: = --------------=20 > Here's another couple of pix to show a 3 rotor being balanced. = Notice the=20 > Mallory Metal added to the front counterweight to shift the = balance axis.=20 > The factory front counterweight was originally drilled off centre = by the=20 > factory due to the rotors not all being the same weight. During = balancing,=20 > all the rotors were reduced back to the same dynamic weight as the = lightest.=20 > Then put on the shaft.=20 >=20 > Cheers,=20 >=20 > Leon ------=_NextPart_000_0019_01C4FC63.C3DEB1D0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Hi Kelly,

Like making allowances for the oil = capacity of the=20 rotor, I can't tell you ALL my secrets!! I'm pretty free = with=20 info, but this particular one falls into the category of "trade=20 secret".

Other guys make up mandrels and attach = weights as=20 is done in normal piston engine balancing practice. But that is = time=20 consuming. One added complication is that the rotor has the = cetre of=20 mass biased slightly on the gear side, so even though the mass = centroid=20 co-incides with the centre line of the eccentric journal, = it's not=20 midway ON the journal.

This distance varies slightly from = rotor model=20 to rotor model (the transfer gear is the same weight, but the = lighter the=20 rotor, the more this shifts towards to gear side, especially = with=20 rotors that have been extensively lightened for racing.

So it's far easier just to use the = rotor itself=20 (with the seals taped in), and then we have all the masses exactly = where=20 they are supposed to be when the engine is running.

As for indexing the actual rotor, = if you=20 think about it, the centroid of mass of the rotor, being = basically=20 an equilateral triangle, is at the centre line of the lobe. = So it=20 doesn't matter how the rotor is "clocked" in relationship to = the=20 eccentric lobe. (I just can't wait for some mathematically = obsessed=20 theoretician to try to "prove" that this isn't the case). = (}:>)

Cheers,

Leon

----- Original Message -----
From:=20 Kelly = Troyer
To: Rotary motors in = aircraft

Sent: Monday, January 17, 2005 = 3:33=20 AM

Subject: [FlyRotary] Re: 3 = Rotor=20 Balancing Stuff

Leon,

How are rotors kept in place on shaft and are they=20 indexed

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

--
Kelly Troyer
Dyke=20 Delta/13B/RD1C/EC2

--------------=20 Original message from "Leon" <peon@pacific.net.au>:=20 --------------

> Here's another couple of pix to show = a 3=20 rotor being balanced. Notice the
> Mallory Metal added to the = front=20 counterweight to shift the balance axis.
> The factory front=20 counterweight was originally drilled off centre by the
> = factory due=20 to the rotors not all being the same weight. During balancing, =
> all=20 the rotors were reduced back to the same dynamic weight as the = lightest.=20
> Then put on the shaft.
>
> Cheers,
> =
>=20 Leon

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