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 2979999 for flyrotary@lancaironline.net; Sun, 22 Jun 2008 21:38:07 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.198.234; envelope-from=wdleonard@gmail.com Received: by rv-out-0506.google.com with SMTP id f6so7769210rvb.7 for ; Sun, 22 Jun 2008 18:37:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:in-reply-to:mime-version:content-type:references; bh=txFKN2EhnhL19tRpefkdt9wuFnaq2y7yKOzshp3aYKA=; b=H3VAze/cybqEUFZlr7Sol3DK7JUKpMnlEde1ILPQzLFJrWasnnm0J4CLFr0sSysSGx /NnZSFsHGh8gvLFRWJKeLCCxy28kke9uVu/cwuWz5JwcushCzHlCtzJ/GFzl4puKNQRK R5mAsLe1iu1/jJlkl7vGmJ7/mTjpRo0ozvI8I= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version :content-type:references; b=Cueu27n6n2HaYNavYaAZBgTgC0IwAVwgb2IKQrOz9ci6q8vBtQeCJrFI+l8OcO1OCG IElhVJMc4cWoIO09luE6A85i/zWPZ818DOM5cs0KY0Gxlz6exkQRJXc/0DbfwsoFj00H dlmKQ2j2U6LB0wXZjlgsX/UV4Qma5FMYUbeIg= Received: by 10.141.79.12 with SMTP id g12mr11779500rvl.126.1214185048654; Sun, 22 Jun 2008 18:37:28 -0700 (PDT) Received: by 10.150.145.16 with HTTP; Sun, 22 Jun 2008 18:37:28 -0700 (PDT) Message-ID: <1c23473f0806221837m76a0a68i2217037be45bc717@mail.gmail.com> Date: Sun, 22 Jun 2008 18:37:28 -0700 From: "David Leonard" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Another Turbo Bites the dust In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_4532_3327140.1214185048484" References: ------=_Part_4532_3327140.1214185048484 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Hi Todd, I did look at the mixture display and as far as I can tell it was unaffecte= d by the smoke, which makes sense. The sensor detects the presence of O2, an= d that should not change significantly with the burning of a little bit of oil. Dave Leonard On Sun, Jun 22, 2008 at 3:50 AM, Todd Bartrim wrote: > Hi Dave; > > When you had all the smoke, did you happen to notice what it > did to your mixture display from the O2 sensor? Since mine is located jus= t > downstream from the turbo I'm thinking that the oil burning in the exhaus= t > would make it go full scale rich. This would be an indicator if one happe= ned > to catch it in time. On one of my initial flights, I had an oil pressure > switch blow out oil directly onto the exhaust, downstream of the O2 senso= r. > I had no indications of it at all in the cockpit. The only reason I knew > about it was I had another RV flying chase with me. He said it looked > exactly like an air show smoke system. After I was told about it, I shut > down the engine, set up glide back to the runway and slowed down to stop = the > prop (so there would still be oil incase I needed to restart to make the > runway). Once I had slowed down, I could smell the smoke in the cockpit. > > So an unexplained full rich mixture reading could be telling > us something we need to pay attention too. > > > > *Todd Bartrim*** > > > > -----Original Message----- > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]*On > Behalf Of *David Leonard > *Sent:* Saturday, June 21, 2008 6:40 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Another Turbo Bites the dust > > > > 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 failu= re > there was no smoke or oil leakage (yet), but I will flip the switch for t= he > 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 > 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. Witho= ut > getting into the specifics of boost ratios vs ambient pressure, suffice i= t > to say that a turbo compressor has to work considerably harder at altitud= e > to maintain the same pressure ratio in the manifold. > > > > The ambient air pressure is of course less at 8000 MSL therefore densit= y > 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 tur= bo > 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 mo= d, > 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 lon= g > duration =96 although 130 hours is better than I thought the stock bearin= gs > would do. > > > > > > A precaution I would take before flying back with the turbo that conditio= n > 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 wan= t > to be dumping that precious engine oil into the exhaust =96 although ther= e > 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 t= o > 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] *O= n > 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 overhea= t, > or overspeed. According to my calculations, turbine speed should have be= en > 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 u= p a > bit by running a best power setting. I figured I was OK because I was hi= gh > enough that I was only showing 21" MAP. But the failure happened in desc= ent > 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 > installation, I don't know anyone who has done more but I'm sure there ar= e, > 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 he= at > 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 > > > --=20 David Leonard Turbo Rotary RV-6 N4VY http://N4VY.RotaryRoster.net http://RotaryRoster.net ------=_Part_4532_3327140.1214185048484 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Hi Todd,
 
I did look at the mixture display and as far as I can tell it was unaf= fected by the smoke, which makes sense.  The sensor detects the presen= ce of O2, and that should not change significantly with the burning of a li= ttle bit of oil.
 
Dave Leonard

On Sun, Jun 22, 2008 at 3:50 AM, Todd Bartrim &l= t;bartrim@gmail.com> wrote:

Hi Dave;

      =       When you had all the smoke, did you h= appen to notice what it did to your mixture display from the O2 sensor? Sin= ce mine is located just downstream from the turbo I'm thinking that the oil= burning in the exhaust would make it go full scale rich. This would be an = indicator if one happened to catch it in time. On one of my initial flights= , I had an oil pressure switch blow out oil directly onto the exhaust, down= stream of the O2 sensor. I had no indications of it at all in the cockpit. = The only reason I knew about it was I had another RV flying chase with me. = He said it looked exactly like an air show smoke system. After I was told a= bout it, I shut down the engine, set up glide back to the runway and slowed= down to stop the prop (so there would still be oil incase I needed to rest= art to make the runway). Once I had slowed down, I could smell the smoke in= the cockpit.

      =       So an unexplained full rich mixture r= eading could be telling us something we need to pay attention too.

 

Todd Bartrim

 

-= ----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of David Leonard
Sent: Saturday, June 21, 20= 08 6:40 PM
To: Rotary mo= tors in aircraft
Subject: [FlyRotary] Re: Another Turbo Bites the dust

<= span style=3D"FONT-SIZE: 12pt"> 

Good point about the oil feed Ed. In fact, when m= y 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 b= oth inside the exhaust on spilling onto the outside of it. 

So after that I installed an electric switch that I can use to cutoff o= il 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 Rotar= y 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 t= he 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 specifi= cs of boost ratios vs ambient pressure, suffice it to say that a turbo comp= ressor has to work considerably harder at altitude to maintain the same pre= ssure ratio in the manifold.

 

  The ambient air pressure is of course l= ess 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 den= se air.  The only way the turbo can do that is to turn faster at altit= ude.  So you have that hot rotary exhaust pushing those small turbine = blades, faster and faster.

 

  As we have discovered, the stock RX-7 t= urbo succumbs quickly to those stresses (simply not designed for them).&nbs= p; Even with the TO4 compressor mod, which clearly helps by reducing the tu= rbine 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 bet= ter than I thought the stock bearings would do.

 

 

A precaution I would take before flying back w= ith 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 co= olant line to the turbo =96 just to make certain no leaks occurred.  <= /span>

 

Just my 0.02.  Glad, nothing more happene= d 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.ht= ml

From:<= /b> Rotary motors in aircraft [mai= lto:flyrot= ary@lancaironline.net] On Behalf O= f George Lendich
Sent: Saturday, June 21, 20= 08 6:24 PM


To: Rotary motors in aircra= ft

Subject: [FlyRotary] Re: Another Tur= bo Bites the dust

 

 

It's amazing how fast 130 hrs goes when you are h= aving 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 - nea= r 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 becau= se I was high enough that I was only showing 21" MAP.  But the fa= ilure happened in descent when I kept best power as I came lower and the en= gine 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 d= one more but I'm sure there are, it's just we/I am not aware of the= m. From what your saying, I think your right on the money - heat is th= e killer (in this case).

 

I personally would like you to try somethin= g remote as per suggestions by others. I think Paul's idea is sound, bu= t may be still to close to the heat for my liking.

George (down under)

 



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

The message was checked by= ESET NOD32 Antivirus.

http://www.eset.com

 




--
David Leonard
=
Turbo Rotary RV-6 N4VY
http= ://N4VY.RotaryRoster.net
http://= RotaryRoster.net=20 ------=_Part_4532_3327140.1214185048484--