X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail03.syd.optusnet.com.au ([211.29.132.184] verified) by logan.com (CommuniGate Pro SMTP 5.2.3) with ESMTPS id 2978770 for flyrotary@lancaironline.net; Sat, 21 Jun 2008 22:39:29 -0400 Received-SPF: pass receiver=logan.com; client-ip=211.29.132.184; envelope-from=lendich@optusnet.com.au Received: from george (d58-104-215-70.dsl.nsw.optusnet.com.au [58.104.215.70]) by mail03.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id m5M2cfaN005086 for ; Sun, 22 Jun 2008 12:38:41 +1000 Message-ID: <003b01c8d411$1579b750$6400a8c0@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Another Turbo Bites the dust Date: Sun, 22 Jun 2008 12:38:41 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0038_01C8D464.E696A6B0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 X-Antivirus: avast! (VPS 0657-0, 12/12/2006), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_0038_01C8D464.E696A6B0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable 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.=20 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. =20 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! --=20 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 = 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 =96 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 = =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. =20 Just my 0.02. Glad, nothing more happened to the engine or you, = Dave. =20 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.:-) =20 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.=20 Version: 7.5.524 / Virus Database: 269.24.1/1469 - Release Date: = 27/05/2008 1:25 PM ------=_NextPart_000_0038_01C8D464.E696A6B0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
So what is that indicator telling us, = if the seal=20 isn't leaking then the bearings aren't gone. If that is the case it must = be the=20 heat that has affected the turbo blades and imbalance contributing to it = not=20 working.
 
Does one blade cause the pressure to = drop off that=20 much?
 
Am I reading this right or am I not = taking into=20 account other factors.
 
George ( down under)
Good=20 point about the oil feed Ed. In fact, when my first turbo went, the = folks on=20 the ground saw all that smoke and reported that we were on fire... we = were not=20 on fire, but there was plenty of oil both inside the exhaust on = spilling onto=20 the outside of it. 

So after that I installed an electric = switch=20 that I can use to cutoff oil flow to the turbo from inside the=20 cockpit.   Interesting, with this failure there was no smoke = or oil=20 leakage (yet), but I will flip the switch for the flight home and cut = off the=20 oil supply.

Thanks for the reminder!

--
David=20 Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.nethttp://RotaryRoster.net

On Sat, Jun 21, 2008 at 4:58 PM, Ed Anderson = <eanderson@carolina.rr.com&g= t;=20 wrote:

In my = opinion, one=20 of the things that we tend to not pay sufficient attention to is the = extent=20 of the demand we are putting on turbos.  Without getting into = the=20 specifics of boost ratios vs ambient pressure, suffice it to say = that a=20 turbo compressor has to work considerably harder at altitude to = maintain the=20 same pressure ratio in the manifold.

 

  = The ambient=20 air pressure is of course less at 8000 MSL therefore density less as = well=20 and the turbo simply has to turn faster to create the same amount of = boost=20 pressure out of the less dense air.  The only way the turbo can = do that=20 is to turn faster at altitude.  So you have that hot rotary = exhaust=20 pushing those small turbine blades, faster and = faster.

 

  As = we have=20 discovered, the stock RX-7 turbo succumbs quickly to those stresses = (simply=20 not designed for them).  Even with the TO4 compressor mod, = which=20 clearly helps by reducing the turbine rpm needed to produce X boost, = the=20 stock turbine and bearing just do not appear up to the stress for = long=20 duration =96 although 130 hours is better than I thought the stock = bearings=20 would do.

 

 

A = precaution I=20 would take before flying back with the turbo that condition is to = disconnect=20 and plug the oil line to the turbo.  Should the bearing have = taken a=20 worst beating 0r continues to deteriorate, you would not want to be = dumping=20 that precious engine oil into the exhaust =96 although there should = be plenty=20 of smoke to tell you when that condition occurred =96 if there is = anybody=20 around in West Texas to let you know {:>).  So I would = disconnect=20 and plug the oil line and coolant line to the turbo =96 just to make = certain=20 no leaks occurred. 

 

Just my = 0.02. =20 Glad, nothing more happened to the engine or you, Dave. =20

 

 

Ed.

 

 

 

Ed=20 Anderson

Rv-6A = N494BW Rotary=20 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<= FONT=20 face=3DArial size=3D2>

From:=20 Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George = Lendich
Sent: Saturday, June 21, 2008 = 6:24 PM


To:=20 Rotary motors in aircraft
Subject: [FlyRotary] Re: = Another Turbo=20 Bites the dust

 

 

It's=20 amazing how fast 130 hrs goes when you are having fun.:-)  =

I=20 took off the exhaust today and too a look.  One of the blades = on the=20 turbine wheel is gone, but the axle seems otherwise intact, though = it may=20 be off kilter and that is what is causing the resistance when I = try to=20 turn it.  So I am to sure if the problem was primarily the = bearing,=20 or overheat, or overspeed.  According to my calculations, = turbine=20 speed should have been well within the green area. (way down = around 60k=20 RPM - near the bottom of the chart.)

One difference with = this=20 fligh...  I usually run well lean of peak, but this = particular leg I=20 was running a little late so I decided to push it up a bit by = running a=20 best power setting.  I figured I was OK because I was high = enough=20 that I was only showing 21" MAP.  But the failure happened in = descent=20 when I kept best power as I came lower and the engine RPM came up = to about=20 6300 (more exhaust available).

Combination of higher than = normal=20 EGT's and 'you number is up, turbo'???

Dave=20 Leonard

Dave,

I follow your = threads=20 carefully as you have put so much into the Turbo installation, I = don't=20 know anyone who has done more but I'm sure there are, it's just = we/I am=20 not aware of them. From what your saying, I think your right on = the=20 money - heat is the killer (in this = case).

 

I personally would = like you to=20 try something remote as per suggestions by others. I think Paul's = idea is=20 sound, but may be still to close to the heat for my=20 liking.

George (down=20 under)

 



__________ Information from ESET = NOD32=20 Antivirus, version of virus signature database 3206 (20080621)=20 __________

The message was checked by ESET NOD32 = Antivirus.

http://www.eset.com



Internal Virus Database is out-of-date.
Checked by AVG. =
Version:=20 7.5.524 / Virus Database: 269.24.1/1469 - Release Date: 27/05/2008 = 1:25=20 PM
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