DESIGN: Electrotor-SloMo - Control - Flight - Auto-Collective by Torque-Pitch - Overview

Overview: DESIGN on Flight Control pages and BUILD on Hub pages

• The primary means of providing a change of thrust is by changing the RPM of the aerodynamic rotor(s).
• One objective of the Torque-Pitch coupling is that of modifying the above by having the blade pitch change slightly and thereby reduce the amount of RPM change for a given change in the thrust.
• The second objective of the Torque-Pitch coupling is that of providing faster responses to the commanded changes of thrust. In other words, a change in torque will immediately cause a change in pitch (and thrust). Then the RPM, which changes at a slower rate, due to its rotational inertia, will change. As it changes the pitch will partially return toward its previous setting. [∆pitch ≈ ∆torque = power - ∆rpm]
• The range of pitch will be small. This is because it does not have to include cyclic control and changes to the RRPM will provide much of the thrust differential.
• The blades will immediately drop into an autorotative pitch, should the power fail.

• The basic Torque-Pitch concept is on OTHER: Rotor Concept - Flight Control - Torque-Pitch Collective Rotor Hub,
• A rotorhub for a small rotorcraft, where the thrust is controlled by an electric throttle.
• The craft might be configured with two bilateral rotors or two coaxial rotors. The total collective mechanism is contained within each of the hubs. The flight controls consist of throttle [collective, and perhaps yaw], cyclic [weight-shift], and perhaps pedals [yaw].
• This hub provides:

• For other information on Torque~Pitch coupling, see; OTHER: Flight Dynamics - General - Cross-Coupling ~ Torque~Pitch
• Also see ComparisonBetweenRotors.html

• Potential Types:
• Elastic straps (bungee chord)
• Die springs over curved pins
• Rotational resistance of elastomer rotor-to-rotor bearing. This may contribute very little resistance.
• Magnetic repelling around the ring of the electro-rotor and the aero-rotor.
• Bent strap springs.
• Potential Locations:
• Between the motor-rotor and the aero-rotor.
• At, but above the motor-rotor and the aero-rotor.
• At, but below the motor-rotor and the aero-rotor.
• Against the arm of the Pitch link.
• At the root end of the stub axle sleeve. Pairs of arms on all three sleeves interact with each other.

• See OTHER: Mechanics - General - Spring-Weight-Damper System

• Putting the torque resistor on rotor and leaving the blades out of it will put the Resistor right where the torque is generated and put less loading on the pitch bearings etc.
• Place the maximum and the minimum pitch stops in between the motor's rotor and the rotorhub, not at the blade, for the same reason as above. The forces at the maximum and the minimum pitch stop will probable be relatively light since the springs will be providing minimum force at the blades' minimum pitch and the springs will be resisting most of the torque generated force at the blade's maximum pitch.

See: 1968.html

• This description referencing the second picture above and the drawing below it:
• The beige inner ring with teeth is the motor's stator (w/o its copper windings). It is affixed to the frame and is stationary.
• The black ring, with beige tape at the top, is the electric-rotor. It contains the magnets and is rotated by the flux from the stator.
• The light blue ring is the rotor hub, which supports the three blades. It is connected to the above electric-rotor.
• This connection between the electric-motor and the aero-rotorhub is by a flexible; spring, or elastomeric, or magnetic coupling.
• The blades will be subjected to drag as they rotate and this drag will cause the aero-rotor to lag behind the electric-rotor by a few degrees. Increasing the torque will increase the lag.
• The brown pitch arms pivot about the blades' feathering axe. The bottoms of the arms are pinned to the electric-rotor. Therefore, the pitch of the blade will automatically increase as the torque is increased.

• Stop for maximum pitch.
• Stop for minimum pitch.
• Rotor-to-rotor torque.
• Matching the pitch on all three rotors, at the contact location of the transmission of pitch from the motor's rotor to the pitch arms.

• The negative pitch stop (for autorotation) will have very little force on it. It may have a replaceable 'plate' for absorbing wear from contact. This plate may have a little load absorption ability. This stop must have position adjustment so that the pitch of all blades is the same for autorotation and for turning off of the power. This adjustment is made on the ground
• The positive pitch stop must absorb the torque from the electric-rotor. It also incorporates the elastomeric device, which provides differing blade pitch for differing torque. This stop must have position adjustment so that the pitch of all blades is the same for all levels of torque. This adjustment is made on the ground. These stops mat also be ground adjustable to optimized speed and pitch for pilots of different weights.
• There is no apparent need for adjustability in flight.

• Can the damper be integrated with the torque resistor?
• See: OTHER: Mechanics - General - Spring-Weight-Damper System

• The torque-pitch mechanism probably does not have to be adjusted for the differences in the weights of pilots.
• In addition, each pilot will get to know his own personnel throttle-thrust relationship.?

• DESIGN: Electrotor-SloMo - Rotorhead - Synchronization - Overview ~ Perturbation

• DESIGN:~ Electrotor-SloMo - Control - Flight - Unique-Collective by Torque-Pitch - Overview
• DESIGN:~ Electrotor-SloMo ~ Rotor - Hub - Torque-Pitch Coupling - Inrunner - Megaflux MF0310
• OTHER: Rotor Concept - Flight Control - Torque-Pitch Collective Rotor Hub. This is the fundamental page for the Torque-Pitch Coupling.
• Database: Auto-Collective, and Motor

• Located the device(s) that create the blade pitch-change resistance to change due to rotor torque remote from the actual pitch arm. They could be located around the lower periphery of the aero-rotor ~ electric-rotor, in the same toroidal space in which the pitch arm bearings move.

• See: DESIGN: Electrotor-SloMo - Rotor - Hub - A - Torque Reactor
• The limits of blade pitch at the root will be from approximately -1º to +10º.
• Motor-rotor -to- Aero-rotor angle differential: For a15º range of pitch change on the blade the range of azimuth change between the motor-rotor and the aero-rotor will be 4.83º. The final ratio will depend on the radius of the pitch arm from the Z-axis centerline and the radius of the control bearing from the pitch axis of the blade.
• Novel idea: The pitch axis of the blade, at the root, is located chordwise at approximately 25% of the chord length. However, it is located vertically below the center of pressure. This will cause the profile and induced drag of the rotating blade to pitch upward toward +10º. Note that this will cause the retreating blades (non-breaststroke) to have a lower pitch and produce less drag, in hover and especially in cruise. Electrotor-SloMo - Control - Flight - Unique Collective by Torque-Pitch
• In addition, there is a 'spring' that is attempting to pitch the blade downward toward -1º.
• The combination of moments from the drag and the spring will offset each other at some pitch angle between the -1º to +10º end stops.
• Increasing power will increase the pitch of the blade whereas a loss of power will result in the pitch of the blade dropping to the autorotative position. This will act similar to a rotor governor, but with a fast response time due to the fact that the pitch change it is based on torque and not on rotor speed.
• There will also be a damper to mitigate any high rate of pitch oscillation.

• During forward flight the above will result in the advancing blade having a higher pitch than the retreating blade. Therefore the pitches of the blades are interlocked so that they have the same pitch. This may not be a disadvantage in forward flight, assuming that the rotation is non-breststroke, since the retreating blades are over the pilot so that the downwash on the pilot is reduced.
• This interlocking of the 2 or 3 blades per rotor may be by;
• The pitch arms of all blades are connected to the motor's rotor.
• Pinion gears acting on a floating or motor driven crown gear.
• Cable linking the rotation.
• Cams
• By .........?????............. Minimize the number of moving parts.
• There should be lateral symmetry of lift and drag between the two rigid rotors. However, it may be possible to do something so that there is lateral symmetry of lift and drag within each of the two rotors, by increasing the pitch on the retreating side. Ref 0871.html

• Not being currently considered. A reason for the Torque-Pitch coupling is that of minimizing the range of RRPM. A heavier pilot will result in the Rotor - Blade - Aerodynamic Twist to cause a lower thrust. To obtain the needed higher thrust will call for a higher RRPM. Potential solution: Provide a ground adjustable blade root pitch adjustment at the Torque/Pitch/RRPM device. However, the fewer adjustments required - the better.

• Presumably not: The motor will be operating to the left of the peak in the Power (Y-axis) to RPM (X-axis) curve. The call for more power will advance this operating point up this curve. It is not a straight line therefore the increase in the torque resistance must increase at a rate greater than a linear one. A spring rate will probably satisfy this but it will probable take a lot of experimentation.
• Elastomeric Bearing between Aero-rotor and Electric-rotor: Could the elastomeric bearing between the aero-rotor and motor-rotor shift in a radial direction and thereby affect the airgap due to the motor's rotor and the motor's stator becoming non-concentric?
• Deterioration of Torque Resistors: Could the magnets, springs or rubber forces deteriorate to the point where the pitch could go up to the maximum angle and remain there, even after the power to the motor was dropped? Also, would this high pitch cause the rotor to stop turning?

• This report A FLIGHT INVESTIGATION OF A LIGHTWEIGHT HELICOPTER TO STUDY THE FEASIBILITY OF FIXED-COLLECTIVE-PITCH AUTOROTATIONS by R.J Pegg is interesting since it considers the requirement for change of collective between slow flight and autorotation. Have hard copy.

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