A120

DESIGN: Electrotor-SloMo ~ Concerns & Tasks

Overview:

A listing of Tasks, Potential Concerns and Thoughts, regarding the Electrotor.

Idea for Consideration:

Eliminate the CVJ & HP rotorhead and locate a 3-blade rotor on the same axis as the motor. Eliminate any lead/lag and flapping provisions in the rotorhead. Excluding the minimal bending of 'Absolutely Rigid Rotor' blades, the tip path plane and the motor plane will always be co-planer. Use conventional flight controls, running up the center of the 'mast' and use a gimbal head with the pitch and roll having a strong resistance to movement. Alternatively, substitute an ARR for this gimbal.

Concerns:

Perhaps a serious problem for Intermeshing and Interleaving configurations. The motor might offer a resistance to turning (cogging) during non-powered autorotation. Overrunning clutches between the rotors and the motors will only be valid if there is a means of interconnecting the two rotors.

If two rotors are located with only an airgap between them, would it be better to have the adjacent poles as having the same polarity. This will make the normal rotational location halfway between each other and the repelling force will increases exponentially as the rotors are rotated in respect to each other. The pitch? Between the magnets is

On this blade pitch concept; will a rotationally offset of the poles of the two rotors reduce the total torque?

Rotor Synchronization and Roll:

The addition of extra electrical power to one rotor, to maintain the synchronization of the rotors, will result in that rotor having greater pitch and therefore greater lift. A possible synchronization ~ roll coupling. A slight reduction in the power of the inside blade on the other rotor may overcome this concern.

Rotor-Rotor Synchronization:

It looks like the rotors must have their azimuths > 45º out of phase for them to clash. This includes the chord width. Hopefully, the electrical system can overcome any chance of rotor getting that much out of synchronization.

Downwash on Pilot:

No pilot in his right mind would go up in this thing ~ at least not until 10 years of testing had been done.

Flight Control during Autorotation:

Include capacitors and/or a 'low battery power' sensors. This should provide power for limited flight control and landing.

Stability of Teetering:

Re: small rotor & no paddle etc. Hub has delta3 (by Control System Geometry).

Musings re a Concern below:

Rotor-Rotor Synchronization:

Torque [ft-lb] = 5252 * HP / RPM

If the rotational velocity of the two rotors and the power at the four motors is equal than the torque of the two rotors must be equal.

Theoretically, if the torque at the two rotors is equal and the pitches of the blades at the two rotors are equal then the thrust of the two rotors must be equal.

The potential concern is the accuracy of the torque-pitch coupling device.

Proposed method:

Hold synchronization ~ This is paramount.
Dissymmetry of thrust might cause a roll.
Because fuselage is tightly coupled to the two rotors in respect to roll, movement about the X-axis will result in the inertia of the fuselage resisting initial roll.
Then the off-center of the gravitational pull on the fuselage will tend to resist the roll.
Perhaps the above will sufice.

Concerns Related to the Concept that has a motor in Each Blade:

Redundancy:

Can Outrunner motors be located in series?.

Safety:

A breakdown in any one of the 4 planetary gear sets or in any one of the 4 pinions will eliminate any flight control.

Pitch control strength:

Will the torque of the motor (maximum of 9.55lbf-ft) be sufficient to rotate and hold the pitch or must the torque of the planetary reducer be used (maximum of 28.4 lbf-ft).

Rotor RPM:

The craft will have variable RRPM and this may cause a problem due to vibrations at one or more of the operating RPMs.

Rotor Synchronization and Roll:

Rotor-Rotor Synchronization:

Downwash on Pilot:

No pilot in his right mind would go up in this thing ~ at least not until 10 years of testing had been done.

Flight Control during Autorotation:

Include capacitors and/or a 'low battery power' sensors. This should provide power for limited flight control and landing.

Loss of Power in a Motor:

All three other motors in the same system will simultaneously have their power cut..

Will the addition of elevators, rudder and ailerons allow for 'run-on landings? These controls might also be an advantage during conventional flight by providing a little faster response to pilot inputs.

Autorotation:

There is no way, currently of consuming the rotors' inertia during an autorotative flare.

Loss of Rotor Synchronization upon Loss of Power:

It appears that is mandatory that the craft can NEVER experience a TOTAL loss of power. Idea; Triple redundancy. Motors with 3 windings in each blade, plus 3 totally independent circuits. and perhaps capacitors as the core in parts of the composite fuselage as additional backup.

Reliability:

Currently, the loss of any electrical item will probably be fatal on a manned craft. There must be redundancy of all electrical items I.e. two independent systems on manned craft at least.

Gears:

Can the gears handle the high RPM.

Frame:

Strength of the frame. Carbon tubes?

Stability of Teetering:

Re: small rotor & no paddle etc. Hub has delta3 (by Control System Geometry).

Tasks (to do):

Xx

Same Page Different Craft: ~ SynchroLite ~ UniCopter

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

Initially displayed: July 23, 2006 ~ Last Revised: June 26, 2008

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