-Flux Permanent-Magnet Machine'. There is mention of "With 16.4◦ stator offset,"

Description of Operation of Proposed Idea for Blade Pitch Control

The rotor is located between two stators. The motor's rotor direct drives the aerodynamic rotor (c/w blades). The stators do not rotate about the mast except for the ability to cycle perhaps 20º azimuth.

The limited rotation of the stators is independent from each other. They have a 'home' position, in respect to this limited rotation of 20º. A spring in each holds them in this 'home' position. Applying power to the stators will create a torque that rotates the rotor. As the torque is increased, the counter-torque will start overcoming spring and both stators will leave their home position. Greater torque will result in a greater angle from the 'home' position.

There is a cam track on a ring that is mounted around the circumference of each stator. These cam tracks cannot rotate. However the can rise and lower and their change in elevation is mechanically set ( by screw) by the change in the angle of each stators rotation from its 'home' position. In other words; both cam tracks will rise as the torque of the electric motor increases.

The pitch link of one blade is attached to a cam-follower, which is located in one of the two tracks. The pitch link of the other blade is located to a cam-follower, which is located in the other track. This will cause the pitch of both blades to increase in unison as the torque increases. The 'home' is the default position for autorotation.

If the power of a stator (by pulse width modulation) is varied at azimuths about the rotation of the rotor then the pitch of that rotor's blade will be changed at azimuths about the azimuth of rotation. This means that if stator-A increases its power when its blade is at 270º azimuth and at the same moment stator-B decreases its power when its blade is at 90º azimuth, the rotor disk will be tipped down at the front.

Another Idea for Flight Control: June 18, 2009 ????

A 2-blade teetering rotor; c/w:

delta-3 teetering hinge.

Light hub-spring restraint at the extreme teetering limits. Perhaps elastomeric teetering hinge and hub-spring.

Some limited torque-pitch coupling built into the composite lay-up of the blades. This pitch changing is basically at the tips and not at the root, as per; OTHER: Rotor Concept - Independent Root & Tip - Torque Tube Method

Two-position root pitch. One position for all powered flight and the other position for autorotation. The pitch angle for autorotation will provide a slightly enhanced aerodynamic driving force over that of the conventional gyrocopter root pitch. The position will be set by mechanical torque vs. no mechanical torque.

Pitch and roll control by gimbal (gyrocopter) head. Or, can electrical force be used to pitch the individual blade while also contributing to rotor rotation/, in an efficient manner, see; Electrotor-BladeMotor?

Yaw control by ??????????

Small gap on coaxials due to shared swashplate-type ring?????

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DESIGN: AeroVantage ~ Motor / Genset / Engine - Fullsize Motor - Hollow Shaft

Initially displayed: July 31, 2006 ~ Last Revised: June 4, 2011

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