Author Topic: Jacobs tailvane bounce  (Read 1473 times)

0 Members and 1 Guest are viewing this topic.

adobejoe

  • Full Member
  • ***
  • Posts: 105
Jacobs tailvane bounce
« on: October 16, 2016, 09:35:02 PM »
Have my Jacobs 2.5 up and running. Getting it wired in to dump load electricity to create heat on resistor elements in my mancave. I notice in 20+ winds the tailvane does this slight up and down bounce, maybe an inch or slightly greater. Any idea why and how can I resolve? Otherwise doing well and seems to trim the blades. Left it going last night and we had a stretch of 40+ winds.

AdobeJoe

Adriaan Kragten

  • Hero Member
  • *****
  • Posts: 1154
  • Country: nl
Re: Jacobs tailvane bounce
« Reply #1 on: October 17, 2016, 07:28:25 AM »
The tail vane will have a certain natural frequency. The rotor may have a certain mass imbalance. At a certain rotational speed, the frequency of the rotor imbalance becomes the same as the natural frequency of the vane and then the vane starts oscillating. If this is the cause, oscillation will stop at higher rotational speeds. The problem can be solved largely by balancing of the masses of the rotor blades. However, the rotor may also have a certain aerodynamic imbalance if the blades and the blade angles are not identical or if the wind speed for the upper blade is higher than for the lower blade. So some oscillation of the vane will remain even for a perfectly balanced rotor.

stofanel

  • Jr. Member
  • **
  • Posts: 51
  • Country: us
Re: Jacobs tailvane bounce
« Reply #2 on: October 17, 2016, 10:32:50 AM »
Yaw and pitch oscillations are notoriously difficult to diagnose. Without further testing, it's nearly impossible to tell what's causing the problem. There is a quick fix, however. Some high end motorcycles use a device called a steering damper. It's basically a shock absorber for the steering fork. Such a device could be easily installed on a wind turbine. 

adobejoe

  • Full Member
  • ***
  • Posts: 105
Re: Jacobs tailvane bounce
« Reply #3 on: October 17, 2016, 02:08:46 PM »
Thanks for input, I will have to examine in a variety of winds. The return spring is a little weak on the tailvane, which might influence things a bit. Also will look closer at the blade rotations.
AdobeJoe