ch-47c
Heliman
Location: san jose, ca
| VibrationThe 2 stroke engines we use in RC helis rotate at such a high freq that it can't be anything but high freq. When I was a Chinook mechanic in the ARMY, we had high freq vibrations from such things as the engines, xsmns, drive shafts, pumps, generators, and any other high rotational speed mechanism. It was defined as 3 to 1 vib. They were detected by feel. You put your finger near an area suspected and if it felt like it was a numbing feeling, it was a high freq vibration. Usually bad Lord mounts or bearings. Low freq items were usually the rotor system which cause a wobble. Defined as a 1 to 1 vib. Or 1 shake per rotation of a shaft. Blade track could cause it. On real helis, that I'm familiar with, have a slower rotor RPM than RC helis. In the low to mid 200 RPMs. If you were anywhere near 300 RPMs, your blades and drive shafts will distort permanently and blade tips will be near supersonic, where you have aerodynamic problems. While flying, you shook in the troop seat with bad 1 to 1 vib. That is why helicopter pilots and flying mechs have a high incidents of hemmoroids. Newer Chinooks, I hear from old buddies still doin it, say it is less noticeable.
If something has a high freq vib, and it is hard mounted, it will transmit thru any hard mounted item attached to it. The main problem is wear and cracks.
The original Synergy motor mount design would have better vibration isolation characteristics, than the newer aluminum design as it would absorb more vibs that aluminum. But neither material is great, like hard rubber, but I feel the older is the better, IMHO. |
