Mailing List flyrotary@lancaironline.net Message #23889
From: George Lendich <lendich@optusnet.com.au>
Subject: Re: [FlyRotary] planetary gear ratios
Date: Wed, 15 Jun 2005 16:57:00 +1000
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Ernest,
If it turns counter clockwise it's the 2.17 ( you don't add the one in the
calculations).
If it turns clockwise it's 3.17.
The 2.17 turns counter clockwise.
The 2.85 turns clockwise ( looking at it from the pilots seat)
George ( down under)

I ran across some information in one of the scientific newsgroups on how
to calculate the gear ratio of a planetary gear set.

ratio = 1 + r / s

where: r = number of ring gear teeth
           s = number of sun gear teeth.

I haven't replace my 3-pinion gear set with a 6-pinion set, because I've
not been able to positively identify it to where I could call out a part
number.  Order strange gearset from the internet is not what I consider
an efficient way to spend money.  So I went out and counted.  74 teeth
on the ring and 34 on the sun.

1+74/34 = 3.176

That is not the 2.17 OR the 2.85 from the Ford gear sets.  Is it
possible that the one isn't added in standard practice, so that what I
actually have is the 2.17 gear set?


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