A125

DESIGN: ~ Electrotor-SloMo - Control (flight & electric)

Overview:

The idea of a Torque-pitch coupling may be flawed. This is because if the blade experiences a downdraft, the induced drag will initially decrease. This will result in the blade advancing in the plane of rotation and this will cause the pitch to decrease. This may be a terminal 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. The use of Free Tip (Aerodynamic Active Blade Twist) may negate this concern. This is because as the downdraft will initially result in a lower torque and thereby a reduced pitch at the root, this downdraft will cause a greater pitch at the tip ~ if the rotor has a 'free tip'.

Increasing the electrical power to both halves of the motor will cause the rotor's RPM to increase, thereby increasing the thrust.
The upper limit to pitch rotation is set by an elastomeric stop. Increasing the individual half-motor's torque will increase the pitch of that motor's blade.
To tilt the rotor disk down at the front, the power will be increased on the half-motors when the are on the retreating side of the disk and decreased when they are on the advancing side.

Functions:

Each rotor has a pair of Pitch-torque coupling mechanisms. See; Electrotor_TorquePitch.html [The information on these 2 pages will probably be combined] and Auto-Collective Rotor Hub

Autorotation: This is the default pitch setting of all four blades.

Collective: The throttle increases or decreased the torque and the pitch in all four blades in unison.

This means that the advancing and retreating blades on the same rotor must be interlocked so that they have the same pitch, even though they do not have the same angle of attack.
It may be viable to balance the torque of the two rotors by a pilot operated trim-wheel of automatically by sensors and/or gyros.

Pitch: For forward pitch; the blades will experience a decrease in power (torque and pitch) when on the advancing side and an increase in power (torque and pitch) when on the retreating side. Conversely, the opposite will be true for a backward pitch.

Roll: The same as the above pitch except the modified power is moved 90º azimuth.

Yaw:

The same as pitch except one rotor has its longitudinal pitch increased while the other rotor has its longitudinal pitch decreased.

Consider the use of Blade Tip Cooling of Motor and the variable blockage of the tip exhausts on one of the two rotors.

Sensor:

Rotor Azimuth: There will be an azimuth sensor on both rotor hubs. Its output will be fed to the onboard ESC. See Group B [Absolute Encoder].

Synchronization of Rotors: Increasing the power to one rotor while decreasing it to the other will allow the former rotor to catch up.

Regeneration: Consider using regeneration to act as a brake on the rotors after landing. The regeneration might also be used to charge up the capacitors.

Braking:

Postings on Rotary Wing;

Karl,

Emergency landings will hopefully be quite rare.

But every landing will be a potential for disaster. A slight stumble will very quickly turn into a dynamic roll over. Look at the injuries paraglider pilots sustain just trying to land parachutes, many many broken ankles and legs.

Remember you have a big gyro right above your head and once it is moving you will be unable to resist it from a standing position.

Reply,

One low cost partial solution might be that of having the motors subject to electrical braking when the pilot fully releases the 'throttle' or when he activates a separate switch. Because the motors are counter-rotating and fixed to a common shaft (stub mast) there should not be any unwanted moments created. This may offer some help.

There is an electric motor in each rotor. The motors direct drive their rotorhubs. The motor's rotors are connected to the blades. The torque on the blade determines the blade pitch. To maintain a specific rotor rpm and thrust while pitching the blade forward. The torque would be increased on the blade near 270º azimuth while the torque was decreased on the blade near 90º azimuth.

Idea for Automatic Collective Control:

The change in the arc between the primary driving magnets (rotor) will not vary much from that of the collective pitch magnets ('rotor').

Musings about Flight-Control Nomenclature:

The conventional references to the helicopter pilot's controls are 'cyclic' and 'collective'.

For a craft that has both a gimbaled head and 'absolutely' rigid rotors, such as a backpack helicopter, these words are misnomers. This craft does not have a cyclic or collective control mechanism, such as the swashplate. In addition, there is no cyclic action taking place in the rotor because the rotor does not teeter, flap or lead-lag.

Perhaps this control system should be considered in the context of a Cylindrical Coordinate System. The cyclic then become the Direction (azimuth) and Tilt (angle, radius, radial distance) The collective then becomes the Throttle (thrust, force, magnitude)

Gimbal v.s. Spherical (Rod End):

The gimbal with longitudinal and lateral axe of rotation will allow pitch change and roll change from a single cyclic stick. (ref gyrocopter)
The spherical bearing will also allow yaw and therefore it will require a cyclic stick for both hands (ref Schoeffman's craft)

Related Pages on this Site:

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

Same Page Different Craft: ~ Electrotor-Simplex ~ Electrotor-MicroLite ~ Electrotor-Plus (no page) ~ | ~ SynchroLite ~ UniCopter

Initially displayed: July 23, 2006 ~ Last Revised; January 19, 2010

The above utility invention is openly and publicly disclosed on the Internet to negate an entity from patenting it, to the exclusion of all others whom may wish to use it. ~ Reference patent law 35 U.S.C. 102 A person shall be entitled to a patent unless - (a) the invention was known ... by others in this country, ..., before the invention thereof by the applicant for patent.