X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 50 [XX] Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 30 Mar 2007 16:40:36 -0400 Message-ID: X-Original-Return-Path: Received: from [68.98.211.24] (HELO systems3.net) by logan.com (CommuniGate Pro SMTP 5.1.7) with ESMTP id 1952291 for lml@lancaironline.net; Fri, 30 Mar 2007 12:30:25 -0400 Received-SPF: none receiver=logan.com; client-ip=68.98.211.24; envelope-from=cberland@systems3.net Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C772E8.A7417032" X-MimeOLE: Produced By Microsoft Exchange V6.5 Subject: [LML] Re: Thielert Diesel Centurion 4.0 X-Original-Date: Fri, 30 Mar 2007 09:29:55 -0700 X-Original-Message-ID: <87C33F695961494D886EB3B6C8A476512568BB@s3server.Systems3.local> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [LML] Re: Thielert Diesel Centurion 4.0 Thread-Index: Acdy2jzCpjMi4LCeT166CDge8INqMgACpbyA From: "Craig Berland" X-Original-To: "Lancair Mailing List" This is a multi-part message in MIME format. ------_=_NextPart_001_01C772E8.A7417032 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Bob Mackey wrote: How to do that? Thermally insulate the surface.=20 That's the idea behind ceramic coatings for the piston crown, combustion chamber,=20 and valve faces. The insulator needs to be able to run hot on one side, and cool=20 enough on the other side to=20 1) not melt or weaken the metal 2) not burn or polymerize the oil 3) not transfer so much heat that the benefits of high compression are=20 lost to cooling drag. If that is worked out, then engine BSFC improves, and cooling losses are reduced.=20 Just as in a gas turbine, the cooling drag is minimized by allowing the=20 hot section to actually run hot. High temperature, high strength alloys, and insulating ceramics are the key to an efficient aircraft diesel engine.=20 FWIW, Aluminum is just about the worst material to use in a diesel head: low strength at high temperatures, high thermal conductivity, poor fatigue life, etc.=20 The argument that "...heat has to be dissipated - - - some way." really boils down to "because we let the heat get into the aluminum, we need to get it back out before the piston melts."=20 =20 Bob, your theory is correct, however the execution is difficult and expensive. I think the expense is the big problem in aviation. The volume is not there to justify the cost of development. I worked at Oldsmobile in the '80's and we made 3600 engines every day. That volume must be compared to aviation volumes. Some of the development costs I am talking about follow. I made a set of titanium rods and found out you must not let titanium rub against anything else. I made a set of inconel 718 pistons and found out the benefits did not justify the costs. They were for a diesel engine by the way. I have made titanium valves. These work pretty well, but the rubbing observation applies. Personally, I have used ceramic coatings in several areas of my IV-P gasoline engine. The new coating technology is something I believe can help every engine. I think I mentioned this here before.....Pro Stock drag cars are currently using about $40,000 worth of "coatings" in their engines, transmissions and axels. At work, we are looking into producing pistons for NASCAR engines. The piston design running successfully today is light years from what was running just a few years ago. I was told a few years ago that a commercial jet cost was 1/2 engines and 1/2 everything else. Assuming what I was told is true, and GA owners were willing to spend this kind of money, maybe the research could be paid for. For example, take a IV-P that would sell for $700,000 where $350,000 was for the engine. This would compare to the current $80,000 engine and $350,000 everything else for $430,000. I would accept going slower (280 kts) and burning more fuel with the "trailing edge of technology" stuff. Craig Berland =20 =20 ________________________________ Bored stiff? = Loosen up... Download and play hundreds of games for free on Yahoo! Games ------_=_NextPart_001_01C772E8.A7417032 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable
 Bob Mackey=20 wrote:
 How to do that?=20 Thermally=20 insulate the surface.
That's the idea=20 behind ceramic coatings for the piston crown, combustion chamber,=20
and valve faces.=20 The insulator needs to be able to run hot on one side, and cool=20
enough on the=20 other side to
1) = not melt or=20 weaken the metal
2) = not burn or=20 polymerize the oil
3) = not transfer so=20 much heat that the benefits of high compression are
   lost=20 to cooling drag.
If = that is worked=20 out, then engine BSFC improves, and cooling losses
are reduced.=20
Just as in a gas=20 turbine, the cooling drag is minimized by allowing the =
hot section to=20 actually run hot. High temperature, high strength alloys,=20 and
insulating=20 ceramics are the key to an efficient aircraft diesel engine.=20
FWIW, Aluminum is=20 just about the worst material to use in a diesel = head:
low strength at=20 high temperatures, high thermal conductivity, poor fatigue life, etc.=20
The argument that=20 "...heat  has to be dissipated - - - some way." really=20 boils
down to "because=20 we let the heat get into the aluminum, we need to get = it
back=20 out before the piston melts." 
 
Bob, your theory is correct, however the = execution is=20 difficult and expensive.  I think the expense is the big problem in = aviation.  The volume is not there to justify the cost of=20 development.  I worked at Oldsmobile in the '80's and we made 3600 = engines=20 every day.  That volume must be compared to aviation volumes.  = Some of=20 the development costs I am talking about follow.  I made a set of = titanium=20 rods and found out you must not let titanium rub against anything = else.  I=20 made a set of inconel 718 pistons and found out the benefits did not = justify the=20 costs. They were for a diesel engine by the way. I have made titanium=20 valves.  These work pretty well, but the rubbing observation = applies. =20 Personally, I have used ceramic coatings in several areas of my IV-P = gasoline=20 engine.  The new coating technology is something I believe can help = every=20 engine.  I think I mentioned this here before.....Pro Stock drag = cars are=20 currently using about $40,000 worth of "coatings" in their engines,=20 transmissions and axels.  At work, we are looking into producing = pistons=20 for NASCAR engines.  The piston design running successfully = today is=20 light years from what was running just a few years ago.  I was told = a few=20 years ago that a commercial jet cost was 1/2 engines and 1/2 everything=20 else.  Assuming what I was told is true, and GA owners were willing = to=20 spend this kind of money, maybe the research could be paid for.  = For=20 example, take a IV-P that would sell for $700,000 where $350,000 = was for=20 the engine.  This would compare to the current $80,000 engine = and=20 $350,000 everything else for $430,000.  I would accept going slower = (280=20 kts) and burning more fuel with the "trailing edge of technology"=20 stuff.
Craig = Berland
 
 

Bored= =20 stiff? Loosen up...
Downl= oad and=20 play hundreds of games for free on Yahoo! Games ------_=_NextPart_001_01C772E8.A7417032--