oldfart
Elite Veteran
Location: Vancouver, Canada
| Man, can't I go away for a weekend fun-fly???
Just had a great time at the Shag '08 in Saskatoon, Saskatchewan, Canada. 48 registered pilots - hosted by the "hosts of hosts" who even provided each registrant a breakfast and steak dinner extraordinaire and a superb 20+ minute fireworks display Saturday night before the nite flying! TWO-THUMBS UP. Well worth the 3000 mile round trip.
But I was a bit worried coming back, as the airline almost refused to bring back my two helis. Fortunately I had brought the FAA/DOT regs with me, to prove they could be transported in the manner I had them packed.
That sounds like a ground resonance issue that happens at a specific UNLOADED rotor speed, probably due to the dynamic relationship between the blades, dampers and long landing gear. I am positive it has nothing to do with the ESC. If you are landing on a hard surface this will be amplified, landing on grass will certainly help.
As the dampers break, in this may well go away.
Also, try keeping your rotor LOADED after landing, using some positive pitch during spool down. The best way to do this is to land, then hit throttle hold during spool down, then hold some collective (3 to 5 degrees) as it spools down.
Resonances are always caused by one item resonating at a harmonic frequency of another in ANY helicopter (I have experienced this with a number of different ones with different blades and damping over the years). As the two landing gear struts are usually the same, their resonance frequency will be the same. So usually changing the resonance frequency of one of them will also do the trick. I would suggest putting a cross brace between the left side and right sides of the rear strut (a good attachment point is where the tail boom struts attach). |
