OTHER: ElectrotorPlus ~ Concerns & Tasks

1. Re Item 1550 and Does the hard coupled moving of the gyro in Item 1550 cause a problem and therefore should the aero-rotor teetering be linked to the motor-rotor teetering by a spring as in Item 1473?
2. A major problem ~ how to maintain rotor-rotor synchronization, particularly if one of the drives fails.

An idea. See; 1550.html - Concern

• Rotor-Rotor Synchronization: There must never be a loss of rotor synchronization.
• Enhanced Reliability:
• Redundancy:
• Motor: The two motors could have multiple distinct control circuits and power circuits (windings and batteries).
• Transmission: The gearbox has 3 sets of planetary gears. Consider making them strong enough that any one (or two) can take the total load. This will require the sun gear to be produces as a 'stack' of 3 separate gears (or gear tracks an a strong common hub). Perhaps one ring gear with wide teeth will serve since the extra with of the teeth will provide additional strength.. This might be considered as triple redundancy. It might be noted that the intermeshing of the Kaman helicopters was dependant on 4 gears, which were extra strong. What if the oil leaks out, etc.
• Synchronization During Normal Flight:
• Electrically?
• This might be accomplished electrically by varying the power to each rotor as required. It looks like the rotors must have their azimuths > 45º out of phase for them to clash Hopefully, the electrical system can overcome any chance of a rotor getting that far out of synchronization.
• It might even be possible to even put the motor of the advanced rotor into an electrical brake mode; if there is no overrunning clutch
• Perturbations: The very high speed of the motors and their high rotational inertia may resist any short term perturbation from decreased the RRPM. However, the overrunning clutch will negate any possibility of the motor assisting in the reduction of the RRPM. The aerodynamic rotor must surly decelerate faster than the motor's rotor. Therefore if one motor is not used as an electrical brake (generator) during electronic synchronization, there is no reason for the aerodynamic rotor to advance ahead of the overrunning clutch, is there?
• Mechanically?
• It may be difficult to mechanically link the two rotors since their planes tilt independently.
• Wild Ideas for the Intermeshing Configuration:
• Large 'sloppy' nylon gears could be attached to the hubs as a mechanical safety device. They could be spring mounted, with damper, to reduce any shock loading. The must be 'sloppy due to the independent rocking of the two rotors
• A type of bicycle wheel could be located just under each hub. The wheel would contain spokes and be open to reduce drag and downwash from the other rotor. The outer rim would consist of teeth, which engage with those of the other rotor. Note that the rotors teeter.
• Note that the diameter of the above wheels will not be much greater than the Torque Plate. Also, the torque plate could be geared and two small 'floating gears could link the Torque Plates' gears. Floating to absorb some shock.
• Note that 'wheels' will have a smaller diameters if the rotorhubs can be brought closer
• In addition these geared Torque plates might serve to control excessive tipping at the critical azimuth. In other words these 'geared' torque plates could be used to eliminate any and all rotor-rotor clashing concerns.
• One motor could drive both rotors during a shallow descent and short duration flare if the two rotors can be positively inter-phased.
• Synchronization During Single Drive Failure:
• Electrically?
• If one motor or gear boxes fails it may be possible for the second MRGA to adjust it"s speed to match the autorotative speed of the failed MRGA. However the overrunning clutch on the operational MRGA will not allow its motor to be used for braking.
• Consider a pair of large bicycle wheel, as mentioned above. However, locate strong permanent magnets around the circumference of both wheels. These magnets would attempt to maintain synchronization of the rotors. In addition they will provide rotational inertia to the rotors.
• If the magnets of the two 'bicycle wheels' had there magnets intermeshing, they would act as sloppy teeth. The phasing would primarily be done by magnetism, with physical contact of the magnets serving as the final act of assuring phasing. This idea could be tested very easily.
• If the magnets are powerful enough, the operational MRGA might provide some limited power to both rotors.
• The repelling magnetic force will want to tilt the disks outward.
• If the magnets on opposing wheels were to align they will do serious (fatal) damage.
• Have one or more large capacitors on the fuselage (or have it be a part of the fuselage). Should the problem be that of lost battery power, the capacitors could act as a small reserve of electricity to allow a synchronized autorotative landing.
• Mechanically?
• A mechanically intermeshing of the rotors, if possible, could allow for one motor to power both rotors, should the other motor or gearbox fail.
• Loss of Power in Battery or Batteries:
• Decreasing Charge in Batteries:
• It would be possible the electrically (automatically) realize that the charge in the batteries was low. Actions that might be taken are.
• Automatic reduction of available torque as the electronic system starts a slow transition into descent.
• The motor become generators during a long descent, thereby allowing them to continue to electrically control the autorotation, plus perhaps do a small amount of recharging the batteries or capacitors for landing.
• Perhaps the electronic system would not provide any power for collective (i.e. full autorotation) and the only power is that of the motors switching between generator and motor to satisfy the cyclic demands.
• Complete Loss of (1 of 2) or (1 of 4) or (1 of 6) Battery Packs:
• An automatic removal of the 'bad' pack and a sharing of one or more of the other packs.
• Note; Six small packs, c/w electronic controllers, should not weigh much if any more than one large pack with the same total amp-hrs.

• Overrunning clutches. This should not be a problem with Item 1550. Otherwise the whole power-train (particularly the gearbox; plus the cooling of the gearbox and motor) must be extremely reliable.
• Perhaps an overrunning clutch could be located between the rotorhub and the gears. This will be OK for the single rotor and perhaps the side-by-side, but not for the Intermeshing and Interleaving without some means of maintaining rotor synchronization. See below.
• It should be able to electronically synchronize them if one of the two motors remains operational.
• It should be easy to put overrunning clutches on Item 1550.
• For an UAV this should not be so important.

• Phase Angle between the rotorhub's moment and the gyro's moment will not be exactly 90º, See; DESIGN: Electrotor+ ~ MRGA - Gyro - General ~ Concern
• Cyclical Coriolis effect will vary the RRPM vs. the MRPM if a design is implemented where the tip-path angle of the rotor is different from the tipped angle of the gyroscope's wheel. Both the rotor and the wheel have high rotational inertia. Perhaps β_ROTOR must always equal β_MOTOR. This should not be a problem with Item 1550.
• The teetering of the rotor will result in the speed of the rotor to change. It is shown on this web page OTHER: Flight Dynamics - General - Lead-Flap Coupling for Intermeshing Rotor ~ Increase Due to Coning that a flap of 10º will cause the blade to advance perhaps 1º in 90º of rotation. If the motor to rotorhub ratio is 20:1 then the motor will have advanced 20º ahead of the other rotorhub's motor. This is (360/20) = 1/18 of the circumference of the motor's air gap. Now consider the number of poles around the circumference of the motor. At 15º the concern will be greater. However, if there are few poles there may not be a concern.
• This concern does not exist for 1547.html and should not exist for the other two - IF the motor teeters at the same rate as the rotor blades.

• The alternative rotorheads are:

1. Hub - 3-blade CVJ w/ Hub Spring, and the
2. Dragonfly Rotor, and to a somewhat lesser amount the
3. Conventional Hub - 2-blade Teetering:

• Is the Electrotor+ really any better than 1 or 2, or, is it just an interesting idea to eliminate 2P vibration on 2-blade rotors with hub-springs or offset hinges?
• All of the above three could be driven by electric motors and also not require gearboxes.

• Will the very high inertia of the craft (about the Y-axis) eliminate the desired precession? See ElectrotorPlus_Gyro.html
• The tooth speed is very high. Will require double or triple reduction.
• The mast may have to be bigger to handle the moment from the additional forces of the hub spring and offset teetering. The holes for the universal joint will weaken the mast. However the holes will be smaller due to the reduced load on the universal. In addition an inserted plug in the mast should back the holes.
• In some concepts the motor is driving the rotor through a knuckle joint. This will result in a pulsation when the rotor is tilted.
• Both the motor and the Rotorhub have parallel Knuckle joints therefore this problem may not exist.
• Alternatively, the motor control should handle this.
• Some power will probably be lost due to the knuckle joint when the rotor is tilted.

1. Give the mast a forward tilt that is midway between hover and cruise, to reduce the larger losses.
2. Moveable mast. See Control.

• Gyroscopic Precession: The planet gears are turning in the wrong direction. Lighten large planet as much as possible.
• Very large gyroscopic forces on the motor's rotor may 'pop magnets. Consider going with radial flux motors.
• The very large gyroscopic forces may effect the air gap. Consider going with radial flux motors.
• Will the 'Gyro' resist changes to the tip path plan resulting from perturbations (re. Improved stability)?
• Will there be a magnetic interaction between the stator and the closely located gears?
• How to assure synchronization between the two rotors of twin-rotor helicopters.
• Look into interaction and clearances between swashplate and planet holder.
• How is reducer to be sealed?

• Include capacitors and/or a 'low battery power' sensors. This should provide power for limited flight control and landing.
• The gearing is located between the motor and the rotor. This means that the overrunning clutch must isolated the rotor from the motor. This, in turn, means that during cyclic maneuvers the rotor will be producing a 2P vibration but the stopped motor will not be providing the offset 2P moments. Perhaps the only solution is for the pilot to know that his control has been diminished and that to minimize the 2P vibration he must make smaller cyclic movements.

• Low blade tips at sides.
• Large obliquity and stager, particularly on Item 1550.
• Rotor-rotor Vibration.

• Build a full-size crude prototype to test the control gyro concept. Design parts. Use motor stuff from used furnace motors?

• Does system waste power (fuel) due to friction dampers? What dampers?
• Layout of components.
• Design of motor.
• Testing of concept.
• Who builds motor?
• Refinement of product.

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