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View Full Version : Barnett flapping hinged rotor.

quadrirotor
03-04-2007, 12:02 PM
has anybody any info on this "new" rotor from Barnett???


http://barnettrotorcraft.com/Barnett123006/Hinge_Hub/IMAG012.GIF
Brian Jackson
03-05-2007, 03:19 PM
For those interested, here's a perspective view of Jerry Barnett's new head.
mark treidel
03-05-2007, 04:07 PM
Send a P/M to SKYPUPPY here on the forum, he has all the barnett info you need.
Al_Hammer
03-05-2007, 04:23 PM
Nice, Brian.
By the way, those would be coning hinges, not flapping hinges.
Take look at the R22 so-called tri-hinge rotothead.
http://www.b-domke.de/AviationImages/Rotorhead/Images/1674.jpg
Robinson calls the outboard hinges coning hinges, because they are only there to allow the blades to cone up. The blades teeter about the central hinge as a unit, so there is no "offset hinge" advantage.

If this were a 3 bladed system, the blades ,not being opposite one another would flap independently and it'd be a different ball of wax, but then lead lag hinges would be needed as well.
Rando
03-05-2007, 04:44 PM
I am waiting for Chuck B. to comment on this.
Doug Riley
03-08-2007, 08:07 AM
Chuck Beaty built a "door hinge" hub for Hughes 269 blades back in the 70's. In that case, though, the hinge pin was centered; it was the teeter bolt.

This one seems to duplicate the setup of the Robinson hubs. I wouldn't expect the outboard hinges to act like flapping hinges, because centrifugal reaction will favor the teeter hinge's doing that job. Jerry's hinges really do seem to be coning hinges.

If OTOH you replaced the teeter hinge with a rigid attachment of hub to spindle, you'd have the old Cierva head. Without undersling, though, a 2-blade version of Cierva's head will have a vicious 2-per-rev.
C. Beaty
03-08-2007, 12:24 PM
This is a tri-hinge hub like a Robinson. Coning hinges aren’t such a bad idea inasmuch as bending moments on the blade roots are relieved.

However, some motion takes place about these hinges due to blade flexing with load shift, inboard to outboard as the rotor turns during forward flight. Either needle or plastic (DU style) lined bearings are necessary. Metal on metal plain bearings will gall and seize.