X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from rv-out-0506.google.com ([209.85.198.234] verified) by logan.com (CommuniGate Pro SMTP 5.2.3) with ESMTP id 2979098 for flyrotary@lancaironline.net; Sun, 22 Jun 2008 08:23:44 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.198.234; envelope-from=cozy4pilot@gmail.com Received: by rv-out-0506.google.com with SMTP id f6so7495388rvb.7 for ; Sun, 22 Jun 2008 05:23:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:reply-to:from:to:in-reply-to :subject:date:message-id:mime-version:content-type:x-priority :x-msmail-priority:x-mailer:importance:x-mimeole; bh=vMut3/lsSBfOrBruw6N1GEJDOaHZ9Vs6CkFu3EpERlU=; b=IZA3BJ+/bdF8MiW8lNIUSPfAexBZFGdT3cn8BXj020eqoilzpzjQdnp1f3kP8G9im+ iTq/RQsZLl08P9yfx3GbcbwI9GM4WI3L4JRd7MyajT5oB8Pfkldq8r7oDbFK+pXJcNFp twz9hWE5zVmEA5cM+9M9KOggteYGHYthJsVu8= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=reply-to:from:to:in-reply-to:subject:date:message-id:mime-version :content-type:x-priority:x-msmail-priority:x-mailer:importance :x-mimeole; b=xz1S/4pnjXDqi24VcybXt+J1RSCYWjpV0NqEEGB8GFJT/fBUlMRH+GaPvCzsl4yo5a qpZKRvnv6RdawGSiBRdAvuMAy5vbWPCv2jofrB1z82B4+717+9sYK4lux+nrMiHyPotg VIPtRHkLPn9bZmjrhYEILEBenRyiMRn7dFWPA= Received: by 10.141.76.21 with SMTP id d21mr10742387rvl.242.1214137382802; Sun, 22 Jun 2008 05:23:02 -0700 (PDT) Return-Path: Received: from HomePC ( [71.50.110.25]) by mx.google.com with ESMTPS id i17sm8153654wxd.8.2008.06.22.05.22.58 (version=SSLv3 cipher=RC4-MD5); Sun, 22 Jun 2008 05:23:00 -0700 (PDT) Reply-To: From: "Steve Brooks" To: "Rotary motors in aircraft" In-Reply-To: Subject: RE: [FlyRotary] Re: Another Turbo Bites the dust Date: Sun, 22 Jun 2008 08:20:05 -0400 Message-ID: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000C_01C8D440.C66DF6F0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6000.16545 This is a multi-part message in MIME format. ------=_NextPart_000_000C_01C8D440.C66DF6F0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 8bit I think that losing a blade created such an imbalance that under high RPM’s at WOT, it most probably caused damage to the bearings, That would be my guess on it. BTW ED, this turbo upgrade does not use the stock bearings. They use a 360 degree thrust bearing for the upgrade. They do however, use the stock hot side chamber and turbine wheel, though they trim the turbine wheel to prevent over speed. It sounds like even the stock turbine won’t stand up to the constant high temperatures. Kelly may be on the right track, when he mentions inconel. I’m not sure what the stock turbine wheel is made of. Steve Brooks -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of George Lendich Sent: Saturday, June 21, 2008 10:39 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Another Turbo Bites the dust So what is that indicator telling us, if the seal isn't leaking then the bearings aren't gone. If that is the case it must be the heat that has affected the turbo blades and imbalance contributing to it not working. Does one blade cause the pressure to drop off that much? Am I reading this right or am I not taking into account other factors. George ( down under) Good point about the oil feed Ed. In fact, when my first turbo went, the folks on the ground saw all that smoke and reported that we were on fire... we were not on fire, but there was plenty of oil both inside the exhaust on spilling onto the outside of it. So after that I installed an electric switch that I can use to cutoff oil flow to the turbo from inside the cockpit. Interesting, with this failure there was no smoke or oil leakage (yet), but I will flip the switch for the flight home and cut off the oil supply. Thanks for the reminder! -- David Leonard Turbo Rotary RV-6 N4VY http://N4VY.RotaryRoster.net http://RotaryRoster.net On Sat, Jun 21, 2008 at 4:58 PM, Ed Anderson < eanderson@carolina.rr.com > wrote: In my opinion, one of the things that we tend to not pay sufficient attention to is the extent of the demand we are putting on turbos. Without getting into the specifics of boost ratios vs ambient pressure, suffice it to say that a turbo compressor has to work considerably harder at altitude to maintain the same pressure ratio in the manifold. The ambient air pressure is of course less at 8000 MSL therefore density less as well and the turbo simply has to turn faster to create the same amount of boost pressure out of the less dense air. The only way the turbo can do that is to turn faster at altitude. So you have that hot rotary exhaust pushing those small turbine blades, faster and faster. As we have discovered, the stock RX-7 turbo succumbs quickly to those stresses (simply not designed for them). Even with the TO4 compressor mod, which clearly helps by reducing the turbine rpm needed to produce X boost, the stock turbine and bearing just do not appear up to the stress for long duration – although 130 hours is better than I thought the stock bearings would do. A precaution I would take before flying back with the turbo that condition is to disconnect and plug the oil line to the turbo. Should the bearing have taken a worst beating 0r continues to deteriorate, you would not want to be dumping that precious engine oil into the exhaust – although there should be plenty of smoke to tell you when that condition occurred – if there is anybody around in West Texas to let you know {:>). So I would disconnect and plug the oil line and coolant line to the turbo – just to make certain no leaks occurred. Just my 0.02. Glad, nothing more happened to the engine or you, Dave. Ed. Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.dmack.net/mazda/index.html _____ From: Rotary motors in aircraft [mailto: flyrotary@lancaironline.net ] On Behalf Of George Lendich Sent: Saturday, June 21, 2008 6:24 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Another Turbo Bites the dust It's amazing how fast 130 hrs goes when you are having fun.:-) I took off the exhaust today and too a look. One of the blades on the turbine wheel is gone, but the axle seems otherwise intact, though it may be off kilter and that is what is causing the resistance when I try to turn it. So I am to sure if the problem was primarily the bearing, or overheat, or overspeed. According to my calculations, turbine speed should have been well within the green area. (way down around 60k RPM - near the bottom of the chart.) One difference with this fligh... I usually run well lean of peak, but this particular leg I was running a little late so I decided to push it up a bit by running a best power setting. I figured I was OK because I was high enough that I was only showing 21" MAP. But the failure happened in descent when I kept best power as I came lower and the engine RPM came up to about 6300 (more exhaust available). Combination of higher than normal EGT's and 'you number is up, turbo'??? Dave Leonard Dave, I follow your threads carefully as you have put so much into the Turbo installation, I don't know anyone who has done more but I'm sure there are, it's just we/I am not aware of them. From what your saying, I think your right on the money - heat is the killer (in this case). I personally would like you to try something remote as per suggestions by others. I think Paul's idea is sound, but may be still to close to the heat for my liking. George (down under) __________ Information from ESET NOD32 Antivirus, version of virus signature database 3206 (20080621) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com _____ Internal Virus Database is out-of-date. Checked by AVG. Version: 7.5.524 / Virus Database: 269.24.1/1469 - Release Date: 27/05/2008 1:25 PM ------=_NextPart_000_000C_01C8D440.C66DF6F0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable

I = think that losing a blade created such an imbalance that under high RPM=92s at = WOT, it most probably caused damage to the bearings,=A0 That would be my guess on it.

 

BT= W ED, this turbo upgrade does not use the stock bearings.=A0 They use a 360 degree thrust bearing for the = upgrade.

 

Th= ey do however, use the stock hot side chamber and turbine wheel, though they = trim the turbine wheel to prevent over speed. =A0It sounds like even the stock turbine won=92t stand up to the constant high = temperatures.

Ke= lly may be on the right track, when he mentions inconel.=A0 =A0I=92m not = sure what the stock turbine wheel is made of.

 

St= eve Brooks

 

 

-----Original Message-----
From: Rotary motors in = aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of George Lendich
Sent: Saturday, June 21, = 2008 10:39 PM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Re: = Another Turbo Bites the dust

 

So what is that indicator telling us, if the seal isn't leaking then the = bearings aren't gone. If that is the case it must be the heat that has affected = the turbo blades and imbalance contributing to it not working. = <= /p>

 <= /p>

Does one blade cause the pressure to drop off that much?<= /p>

 <= /p>

Am I reading this right or am I not taking into account other = factors.<= /p>

 <= /p>

George ( down under)

Good point about the oil feed Ed. In fact, when my first turbo went, the folks on = the ground saw all that smoke and reported that we were on fire... we were = not on fire, but there was plenty of oil both inside the exhaust on spilling = onto the outside of it. 

So after that I installed an electric switch that I can use to cutoff = oil flow to the turbo from inside the cockpit.   Interesting, with this failure there was no smoke or oil leakage (yet), but I will flip the = switch for the flight home and cut off the oil supply.

Thanks for the reminder!

--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net http://RotaryRoster.net<= /p>

On = Sat, Jun 21, 2008 at 4:58 PM, Ed Anderson <eanderson@carolina.rr.com&g= t; wrote:

In my opinion, one = of the things that we tend to not pay sufficient attention to is the extent of the = demand we are putting on turbos.  Without getting into the specifics of boost = ratios vs ambient pressure, suffice it to say that a turbo compressor has to = work considerably harder at altitude to maintain the same pressure ratio in = the manifold.

 <= /p>

  The ambient air pressure is of course less at 8000 MSL therefore density = less as well and the turbo simply has to turn faster to create the same = amount of boost pressure out of the less dense air.  The only way the turbo = can do that is to turn faster at altitude.  So you have that hot rotary = exhaust pushing those small turbine blades, faster and = faster.<= /p>

 <= /p>

  As we have discovered, the stock RX-7 turbo succumbs quickly to those = stresses (simply not designed for them).  Even with the TO4 compressor mod, = which clearly helps by reducing the turbine rpm needed to produce X boost, the = stock turbine and bearing just do not appear up to the stress for long = duration =96 although 130 hours is better than I thought the stock bearings would = do.<= /p>

 <= /p>

 <= /p>

A precaution I would take before flying back with the turbo that condition = is to disconnect and plug the oil line to the turbo.  Should the bearing = have taken a worst beating 0r continues to deteriorate, you would not want to = be dumping that precious engine oil into the exhaust =96 although there = should be plenty of smoke to tell you when that condition occurred =96 if there is = anybody around in West Texas to let you know {:>).  So I would = disconnect and plug the oil line and coolant line to the turbo =96 just to make certain = no leaks occurred. 

 <= /p>

Just my 0.02.  Glad, nothing more happened to the engine or you, = Dave.  <= /p>

 <= /p>

 <= /p>

Ed.= <= /p>

 <= /p>

 <= /p>

 <= /p>

Ed Anderson<= /p>

Rv-6A N494BW Rotary Powered<= /p>

Matthews, NC<= /p>

eanderson@carolina.rr.com<= /p>

http://www.andersonee.com<= /p>

http://members.cox.net/rogersda/rotary/con= figs.htm#N494BW<= /p>

http://www.dmack.net/mazda/index.html<= /p>

From: Rotary motors = in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George = Lendich
Sent: Saturday, June 21, = 2008 6:24 PM


To: Rotary motors in = aircraft

Subject: [FlyRotary] Re: Another Turbo Bites the = dust <= /p>

 <= /p>

 <= /p>

It's amazing how fast 130 hrs goes when you are having fun.:-) 

I took off the exhaust today and too a look.  One of the blades on = the turbine wheel is gone, but the axle seems otherwise intact, though it = may be off kilter and that is what is causing the resistance when I try to turn it.  So I am to sure if the problem was primarily the bearing, or overheat, or overspeed.  According to my calculations, turbine = speed should have been well within the green area. (way down around 60k RPM - = near the bottom of the chart.)

One difference with this fligh...  I usually run well lean of peak, = but this particular leg I was running a little late so I decided to push it = up a bit by running a best power setting.  I figured I was OK because I = was high enough that I was only showing 21" MAP.  But the failure = happened in descent when I kept best power as I came lower and the engine RPM = came up to about 6300 (more exhaust available).

Combination of higher than normal EGT's and 'you number is up, = turbo'???

Dave Leonard

Dave,<= /p>

I follow your threads carefully as you have put so much into the Turbo installation, I don't know anyone who has done more but I'm sure there = are, it's just we/I am not aware of them. From what your saying, I think your = right on the money - heat is the killer (in this = case).<= /p>

 <= /p>

I personally would like you to try something remote as per suggestions by = others. I think Paul's idea is sound, but may be still to close to the heat for = my liking.

George (dow= n under)

 <= /p>



__________ Information from ESET NOD32 Antivirus, version of virus = signature database 3206 (20080621) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com<= /p>

 <= /p>

Internal Virus Database is out-of-date.
Checked by AVG.
Version: 7.5.524 / Virus Database: 269.24.1/1469 - Release Date: = 27/05/2008 1:25 PM

------=_NextPart_000_000C_01C8D440.C66DF6F0--