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Recently I have had to help people with machines that despite being perfectly balanced, no bent shafts, tracking spot on… simply shook.
After lots of head scratching and double checking of everything, trying different blades, dampers, etc.. it dawned on me that perhaps the static tracking was out.
Static what? Some of you be thinking..
I first came across this on the original XCell 60 series of helicopters in the early 90’s. They had a couple of grub screws in the base of the head block that tightened against the main shaft. The purpose of these was to allow you to adjust the static tracking of the blades.
Static tracking the blades is much like normal tracking.. however you do it without the head spinning.
Simply measure the height of one blade tip and the rotate the blades through 180 degrees and see where the other blade tip is. I do this by extending the aerial of my transmitter so it just brushes the bottom of one blade tip. Ideally they should be under ½ cm in difference. However these machines I mentioned earlier were suffering from blade tips that were several cm’s out.
Adjustment on these machines was pretty straight forward as they had 2 piece head blocks. A quick slackening and re-tightening of them allowed us to shift them enough to bring the static alignment into an acceptable region.
If your machine has a one piece head block and has recently been “pranged” then there is a good chance that this might be ever so slightly out. Maybe not enough to visibly wobble.. but that amplified at the end of the blade tip it can be quite visible.
Mark
After lots of head scratching and double checking of everything, trying different blades, dampers, etc.. it dawned on me that perhaps the static tracking was out.
Static what? Some of you be thinking..
I first came across this on the original XCell 60 series of helicopters in the early 90’s. They had a couple of grub screws in the base of the head block that tightened against the main shaft. The purpose of these was to allow you to adjust the static tracking of the blades.
Static tracking the blades is much like normal tracking.. however you do it without the head spinning.
Simply measure the height of one blade tip and the rotate the blades through 180 degrees and see where the other blade tip is. I do this by extending the aerial of my transmitter so it just brushes the bottom of one blade tip. Ideally they should be under ½ cm in difference. However these machines I mentioned earlier were suffering from blade tips that were several cm’s out.
Adjustment on these machines was pretty straight forward as they had 2 piece head blocks. A quick slackening and re-tightening of them allowed us to shift them enough to bring the static alignment into an acceptable region.
If your machine has a one piece head block and has recently been “pranged” then there is a good chance that this might be ever so slightly out. Maybe not enough to visibly wobble.. but that amplified at the end of the blade tip it can be quite visible.
Mark
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