X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 02 Jun 2011 08:28:33 -0400 Message-ID: X-Original-Return-Path: Received: from qmta10.emeryville.ca.mail.comcast.net ([76.96.30.17] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 5000894 for lml@lancaironline.net; Wed, 01 Jun 2011 21:05:11 -0400 Received-SPF: pass receiver=logan.com; client-ip=76.96.30.17; envelope-from=jmorgan1023@comcast.net Received: from omta17.emeryville.ca.mail.comcast.net ([76.96.30.73]) by qmta10.emeryville.ca.mail.comcast.net with comcast id qoXt1g0031afHeLAAp4ccK; Thu, 02 Jun 2011 01:04:36 +0000 Received: from [192.168.1.108] ([71.238.168.79]) by omta17.emeryville.ca.mail.comcast.net with comcast id qp4T1g01h1j7MyX8dp4V6v; Thu, 02 Jun 2011 01:04:33 +0000 From: Jack Morgan Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-2-104472182 Subject: Re: [LML] Re: L-IV Choice of Engine X-Original-Date: Wed, 1 Jun 2011 21:04:30 -0400 In-Reply-To: X-Original-To: Lancair Mailing List References: X-Original-Message-Id: <2B94F271-37D0-481A-AFC0-1383EF14CA84@comcast.net> X-Mailer: Apple Mail (2.1084) --Apple-Mail-2-104472182 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii The most important issue being missed is the torsional resonance the = auto crankshaft receives from the propellor. The application of viscous = couplings is often tried to isolate the auto crank from the propellor = with some success but the weakness still remains. An automotive = crankshaft will fatigue fail if the engine is in aircraft service for = more than a few hundred hours in most cases. The fancy billet cranks = offer little relief from the fatigue problem. Keep in mind that the = propellor blades are constantly flexing under the air loads which = translates into fatigue flexing of the crankshaft along it's entire = length. Just look at a side by side picture of an auto crankshaft and a = comparable power aircraft crankshaft. The aircraft unit is substantially = heaver. This weight is not added to the aircraft engine for no reason. The second issue is the high power requirement. The auto industry indeed = designs their engines for high RPM/HP operation but the assumption is = that this output is required for a very small percentage of the engines = usage profile. Both fatigue and wear are dramatically increased at near = red line operation (the rotational loads are square law to RPM). Others = have commented on the high cooling load at near red line operation which = can be managed. The take away from the high cooling load should jog = thoughts of fatigue and wear rates. I am all for enjoying home built engine experimentation, but the IV is = not a good platform for the fun. Jack Morgan On Jun 1, 2011, at 6:00 AM, Lancair Mailing List wrote: >=20 >=20 > From: Ted Noel > Date: May 31, 2011 1:41:38 PM EDT > To: lml@lancaironline.net > Subject: Re: [LML] Re: L-IV Choice of Engine >=20 >=20 > Swaid, >=20 > Your comments below are part of what drives me nuts in this = conversation. A fuel line failure is NOT an engine issue. It is a = systems issue that applies to every aircraft that ever flew (except = electrics). Thus, using it as a condemnation of a one-off application is = not germane to the topic. >=20 > Electronic ignition systems are as reliable as the day is long. Solid = state electronics generally last longer than whatever they're stuck in. = And I have redundant computers, with automotive exhaust oxygen sensors = to let me get the induction and ignition maps exactly right. >=20 > LS-1 coils at 1 per plug are as reliable as the day is long. Millions = of cars have proved that, and there's no high-altitude issue, because of = their construction. >=20 > Automotive injectors are incredibly reliable, and I've got two sets, = user selectable, so if my wiring fails to one, the other will work. = (BTW, I expect to select alternate injectors and computers on a calendar = basis, so all will be known-good all the time.) >=20 > The engine internals are designed to be able to run all day at 7,000 = RPM, but I'm rev-limiting to 3,500. I can't imagine needing more than = the 600 hp I make at that speed. The hydraulic roller lifters should = have no problem, since billions of them run forever with no problems. >=20 > Where do we have concerns? The gearbox. It was designed with the help = of Timken's helicopter people to run at 1,000 HP continuously. It has = separate lubrication and oil cooling, with a full suite of sensors. It = also has three helical cut gears so that it has 3.4 teeth engaged at all = times, unlike spur gear setups with 1 tooth engagement. The thrust = bearing is designed for 1,000 HP. >=20 > Garrett turbochargers and wastegates are reliable as the day is long, = and run on Continentals and Lycomings every day. >=20 > Have I missed something? Maybe. The designer is very experienced, and = Don Goetz flies behind a Continental he prepared. He's designed = everything from stationary power generator engines to Indy race engines = to aircraft engines for DARPA. I think he's answered a lot of questions. = Did he miss anything? Maybe. That's what testing is for. But as for the = internals, any speed shop can repair the engine for a lot less than your = Lyconental. The only part that isn't field repairable is the gearbox. >=20 > Do I have a risk of failure? Yes. Do you? Yes. The prime difference = between us is that Lyconental failures are better known from a large = statistical database. Mine are somewhat predictable, but don't have the = experience yours have. >=20 > I expect to start testing today. News when available. >=20 > Ted Noel > N540TF --Apple-Mail-2-104472182 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii The = most important issue being missed is the torsional resonance the auto = crankshaft receives from the propellor. The application of viscous = couplings is often tried to isolate the auto crank from the propellor = with some success but the weakness still remains. An automotive = crankshaft will fatigue fail if the engine is in aircraft service for = more than a few hundred hours in most cases. The fancy billet cranks = offer little relief from the fatigue problem. Keep in mind that the = propellor blades are constantly flexing under the air loads which = translates into fatigue flexing of the crankshaft along it's entire = length. Just look at a side by side picture of an auto crankshaft and a = comparable power aircraft crankshaft. The aircraft unit is substantially = heaver. This weight is not added to the aircraft engine for no = reason.

The second issue is the high power = requirement. The auto industry indeed designs their engines for high = RPM/HP operation but the assumption is that this output is required for = a very small percentage of the engines usage profile. Both fatigue and = wear are dramatically increased at near red line operation (the = rotational loads are square law to RPM). Others have commented on the = high cooling load at near red line operation which can be managed. The = take away from the high cooling load should jog thoughts of fatigue and = wear rates.

I am all for enjoying home built = engine experimentation, but the IV is not a good platform for the = fun.

Jack Morgan

On Jun = 1, 2011, at 6:00 AM, Lancair Mailing List wrote:





Swaid,

Your = comments below are part of what drives me nuts in this conversation. A = fuel line failure is NOT an engine issue. It is a systems issue that = applies to every aircraft that ever flew (except electrics). Thus, using = it as a condemnation of a one-off application is not germane to the = topic.

Electronic ignition systems are as reliable as the day is = long. Solid state electronics generally last longer than whatever = they're stuck in. And I have redundant computers, with automotive = exhaust oxygen sensors to let me get the induction and ignition maps = exactly right.

LS-1 coils at 1 per plug are as reliable as the = day is long. Millions of cars have proved that, and there's no = high-altitude issue, because of their construction.

Automotive = injectors are incredibly reliable, and I've got two sets, user = selectable, so if my wiring fails to one, the other will work. (BTW, I = expect to select alternate injectors and computers on a calendar basis, = so all will be known-good all the time.)

The engine internals are = designed to be able to run all day at 7,000 RPM, but I'm rev-limiting to = 3,500. I can't imagine needing more than the 600 hp I make at that = speed. The hydraulic roller lifters should have no problem, since = billions of them run forever with no problems.

Where do we have = concerns? The gearbox. It was designed with the help of Timken's = helicopter people to run at 1,000 HP continuously. It has separate = lubrication and oil cooling, with a full suite of sensors. It also has = three helical cut gears so that it has 3.4 teeth engaged at all times, = unlike spur gear setups with 1 tooth engagement. The thrust bearing is = designed for 1,000 HP.

Garrett turbochargers and wastegates are = reliable as the day is long, and run on Continentals and Lycomings every = day.

Have I missed something? Maybe. The designer is very = experienced, and Don Goetz flies behind a Continental he prepared. He's = designed everything from stationary power generator engines to Indy race = engines to aircraft engines for DARPA. I think he's answered a lot of = questions. Did he miss anything? Maybe. That's what testing is for. But = as for the internals, any speed shop can repair the engine for a lot = less than your Lyconental. The only part that isn't field repairable is = the gearbox.

Do I have a risk of failure? Yes. Do you? Yes. The = prime difference between us is that Lyconental failures are better known = from a large statistical database. Mine are somewhat predictable, but = don't have the experience yours have.

I expect to start testing = today. News when available.

Ted = Noel
N540TF

= --Apple-Mail-2-104472182--