X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fmailhost04.isp.att.net ([204.127.217.104] verified) by logan.com (CommuniGate Pro SMTP 5.2.3) with ESMTP id 2978758 for flyrotary@lancaironline.net; Sat, 21 Jun 2008 22:15:00 -0400 Received-SPF: pass receiver=logan.com; client-ip=204.127.217.104; envelope-from=bobperk9@bellsouth.net Received: from fwebmail16.isp.att.net ([207.115.9.156]) by isp.att.net (frfwmhc04) with SMTP id <20080622021420H040096shle>; Sun, 22 Jun 2008 02:14:20 +0000 X-Originating-IP: [207.115.9.156] Received: from [74.249.201.99] by fwebmail16.isp.att.net; Sun, 22 Jun 2008 02:14:20 +0000 From: "Bob Perkinson" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Another Turbo Bites the dust Date: Sun, 22 Jun 2008 02:14:20 +0000 Message-Id: <062220080214.28050.485DB57B0008915A00006D9222218801869B0A02D2089B9A019C04040A0DBFC7059D0A9F0D010D@att.net> In-Reply-To: X-Mailer: AT&T Message Center Version 1 (Jun 10 2008) X-Authenticated-Sender: Ym9icGVyazlAYmVsbHNvdXRoLm5ldA== MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="NextPart_Webmail_9m3u9jl4l_28050_1214100860_0" --NextPart_Webmail_9m3u9jl4l_28050_1214100860_0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Dave, I am not sure what type of solenoid valve you have installed but that could= possibly be a point of failure, that or the switch. Just a thought. Bob Perkinson -------------- Original message from "David Leonard" := --------------=20 Good point about the oil feed Ed. In fact, when my first turbo went, the fo= lks on the ground saw all that smoke and reported that we were on fire... w= e were not on fire, but there was plenty of oil both inside the exhaust on = spilling onto the outside of it.=20=20 So after that I installed an electric switch that I can use to cutoff oil f= low 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 wr= ote: In my opinion, one of the things that we tend to not pay sufficient attenti= on to is the extent of the demand we are putting on turbos. Without gettin= g 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 mai= ntain 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 amo= unt of boost pressure out of the less dense air. The only way the turbo ca= n do that is to turn faster at altitude. So you have that hot rotary exhau= st pushing those small turbine blades, faster and faster. As we have discovered, the stock RX-7 turbo succumbs quickly to those str= esses (simply not designed for them). Even with the TO4 compressor mod, wh= ich clearly helps by reducing the turbine rpm needed to produce X boost, th= e stock turbine and bearing just do not appear up to the stress for long du= ration =E2=80=93 although 130 hours is better than I thought the stock bear= ings 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 ha= ve taken a worst beating 0r continues to deteriorate, you would not want to= be dumping that precious engine oil into the exhaust =E2=80=93 although th= ere should be plenty of smoke to tell you when that condition occurred =E2= =80=93 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 =E2= =80=93 just to make certain no leaks occurred.=20=20 Just my 0.02. Glad, nothing more happened to the engine or you, Dave.=20= =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 Beh= alf Of George Lendich Sent: Saturday, June 21, 2008 6:24 PM=20 To: Rotary motors in aircraft Subject: [FlyRotary] Re: Another Turbo Bites the dust=20 It's amazing how fast 130 hrs goes when you are having fun.:-)=20=20 I took off the exhaust today and too a look. One of the blades on the turb= ine wheel is gone, but the axle seems otherwise intact, though it may be of= f 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 we= ll 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 thi= s particular leg I was running a little late so I decided to push it up a b= it 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 descen= t when I kept best power as I came lower and the engine RPM came up to abou= t 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 inst= allation, 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 o= thers. 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 signatur= e database 3206 (20080621) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com --NextPart_Webmail_9m3u9jl4l_28050_1214100860_0 Content-Type: multipart/related; boundary="NextPart_Webmail_9m3u9jl4l_28050_1214100860_1" --NextPart_Webmail_9m3u9jl4l_28050_1214100860_1 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable
Dave,
I am not sure what type of solenoid valve you have installed but = that could possibly be a point of failure, that or the switch.&nb= sp; Just a thought.
 
Bob Perkinson
-------------- Original message from "David Leonard" <wdl= eonard@gmail.com>: --------------

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 i= t. 

So after that I installed an electric switch that I can us= e to cutoff oil flow to the turbo from inside the cockpit.   Inte= resting, with this failure there was no smoke or oil leakage (yet), but I w= ill 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.RotaryRost= er.net
http://RotaryRoster.net<= /A>

On Sat, Jun 21, 2008 at 4:58 PM, Ed Anderson <<= A href=3D"mailto:eanderson@carolina.rr.com">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.

 

  The ambient air pressure is of cou= rse less at 8000 MSL therefore density less as well and the turbo simply ha= s to turn faster to create the same amount of boost pressure out of the les= s 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 tur= bine blades, faster and faster.

 

  As we have discovered, the stock R= X-7 turbo succumbs quickly to those stresses (simply not designed for them)= .  Even with the TO4 compressor mod, which clearly helps by reducing t= he turbine rpm needed to produce X boost, the stock turbine and bearing jus= t do not appear up to the stress for long duration =E2=80=93 although 130 h= ours is better than I thought the stock bearings would do.

 

 

A precaution I would take before flying b= ack 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 continue= s to deteriorate, you would not want to be dumping that precious engine oil= into the exhaust =E2=80=93 although there should be plenty of smoke to tel= l you when that condition occurred =E2=80=93 if there is anybody around in = West Texas to let you know {:>).  So I would disconnect and plug th= e oil line and coolant line to the turbo =E2=80=93 just to make certain no = leaks occurred. 

 

Just my 0.02.  Glad, nothing more ha= ppened to the engine or you, Dave. 

 

 

Ed.

 

 

 

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


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

=  

=  

= 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 t= he turbine wheel is gone, but the axle seems otherwise intact, though it ma= y be off kilter and that is what is causing the resistance when I try to tu= rn it.  So I am to sure if the problem was primarily the bearing, or o= verheat, or overspeed.  According to my calculations, turbine speed sh= ould 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 litt= le late so I decided to push it up a bit by running a best power setting.&n= bsp; I figured I was OK because I was high enough that I was only showing 2= 1" 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 availa= ble).

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 Tu= rbo 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 yo= ur right on the money - heat is the killer (in this case).

=  

I personally would like you to try something remote as per suggesti= ons by others. I think Paul's idea is sound, but may be still to close to t= he heat for my liking.

George (down under)

=  

=

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

The message was checke= d by ESET NOD32 Antivirus.

http://www.eset.com



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