Brendan,
It was a real case ! and I think that it does happen with other large OTA's
The P-ME was "built", rather than really engineered and designed at the sort of levels mooted here !
We can only assume it was a resonance, not necessarily high frequency, but that depends on what you mean by high.
Whilst it could be the pier or the pier as part of that particular system, I believe this is unlikely, it occurred in different situations and appeared to be unaffected by any dampening applied to the pier or the piers ground connection.
It seemed to be an OTA/Mount system related problem, that was able to be remedied by changing the counterweight mass around.
That was a solution but not necessarily a fix of the source.
It wasn't specifically an overloading mass related problem because the total mass was ultimately increased to solve the problem !
I didn't solve it, just supplied some of the pieces.
In any event the purpose of this example was to illustrate that vibration in telescope systems does exist and does cause real problems in all sorts of unexpected and complex ways.
Rally
Quote:
Originally Posted by bmitchell82
Thankyou for your reply Rally,
So your issue was high frequency vibrations forming a dynamic resonance. Is this a issue of the pier or is this a issue of the mount?
To me it would be more a case of in the pier, with adjustments and tolorances. Possibly due to the telescope being sufficiently big enough coming upto the PME's rated capacity and hence any dynamic vibrations start to affect.
If this where a real case and it happend all the time wouldn't mount design take this phenomena into account?
I also think that placing the CW further out would make the issue worse not better. Yes the leaver arm is bigger hence less weight but the ability for a weight further out where your natrual frequency decreases and hence has more chance of coming into resonance.
It is a tricky one high frequencies because they are hard to measure unless you have some really expensive tools.
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