1683

Item 1683

OTHER: Aircraft - Gyro/Heli - w/ Torque Compensated Single Rotor
Forget this idea ~ It looks like the idea of transferring power aerodynamically will effect the balance of torque.
Objective:

A low-cost, reliable, and easy to fly gyrocopter with VTOL capability.

Overview:

A mechanically powered single 2-blade teetering rotor, which does not require a tail-rotor to counteract it's torque.

A single propeller that is located above the 2-blade rotor.

This propeller provides;

Additional lift to the craft, which is in addition to that provided by the rotor.Some additional power to the rotor, which is transmitted aerodynamically.
Some additional power (torque) to the rotor, by aerodynamic means.
Counteraction of the torque that is mechanically delivered to the rotor.

Collective control by the throttle ~ no collective lever.
Full autorotation capabilities

Light-hearted Description of Conversion from Gyro to Gyro/Heli:

Sell the prerotor.

Replace the conventional gyro head with one that has a larger diameter and a constant velocity joint in it's center.

Replace the pusher propeller with a larger diameter propeller; to be located above the rotor.

Reorient the motor and have it drive a planetary differential, which has a tube to the rotor and a shaft to the propeller.

Replace the current rotor hub with a custom hub.

Etc., etc.

Go practice powered vertical takeoff and landing, plus autorotation landings.

=
This sketch needs revisions.

See bottom of this page for Bruno Nagler's NH-160:

Drawing of Propeller, Rotor and Rotor Head:

Consider using standard gyro rotor blades located outside a special hub-fan??

Samara:

The following is 1670-2.dc.

Its samara Maple seed profile may represent the optimum rotor shape for hover and VERY slow-speed flight.

A modification of this may be ideal for hover and slow-speed flight.

This drawing is associated with the ' Control - Flight ~ Later Idea: June 23, 2009' section below.

Drawing of Rotor Head - Gimbal w/ CVJ:

(Gimbal head is initially from Electrotor - Simplex. Must be modified further to suit this application.

Hub spring for centering CVJ's central member must be put back in.

Note: The gyro-hub will have the necessary clearances to tip and teeter about the mast to the propellers.

Brief Description:

An idea for a VTOL gyrocopter.

Take a conventional gyrocopter.
Open up the center of it's hub so that a mast and shaft can be located in the 'hole'.
At the top of the mast and above the teetering rotor place a large diameter propeller.
The gyrocopter's blades are the only 'special' item, in that they allow for blade twist at their root end. The most negative root pitch will be that of a conventional gyro blade (for autorotation). The most positive root pitch will be approximately 45-degrees. This 45-degree pitch will be created by the thrust of the propeller.
The propeller drives the rotor aerodynamically, while at the same time the propeller is contributing directly to the lift. Collective is applied by adjusting the power from the motor. The propeller, being smaller than the rotor, respond almost instantly and then the rotor 'catches up'.
Cyclic control is by the gimbal gyrocopter rotorhead, which must also contain a CVG for powering this gimbaled rotor.
Other than the active twist-ability of the rotor blades, the craft is little more complex than a conventional gyrocopter with coaxial pusher props. Perhaps this craft may therefore conform to existing regulations.

Rotor:

Hub:

Gimbal:

See; DESIGN: Electrotor-Simplex ~ Rotor - Hub - Gyrobee Information and also the drawings of the hub.

The drawing on the Electrotor-Simplex gives an idea of how to get the greater clearance inside the gyro hub for the mast to the propellers to pass through. The gyro-hub will be tipping and the blades teetering about this mast to the propeller.

- Vertical Spacing of Pitch and Roll Hinges:

The diameter of the clearances for the gyro hub to teeter about the mast to the propellers can be reduced if the vertical distance between the teetering hinge or main bearing and the vertical and lateral pitch axes can be reduced.

For information on this subject see; DESIGN: Electrotor-Simplex ~ Gimbal

The incorporation of a double universal joint in the same plane as the main rotor bearing may serve this idea. For double universal joint see; DESIGN: SynchroLite ~ Rotor - Hub - 3-blade - CVJ & HS - Layout

Constant Velocity Joint:

Located inside the gimbal frame.

To allow the gimbal head with its power rotor to pivot in respect to the mast-tube that is mechanically powering it.

Picture of similar unit from; DESIGN: SynchroLite ~ Rotor - Hub - 3-blade - CVJ & HS - Layout

Blades:

General:

Very large taper. Perhaps part way between linear and ideal.

Very large aerodynamically induced active blade twist. -5º to +45º

Active Blade Twist:

This method could be the fundamental for the desired blade; UniCopter ~ Rotor - Blade - NACA 00xx - IRAT - Torque Tube Method

The blade tip will have a fixed pitch.

The blade root will rotate about the pitch axis between to fixed rotation stops. Aerodynamic forces cause the rotation; where the thrust of the propellers increases the pitch to its upper stop and autorotation decreases the pitch to its lower stop.

Propeller:

Diameter:

+/- 8 ft.

Blade Count:

8 ??

Control - Flight:

Authority:

Better cyclic control means worse collective control, and visa versa. It appears that increasing the thrust of the rotor (i.e consuming more of the propeller's thrust by the rotor) will increase the craft's cyclic control authority. However, it will decrease the craft's speed of response to collective authority. In other words, if the rotor were to consume all the thrust from the propeller, then an instantaneous increase in rpm and its increased thrust from the propeller would not give an instantaneous lift for the craft.
The consumption of a percentage of the propellers thrust by the rotor may reduce the 'collective' thrust authority, but, when in ground effect, which is the most important, this reduction MAY not be quite as pronounced since the air is still getting down under the disk area.

Thoughts:

Ease of changing pitch:

The propeller is turning at approximately 2270 rpm, which is 38 rps. Times 8 blades is 303 cycles per second, which should result in a smooth flow of air in the propeller's streamtube.

The rotor is turning at approximately 450 rpm, which is 7.5 rps. Times 2 blades is 15 rps. So what?

The root end of the blade must not experience any change in pitching moment at any angle from +5º to -45º. If it does it will probably make control impossible.

The above may be fine for autorotation, but it probably will not be any good for powered flight since the downwash from the propeller will srike the blade and angles fare in excess of the stall angle. With most of this air striking the blade behind the pitch axis it may mak it impossible to manually pitch the blade down. Then again, there will be an opposing moment on the other blade and they may self cancel.

Percentage of propeller's streamtube striking the rotor blades vs. percentage passing straight drown between blades:

Consider a pair of short blades at 90º to the normal blades. These short blades will be attached to the rotor's mast but below the CVJ. .This may be starting to make this concept too complex.

Autorotation and the Propeller:

A overrunning clutch allows the propeller to freewheel in the reverse direction of rotation during autorotative descent.
A possible concern is that upon landing the rotational inertia in the propeller will want to drive the craft down, but this should be relatively insignificant.

Yaw Control:

Pedal control to rudder; plus longitudinally hinges flap in the downwash? What about during autorotation?

Control - Flight ~ Later Idea: June 23, 2009

This section is associated with the samara Maple seed airfoil profile above:

The propeller rigidly connected to the 'mast'. Cyclic control is by weight-shifting.
The rotor is teetering. Cyclic control of it is by gimbal (gyrocopter control).
It is intended that the combining of the above two methods will provide cyclic control that is faster than a simple teetering rotor while at the same time offering little resistance to cyclic stick movement by the pilot.

Engine:

The following is from the Mosquito Web Site:

Note that the motor has the crankshaft vertical, which will be ideal for a planetary reducer and differential to the prop and rotor.

"Compact Radial Engine's - MZ202, 60-hp, powers The Mosquito a two cycle, two-cylinder engine with the highest power to weight ratio on the market today. This engine employs Reed Induction which yields a very flat torque curve ensuring power is delivered constantly over the required operating range. The MZ202 also has a lower operating speed of 6000 rpm when compared to other engines with similar power range that typically operate at 6500 to 7000 rpm resulting in less stress on the engine and improving reliability."

"The complete engine package only weighs 69 pounds and comes with a 180-watt alternator that provides power to run the electrical system, which also features an electric start system."

Since the 60-hp MZ202 can be mounted with a vertical crankshaft, there is reason to believe that the 85 hp, 3-cylinder MZ301 can, or could, be mounted the same; if there is a need for more power.

Power Train:

Mosquito XE / XEL roughly used for preliminary calculations. Rotor diameter 20 ft, Rotor speed, 540 RPM, tip speed 566 fps.

Sun gear ~ 36 teeth ~ In put from motor ~ +5,000 rpm or +5,000 rpm

Planet ring ~ 9 teeth ~ Output to propeller ~ -1,730 rpm or -2,270 rpm

Ring gear ~ 54 teeth ~ Output to rotor ~ -450 rpm or +450 rpm

Fuselage:

Consider using the SynchroLite's:

Landing Gear:

Consider using the SynchroLite's:

Weight and Balance:

Locating the engine's crankshaft, the planetary gearbox and the gimbal rotorhead on a common vertical axis will probably not be possible since it may put the craft's center of gravity too far ahead of the mast.

Complexity, Cost and Development work that must be done: There is a lot. Perhaps too much and therefore the Root Turbofan Rotor below would be a better project.

Planetary drive.

Larger diameter gimbal hub with internal CVJ & Hub spring

Rotor blades which have automatic aerodynamic large twist.

Propeller with many thin and light blades.

Concerns:

Consider what makes this any better than a simple coaxial helicopter?

Twist is detrimental to forward flight. Therefore the exceptionally large twist on the rotor will very likely be a disadvantage. At only 50 mph and a rotor speed of 450 rpm any blade inside 18" radius will be experiencing reverse flow on the retreating side. The propeller should not be a problem since it is turning much faster. A possible solution is to enlarge the diameter of the rotor's cutout. The thrust from the root of the propeller's blades will be minimal anyways, and it is downwash on the fuselage and pilot.

Autorotation: Is it possible, or advisable, to have the disks automatically tilted rearward as the craft transitions from powered flight to autorotation?

The 'steering' may not work. The vectored force, which is provided by the tipped rotor to change the direction of the craft, will probably be opposed by an identical and opposite vectored force, which is driving the rotor. However, maybe this is not true. In an extreme and hypothetically situation, if the blades have a +45º twist at their roots and the rotor's disk is tipped 45º then the thrust from the propellers will be striking the advancing root at a right angle to it's top surface and applying a large rotational force (flat plate drag). Meanwhile, the thrust from the propellers will be striking the retreating root at an angle that is inline with the chord of the root (profile drag and no induced drag). This must impart a significant rotational speed to the rotor and that the vector of this 'power transmission' does not have a significant opposition to the thrust vector of the rotor.

More thinking or a model is required.

Can sufficient power be aerodynamically transferred from the propeller to the teetering rotor so that the cyclic control moments of the rotor are not excessively diminished. It must be noted that the teetering rotor already has less control authority then other rotorhubs, such as those with offset flapping hinges etc.

Large taper to get more of the propeller's power &/or 2 additional very low aspect rotor-blades at 90º to the existing blades. Or, to heck with the tapering and twisting of the blade and just locate a multi-bladed 8-ft diameter ring on the gimbal rotor head. It could be attached to the blades, which would have a 4-ft cutout.

Or it might be attached to the tube that is driving the rotor and be mounted below the CVJ so that the ring does not have to teeter.

In other words the tube mast that supports and rotates the teetering rotor is driven mechanically at its bottom end AND driven aerodynamically at its top end.
Both this aerodynamic drive ate the top and the so-called propeller could both be 8-ft diameter multi-bladed devices; with a thin ring?

Will the powertrain, propellers or rotor transmit any torque, about the vertical axis, to the fuselage? See [Yaw] above for potential solution.

Will the downwash from the propeller effect the teetering or cyclic action of the rotor?

Outside Thread on this Concept:

Rotary Wing Forum ~ HeliGyro Idea for aspiring conceptualists

May be of related interest; Rotary Wing Forum ~ Ultralight Compound Coaxial Helicopter
Yuneec

Thoughts re Model:

General:

Mount 1 propeller on the rotor and the other propeller on the stator of a brushless motor. This will give a 2:1 reduction in the RPM of the propellers and give a torque-balanced condition. The propellers can now have a larger diameter and this will help with the aerodynamic transmission of power from the propellers to the rotor.

Drive:

Use an inboard motor with a front mount.
Arrange it with the axis of rotation vertical.
Drive the upper propeller with a shaft from the motor's rotor.
Drive the lower rotor with a tube from the motor's stator.
The stator and the base of the above tube are connected to a stationary frame via a couple of ball bearings.
A small diameter (low friction) commentator will transmit the electrical power to the motor.
Hopefully, this should provide a balances torque to the two propellers. (Any yaw imparted to the fuselage may be partially counteracted by the friction of the rotor's bearing, which must be turning in the opposite direction).
Use propellers with larger than normal diameters; because this arrangement allows this with its 2:1 reduction in the propeller speeds.

Propeller:

Buy 4-blade propeller. Example - xxx

Helix Propellers

Rotor:

The Gyrobee rotor diameter is 25 ft. and it delivers all the thrust This rotor will be delivering < 100% of the trust therefore this craft can have a greater GW than the Gyrobee???

Rotor Hub:

Have made a gimbaled hub that is similar to the Gyrobee's Hub except for having a large opening in the center, similar to that of the Electrotor-Simplex

Rotor Blade:

Must be custom made.
Perhaps the initial pair for testing could have a fixed high twist. What about modifying a curved metal slat from a venetian blind??? Or can a strip of balsa wood be warped 45º?

Flight Controls:

2 servos required.

Yaw:

Mount 1 propeller on the rotor and the other propeller on the stator of a brushless motor. This will give a 2:1 reduction in the RPM of the propellers and give a torque-balanced condition.

The stator will be mounted on a bearing that is mounted on the propeller's mast. This bearing and the commentator to the stator will result in a small rotational friction. The bearing between the rotorhub and it's mast will also result in a small rotational friction. Rotating them in opposite directions may minimize the transmission of a yaw to the fuselage.

Partial Alternative ~ Buy a Gyrocopter Kit and Modify it:

Possible Precursor to:

The above method of driving the rotor has a similarity with the method on this page: OTHER: Miscellaneous - Thoughtless Ideas - Root Turbofan Rotor

Previous Somewhat Similar Idea:

Bruno Nagler NH-160:

"NH-160 1956 = 1pOH; 72hp McCulloch; rotor: 20'4" length: 12'2" load: 430#. Two co-axial rotors, one on top and one smaller, believe it or not, under the pilot's seat."

Rough Notes:

[*]Make the propeller larger and with 4 or more blades, but make it very light.

[*]This propeller and the rotor are driven mechanical in counter-rotation to each other.

[*]The object is to make the propeller aerodynamically drive the rotor below it.

[*]In other words; The rotor is driven mechanically by the motor AND aerodynamically by the propeller, while the aerodynamic drag (torque) from the two of them is self-canceling.

[*]The propeller is rigidly affixed to the top of the mast (i.e no teetering or flapping).

[*]The rotor is a conventional gyro rotor and hub, but with the 3 following exceptions.

[*]The hub is built so as to allow the mast to pass up to the propeller.

[*}The hub contains a CVJ to allow the motor to drive the pivoting rotor head.

[*]The root of the rotor blades is tapered and twisted so as to 'capture' as much of the propellers aerodynamic power as possible, with the remaining thrust just passing on down as somewhat inefficient lift.

And there's a little more.

[*]The lightness of the propeller will minimize any gyroscopic precession that it will want to impart to the craft when cyclic is applied to the rotor.

[*]The root of the rotor blades must be free to actively twist about 50-degrees, depending on whether the thrust on the rotor blade roots is coming from the propeller above or coming from below due to an Autorotative descent.

[*]Collective is by increasing power. It is assumed that the trust that gets past the rotor will give a reasonably fast response.

Initially displayed: January 27, 2008 ~ Posted on Rotary Wing: December 1, 2008 ~ Latest revision; June 23, 2009