Oops! I made a mistake: the rotor path during cyclic flapping is not identical in both cases.
With Bell-47 cyclic, teeter pivot lies along control axis.
With Robinson cyclic. teeter pivot remains on shaft axis.
Reference axes of helicopter.
IPS is not directly representive of mecanical stress, when the frequency is different.
I've said all this before,
I'd say "no" there isn't any modification or adjustment you can make, especially if you're flying a factory gyro and your local rules don't allow you to make major changes.
If you are allowed to change things and if you're an experienced gyro builder like CB or Norm (Phantom) then there have been discussions on this forum before and I won't repeat them here, they include such mods as a slider roll pivot, stiffer in-plane rotors, softer ("limber") masts etc.
The one thing you CAN do that I would encourage every owner of a factory built gyro to do is to find somebody with a balancer that includes a frequency analyser, record the vibration at the mast and see how high the 2/rev is. If it's over say 1.0 IPS (I chose that arbitrarily, that doesn't mean that less than is acceptable) ask your manufacturer or his rep why it is so high and what are the acceptable limits, and report back here.
The manufacturers don't want to do anything about it and you can't blame them, they are commercial operations that are trying to make money (the American dream) and there is no incentive for them to spend any time and money trying to resolve a problem that only Mike G seems to be concerned about. If I was a manufacturer trying to stay profitable I wouldn't, would you?
If you do measure the vibrations of your gyro and the 1/rev is reasonable and the 2/rev is higher, then you either accept it or you complain and it's only when enough owners complain that the manufacturers might consider doing something.
Thanks for the comments.
I just realised that I left out the text about tracking adjustments under "Dynamic tracking" so I've edited the text above.
I've promised myself for the last couple of years to go to Bensen Days or Mentone to do a forum about balancing and each year something has cropped up, this year is no exception but I'm waiting for a confirmation of a meeting, if it falls thro I might just come over, I owe you and Laura a dinner from when I was last there and I really want to meet CB.
Now I'm retired money's a bit tight so you might have to let me sleep in your hanger
I would really like to balance your Aviomania, the French one is still grounded due to engine problems.
Wolfy OK perhaps we'd be better doing by email or Skype or something so as not to clutter up this thread.
You understood perfectly.
Rambler thanks for the link I'll edit it into the text.
I really had hoped to attend Bensen Days this year, I wanted to balance your rotor for you and get some data on the Aviomania and Ernie's rotor system for my personal data base. I also wanted to meet up with CB and the others I "know" from the forum. I put out a couple of feelers to see if there were others interested apart from yourself and got no feedback. I got yours but by then it was too late because I was under pressure to attend another balancing meeting in the UK on the same dates and with no feedback from Florida I accepted the other meeting.
I feel really bad for you and frustrated because I wanted to get data from your gyro and other American models to add to my knowledge.
What I propose is the following. If you have the time to spend setting up a PB3 and doing all the test flying to establish moves lines etc ( it's long, tedious and boring) and climb the learning curve I'll "lend" (I want it back) you a spare PB3 that I have and talk you through the setup etc via email, skype, telephone or even this forum. I'm interested in doing this to help you and to get the data so you'll have to have the time to do a couple of days flying circuits gathering data while I explain things to you.
It's the best I can do for you, pm me your address if you want to try this.