What helicopters use direct tilt teetering hinge like gyrocopters?

DennisFetters

Gold Supporter
Joined
Jul 18, 2005
Messages
3,321
Location
Abu Dhabi UAE
Aircraft
582 Commander Elite
Total Flight Time
Stopped counting years ago after 5,000
.......................................................................

I wish I could find more of these old pictures of me flying. Guess I just lost them all in the flood.
 

Attachments

  • ch6-banking-colour.JPG
    ch6-banking-colour.JPG
    27.9 KB · Views: 0

kolibri282

Super Member
Joined
Aug 2, 2009
Messages
2,918
Location
Duesseldorf
Don Hillberg->....some times the electrons go on strike,what do you do? Go along for the ride?
So you've quit flying with major airlines (= not the ones which still use DC-3s or Martin 404s) 10-15 years ago? (by which time any modern passenger aircraft was exclusively controlled by the power of electrons..;-)
PS: if you'd have to bring in a space shuttle without electrons a wing and a prayer might not be sufficient, it might take the combined prayers of the whole ground crew and these ships are pretty old girls now.

Don Hillberg->..You have broken the First rule, Keep it Simple stupid
What is more simple, push rods, dozens of joints and bearings or a tiny cable that runs from your stick straight to an actuator in the blade in a setup that even does away with a feathering bearing for the blade?


Don Hillberg->....only adds a piece that no one can repair
You can't repair a ball bearing either, you have to replace it. Same with a chip that quits.

No offense meant Don, just a few thoughts.


Bryan Cobb-> Looks like to tilt that much rotating gyroscopic mass would take a hydraulic cylinder with a 1" ram to me???

naca measured the control forces of a Kellet YG-1 gyro, a pretty big ship. The results are available on the web, you'll find a link here:
http://www.rotaryforum.com/forum/showthread.php?t=28127
 
Last edited:

Rotor Rooter

Dave Jackson
Joined
Feb 23, 2004
Messages
2,835
Location
Yes
Tom,

Here is a video of the Scheutzow BEE Helicopter that you mentioned.
Scheutzow BEE Promotional Video on Vimeo


________________________________________


The swashplate has been the preeminent means for helicopter flight control over the years, however, many are striving to eliminate it; and all its many moving parts.

Here is a proposed method for the flight control of a teetering rotor. It uses the gyrocopter method for cyclic control and power-change for collective control. Electrotor ~ Simplex

There appears to be no reason why the above hub mounted electric motor cannot be replaced by a fuselage mounted engine. This engine would drive the tilting rotor at a constant speed by locating a constant velocity joint between the motor and the tilting & teetering rotor.


Dave
 

C. Beaty

Gold Supporter
Joined
Apr 16, 2004
Messages
10,080
Location
Florida
Here’s a diagrammatic view of a Bell-47 and similar rotorheads. The feathering bearings are linked together in such a way that rotation is possible only for collective pitch application.

Cyclic pitch is accomplished by rocking the hub about the feathering axis; whether by single or double pushrods from a swashplate or by some other means is irrelevant.

Whatever the case, drive torque is isolated from the cyclic control system.
 

Attachments

  • B-47 cyclic 1.jpg
    B-47 cyclic 1.jpg
    35.4 KB · Views: 2

bryancobb

Junior Member
Joined
Aug 2, 2010
Messages
5,061
Location
Cartersville, GA
Aircraft
Owned Brantly B-2b/Fly Kitfox III/Mini-500b
Total Flight Time
1350
Ok

Ok

Bryan,

Tilting the head on a gyro is the functional equivalent of a swashplate control.

Let's say you want to roll the aircraft to the left. Tilting the head to the left applies a cyclic input to the blades when they are in the 12 & 6 o'clock position. The 12 o'clock blade starts to pitch down and the 6 o'clock blade starts to pitch up as they spin, assuming CCW rotation as viewed from above. No inputs are made at the 3 & 9 o'clock postion because of the teetering hinge (remember we are dealing with a left roll input only at this point). Although the actual pitch inputs are made at the 6 &12 position the effect isn't felt until 90º later due to gyroscopic precession. It takes a few revolutions for the blades to "fly" the rotor disc to it's new orientation.

To apply a pitch input, the same applies but the cyclic inputs are made at 3 & 9, and the effects are felt at 6 & 12 o'clock. Really no different than a Bell 206.

The reason you don't have to have Herculean strength is that it doesn't take much power to tilt the head and pitch the blades. Reorienting the rotor disc is done aerodynamically.

Heavier blades take a little longer to fly themselves to a new orientation vs. lighter or faster spinning blades so more feedback in the stick may be felt, but it's not a case of manhandling a 50 lb. spinning mass like a giant bicycle wheel.

If I understand you correctly, the tip path of a gyro is tilted aerodamically just like a helicopter? I totally understand this method. The Original Poster seemed to think that the tip path is tilted by MECHANICALLY tilting the AXLE (mast/shaft) that the blades rotate around?

If control inputs are transferred to individual blades on a gyro, which "feather" to aerodynamically tilt the tip path, then there MUST be a swashplate, even if it's not called that!

If control inputs on a gyro merely tilt the AXLE (mast/shaft) that the rotor spins on, then there is no swashlate and I do not understand why it doesn't take massive forces to do it?

It's unbelievable to me, how ignorant I am about a gyro head, since I have been a commercial helicopter pilot since 1992. I just never was interested in gyros very much so never sought the knowledge.
 

leviterande

Member
Joined
Feb 27, 2009
Messages
127
Location
Stockholm
Here’s a diagrammatic view of a Bell-47 and similar rotorheads. The feathering bearings are linked together in such a way that rotation is possible only for collective pitch application.

Cyclic pitch is accomplished by rocking the hub about the feathering axis; whether by single or double pushrods from a swashplate or by some other means is irrelevant.

Whatever the case, drive torque is isolated from the cyclic control system.

Thank you for confirming that cyclic is not controlled by feathering( no feather bearings, no pushrods to a swashplate) in this helicopter, but cyclic is controlled ala gyrocopter style. How many and which other helicopters beside Bell 47 and Scorpion use this method?






BTW, Animal, or should I call you Tim, concerning the lag in your heli, how big is it? split of a second, two seonds? does it feel so much.

Kalle
 
Last edited:

bryancobb

Junior Member
Joined
Aug 2, 2010
Messages
5,061
Location
Cartersville, GA
Aircraft
Owned Brantly B-2b/Fly Kitfox III/Mini-500b
Total Flight Time
1350
Stan,
So did the blades on your model feather at all?
It is my understanding that gyro blades do not feather independently but are fixed to the head/yoke at a preset angle of incidence that is the "alpha" where best LIFT/DRAG max occurs.
Then the whole blade/blade/head can teter or flap (as a unit) to correct for dissymmetry of lift, and feather (as a unit) to aerodynamically tilt the tip path.
Sounds like yor model could teter but not feather?
 

bryancobb

Junior Member
Joined
Aug 2, 2010
Messages
5,061
Location
Cartersville, GA
Aircraft
Owned Brantly B-2b/Fly Kitfox III/Mini-500b
Total Flight Time
1350
It MUST be

It MUST be

Thank you for confirming that cyclic is not controlled by feathering...helicopters beside Bell 47 and Scorpion use this method?

Kalle

The Bell 47 DEFINITELY controls cyclic by feathering! The cyclic moves the swashplate, the swashplate pushes and pulls the pushrods, the pushrods cause the stabilizer bar to teter, the stabilizer bar causes the rotor to feather (AS A UNIT). This feathering accomplishes the cyclic input desired by the pilot.
 

C. Beaty

Gold Supporter
Joined
Apr 16, 2004
Messages
10,080
Location
Florida
To the best of my knowledge and I could be wrong, the R-22 was the first seesaw rotor helicopter to use the feathering bearings for cyclic control.

The reason is simple. Bell-47 style cyclic does not require fancy feathering bearings; typically a ball bearing stack that must resist several tons of centrifugal force and be sufficiently stiff in a lead-lag direction to avoid 1/rev in-plane resonance of the rotor and all the while keeping rotational torque down to a few ounce-inches. The B-47 used a steel shim pack as a torsion hinge.

The Hiller series of helicopters was similar to a B-47 except cyclic control was applied to the servo rotor which in turn controlled the main rotor, cyclically.

Cyclic is not controlled gyro style in these helicopters. That is impossible without “power steering.”
 

leviterande

Member
Joined
Feb 27, 2009
Messages
127
Location
Stockholm
So who is right, bryan or beaty here? does bell 47 control cyclic by feathering(feather bearings) or not?
 
Last edited:

bryancobb

Junior Member
Joined
Aug 2, 2010
Messages
5,061
Location
Cartersville, GA
Aircraft
Owned Brantly B-2b/Fly Kitfox III/Mini-500b
Total Flight Time
1350
No feather bearings!

No feather bearings!

The Bell 47 has feathering bearings. How else would collective pitch work? Rotor RPM remains constant while flying. Climbs and descents and accelerations/decelerations are done by collectively feathering both blades THE SAME AMOUNT in THE SAME DIRECTION.

The definition of feathering is "a blade's ability to rotate about its' chord axis."

For CYCLIC inputs, (Tilting the tip path) the Blades on a Bell 47 DO NOT pivot on their feathering bearings, THEY DO pivot about their chord axis AS A UNIT.
That is..In Unison... as one blade feathers toward a more positive angle, the opposite blade feathers toward a more negative angle, THE SAME AMOUNT in the OPPOSITE DIRECTION. Both blades are part of an assembly. Each blade is connected to the assembly in a way that allows collective feathering individually, and CYCLIC feathering as a unit.

The 47's head is a textbook example of a semi-rigid type.
 
Last edited:

animal

Platinum Member
Joined
Mar 31, 2004
Messages
5,933
Location
Deleon Springs Florida.
Aircraft
Hillman Hornet N8063D
Thank you for confirming that cyclic is not controlled by feathering( no feather bearings, no pushrods to a swashplate) in this helicopter, but cyclic is controlled ala gyrocopter style. How many and which other helicopters beside Bell 47 and Scorpion use this method?






BTW, Animal, or should I call you Tim, concerning the lag in your heli, how big is it? split of a second, two seonds? does it feel so much.

Kalle
I never really timed it, I did not leave the Cable system on my Scorpion long after I got it. I would say it was at least 2 or 3 seconds.
 

animal

Platinum Member
Joined
Mar 31, 2004
Messages
5,933
Location
Deleon Springs Florida.
Aircraft
Hillman Hornet N8063D
Tom,

Here is a video of the Scheutzow BEE Helicopter that you mentioned.
Scheutzow BEE Promotional Video on Vimeo


________________________________________


The swashplate has been the preeminent means for helicopter flight control over the years, however, many are striving to eliminate it; and all its many moving parts.

Here is a proposed method for the flight control of a teetering rotor. It uses the gyrocopter method for cyclic control and power-change for collective control. Electrotor ~ Simplex

There appears to be no reason why the above hub mounted electric motor cannot be replaced by a fuselage mounted engine. This engine would drive the tilting rotor at a constant speed by locating a constant velocity joint between the motor and the tilting & teetering rotor.


Dave
thanks for the link to the Bee video,I have always thought that was a neat design and wondered what happened to it.

I have the sport Avaition magizines that covered the designing and certifying the Bee.
 

C. Beaty

Gold Supporter
Joined
Apr 16, 2004
Messages
10,080
Location
Florida
There is a brief mention of helicopter cyclic control by direct hub tilt in “Principles of Helicopter Engineering” by Jacob Shapiro.

Anyone interested and adept at searching British archival material may be able to find more information on the Cierva W9.

And Andre, as I had mentioned previously, counter-rotation eliminates torque in the tilt pivots.
 

Attachments

  • Cierva hub tilt.jpg
    Cierva hub tilt.jpg
    61.2 KB · Views: 0

leviterande

Member
Joined
Feb 27, 2009
Messages
127
Location
Stockholm
The Bell 47 has feathering bearings. How else would collective pitch work? Rotor RPM remains constant while flying. Climbs and descents and accelerations/decelerations are done by collectively feathering both blades THE SAME AMOUNT in THE SAME DIRECTION.

The definition of feathering is "a blade's ability to rotate about its' chord axis."

For CYCLIC inputs, (Tilting the tip path) the Blades on a Bell 47 DO NOT pivot on their feathering bearings, THEY DO pivot about their chord axis AS A UNIT.
That is..In Unison... as one blade feathers toward a more positive angle, the opposite blade feathers toward a more negative angle, THE SAME AMOUNT in the OPPOSITE DIRECTION. Both blades are part of an assembly. Each blade is connected to the assembly in a way that allows collective feathering individually, and CYCLIC feathering as a unit.

The 47's head is a textbook example of a semi-rigid type.

I never said bell 47 doesnt have feathering bearings. I asked if it used those bearings for cyclic which it doesnt. So, to put it correctly now, the pushrods connected to the feathering bearings are for collective and are not the ones controlling cyclic. the hub is tilted as a whole for " chord wise cyclic feathering" right?
 

bryancobb

Junior Member
Joined
Aug 2, 2010
Messages
5,061
Location
Cartersville, GA
Aircraft
Owned Brantly B-2b/Fly Kitfox III/Mini-500b
Total Flight Time
1350
I'm doubting MYSELF now on what I said about the method the 47 uses for cyclic feathering. I'll get back with you.
 

leviterande

Member
Joined
Feb 27, 2009
Messages
127
Location
Stockholm
I have been asked what is it that I want from this. I am building a 1/3 scale RC heli
(I fly RC helis) to test a gyrocopter based rotor with a buffed up prerotator. I am getting the parts now. There will be no collective on it and will be used as a ground effect machine only. As tested in x-plane there will be no need for a tail rotor either. Deflected vanes will be there instead. a 10ft rc diameter model should give some clues I hope but before I build it I wanted to know how a simple teetering hinge performes. As from a poster above, it looks like there is a huge 2-3 seconds delay between cyclic input and reaction.



If I understand you correctly, the tip path of a gyro is tilted aerodamically just like a helicopter? I totally understand this method. The Original Poster seemed to think that the tip path is tilted by MECHANICALLY tilting the AXLE (mast/shaft) that the blades rotate around?

Yes, in a way the autogyro axis IS tilted mechanically and NO there is no swashplate :) BUT! since the rotorblades teeter freely on a bolthinge they will never "respond to your tilt immideately since they will always hinge". The rotorblades feather as one piece and tilt to the new tip path 90 degrees later aerodynamically. The final net end result is the exact as any helicopter. How it is achieved is a little different.

It took me a little while to understand the mechanism of gyrocopters and helicopters thinking that they are different, only to find out they are producing the same end result differently



Thanx for all the info
Kalle
 
Last edited:

gyromike

Administrator
Staff member
Joined
Oct 29, 2003
Messages
3,741
Location
Abbeville, Louisiana
Aircraft
Bensen B8MG
If I understand you correctly, the tip path of a gyro is tilted aerodamically just like a helicopter?
Yes. A cyclic input causes the rotors to fly themselves to a new orientation.

I totally understand this method. The Original Poster seemed to think that the tip path is tilted by MECHANICALLY tilting the AXLE (mast/shaft) that the blades rotate around?
The axle, or spindle, is tilited mechanically. It it connected directly to the controls. Pushing the stick to the left makes the spindle (and rotor head) tilt to the left. Pushing it forward tilts the spindle forward, etc.

If control inputs are transferred to individual blades on a gyro, which "feather" to aerodynamically tilt the tip path, then there MUST be a swashplate, even if it's not called that!
Nope. No swash plate necessary. The gimble mount serves the same purpose though.

If control inputs on a gyro merely tilt the AXLE (mast/shaft) that the rotor spins on, then there is no swashlate and I do not understand why it doesn't take massive forces to do it?
Because the rotor hub and blades are not attached directly to the spindle. The hub bar is mounted using a teetering hinge. This allows you to only make a cyclic input. The blades are rigidly connected to the hub bar with no feathering hinges, so a nose down cyclic input on one blade is a nose up input on the other as the blades pitch on their spanwise axis as a unit.

Let's go back to our left turn. As the blades are spinning and I start moving the stick to the left, nothing happens when the blades are at the 3 & 9 position. That's because the teetering hinge is isolating the spindle movement from the hub bar. The head begins to tilt but the rotors want to remain in the same plane. But as the rotor advances to the 12 & 6 position, the advancing blade starts to receive a nose down input and the retreating blade receives a nose up input. At 12 & 6 they have pitched as much as they are going to, depending on how much the spindle has been tilted, but the rotor disc hasn't tilted yet. As they continue their rotation they begin to fly themselves to their new orientation, but when they reach the 3 & 9 position, the teetering hinge again isolates the blades from the spindle movement. The disc has begun to tilt but not because I forced it into a new position. I just gave it an input that would cause it to fly into a new orientation 90º later in the rotation due to gyroscopic precession. The cycle continues until the tip path plane catches up to the spindle axis. As soon as you stop tilting the spindle, the cyclic inputs stop and the rotor will align itself perpindicular to the spindle (discounting effects such as blowback from disymmetry of lift, etc.) It may take a few revolutions for the rotor to "catch up" to the spindle axis, depending on RPM, the weight of the rotors and how fast you move the controls.

If the hub bar were mounted directly to the spindle, it would take a massive amount of force to move the blades, and the control inputs would have to lead the blades by 90º. You would have to eat a lot of spinach to muscle the blades around that way. :)
 

C. Beaty

Gold Supporter
Joined
Apr 16, 2004
Messages
10,080
Location
Florida
Of course a RC helicopter model can be controlled cyclically by direct rotorhead tilt. It’s unlikely there would ever be a large enough component of main rotor torque to overpower the servos. Makes no difference whether it’s a seesaw rotor or a Cierva type rotor so long as the flap hinges are near the center of rotation.
 
Top