Tip Of The Day- Keep An Eye On Your Ball Links!
Posted on January 22, 2009 by aaronredbaron
The plastic ball links that make radio control helicopter heads possible are one of the cheapest components on your helicopter, and yet one of the most critical. Every radio control helicopter on the market requires free moving, universal ball links in order to function, and we are fortunate to have such abundant access to high quality factory and aftermarket replacement links at reasonable prices. It is critical to keep an eye on your ball links because they can fail, and they eventually do wear out. For all practical purposes, every ball link on the helicopter is critical; if one fails your helicopter is going down. Although it may be possible to maintain some degree of control in a rare case, usually the result is either an instant boom strike, or the head simply explodes.
What Causes A Failure?
A link may fail because of a crack which develops but is not diagnosed, or they may simply fall off under normal use if they wear out. Ball links are also one of the easiest (in most cases) parts to replace, so there is no excuse for not keeping a vigilant watch over your ball link’s condition. The bigger the helicopter, the more dangerous a failed link is because the blade has much more energy. When the link fails the blade it was controlling instantly flutters, and the vibration it induces to the rotor head is so severe it just tears the head apart. If the blade goes out of track dramatically instead of fluttering, that is when a boom strike occurs. The only case you may be able to save your bird is on a tail or a link to the Hiller control. If the tail fails, you can do an autorotation to a safe landing because the helicopter will stop pirouetting out of control when you cut the power. If a link to the Hiller flybar control fails, the flybar will still have its gyroscopic stability, although cyclic agility is drastically reduced and the rotor head will not center properly or maintain trim.
What Should I Do To Avoid A Failure?
Go over your helicopter before the beginning of every flying session or even every flight. Wiggle and tug on each link, they should move totally free, but not allow any free play. Watch for any stress cracks where the plastic looks fatigued or if a crack has already started. Be sure to also watch the condition of the metal balls themselves, as they can wear out depending on the conditions. In dusty conditions, nitro powered helis tend to collect a very gritty residue between the link and the ball, and it can wear out the metal as if it were sandpaper. Clean your links frequently if you fly in dusty conditions, your links are much more prone fall off prematurely because of wear. Denatured or Rubbing alcohol can be sprayed on the links to cut the grease, and then they can be wiped clean. Even electric flyers should keep watch over their links, they are the simplest, most universal part in this entire hobby, and a single one failing could cost you your entire helicopter. Taking care of your links and keeping them in good condition will also lead to a more stable, responsive, and locked-in model.
