: -------------- > Here's another couple of pix to show a 3 rotor being balanced. Notice the > Mallory Metal added to the front counterweight to shift the balance axis. > The factory front counterweight was originally drilled off centre by the > factory due to the rotors not all being the same weight. During balancing, > all the rotors were reduced back to the same dynamic weight as the lightest. > Then put on the shaft. > > Cheers, > > Leon --NextPart_Webmail_9m3u9jl4l_13829_1105907675_0 Content-Type: text/html Content-Transfer-Encoding: 8bit

Thanks a lot Leon.......I am not smart enough to do anything with

your info .......Just curious about things that seem obvious even

to me !!

--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2

-------------- Original message from "Leon" <peon@pacific.net.au>: --------------

Hi Kelly,

Like making allowances for the oil capacity of the rotor, I can't tell you ALL my secrets!! I'm pretty free with info, but this particular one falls into the category of "trade secret".

Other guys make up mandrels and attach weights as is done in normal piston engine balancing practice. But that is time consuming. One added complication is that the rotor has the cetre of mass biased slightly on the gear side, so even though the mass centroid co-incides with the centre line of the eccentric journal, it's not midway ON the journal.

This distance varies slightly from rotor model to rotor model (the transfer gear is the same weight, but the lighter the rotor, the more this shifts towards to gear side, especially with rotors that have been extensively lightened for racing.

So it's far easier just to use the rotor itself (with the seals taped in), and then we have all the masses exactly where they are supposed to be when the engine is running.

As for indexing the actual rotor, if you think about it, the centroid of mass of the rotor, being basically an equilateral triangle, is at the centre line of the lobe. So it doesn't matter how the rotor is "clocked" in relationship to the eccentric lobe. (I just can't wait for some mathematically obsessed theoretician to try to "prove" that this isn't the case). (}:>)

Cheers,

Leon

----- Original Message -----

From: Kelly Troyer

To: Rotary motors in aircraft

Sent: Monday, January 17, 2005 3:33 AM

Subject: [FlyRotary] Re: 3 Rotor Balancing Stuff

Leon,

How are rotors kept in place on shaft and are they indexed

relative to each other as they are in a running engine ?

--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2

-------------- Original message from "Leon" <peon@pacific.net.au>: --------------

> Here's another couple of pix to show a 3 rotor being balanced. Notice the
> Mallory Metal added to the front counterweight to shift the balance axis.
> The factory front counterweight was originally drilled off centre by the
> factory due to the rotors not all being the same weight. During balancing,
> all the rotors were reduced back to the same dynamic weight as the lightest.
> Then put on the shaft.
>
> Cheers,
>
> Leon

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