flyrotary@lancaironline.net Mailing List Archive

Bill,

Your photo is very timely - I do remember it!

I would like to mention that it is the opinion of some, that the reason the Renesis moved back to the groove in the Rotor Housing might be because of the fact of the cast iron being so thin in that area, whereas the rotor housings have a steel liner to help retain and withstand the pressure of the "O" ring in that area.

Their argument seems reasonable to me!

George (down under)

Back in 2002, the attached pictures were distributed, showing what happens when the o-ring fills the groove too completely. Upon heatup, the silicon expands and creates enough hydraulic pressure to break the cast iron. There was discussion at the time, but I don't have time to try to find the text that went with these pictures, just make sure you don't fill the o-ring groove completely.

Bill Schertz
KIS Cruiser # 4045

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

From: George Lendich

To: Rotary motors in aircraft

Sent: Thursday, July 21, 2005 11:50 PM

Subject: [FlyRotary] Re: TES "O" Rings

Kelly,

Good questions, even a percentage would do!

I think Jeff is sick of me, I will leave that up one up to you old mate!

Given he has suggested shrinking the "O" rings with a heat gun, I assume they shrink not expand BUT may be expand before shrinking!?

George ( down under)

George,

     Just what I was looking for !! Now I wonder what percentage of the

groove area that "Creavy" says needs to be filled and do the teflon-

silicon O-rings expand (grow) under heat ??

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

-------------- Original message from "George Lendich" <lendich@optusnet.com.au>: --------------

Kelly,

I see what you mean - a quick check of areas reveal a ratio of area of grove  to "O" ring cross sectional area as:-

1. .093 = 1: .924343 ( for the .065x .113) proven fit - outer "O" ring!!

2. .098 = 1: .859     ( for the .065x .135) OK

3. .1    = 1: .8945868( for the .065x .135) OK

4. .103 = 1: .9490484 ( for the .065x.135) TOO BIG.

Given the crush 'cross section' is different, but the Teflon flows under that pressure, 2 and 3 should be OK - I'm using your dimension measurements.

George ( down under)

George and All,

      I just realized I did not answer your question.......I wanted to find a

cross section of the PFA-SIL that was close to the .098 as called out

in earlier posts for the inner coolent O-ring......I measured the coolent

O-ring grooves of my housings........Both inner and outer grooves

measured .065 thousands deep.......Width of the inner was.135 thousands

and width of the outer was .113 thousands........Now can someone much

better in math than me figure what diameter of O-ring can we use in the inner

groove wthout causing a hydraulic rupture......The inner coolent O-ring sees

more heat and pressure than the outer O-ring !! On paper it appears that

a .093 thousands O-ring has enough crush according to the depth of the

groove but it is free to rattle around in the .135 width.........IMHO

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

-------------- Original message from keltro@att.net (Kelly Troyer): --------------

George,

     I was trying to find out what diameters (cross section) of the high temp

(500 degree f) PFA-SIL was available.........I wonder if the (450 degree f)

FEP-SIL might be good enough for the coolent O-rings but use the high

temp for the rotor side seal O-rings........If the coolent seals ever see even

450 degrees the aluminum rotor hsgs will probably start to crush !!

"Opinions"

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

-------------- Original message from "George Lendich" <lendich@optusnet.com.au>: --------------

Kelly,

What was that in relation to.

George ( down under)

Group,

   More info from "Creavey"

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

From:

"Jeff Chrysler" <jeff@creavey.com>     Save Address     Reminder

To:    "Kelly Troyer" <keltro@att.net>

Subject:    RE: Sil-PFA .098 availability

Date:    Thu, 21 Jul 2005 17:12:27 +0000   [View Source]

PFA is available in .103” cross section.

Jeff

From: Kelly Troyer [mailto:keltro@att.net]
Sent: Thursday, July 21, 2005 11:48 AM
To: Jeff Chrysler
Subject: RE: Sil-PFA .098 availability

    Jeff,

      Thanks Jeff........What diameters are available in PFA-SIL........ .100

would probably work if available.

Kelly Troyer

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