X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mtiwmhc11.worldnet.att.net ([204.127.131.115] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 1036088 for flyrotary@lancaironline.net; Thu, 16 Mar 2006 09:54:59 -0500 Received-SPF: none receiver=logan.com; client-ip=204.127.131.115; envelope-from=keltro@att.net Received: from mwebmail20.att.net ([204.127.135.59]) by worldnet.att.net (mtiwmhc11) with SMTP id <20060316145410111004ca6qe>; Thu, 16 Mar 2006 14:54:15 +0000 Received: from [63.157.92.236] by mwebmail20.att.net; Thu, 16 Mar 2006 14:54:09 +0000 From: keltro@att.net (Kelly Troyer) To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Motor teardown results Date: Thu, 16 Mar 2006 14:54:09 +0000 Message-Id: <031620061454.1068.44197C0E0003F18C0000042C2160280651019D9B040A05@att.net> X-Mailer: AT&T Message Center Version 1 (Feb 28 2006) X-Authenticated-Sender: a2VsdHJvQGF0dC5uZXQ= MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="NextPart_Webmail_9m3u9jl4l_1068_1142520849_0" --NextPart_Webmail_9m3u9jl4l_1068_1142520849_0 Content-Type: text/plain Content-Transfer-Encoding: 8bit Chuck, As a clarification how do you lube your apex seals ? Do you mix with fuel or use injection metering pump ? -- Kelly Troyer Dyke Delta/13B/RD1C/EC2 -------------- Original message from "Ed Anderson" : -------------- > Certainly, I don't feel we can rule anything out at this point, Doug. > Degree of Lubrication could certainly play a role, but I personally doubt > that it is the root cause - could be wrong about that, of course. I believe > it may have to do with the amount of play in the rotor housing apex seal > slots. I suspect that if the seals were pressing against the rotor housing > wall in the manner they were designed to - the rounded top tangential to the > surface of the housing - there is minimal drag and friction. As the slots > wear the seals become able to "flop" from one side to the other of the > housing as its chamber undergoes the 4 cycles. When "flopped" the seal's > rounded top is no longer in contact as designed and the top edge > (non-rounded part) of the seal may start to drag and cause unusual wear. > > If lubrication was sparse and this condition existed, I think it would > contribute to accelerated wear and chatter marks. But, just a hypothesis. > > Ed > > Ed Anderson > Rv-6A N494BW Rotary Powered > Matthews, NC > eanderson@carolina.rr.com........... > > > ----- Original Message ----- > From: "Doug Mueller" > To: "Rotary motors in aircraft" > Sent: Thursday, March 16, 2006 12:30 AM > Subject: [FlyRotary] Re: Motor teardown results > > > > Hi Chuck and Ed could there be any relationship to the lack of lubrication > > to > > these housings? The Lubrication increase could dampen any resonant > > frequency causing chatter? What would your opinion be on that idea? > > Anyone? > >> > >> From: "Ed Anderson" > >> Date: 2006/03/16 Thu AM 12:21:11 EST > >> To: "Rotary motors in aircraft" > >> Subject: [FlyRotary] Re: Motor teardown results > >> > >> MessageThe chatter marks are certainly apparent, Chuck. Whoa! 150 > > hours is certainly not much out of a brand new housing. It could be as > > you > > suggest that the two piece seal played a role. However, I have another > > suggestion. Measure the apex seal slot at the top (across the gap) and > > see > > what the distance is. Do it both on the good rotor and the damaged one if > > you can find an undamaged spot. If like my rotor, the slots are worn, I > > believe they may contribute to the chatter and breaking of the apex seal. > >> > >> Here's the theory. As the slot "V"s there is less support for the seal > >> near > > its top, the bottom is still fairly well constrained. As a consequence, > > the top > > portion of the seal is more able to be swayed back and forth by > > combustion > > and friction forces. In other words, instead of just rubbing on the rotor > > housing wall with the smooth top of the seal, the edge of the seal starts > > to > > drag along the wall. The seal (with less support at the top) acts like a > > stiff > > spring (up to a limit) and "vibrates" as it slides along the housing wall > > leaving > > the chatter marks. At some point the forces become too much and the seal > > breaks. > >> > >> It might be interesting to determine the vibration frequency of a seal > > ( given its dimensions and composition) and then measure the average > > distance between the peaks (or valleys) of the chatter. Then given the > > resonant frequency of the seal determine at what rotor rpm it would leave > > chatter marks of the measured distance. {:>). No, I don't have a clue > > about > > how to do this, but I'll bet some mechanical engineer could come up with > > something. > >> > >> Just a theory, of course, but if your apex slot tops are within the > > specifications called for by Mazda then that would discredit the theory. > > If > > they are worn then it might tend to give it support. > >> > >> > >> When my seal broke it also caught the next seal down in is slot and > > smeared the top of the slot such that it could not come back up. > >> > >> You and I are apparently the only ones (that I know of ) that seem to > >> have > > had this failure mode of an apex seal disintegrating for no apparent > > reason. > >> > >> Thanks for sharing the photos and information. > >> > >> Are you going to try for Sun & Fun? > >> > >> Ed > >> > >> > >> Ed Anderson > >> Rv-6A N494BW Rotary Powered > >> Matthews, NC > >> eanderson@carolina.rr.com > >> > >> Ed > >> > >> > >> > >> ----- Original Message ----- > >> From: Chuck Dunlap > >> To: Rotary motors in aircraft > >> Sent: Wednesday, March 15, 2006 10:44 PM > >> Subject: [FlyRotary] Motor teardown results > >> > >> > >> > >> > >> I finally got time to get my failed 13b apart. The rear rotor was > >> missing > > one apex seal, the other 2 were intact but jammed due to the fragments of > > the broken one. The rotor housing has the classic chatter marks all > > around. > > Doing a Google of "13B apex seal chatter" results in plenty of examples of > > this failure mode. Apparently the chatter is from the natural resonant > > frequency of the seal, it eventually fatigues the seal causing failure. > >> The front rotor was in good shape, but the housing had the same chatter > > marks, but not as severe as the rear rotor. The front rotor housing was > > brand > > new 150 hours ago when I rebuilt this motor after the Grand Canyon forced > > landing. At that time the good rotor housing had slight chatter marks but > > I > > reused it. The front rotor was destroyed at that time due to foreign > > object > > entering the rotor. > >> Both rotors were missing the corner seal rubber plugs on the side with > > the short apex seal segment. Perhaps the small segment vibrated more, > > disintegrating the rubber seals? > >> The first 260 hours of flying my rotary bird was with stock 3-piece > >> seals, > > and I never saw any chatter marks. The last 250 hours has been flown with > > 2 > > piece seals and now I have chatter marks . > >> I now have Tracy's 2 piece apex seals and I wonder how they will > >> perform, > > it appears that the heavier weight of the 2 piece seals puts the resonant > > frequency in the cruising range of 6000RPM? > >> > >> Chuck Dunlap > >> RV6 13B > >> > >> > >> > > ----------------------------------------------------------------- > > ------------- > >> > >> > >> -- > >> Homepage: http://www.flyrotary.com/ > >> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ > >> > >> > > > > Doug Mueller > > RX-6 13BT > > N900DM > > Boulder City(61B),Nevada > > > > > > -- > > Homepage: http://www.flyrotary.com/ > > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ > > > > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ --NextPart_Webmail_9m3u9jl4l_1068_1142520849_0 Content-Type: text/html Content-Transfer-Encoding: 8bit
Chuck,
   As a clarification how do you lube your apex seals ? Do you mix with fuel or
use injection metering pump ?
    
--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2




-------------- Original message from "Ed Anderson" <eanderson@carolina.rr.com>: --------------


> Certainly, I don't feel we can rule anything out at this point, Doug.
> Degree of Lubrication could certainly play a role, but I personally doubt
> that it is the root cause - could be wrong about that, of course. I believe
> it may have to do with the amount of play in the rotor housing apex seal
> slots. I suspect that if the seals were pressing against the rotor housing
> wall in the manner they were designed to - the rounded top tangential to the
> surface of the housing - there is minimal drag and friction. As the slots
> wear the seals become able to "flop" from one side to the other of the
> housing as its chamber undergoes the 4 cycles. When "flopped" the seal's
> rounded top is no longer in contact as designe d and the top edge
> (non-rounded part) of the seal may start to drag and cause unusual wear.
>
> If lubrication was sparse and this condition existed, I think it would
> contribute to accelerated wear and chatter marks. But, just a hypothesis.
>
> Ed
>
> Ed Anderson
> Rv-6A N494BW Rotary Powered
> Matthews, NC
> eanderson@carolina.rr.com...........
>
>
> ----- Original Message -----
> From: "Doug Mueller"
> To: "Rotary motors in aircraft"
> Sent: Thursday, March 16, 2006 12:30 AM
> Subject: [FlyRotary] Re: Motor teardown results
>
>
> > Hi Chuck and Ed could there be any relationship to the lack of lubrication
> > to
> > these housings? The Lubrication increase could dampen any resonant
> > frequency causing chatter? What would your opinion be on that idea?
> > Anyone?
> >>
> >> From: "Ed Anderson"
> >> Date: 2006/03/16 Thu AM 12:21:11 EST
> >> To: "Rotary motors in aircraft"
> >> Subject: [FlyRotary] Re: Motor teardown results
> >>
> >> MessageThe chatter marks are certainly apparent, Chuck. Whoa! 150
> > hours is certainly not much out of a brand new housing. It could be as
> > you
> > suggest that the two piece seal played a role. However, I have another
> > suggestion. Measure the apex seal slot at the top (across the gap) and
> > see
> > what the distance is. Do it both on the good rotor and the damaged one if
> > you can find an undamaged spot. If like my rotor, the slots are worn, I
> > believe they may contribute to the chatter and breaking of the apex seal.
> >>
> >> Here's the theory. As the slot "V"s there is less support for the seal
> >> near
> > its top, the bottom is still fairly well constrained. As a consequence,
> > the top
> > portion of the seal is more able to be swayed back and forth by
> > combustion
> > and friction forces. In other words, instead of just rubbing on the rotor
> > housing wall with the smooth top of the seal, the edge of the seal starts
> > to
> > drag along the wall. The seal (with less support at the top) acts like a
> > stiff
> > spring (up to a limit) and "vibrates" as it slides along the housing wall
> > leaving
> > the chatter marks. At some point the forces become too much and the seal
> > breaks.
> >>
> >> It might be interesting to determine the vibration frequency of a seal
> > ( given its dimensions and composition) and then m easure the average
> > distance between the peaks (or valleys) of the chatter. Then given the
> > resonant frequency of the seal determine at what rotor rpm it would leave
> > chatter marks of the measured distance. {:>). No, I don't have a clue
> > about
> > how to do this, but I'll bet some mechanical engineer could come up with
> > something.
> >>
> >> Just a theory, of course, but if your apex slot tops are within the
> > specifications called for by Mazda then that would discredit the theory.
> > If
> > they are worn then it might tend to give it support.
> >>
> >>
> >> When my seal broke it also caught the next seal down in is slot and
> > smeared the top of the slot such that it could not come back up.
> >>
> >> You and I are apparently the only ones (that I know of ) that seem to
> >> have
> > had this failure mode of an apex seal disintegrating for no apparent
> > reason.
> >>
> >> Thanks for sharing the photos and information.
> >>
> >> Are you going to try for Sun & Fun?
> >>
> >> Ed
> >>
> >>
> >> Ed Anderson
> >> Rv-6A N494BW Rotary Powered
> >> Matthews, NC
> >> eanderson@carolina.rr.com
> >>
> >> Ed
> >>
> >>
> >>
> >> ----- Original Message -----
> >> From: Chuck Dunlap
> >> To: Rotary motors in aircraft
> >> Sent: Wednesday, March 15, 2006 10:44 PM
> >> Subject: [FlyRotary] Motor teardown results
> >>
> >>
> >>
> >>
> >> I finally got time to get my failed 13b apart. The rear rotor was
> >> missing
> > one apex seal, the other 2 were intact but jammed due to the fragments of
> > the broken one. The rotor housing has the classic chatter marks all
> > around.
> > Doing a Google of "13B apex seal chatter" results in plenty of examples of
> > this failure mode. Apparently the chatter is from the natural resonant
> > frequency of the seal, it eventually fatigues the seal causing failure.
> >> The front rotor was in good shape, but the housing had the same chatter
> > marks, but not as severe as the rear rotor. The front rotor housing was
> > brand
> > new 150 hours ago when I rebuilt this motor after the Grand Canyon forced
> > landing. At that time the good rotor housing had slight chatter marks but
> > I
> > reused it. The front rotor was destroyed at that time due to foreign
> > object
> & gt; entering the rotor.
> >> Both rotors were missing the corner seal rubber plugs on the side with
> > the short apex seal segment. Perhaps the small segment vibrated more,
> > disintegrating the rubber seals?
> >> The first 260 hours of flying my rotary bird was with stock 3-piece
> >> seals,
> > and I never saw any chatter marks. The last 250 hours has been flown with
> > 2
> > piece seals and now I have chatter marks .
> >> I now have Tracy's 2 piece apex seals and I wonder how they will
> >> perform,
> > it appears that the heavier weight of the 2 piece seals puts the resonant
> > frequency in the cruising range of 6000RPM?
> >>
> >> Chuck Dunlap
> >> RV6 13B
> >>
> >>
> >>
> > -----------------------------------------------------------------
> > - ------------
> >>
> >>
> >> --
> >> Homepage: http://www.flyrotary.com/
> >> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/
> >>
> >>
> >
> > Doug Mueller
> > RX-6 13BT
> > N900DM
> > Boulder City(61B),Nevada
> >
> >
> > --
> > Homepage: http://www.flyrotary.com/
> > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/
> >
>
>
>
> --
> Homepage: http://www.flyrotary.com/
> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/
--NextPart_Webmail_9m3u9jl4l_1068_1142520849_0--