hawk pro l/r shake...help

[929freak]

my hawk pro (w/ o.s..32) has a newly developed problem...when in a hover it has a
shake or shimmy,its easy to see in the landing gear,its like a fast left to right shimmy,not like the nose is trying to rotate back and forth but like a l/r shimmy on its own centerline..
any ideas on where to start?? thanks for the help

[lrogers]

Check your flybar/paddles. I saw a buddy fly his X-Spec for the first time Sunday and it had a "shake" (he bought it used). When we took the blades off, we found the fly bar was WAY out of balance. Further checking showed the flybar was off center by about a 3/16". After recentering things, the shake went away. Worth a look anyway.

[Coolice]

Hey,

I have another option that me be your problem. Are you a beginner flying with a training under carriage?

If so I think the shake you are experiencing is due to the training under carriage resonating with the heli. This is quite apparnet on newly built helis where the rotor head dampers then start to bed in, loosen up and allow a resonance to creep in.

Try raising or lower your head speed, you should see a change as it is normally speed dependant and if you get past the resonance point it should calm down.
Also you may need to shorten your training skids by a couple of inches as I find this helps a lot with beginners, from new they are normally way to long anyway and this does not help with the shakes.
.

[RAV50]

I think Coolice has it figured.

Even without training gear. Now that the outside temps are colder, the damping and needle relationships change a bit (harder damping & lower headspeeds are the result). So, I would bet if yu upped your head speed a bit (up the points on your throttle curve and/or retuned your hover screw and main needle) your shimmy would go away.

[Coolice]

Hey Rav,

I think I saw he's sorted this problem according to what I may havee seen on another forum (the wrong one) and it turned out the so called experts at his club richened up the mixture to much to make the model smoke.
As he was using low nitro fuel the head speed dropped and a damper wobble set in.

But we'll await a response here to his findings.
.

[RAV50]

Yep, that would do it.