• Low cost.
• FAR (part 103) compliant; less than 254 lb empty weight.
• Single teetering rotor and no tail rotor or other device required to counter the rotor's torque.
• The rotor is powered by an electric motor(s) and propellers, which are located on both blades.
• A unique feature of this craft might be the coupling between the rotational inertia of the blade-mounted motor+props and the pitch of the blades, due to gyroscopic precession. This feature was originally developed for the Single-Bladed All Electric Rotor.
• The ability for a builder/pilot to make the frame for a Ultralight gyrocopter from plans, and then basically bolt on a purchased blade assembly (blade c/w motor, controller and propeller) may be an attractive one.

• The four motors are Plettenburg Terminators, 36.2 V, 118.2 A, = 4279 W = 5.8 HP. 5580 RPM, Thrust 37.2 lb
• The leading propeller is possibly 26" diameter
• The trailing propeller is possibly 26" diameter, folding
• Some information on propellers is http://www.plettenberg-motoren.com/UK/Motoren/aussen/Terminator/Luftschrauben.htm and Plettenburg Terminator Propellers
• The leading motor rotates CCW and the trailing motor rotates CW, when view from the rear.
• The propellers are counter rotating to reclaim swirl.
• The two propellers, two motors and mounting bracket, perhaps with controllers inside, are mounted to blade. Risky but perhaps this assembly could be bolted to a Vortex extruded aluminum blade for testing. The power and control wires would ron up the hollow 'spar' portion of the extrusion , or any hollow.
• Collective - Blade pitch:
• The blades on both propellers will experience a slower free air velocity when they are pointing toward the mast then when they are pointing away from it. It is assumed that the when blades on both propellers are pointing toward the mast they will be imparting more of a tangential (swirl) to the air then they will when they are pointing away from the mast. The hope is that the leading CCW propeller, when viewed from the rear, will therefore create a lift on the leading edge of the rotor-blade and that the trailing CW propeller will depress the trailing edge of the rotor-blade. If so, it means that there is a torque-pitch coupling between the propellers and the rotor blade where greater power means a greater rotor-blade pitch.
• Gyroscopic precession from the trailing motor & propeller will also contribute to positive blade pitch. However, gyroscopic precession from the leading motor & propeller will result in a canceling negative blade pitch. Adding small tip weights to the trailing propeller blades should result in a favorable positive pitch.
• If the above two methods are not sufficient then the torque from one or both of the motor frame's could be used in conjunction with an elastomeric spring, and perhaps damper, to actual a Kaman style servo-flap.
• A third method that might help may be to take the swirl of the up going tractor blade to lift the leading edge of the rotor-blade and the swirl of the down going pusher blade to lower the trailing edge of the rotor-blade. This might be done buy extending fixed leading and trailing flaps toward the propeller blade wihich is pointing away from the hub.
• Hopefully, the blade pitching moment will not cause an undesirable force on the pilots cyclic stick. This is because the pitch moment on one blade will be opposed by the pitch moment of the opposite blade.
• Cyclic:
• By conventional gyrocopter method.

• The motor and propeller are rotating at a very high speed in a CW direction, when view from the rear. In addition, both of the motor+propeller units are rotating, with their blades, about the craft's 'mast'. As each motor+propeller unit rotates about the craft's mast, the gyroscopic precession on these units wants to pitch the leading end of these units upward.
• The motor+propeller unit is an integral part of the blade. Therefore this gyroscopic precession will also pitch the outer portion of both blades up, by twisting the blades. This blade twist is similar to that which the servo-flaps do to the Kaman blades.
• In other words, increasing the power to the motors will increase the RPM of the rotor and increase the pitch of both blades.
• See; [Concerns: Direction of Propeller Rotation]

• ~ Indicates that which is different from a conventional gyrocopter.

• The Gyrobee gyrocopter or this set of plans for a Hornet gyrocopter.
• ~ The engine, propeller, transmission, and fuel tank are not required.
• ~ The flight controls may not be required, depending on method.

• Hub:
• The conventional gyrocopter rotor head with teetering hinge and main bearing(s) may be used. ~ The pitch and roll hinges may not be required, depending on method.
• ~ Hub Bar: The hub bar to be made of composite construction. The lay-up of the cloth and its material would be such that it would allow twist (for root pitch change), allow limited out-of-plane bending (for coning), and resist in-plane bending (no lead/lag). The hub bar will have a built-in twist or the root of the blade will have a built-in twist. If this twist is in the hub bar then the root of the blade will have the advantage of greater twist change.
• Alternative: Use a conventional hub bar and give the connection between the hub bar and the blade the ability to pitch with elastomeric connection.
• ~ There are slip rings on the hub that transfers electrical power and electronic control to the motor(s).
• Disk:
• Rotor diameter 23 - 25 ft .
• Rotational speed of 305 rpm in cruise, or slightly faster. 325 rpm
• ~ Blades (special):
• The roots of the blades are firmly attached to the hub bar at a pitch of ≈ +3º. To be evaluated.
• The blades are manufactured with a negative twist of ≈ -3º. To be evaluated.
• The propellers are located at a radius of ≈ 4 ft.
• The propellers are located behind the blade's training edge. It is a folding propeller, so that it's drag is minimized during autorotation.
• The electric motors may be aerodynamically located within both blades at a radius of ≈ 4 ft., depending on the method used.
• A controller is located on each blade or hub bar, near its electric motor.
• For model blade consider; Balsa wood rotor blades: http://aerobalsa.com/pages/airfoil.htm
• Seriously, consider using wide chord, low tip speed blades and rotor.
• Blades (not special):
• Rotordyne ~ 7 3/4" chord

• ~ Collective:
• The pilot's cyclic control stick will have a single electric power control (throttle) for the two motors. Both motors receive the same power. The rotational speed of the rotor will be determined by the amount of this power.
• During hover and vertical assent; both motors will be receiving the same power. Therefore their RPMs will be the same and their thrust will be the same.
• During forward flight the advancing blade will experience a faster free stream velocity then the retreating blade will. Since the motors are receiving the same power (watts), the advancing motor will be delivering greater torque but a lesser rpm than the retreating motor will. The slower RPM of the advancing motor will mean that it is producing a lower gyroscopic force, and this means that the blade-pitch will be lower than the mean pitch. However, the faster RPM of the retreating motor will mean that it is producing a higher gyroscopic force, and this means that the blade-pitch will be higher than the mean pitch. In other words, the retreating blade will have a greater pitch than the advancing blade.
• ~ Cyclic: This may not be applicable for a gyrocopter.
• To increase the pitch of Blade A and decrease the pitch of the opposite Blade B, simply involves a temporary cyclical increase in the rotational speed and inertia of motor+prop on Blade A while the motor+prop on Blade B has its rotational speed decreased.
• Alternatively, the pitch is cyclically increased and decreased by cyclically adding a electrical 'spike' {pulse width modulation] to Motor A to speed it up, and causing Motor B to become a generator and thereby slow it down.
• The optimum method has yet to be selected.

• xx

• Rotor diameter: 22 ft.
• Chord: 0.75 ft.
• Cutout; 2 ft.
• Disk loading; 0.72 lb/ft.
• Rotor Speed: 325 RPM
• Gross weight; 500 lb.
• Pitch; 5º
• Required power to hover, from Prouty's calculations; Momentum; 21.9 hp; Blade Element; 17.3 hp.

• A potential power source is two predator motors, controller and battery pack Not for Method 5.
• BUY: Electric - Motor - Plettenberg - Predator 30
• The above example is not very robust and it's life expectancy would probably be counted in minutes. However it is interesting in that;
• It weighs 3 lbs.
• It can produce 12 horsepower.
• A motor with a higher RPM, smaller diameter and an attached planetary gearbox might be best.
• Reliability: A stronger motor, complete with a much stronger shaft and bearings, will be required for a realistic product due to the moments and force.

• A more powerful alternative is BUY: Electric - Motor - Plettenberg - Predator 37

• The electrical power system and electronic control system must have redundancy; from battery packs, to controllers, to the coils within the motors.

• Efficiency of the Propellers:
• Free air stream [remote velocity] through the propeller: There is no way to optimize the thrust of the propeller's blades since their is no practical way to actively change their pitch. The propeller's blades will be experiencing a much faster free stream velocity when they are pointing outward, away from the mast, then when they are pointing inward, toward the mast. This is due to the distance of the propeller's blades from the center of the mast. This problem exists when the craft is at hover or in transitional flight. It also exists, in differing ratios at all rotor azimuths during forward flight.
• Potential Solutions:
• If the propellers are located further outboard on the rotor's blades, and two smaller propellers replaced the single propeller, or the propeller was given 3 or 4 blades and a smaller diameter, the inflow airspeed differential across the propeller, mentioned above, will be reduced. To implement two propellers, a single motor with two output shafts could drive a tractor and a pusher propeller. This increase in the velocity of the airflow will result in a decrease in the efficiency of the drive.
• A large chord and lower rotational tip speed; should improve the craft's lift/power ratio. See 1541.html, In addition, the slower rotational speed of the rotor means that the free air-speed differential on the propeller's blades, when pointing toward the rotor-blades root v.s. toward the rotor-blade's tip, will not be as great; which is good..
• Losses: The propeller will have an efficiency of ≈ 85%. This is much lower than the efficiency of a gearbox. However, it may be less than that of the tail rotor and transmission on a conventional helicopter.
• Yaw Control; Limited to rotor downwash on tail fins and/or forward velocity, with additional limitations during autorotation. However, during un-powered autorotation the performance should not differ from that of a conventional gyrocopter in the same situation.
• Takeoff and Landing; Vertical response will not be as 'crisp' as that of a conventional helicopter.
• Safety:

• Conflict between two positive features: Having the propellers rotate inside downward should have the advantage of pushing air downward because the free airspeed is much less then it is on the outboard side of the propeller. However, having the propeller and motor rotate outside down will result in gyroscopic precession pitching the blade up as the speed of the power increases.
• Methods 2, 3 and 4 will give faster responses than method 1; and this is good. However, Methods 2,3 and 4 may enhance the effects of external perturbations on the blades. Look into further.

• The opportunity exists for adding a third blade. All three blades will have their teetering axis intersect the vertical axis of a non-rotating mast. axis [show or link to picture].Alternatively, a non-rotating Constant Velocity Joint might be used.[show Doman's head] or independent flapping hinges that intersect the mast's axis [show or link to picture].
• These three blades would have slightly shorter chords and perhaps a smaller span then those used on the 2-blade rotor.
• A hub spring gives a faster control response and it could be incorporated into a 3-blade rotor.

• The propellers should probably be made of carbon composite. This is so that they are very stiff and will contribute to the gyroscopic precession.
• The axis of the propellers and motors may have a negative pitch of 2 or 3º in respect to the blade's angle of zero lift.
• The axis of the propellers and motors may be normal to a line from the center of the propeller hub to the center of the mast. In other words, the propeller's axis is a couple of degrees off of normal with the rotor-blade's pitch axis.
• To increase the torque-pitch effect consider locating the centerline of the prop below the centerline of the blade.

• Curtiss-Bleeker Prop Copter. The propeller rotates downward on the inside. It is located at approximately 0.3 R.
• Emdee's Propcopter Ultralight Helicopter: The propeller rotates downward on the inside. It is located at approximately 0.25 R.

• Predator Motor
• Propeller for Predator motor CFK 28,5x12 RASA Kl. -2,5°. RPM is 6340. (28.5 * pi * 6340) = 789 ips = 0.76 mach. Too slow.
• See; 1/4 Scale UniCopter - Pusher Prop Capacity 100-150 ccm 140-180 ccm (cubic centimeter) Electrical propeller (2 blade) 26x15
• Carbon fiber electrical prop; 26 15 http://64.233.179.104/translate_c?hl=en&u=http://www.mz-modellbau.de/elektro-propeller.htm&prev=/search%3Fq%3DPropeller%2B%2522CFK%2522%2B%26hl%3Den%26lr%3D%26sa%3DG Not a big enough pitch. It appears that 20º might be the maximum.
• Rough calculations by me
• For a 26" diameter propeller a pitch of 20º gives geometric pitch of 28"
• Air speed at propeller; 6,500 rpm x 28" x 0.80 efficiency = 12,133 fpm = 138 mph = 202 fps.
• Tip speed of propeller; 6,500 rpm x (26/12) x 22/7 = 44,261 fpm = 0.68 mach1
• Current rotor tip speed at R = 10 ft = 586 fps. Therefore the center of the propeller will be at 202/586 = 0.345 R = 3.45 ft. = 41" Too short.
• If the rotor's rpm is 325 and the rotor radius is 11 ft. then the tip speed is 374 fps. 0.335 mach1
• Therefore the center of the propeller will be at (202/374) x 11 = 5.94 ft. = 71". Since the speed differential between inboard tip and outboard 71 - (26/2) = 71 + (26/2) = 58 and 71 + (26/2) = 84". The ratio is 84:58 = 1.45:1 Perhaps OK.
• One engine on the 2-engine SynchroLite produces a maximum torque of 226 ft-lb at the one rotor, A predator's maximum thrust is 68 lbs (and slightly greater), 71"/12" x 68 lbs = 343 ft-lb torque, x 0.8 efficiency = 274 ft-lb torque.
• Consider two Terminators per blade at 37 lb of thrust, as an alternative to the Predator. 3" diameter instead of the Predator's 5' diameter. Clamp on to blade.
• Solutions????.
• Slow rotor down more????
• Increase the size of the propeller????
• 3-blade propeller and greater pitch????.
• Add a second prop behind the first (somehow counter rotating???) and greater pitch???
• Move the propeller further out the blade's span and increase the pitch of the blades.
• Implement a blade profile for the propeller that has a wider chord in the center (Scimitar?) and take the rotational speed up higher and/or increase the radius of the blade.

• Electric Autogyro? By Jukka Tervamäki; Courtesy of quadrirotor on Rotary Wing Forum; September 19, 2006
• Prop-Copter ~ http://web.northstate.net/~emdeedee/page1propcopter.htm, http://www.internetage.com/rotorcraft/propcopter1.htm
• A couple of designers by the name of CURTISS and BLEEKER designed a helicopter with props on the blades that held the World Record for amount of weight lifted per horsepower for many years.
• Rotary Wing Forum thread ~ A Helicopter for the Price of a Gyrocopter

• The carbon filament torque-tube between the motor and the blade mounted gearbox bends with the blade but it does not twist.
• The direction of rotation of the two torque-tubes twists the blade mounted gearboxes and thereby increases the pitch of the blades while power is being applied. A dead motor will result in the blades pitching down into the autorotation position.
• The propellers should probably turn with the blade closes to the mast going downward. inside blade downward. The current 2nd to last note in the [Concerns] above gives what I think is a valid reason for this.
• The torque-tube and the gyroscopic precession of the propeller are opposite in regard to the effect that they have on the blade pitch. Hopefully the torque-tube is the dominant one. Eventual calculations should tell.
• The craft varies the electrical power for collective and uses conventional gyrocopter controls for cyclic.

• OTHER: Helicopter - Inside - Single Rotor - All Electric Backpack (PAV) (UAV)
• Single-Bladed All Electric Rotor
• OTHER: Aircraft - Gyro/Heli - Non-powered

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