oldfart
Elite Veteran
Location: Vancouver, Canada
My Posts This: Topic Forum | Flutter1)The more dynamically stable the blades are (the less leading they have)the less power is required from the control system to stabalize them. Consequently the less precise and powerful the control system will have to be to evade flutter.
An easy way to check how much they do lead (I do not know of any woody 60 size blades under 250 grams that do not lead, as it would take that much lead in the leading edge to get their chordwise center of gravity far enough forward) is to hang each blade from their blade bolt hole off the side of your workbench, using a 3mm or so pivot. Then hang a plumb bob behind them along the trailing edge. This will indicate the amount of "lead". the less the better.
Surprisingly, I found that there are some composite blade brands that are relatively inexpensive that are extremely good here and some expensive brands that are not very good at all. So test them, don't rely on cost and brand name.
2) Check the control system and minimize all slop, or as much as possible.
3) Check the bearing in the lower star of your swashplate. I had flutter happen on a standard X-Cell that was traced to this bearing. Under normal inspection it seemed secure, but with presure applied to the blade in pitch, I found I could get it to move up and down in its seat. Readjustment of the retaining allen screws solved the problem. NOTE: The more unstable a blade is dynamically, the more they work the system. Consequently the quicker they will work such things as these bearings loose and wear other components. |
