View Full Version : Control Rod Vibration
04-17-2004, 10:24 AM
I was reviewing a HoneyBee video by the former GyroTech today to confirm what I thought was excessive aerodynamic vibration/flutter of the vertical control rods attached to the head. This, to me, looks like a failure mode waiting to happen. Is this the reason a number of designs out there have a "scissors" design about half way up the mast to eliminate/minimize this vibration?
I've noticed John Landry did this as well as the SparrowHawk folks in Buckeye, AZ whom I visited yesterday. Does anyone know if the StarBee folks have incorporated this change in their kit?
04-17-2004, 11:28 AM
You want to look at that video really closely. Were the rotor blades visible behind/in front of the control rod area where you were seeing the vibration? I saw this same thing on that video but not all the time or at every angle. Then I realized I only saw it when the rotors were spinning in the background or the view was looking through the rotors. Since you are not seeing a real time image but a stop action image(at a distance I might add) I believe the rotors in the forground/background affect the video image of that thin control tube.
Some gyros use the scissor configuration to allow for the inability to run a one piece rod from the control input to the rotorhead in a straight line due to obstructions or to allow a folding mast. I also think some may do it to break up the single long colum into two more compression resistant shorter ones.
04-17-2004, 03:05 PM
When I had the RAF blades, my upper control rods shook substantially during prerotation and flight. With the Sportcopter blades, that has completely disappeared. The lateral vibes are the source.
04-17-2004, 05:30 PM
Thanks Mike & Ken,
After I wrote the post, I went back again and tried to look more closely. I too was wondering if I wasn't seeing some video effect or shadowing effect looking thru the turning rotors. Surely the control rods weren't vibrating that much!
I recall either one of the Mentone Gyrobees (2002?) or one I saw at I'm Fly'n Mfg in the Phoenix area that had the scissors mod. The mast is taller than average but I believe is a pretty straight shot to the torque tube.
04-17-2004, 05:31 PM
I meant to thank Ken AND Ron in the last post - not myself!
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