X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from relay02.roc.ny.frontiernet.net ([66.133.182.165] verified) by logan.com (CommuniGate Pro SMTP 4.3.4) with ESMTP id 987553 for flyrotary@lancaironline.net; Tue, 07 Jun 2005 15:14:06 -0400 Received-SPF: pass receiver=logan.com; client-ip=66.133.182.165; envelope-from=canarder@frontiernet.net Received: from filter03.roc.ny.frontiernet.net (filter03.roc.ny.frontiernet.net [66.133.183.70]) by relay02.roc.ny.frontiernet.net (Postfix) with ESMTP id E7EF537052B for ; Tue, 7 Jun 2005 19:13:15 +0000 (UTC) Received: from relay02.roc.ny.frontiernet.net ([66.133.182.165]) by filter03.roc.ny.frontiernet.net (filter03.roc.ny.frontiernet.net [66.133.183.70]) (amavisd-new, port 10024) with LMTP id 24827-02-62 for ; Tue, 7 Jun 2005 19:13:15 +0000 (UTC) Received: from [127.0.0.1] (67-137-78-176.dsl2.cok.tn.frontiernet.net [67.137.78.176]) by relay02.roc.ny.frontiernet.net (Postfix) with ESMTP id ED4C33706BF for ; Tue, 7 Jun 2005 19:13:14 +0000 (UTC) Message-ID: <42A5F1BE.1090902@frontiernet.net> Date: Tue, 07 Jun 2005 14:13:02 -0500 From: Jim Sower User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040514 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: rotary risks. MTBE and the gospel ... References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------090906040708060700070802" X-Antivirus: avast! (VPS 0523-2, 06/07/2005), Outbound message X-Antivirus-Status: Clean X-Virus-Scanned: by amavisd-new-20040701 (2.0) at filter03.roc.ny.frontiernet.net This is a multi-part message in MIME format. --------------090906040708060700070802 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit al p wick wrote: >Wow. The emotional responses! Take a look at my statement: "It only has >three moving parts, therefore it's safer". I can't believe all the stuff >you guys are reading into it! > > All other things being equal, YES. A device with three shoddy parts just might not be as reliable as one with 500 carefully designed and manufactured parts. If the 3-part device is operated much more strenuously than the 500-part device, it might or might not be as reliable. >Let me explain. If your goal is to determine if one thing is safer than >another...guess what? Counting the number of pieces is NOT the definition >of safety. You have to look at the whole picture. You don't focus on one >feature. > > Early on, absent reliable system failure data, given roughly equivalent engineering manufacturing standards, it is the ONLY DEFINITION AVAILABLE. Provided the data is available, one can study the reliability of parts and components and subsystems and make an educated guess, but as I said before, other things being equal, parts count is a PIVOTAL consideration. If you think it's not, what, pray tell, do you think is a better indicator?? >Let's try this word experiment. Our job is to make clocks. Two types are >made. The Alwick 2000 all electronic clock and the billybob100 with 100 >mechanical components. Gears, all that traditional stuff. We sell these. >At the end of a year, the customers return 1% of the Alwick 2000 >electronic clock. >Customers return 50% of the Billybob 100 multi gear clocks. Seems gears 2 >and 17 bind and it stops working. > >Which has the higher failure risk? Well the Billybob 100 of course. The >return rate is conclusive evidence. > >But what if the return rates were the opposite? Which then would be >higher risk? It would be the Alwick 2000. > >So the point is, that parts count is not the definition of risk. Yes, in >many things they coincide. But you don't get to make that assumption. You >have to compare your theory to the facts. > > OK. How's this: In the racing circuits: The recip guys rebuild their engine pretty much after every race. The rotary guys rebuild their engine at the end of the season whether it needs it or not. Why do you suppose that is? We're talking Toyota, Nissan, Porche, Soob?, whoever. >-al > >On Mon, 6 Jun 2005 20:48:09 -0400 WALTER B KERR writes: > > >>Al W wrote:> >> >> >> >>>Here's an excellent example. I've seen people describe their >>>reasoning >>>for going rotary. Often I would hear: "It only has three moving >>>parts, >>>therefore it's safer". I suspect that 80% of you believed that. >>> >>> >>That >> >> >>>is a >>>gross error in perspective. No maybe, it's a huge distortion. It's >>> >>> >>>a >>>wonderful theory, it has a component of truth in it, but totally >>>fails >>>the tests for significance. If a logical theory is not >>> >>> >>significant, >> >> >>>you >>>dump the theory. >>> >>> >>-------------------------------------------------------- >> >>Have stayed out of this as long as I can, but it seems strange to me >>as a >>gas turbine designer of 33 years that Al would make this comment >>without >>at least backing his words up a bit. I find it hard to believe that >>a >>modern technology reciprocating engine that is snapping pistons back >>and >>forth at 5000 rpm with cams and valves is anywhere as safe as a >>rotary. >>If the modern tech recip requires a PSRU and the addition of water >>cooling those things components are canceling. >>Having participated in many FEMA studies over the years ,I find some >>of >>Al's comments a bit strange. His heart may be in the right place to >>try >>to help us Rotorheads, but am not convinced he is helping us sort >>out >>what is important to take care of to eliminate failures. >> >>Will never forget my intro to rotary's. A friend at work raced a >>rotary >>powered car. He took the car to the Daytona 24 hour without detuning >>and >>after returning he left the car on the trailer and went to miami >>next >>week without any additional work. This was a totally different story >>from >>the recip guys. They installed very expensive forged lightweight >>parts >>and deturned the engine. After the race they replaced all of them >>before >>the next event. Does that say something to you about the robustness >>of >>the rotary? Does to me and is one of the big reasons I am flying >>one >>today. >> >>Bernie Kerr, 40 hours on 13B powered RV9A, >> >>PS. Do I feel as comfortable with the 9A as I did when I sold the >>Lycoming powered 6A ? Not Yet! >> >> >>> >>> >>>> Homepage: http://www.flyrotary.com/ >>>> Archive: http://lancaironline.net/lists/flyrotary/List.html >>>> >>>> >> >> > > >-al wick >Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 >N9032U 200+ hours on engine/airframe from Portland, Oregon >Prop construct, Subaru install, Risk assessment, Glass panel design info: >http://www.maddyhome.com/canardpages/pages/alwick/index.html > > > >>> Homepage: http://www.flyrotary.com/ >>> Archive: http://lancaironline.net/lists/flyrotary/List.html >>> >>> > > > > --------------090906040708060700070802 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit al p wick wrote:
Wow. The emotional responses! Take a look at my statement: "It only has
three moving parts, therefore it's safer". I can't believe all the stuff
you guys are reading into it!
All other things being equal, YES.  A device with three shoddy parts just might not be as reliable as one with 500 carefully designed and manufactured parts.  If the 3-part device is operated much more strenuously than the 500-part device, it might or might not be as reliable.
Let me explain. If your goal is to determine if one thing is safer than
another...guess what? Counting the number of pieces is NOT the definition
of safety. You have to look at the whole picture. You don't focus on one
feature.
Early on, absent reliable system failure data, given roughly equivalent engineering manufacturing standards, it is the ONLY DEFINITION AVAILABLE.  Provided the data is available, one can study the reliability of parts and components and subsystems and make an educated guess, but as I said before, other things being equal, parts count is a PIVOTAL consideration.  If you think it's not, what, pray tell, do you think is a better indicator??
Let's try this word experiment. Our job is to make clocks. Two types are
made. The Alwick 2000 all electronic clock and the billybob100 with 100
mechanical components. Gears, all that traditional stuff. We sell these. 
At the end of a year, the customers return 1% of the Alwick 2000
electronic clock. 
Customers return 50% of the Billybob 100 multi gear clocks. Seems gears 2
and 17 bind and it stops working. 

Which has the higher failure risk? Well the Billybob 100 of course. The
return rate is conclusive evidence. 

But what if the return rates were the opposite? Which then would be
higher risk? It would be the Alwick 2000. 

So the point is, that parts count is not the definition of risk. Yes, in
many things they coincide. But you don't get to make that assumption. You
have to compare your theory to the facts.
OK.  How's this:  In the racing circuits:
The recip guys rebuild their engine pretty much after every race.
The rotary guys rebuild their engine at the end of the season whether it needs it or not.
Why do you suppose that is?  We're talking Toyota, Nissan, Porche, Soob?, whoever.
 
-al

On Mon, 6 Jun 2005 20:48:09 -0400 WALTER B KERR <jbker@juno.com> writes:
  
Al W wrote:>
 
    
Here's an excellent example. I've seen people describe their 
reasoning
for going rotary. Often I would hear: "It only has three moving 
parts,
therefore it's safer". I suspect that 80% of you believed that. 
      
That 
    
is a
gross error in perspective. No maybe, it's a huge distortion. It's 
      
a
wonderful theory, it has a component of truth in it, but totally 
fails
the tests for significance. If a logical theory is not 
      
significant, 
    
you
dump the theory. 
      
--------------------------------------------------------

Have stayed out of this as long as I can, but it seems strange to me 
as a
gas turbine designer of 33 years that Al would make this comment 
without
at least backing his words up a bit. I find it hard to believe that 
a
modern technology reciprocating engine that is snapping pistons back 
and
forth at 5000 rpm with cams and valves  is anywhere as safe as a 
rotary.
If the modern tech recip requires a PSRU and the addition of water
cooling those things components are canceling.
Having participated in many FEMA studies over the years ,I find some 
of
Al's comments a bit strange. His heart may be in the right place to 
try
to help us Rotorheads, but am not convinced he is helping us sort 
out
what is important to take care of to eliminate failures.

Will never forget my intro to rotary's. A friend at work raced a 
rotary
powered car. He took the car to the Daytona 24 hour without detuning 
and
after returning he left the car on the trailer and went to miami 
next
week without any additional work. This was a totally different story 
from
the recip guys. They installed very expensive forged lightweight 
parts
and deturned the engine. After the race they replaced all of them 
before
the next event. Does that say something to you about the robustness 
of
the rotary? Does to me and is one of the big reasons I am flying 
one
today.

Bernie Kerr, 40 hours on 13B powered RV9A, 

PS. Do I feel as comfortable with the 9A as I did when I sold the
Lycoming powered 6A ?  Not Yet!
    
      
 Homepage:  http://www.flyrotary.com/
 Archive:   http://lancaironline.net/lists/flyrotary/List.html
        
    


-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html

  
 Homepage:  http://www.flyrotary.com/
 Archive:   http://lancaironline.net/lists/flyrotary/List.html
--------------090906040708060700070802--