From: "Eric Parlow" <ericparlow@hotmail.com>
To: lancair.list@olsusa.com
Subject: TCM-12, 100LL
Date: Mon, 23 Oct 2000 21:32:19 GMT
Message-ID: <F283GNuVZWGqjovoP6e0000cc29@hotmail.com>
Reply-To: lancair.list@olsusa.com
Mime-Version: 1.0

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Fred,

You hit on a big one.  I'll tell you what I know.  It's not much more.  You 
took good notes.

Q--*  Tetraethyl lead (TEL) is produced in only one plant in the world in 
the UK.  The firm operating this plant [Octel. Inc.] bought the plant in 
East Germany and shut it down. [Confirmed.]  The plant in Chechnya is 
unlikely to resume production anytime soon.
A-- I can confirm this.  It comes down to money.  Is it profitable?

Q--*  The last corners of the world using leaded motor gas will cease doing 
so this year thus completing the worldwide removal of leaded fuel from the 
motor gas pool.
A--This will happen but farther out than the end of this year.

Q--*  Demand for TEL is dropping 15% per year.
A-- I heard 10%.  But still, it's dropping fast!

Q--*  100 LL will be phased out between 2005 and 2010.  The regular 
production of TEL will cease in 2005 and 100 LL after that date will use 
stored supplies of TEL.  [I found the Octel web site and sent an e-mail 
asking for confirmation.]
A-- I cannot confirm this but it sounds reasonable to assume.

Q--*  Usage of 100LL is dropping rapidly.  The large engine piston fleet is 
being retired in favor of turbine engines in corporate and commuter use, and 
old freighters like DC-6's are also being retired due to lack of spare parts 
for big round engines.
A--True, the commercial market is getting smaller.

Q--*  About 70% of the general aviation fleet can use 82UL.
A--I would say 80%.  But that 80% only use 20% of the 100LL.

Q--*  FBOs only want to stock one type of fuel because of the cost of
equipment and inventory.  So they stock what everyone can use -100LL.
A--True.  We must have a single fuel option to be viable.

Q--*  Only seven refineries in the U.S. can produce 100LL, while every
refinery in the US (about 400) is capable of producing 82 UL today, if it 
chooses.
A--Not sure on the exact number but seven sounds close.

Q--*  Cessna's approach has been to use low compression engines capable of 
using 82UL for lower horsepower applications, and rely on new diesel
engines for higher powers for future larger aircraft.
A--I heard this also.  High power diesel(jet A) piston aero engines are five 
years away minimum.

Q--*  Diesel engine progress has been poor because aero diesel engines must 
use jet fuel.  Jet has a much lower cetane rating than diesel fuel. This 
leads to higher peak pressures in the engine (somewhat like knock)resulting 
in heavy engines, [confirmed in Taylor's classic text book] and so far they 
will probably be too heavy for use in current
aircraft.  Additives can raise the cetane rating of Jet fuel, but the cost 
adder is unacceptable to turbine engine operators.  So a high cetane jet 
fuel blend would have to be separately produced and stocked. But recall from 
above that FBOs only want to stock one fuel for piston engines.
A--True it is not the answer for every installation.  Jet A fuel poses some 
problems but the GAP engine will address them.  The base GAP engine will be 
equal in weight to a comparable 200 bhp engine(TCM IO-360).  The weight 
penalty comes from the cooling system and turbocharger.  But adding these 
features is not an apples to apples comparison.  Liquid cooling reduces 
cooling drag and  turbo normalization gives altitude performance.  It will 
be a compromise in the end for sure.

Q--*  100 LL is actually about 102-104 octane (motor method), and this high 
level is needed because of high possible cylinder head temperatures (in some 
cases combined with high manifold pressures in turbo'ed units) in air cooled 
engines.  Certification requires that these must operate up to red line CHT 
without detonation when full rich.
EPA and the regulators are not trying to ban leaded avgas because the
industry is working on the problem.  However, it will be effectively banned 
sometime after 2005 as the demand drops and price reaches such high levels 
that it is effectively no longer available.
A--This is a very clear picture of things to come.

Q--*  [Refineries can make high octane unleaded fuel, but at prohibitive
prices.  Unocal has a limited number of outlets for racers in the Los
Angeles area, but fuel costs are typically $5-6 per gallon without taxes
since these are not road fuels.]
A--This would only address part of the issue.

Q--*  Every 20F drop in cylinder head temperature reduces the engine octane 
requirement by approximately 2 points.  Smaller four cylinder engines in the 
160 to 180 HP class can use 82 UL today.
A--I cannot confirm this exact number on TCM engines.  But the lower CHT 
allows lower octane requirements.

Q--*  There will be an unleaded Avgas produced to replace 100 LL, but it 
will not be as high octane as 100 LL.  It will probably be a low vapor 
pressure formulation that will be around 94 octane tailored to meet 
technical and cost requirements.
A--TEL also helps with detonation and lubrication of the upper cylinder.  
The oil industry has not developed a fuel which can directly replace 100LL.  
It must be a hybrid solution involving the fuels and engines.

Q--*  Consequently, larger engines, 200 HP and up, 500 cubic inches and up, 
and turbocharged engines have an uncertain future past 2005 as 100LL 
supplies dry up and the price skyrockets.
A--All indications show this to be true.  FADEC offers hope on the engine 
side.

Q--*  Liquid cooled engines can operate with much lower octane because of 
lower combustion chamber temperatures.  Lowering head temperatures from 400F 
to 200F can reduce the motor octane rating as much as 10 points, down to 
92-94 octane.   [However, details of combustion chamber design can also be 
important.]
A--Liquid cooling does offer a partial solution but is impractical as a 
retrofit on most airframes.

Q--*  In the opinion of the EAA representative, the only solution is "modern 
engines, liquid cooled, with electronically controlled fuel injection and 
ignition systems such as those that have been demonstrated to run 
[efficiently] on 92 octane auto fuel today."
A--I agree.

Q--I conclude from this that the long term future of Continental TSIO-550's 
in Lancairs and TSIO-540 Lycoming engines in Malibus is dim indeed. UNLESS 
the engine manufacturers produce retrofit packages for the existing fleet of 
engines.  Perhaps these would be derived form current FADEC systems, for 
example, and take the control of the mixture and propeller away from the 
pilot to avoid detonation.  However, the recertification problems in all the 
different air frames would seem to be immense.
A--The current high BMEP engine's future using 100LL is uncertain.  FADEC 
offers a partial solution with its knock sensing capabilities and timing 
control.  FADEC will be retrofittable relatively easily to all TCM and Lyc. 
engines.  A cam gear change is the major work required.

Q--Are current generation certified turbocharged high performance piston
engine airplanes endangered species?
A--The High BMEP engines we know and love today will be history in 10 years. 
  So says my crystal ball.

ERic--

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