Mailing List flyrotary@lancaironline.net Message #38781
From: Tracy Crook <tracy@rotaryaviation.com>
Sender: <rwstracy@gmail.com>
Subject: Re: [FlyRotary] Gear mesh area? Was [FlyRotary] Re: Gear redrives.com
Date: Sat, 28 Jul 2007 18:57:24 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Hi Ed,
My quick & dirty answer is that the 6 pinion planet set is equivalent to a spur gear drive with a gear width totaling the width of all 6 planets.  That would be:
 
6 * .785" = 4.71"    Thats a mighty big & heavy spur gear!  
 
That's bigger than the one in a P-51 R.R. Merlin engine I think.  Not an apples to apples comparison due to the difference in bending strength of the tooth root but the biggie factor in power handling capability is indeed the gear contact patch.
 
Tracy

 
On 7/28/07, Ed Anderson <eanderson@carolina.rr.com> wrote:
 Well, Tracy, its sort of like flying 400 hours with a "Plugs Up" installation - can't possibly work - the "experts" have said so {:>).
 
  It continues to amaze me (as it does you) how people can just accept something sprouted out by some little (or unknown)  self-styled expert without attempt to ascertain whether there are  any independent sources/ facts supporting that position. 
 
As several individuals have pointed out most high powered (1500+) engines of WWII had planetary gear boxes not to mention the dozens of different  turboprop engines.  But, I guess all of that evidence does not out-weigh the opinions of "experts". 
 
I have not done this but it would be interesting to calculate the teeth mesh area of one of the spur gear PSRU and then compare it to the area of the six pinion sun and planetary gear area engaged to transfer a similar amount of power.  I could be wrong, but my gut feel is that the sun and planetary probably have more metal to metal contact area for transferring power than the Sun gear. 
 
 But, like I said - just a hunch, would be interesting to know.  Anybody have a quick answer??
 
 
 
Ed
 
 
----- Original Message -----
Sent: Saturday, July 28, 2007 1:47 PM
Subject: [FlyRotary] Re: Gear redrives.com

 
Thought I'd see what else I was doing wrong so took a fresh look at the geareddrives.com website.
 
The kiss of death for a set of gears is in not using the proper lubrication. Separate lubrication systems are required for safety and for proper engine and gear function. Sharing engine oil with the PSRU is asking for engine and/or PSRU failure in advance.
There is absolutely nothing I'm doing right!
 
But the company does not look like it is for sale though.  But Gershwinder (Sp?) drive company is for sale now.  Their chain drives were among the best I've seen. 
 
Tracy

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