Return-Path: Received: from [24.25.9.101] (HELO ms-smtp-02-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2b6) with ESMTP id 245068 for flyrotary@lancaironline.net; Tue, 06 Jul 2004 16:05:20 -0400 Received: from EDWARD (clt25-78-058.carolina.rr.com [24.25.78.58]) by ms-smtp-02-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id i66K4gNs000350 for ; Tue, 6 Jul 2004 16:04:44 -0400 (EDT) Message-ID: <001601c46394$7f902800$2402a8c0@EDWARD> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Second stock turbo bites the dust Date: Tue, 6 Jul 2004 16:04:51 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0013_01C46372.F8371EC0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0013_01C46372.F8371EC0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sorry to hear about blowing another turbo, John.=20 I suspect that the period will vary for different people (depending on = how much and often boost is used) but - if you use any appreciable = amount of boost continuously, it sure looks to me that you will end up = overspeeding and overheating the unit which would eventually lead to the = turbine/compressor wheels failing.=20 The size of the exhaust housing is probably more the problem than the = compressor - although that could stand to be a bit larger as well. The = Mazda engineers probably only designed the turbo for the 0-60 time to = give the RX-7 that "kick in the pants" feeling. So the average driver = would probably not stay in high boost more than a few seconds at a time. = Another consideration is the turbo in the car application would get a = chance to cool down a bit once the car reached top cruise speed and = boost decayed - that opportunity is much less when under constant boost = (even small amounts).=20 Given how much mass flow is produced by the engine at 5000 rpm and = higher, even the stock waste gate has trouble venting enough exhaust = gas. Even with the Rx7, some drivers refer to the problem of Boost Creep = whereby the boost exceeds the capability of the waste gate to hold it = down and therefore more energy spins the turbine which increases the = boost more, which ..... . You have not mentioned any problem holding the boost under control, so = the problem could be more due to a continuos heat load, really sort of = hard to tell. Another failure mechanism is a compressor wheel operating in the surge = zone. What is a safe operating zone at sea level may not be at altitude = at the same boost level. The pressure ratio continues to increase (for = the same boost level) as you increase your altitude and decrease the = ambient air pressure. This pushes the operating point more or less = vertically and to the left up the compressor map chart from the sea = level operating point (mass flow vs pressure ratio). If you will notice = on almost all compressor maps going that direction far enough will put = you operating in the surge zone. =20 I've attached a compressor map (don't have any idea how close a match to = the Mazda one - just an example). Assuming that ambient pressure was = around 7 psi at 11,000 and assuming you were flying with approx 4.5 psi = boost (9 inches Hg). At sea level that and 5000 rpm would give you a = mass flow of approx 20 lbm/min but at 11000 feet it would be closer to = 15 lbm/min. Also at sea level a boost of 4.5 psi would give you a = pressure ratio of approx 1.3. The same boost level at 11000 ft on the = other hand would give you a pressure ratio of 1.6. Note on the chart, = both the lesser mass flow (from 20 lbm -> 15 lbm) and higher pressure = ratio (1.3 ->1.6 at the same 4.5 boost) move you closer to the surge = zone of the compressor map. Now with this compressor map you are still = OK in fact right in the middle of your efficiency zone. But running = more boost at less rpm moves you further up and to the left on the chart = closer to the zone. However, if you had hit the surge zone I would expect you would see = pressure fluctuations, possible hear or feel the vibrations of the turbo = surging and you did not report any. So not too likely that was the = problem. Just several things which could cause it and without = instrumentation, I don't know how you can tell. A different turbine housing with an larger A/r and external waste gate = (and now we are starting to talk additional weight) OR the modification = offered by the Australian firm opening up the turbine housing as well as = the internal exhaust gate port would be something I would strongly = consider. I never hear it Richard? from Blue Mountain Instruments? ever had any = trouble with this turbo unit. I forget which one it was, but it was not = the stock Mazda. Ed Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC ----- Original Message -----=20 From: John Slade=20 To: Rotary motors in aircraft=20 Sent: Tuesday, July 06, 2004 1:26 PM Subject: [FlyRotary] Second stock turbo bites the dust Steve, Dave and anyone else running a stock single stage turbo - you = might want to pay attention.... This morning I managed to break Rusty's turbo. I had been cruising at = 11,000 ft with MAP 38, rpm 5100 and 175 kts TAS (about 155 IAS) for = almost 2 hours when rpm suddenly dropped to 2500. A 1/4 turn of the = mixture toward rich brought it up to 3500. Fuel pressure was 40psi, but = I turned on the other pump anyway. Coolant temp dropped from 185 to 150 = and EGT dropped from 1400 to 1000. Oil pressure was constant at 90PSI.=20 I was 38 miles from home over a desolate little strip by Lake = Okeechobee. I figured I could glide to either field from halfway, so I = headed home. The engine ran consistently at reduced power. I maintained = 11,000 to the halfway point, then began a gradual decent to arrive over = the field at 6000. Once assured of the field I tried killing alternate = sets of coils - both gave a decrease in rpm - and alternate sets of = injectors - both killed the engine, (or reduced rpm enough that I didn't = want to know). One [more] high & fast precautionary landing later and the plane was = back in the hangar. I'd thought the new Radio Shack resistors on my = secondary injectors might have given out, but no. A quick look up the = exhaust pipe told the story. The compressor wheel is sitting at an odd = angle blocking the outlet, just like last time. Apparently I was = trailing a vortex of black smoke as I descended into the pattern. This = probably helped keep the spam cans and whirly birds at bay while I took = the active. :)=20 One failure might be a bad turbo. A second one is enough to prove to = me that the stock turbo just can't handle the punishment of continual = boost. (just like Ed said it wouldn't :) I thought you guys running or planning to run the same turbo might = like to hear the story as soon as possible.=20 Regards, John (boost for all you're worth) Slade Now where's the phone number of that Ozzie guy???? -----Original Message----- From: Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net]On Behalf Of Alex Madsen Sent: Tuesday, July 06, 2004 10:15 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Into the blue again :-) No they use solid state. I think it is 2GB Compact Flash. It says = somewhere on their web site. You can get 2 GB CF cards and IDE adapters = for them. =20 Alex Madsen =20 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Finn Lassen Sent: Tuesday, July 06, 2004 7:27 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Into the blue again :-) =20 Hmmm.... Doesn't the Blue Mountain and other glass panels use = harddrives?=20 I thought that the inside of a harddrive was sealed. Picking a random drive on Seagate's website: Environmental=20 Operating Temperature (=B0C) 0 to 60 Nonoperating Temperature (=B0C) 70 to -40 Operating Shock (Gs) @ 2 msec 63 Non Operating Shock (Gs) @ 2 msec 350 Acoustics,Idle (Bels-typ sound power) 2.2 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 No mention of ambient pressure. Finn Ed Anderson wrote: Boy, now here is an example of what kind of information we have access = to onthis list. Now that Ernest mentions it, yeah, I recall that the = heads ofthe hard disk float on a cushion of air - but, I would never = have thought toassociate altitude with hard drive crashes! Thanks = Ernest. Ed Ed AndersonRV-6A N494BW Rotary PoweredMatthews, NC----- = Original Message ----- From: "Ernest Christley" = To: "Rotary motors in aircraft" = Sent: Sunday, July 04, 2004 5:48 PMSubject: = [FlyRotary] Re: Into the blue again :-) Haywire wrote: Message = Today we flew for 6.3 hrs and everything was great again. Wecalibrated a = few items including the electronic governor for the IVO prop. What = a difference that makes. Also calibrated the PSS AOA and the Dynon = AOA and they each are phenomenal tools. The engine is running great = with nomajor issues at all. I do have a little tweaking to do on the low = MAP table, but nothing urgent. Then only problem that I had today = was that my Sony Vaio laptop doesn't seem to like high altitude. I = have a small Vaio and havebuilt a place for it to mount easily and use = it to display Jeppenson'sFlightMap in-flight GPS program. It works great = until 10,300' where it would then display the blue screen and then = reboot. After the 4th time it refused to reboot again so now I'm = forced to use the system recovery disc and wipe the disc clean. I = hate to think about all the files that I said I wouldback-up soon... = :-(. My old laptop still works fine(using it now) so maybe I'll = try it tomorrow. All hard drives have a spinning platter with a = read/write head riding acushion of air just above it. Go to 10,300' and = there isn't much of acushion left. The head will fall into the platter = turning at 7500 or10000 rpm. I think you'll be lucky if the drive ever = works again. -- http://www.ernest.isa-geek.org/"Ignorance is mankinds = normal state, alleviated by information and experience." = Veeduber Homepage: http://www.flyrotary.com/ = Archive: http://lancaironline.net/lists/flyrotary/List.html = Homepage: http://www.flyrotary.com/ Archive: = http://lancaironline.net/lists/flyrotary/List.html ------=_NextPart_000_0013_01C46372.F8371EC0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Sorry to hear about blowing another = turbo,=20 John. 
 
 I suspect that the period will = vary for=20 different people (depending on how much and often boost is used)  = but=20 - if you use any appreciable amount of  boost continuously, it = sure=20 looks to me that you will end up overspeeding and overheating the unit = which=20 would eventually lead to the turbine/compressor wheels=20 failing. 
 
 The size of the exhaust housing = is probably=20 more the problem than the compressor - although that could stand to be a = bit=20 larger as well.  The Mazda engineers probably only designed the = turbo for=20 the 0-60 time to give the RX-7 that "kick in the pants" feeling.  = So the=20 average driver would probably not stay in high boost more than a few = seconds at=20 a time.  Another consideration is the turbo in the car application = would=20 get a chance to cool down a bit once the car reached top cruise speed = and boost=20 decayed - that opportunity is much less when under constant boost (even = small=20 amounts). 
 
Given how much mass flow is produced by = the engine=20 at 5000 rpm and higher, even the stock waste gate has trouble venting = enough=20 exhaust gas. Even with the Rx7, some drivers refer to the = problem of=20 Boost Creep whereby the boost exceeds the capability of the waste gate = to hold=20 it down and therefore more energy spins the turbine which increases the = boost=20 more, which ..... .
You have not mentioned any problem = holding the=20 boost under control, so the problem could be more due to a continuos = heat load,=20 really sort of hard to tell.
 
Another failure mechanism is a = compressor wheel=20 operating in the surge zone.  What is a safe operating zone at sea = level=20 may not be at altitude at the same boost level.  The pressure ratio = continues to increase (for the same boost level) as you increase your = altitude=20 and decrease the ambient air pressure.  This pushes the operating = point=20 more or less vertically and to the left up the compressor map chart from = the sea=20 level operating point (mass flow vs pressure ratio).  If you will = notice on=20 almost all compressor maps going that direction far enough will put you=20 operating in the surge zone. 
 
I've attached a compressor map (don't = have any idea=20 how close a match to the Mazda one - just an example). Assuming that = ambient=20 pressure was around 7 psi at 11,000 and assuming you were flying with = approx 4.5=20 psi boost (9 inches Hg).  At sea level that and 5000 rpm would give = you a=20 mass flow of approx 20 lbm/min but at 11000 feet it would be closer to = 15=20 lbm/min.  Also at sea level a boost of 4.5 psi would give you a = pressure=20 ratio of approx 1.3.  The same boost level at 11000 ft on the other = hand=20 would give you a pressure ratio of 1.6.  Note on the chart, both = the lesser=20 mass flow (from 20 lbm -> 15 lbm) and higher pressure ratio (1.3 = ->1.6 at=20 the same 4.5 boost)  move you closer to the surge zone of the = compressor=20 map.  Now with this compressor map you are still OK in fact right = in the=20 middle of your efficiency zone.  But running more boost at less rpm = moves=20 you further up and to the left on the chart closer to the = zone.
 
However, if you had hit the surge zone = I would=20 expect you would see pressure fluctuations, possible hear or feel the = vibrations=20 of the turbo surging and you did not report any.  So not too likely = that=20 was the problem.  Just several things which could cause it and = without=20 instrumentation, I don't know how you can tell.
 
 A different turbine housing with = an larger=20 A/r and external waste gate (and now we are starting to talk additional=20 weight)  OR the modification offered by the Australian firm opening = up the=20 turbine housing as well as the internal exhaust gate port would be = something I=20 would strongly consider.
 
I never hear it Richard? from Blue = Mountain=20 Instruments? ever had any trouble with this turbo unit.  I = forget=20 which one it was, but it was not the stock Mazda.
 
Ed
 
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
From:=20 John=20 Slade
Sent: Tuesday, July 06, 2004 = 1:26=20 PM
Subject: [FlyRotary] Second = stock turbo=20 bites the dust

Steve, Dave and anyone else running a stock single stage = turbo - you=20 might want to pay attention....
 
This=20 morning I managed to break Rusty's turbo.  I had been cruising at = 11,000=20 ft with MAP 38, rpm 5100 and 175 kts TAS (about 155 IAS) for almost 2 = hours=20 when rpm suddenly dropped to 2500. A 1/4 turn of the mixture toward = rich=20 brought it up to 3500. Fuel pressure was 40psi, but I turned on the = other pump=20 anyway. Coolant temp dropped from 185 to 150 and EGT dropped from = 1400 to=20 1000. Oil pressure was constant at 90PSI.
 
I=20 was 38 miles from home over a desolate little strip by Lake = Okeechobee. I=20 figured I could glide to either field from halfway, so I headed home. = The=20 engine ran consistently at reduced power. I maintained 11,000 to the = halfway=20 point, then began a gradual decent to arrive over the field at 6000. = Once=20 assured of the field I tried killing alternate sets of coils - both = gave a=20 decrease in rpm - and alternate sets of injectors - both killed the = engine,=20 (or reduced rpm enough that I didn't want to = know).
 
One=20 [more] high & fast precautionary landing later and the plane = was back=20 in the hangar. I'd thought the new Radio Shack resistors on my = secondary=20 injectors might have given out, but no. A quick look up the exhaust = pipe told=20 the story. The compressor wheel is sitting at an odd angle blocking = the=20 outlet, just like last time. Apparently I was trailing a vortex of = black smoke=20 as I descended into the pattern. This probably helped keep the = spam cans=20 and whirly birds at bay while I took the active. :) =
 
One=20 failure might be a bad turbo. A second one is enough to prove to me = that the=20 stock turbo just can't handle the punishment of continual boost. (just = like Ed=20 said it wouldn't :)
 
I=20 thought you guys running or planning to run the same turbo might like = to hear=20 the story as soon as possible.
Regards,
John=20 (boost for all you're worth) Slade
 
Now=20 where's the phone number of that Ozzie guy????
 
 
 
 
-----Original Message-----
From: Rotary motors in = aircraft=20 [mailto:flyrotary@lancaironline.net]On Behalf Of Alex=20 Madsen
Sent: Tuesday, July 06, 2004 10:15 PM
To: = Rotary=20 motors in aircraft
Subject: [FlyRotary] Re: Into the blue = again=20 :-)

No they = use solid=20 state. I think it is 2GB Compact Flash.  It says somewhere on their = web site.=20 You can get 2 GB CF cards and IDE adapters for=20 them.

 

Alex=20 Madsen

 

-----Original=20 Message-----
From: Rotary=20 motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Finn = Lassen
Sent: Tuesday, July 06, 2004 = 7:27=20 AM
To: Rotary = motors in=20 aircraft
Subject: = [FlyRotary] Re: Into the blue again :-)

 

Hmmm.... = Doesn't the Blue=20 Mountain and other glass panels use harddrives?
I thought that = the=20 inside of a harddrive was sealed.
Picking a random drive on = Seagate's=20 website:

Environmental
Operating Temperature (=B0C) 0 to=20 60
Nonoperating Temperature (=B0C) 70 to -40
Operating Shock = (Gs) @ 2=20 msec 63
Non Operating Shock (Gs) @ 2 msec 350
Acoustics,Idle = (Bels-typ=20 sound power) 2.2

 

 

 

 

 

 

 


No = mention of ambient=20 pressure.

Finn

Ed Anderson wrote:

Boy, now here is =
an example of what kind of information we have access to =
on
this list.  Now that =
Ernest mentions it, yeah, I recall that the heads =
of
the hard disk float on a cushion of air - but, I would never have =
thought to
associate altitude with hard drive =
crashes!  Thanks =
Ernest.
 
Ed
 
 
Ed Anderson
RV-6A N494BW Rotary =
Powered
Matthews, =
NC
----- Original Message ----- 
From: "Ernest Christley" <echristley@nc.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.n=
et>
Sent: Sunday, July 04, 2004 5:48 =
PM
Subject: [FlyRotary] Re: Into the blue again =
:-)
 
 
  =

Haywire wrote:
    
Message    =
Today we flew for 6.3 hrs and everything was great again. =
We
calibrated a few items including the electronic governor for the =
IVO
      =

prop.
  =

What a difference that makes. Also calibrated the PSS AOA and the =
Dynon
      =

AOA
  =

and they each are phenomenal tools. The engine is running great =
with no
major issues at all. I do have a little =
tweaking to do on the low MAP
      =

table,
  =

but nothing urgent. Then only problem that I had today was that my =
Sony
      =

Vaio
  =

laptop doesn't seem to like high altitude. I have a small Vaio and =
have
built a place for it to mount easily and use =
it to display Jeppenson's
FlightMap in-flight GPS =
program. It works great until 10,300' where =
it
      =

would
  =

then display the blue screen and then reboot. After the 4th time =
it
      =

refused
  =

to reboot again so now I'm forced to use the system recovery disc =
and
      =

wipe
  =

the disc clean. I hate to think about all the files that I said I =
would
back-up soon... :-(. My old laptop still works =
fine(using it now) so
      =

maybe
  =

I'll try it tomorrow.
      
All hard drives =
have a spinning platter with a read/write head riding =
a
cushion of air just above it.  Go to 10,300' and there isn't much of =
a
cushion left.  The =
head will fall into the platter turning at 7500 =
or
10000 rpm.  I think =
you'll be lucky if the drive ever works =
again.
 
-- =

http://www.ernest.isa-geek.org/<=
/A>
"Ignorance is mankinds normal =
state,
   =
alleviated by information and =
experience."
           &n=
bsp;           &nb=
sp;           =
Veeduber
 
    
 Homepage:  http://www.flyrotary.com/
 Archive:   http://lancai=
ronline.net/lists/flyrotary/List.html
<= PRE style=3D"MARGIN-LEFT: 0.5in">        = 
 
 
 
  =

 Homepage:  http://www.flyrotary.com/
 Archive:   http://lancai=
ronline.net/lists/flyrotary/List.html
<= PRE style=3D"MARGIN-LEFT: 0.5in">      = 
 
  =
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