Mailing List flyrotary@lancaironline.net Message #20572
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Finn NOT 2mm Seals - 2mm Slots Re: [FlyRotary] Re: New Rotors!
Date: Wed, 20 Apr 2005 20:18:30 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Finn, the Mystery is solved. 
 
 The seals themselves are .075" or 1.905mm thick not 2mm, The slots are approx 1.93mm wide - closer to 2mm but not quite there either.  My previous slot width numbers were in error.  I discovered that I apparently was not holding the dial calipers perpendicular to the slot, it makes a different. After slowly rocking the calipers, I could find Perpendicular.   I also stuck a seal in the slot and the smallest leaf gauge I have in the set is 0.0015" (.0381mm) and it was a tight fit and would not go in some cases indicating the clearance between apex seal and wall is 0.0015" OR LESS.  The measurement would indicate closer to .0010" or  0.0254mm, so a reasonably tight fit compared to the 0.18mm gap I had in some slots on the old rotor.  Something like 7 times the new clearance!
 
Hope this enables you to sleep tonight, Finn {:>)
 
Ed
 
 
----- Original Message -----
Sent: Wednesday, April 20, 2005 10:27 AM
Subject: [FlyRotary] Re: New Rotors!

Those numbers do not make sense. Aren't the seal  2 mm? How will they fit in a 1.778mm groove?

Finn

Ed Anderson wrote:
Got the new rotors today - first time I've ever seen a new rotor - the are bright metallic {:>). 
 
The depth of the apex seal slot on the new rotors ranged from 9.65mm to 9.77 mm.  Interestingly the width of the bottom of the apex slot was 1.88mm but the top was narrower at 1.778mm.  I noticed that the lip of the apex seal slot had a tiny burr of metal along it as if they were not using a sharp enough tool or else pushing it along too fast.  Or perhaps no one took the time to deburr the slot.
 
Just in case any of you ever wonder whether you are looking at a 9.7:1 rotor or some other rotor, there is a fairly easy way to tell.  Lay a straight edge across the depression in the rotor and measure from its bottom to the center of the depression, it should measure right at 4 mm.  The 9.1 measure around 7mm for comparison.  Just thought you might want to know.
 
Ed
 
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
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