biodiesel

Perhaps the comparison test was about performance. I'll wait and
    see what
    he says.   AGE-85 is formulated with aircraft in mind, using
many of the
    performance enhancing additives that gasoline normally has
including
    a wee
    bit of biodiesel, whereas Baylor's E-95 (at this point) is just
    denatured
    ethanol. Don't race cars run on methanol?

    Doug Fir

Doug,
Yes racecars usually run Methanol, which is even worse energy wise.
Simple fact is gasoline comes in at 115,000 BTU/gal and ethanol at
84,000 BTU/gal, or about 73% the energy available in a gallon of
gasoline. Gas is hard to beat. Some of the effects of burning
ethanol
may help bring it closer to gasoline. Tolerance of higher
compression
without detonation or per-ignition, and less thermal energy wasted
to
cooling do help, but ethanol comes in with a large gap relative to
gasoline. It's a cleaner burning fuel but you can't make the physics
change much. The rotaries tolerance for a wide range of fuels is
useful,
but spark ignition bio-diesel might do you better for milage.
Bill Jepson

Spark ignition bio-diesel is a new one on me. Please explain. Do you
mix it with gasoline, and if so in what ratio?

#2 diesel has much more energy than gasoline. The biodiesel I am
familiar with has slightly less, but still more than gasoline.

Doc Custer
Retired software engineer and sometime Audiologist
Building RV9-A. Fuselage

The Wankel will run on direct injection diesel fuel
as long as you fire it with a spark plug.

CW and perhaps John Deere were running the engine on heavy fuel
years ago. There are many SAE and other tech papers on the subject.

Wankel Gmbh demonstrated such a turbo charged engine at OSH
several years ago. Here are some pictures from the factory
in Korf Germany

Mistral in Geneva Switzerland is/was also working on a
NA such engine. Here are some pictures of the engine
on the Mistral dyno in Geneva.

Paul Lamar ...No rotor no motor.

Wow!

I have trouble seeing biodiesel as an aircraft fuel for the same
reasons #2 diesel is not suitable: the tendency to gel and/or solidify
at the low temperatures commonly encountered at high altitudes. JetA
would probably be more suitable, particularly if it were heated. The
heat would have to be controlled somehow. Biodiesel, if made from the
right vegetable oil stock, might also be suitable if heated.

The other problems I can see right off the top of my head are that of
low vapor pressure and higher viscosity. If the fuel was sprayed
directly on hot metal, the low vapor pressure might not be a factor,
particularly if special injectors were used. Maybe. The higher
viscosity would require a modified fuel system including injectors.
And probably the fuel map would have to be made temperature aware as
the viscosity of some of these fuels change dramatically with changing
temperature. On the plus side, a lower volume of fuel would have to be
dealt with per cycle for the same power/energy; and range would be
improved.

Looks like a major development effort to me.

Doc Custer
Retired software engineer and sometime Audiologist
Building RV9-A. Fuselage

Hello Doc, Paul and all,

Yes, developing heavy-fuel capability is a major development effort indeed.
Here at Mistral, it is definitely our most ambitious development project. I
take the opportunity to inform you all of our progress on this front.

First, let me say that we are developing an engine to use and to be
certified with Jet-A. If we succeed, then there are a priori no reason for
that engine not to work on diesel or biodiesel fuels. However, as Doc
pointed out, these fuels are pretty much inappropriate for aviation use with
the exception of some special applications such as agricultural spraying.

You can get a rotary running on Jet-A with NO modification. However, at
about 25HP per rotor, you'll encounter BRUTAL detonation. With direct
high-pressure (10,000 PSI) injection, with the injector replacing one of the
spark plugs, you can push this limit to approximately 50HP per rotor.
Relatively easy so far.

But to push the limit back to 100HP per rotor or more, where you ought to be
to have a decent aviation engine, then you have to work VERY hard on where
you locate the injector, under what angle and what spray pattern you inject
fuel. You also have to determine optimal compression ratio and "bath tub"
geometry. It just cannot be a trial-and-error type of development anymore,
but a scientifically driven one.

Mistral has partnered with the Swiss Institute of Technology in Lausanne
(one of the two most prominent engineering school in Switzerland) and its
Laboratory for Industrial Energetics to develop a rotary engine
direct-injection and combustion simulation software and then to apply it on
the particular issue. It is a two-year project for two full-time plus two
part-time engineers.

However, we already know quite a few things. Comparing a two-rotor
turbocharged gasoline engine (our G-230TS model) with a two-rotor
turbocharged (it's got to be turbocharged) kerosene engine, the following
trade-offs apply:

The good news:
-    The K-series engine will use Jet-A and its fuel consumption will be
inferior to that of the G-series engine by ~5% in weight (because of the
slightly better efficiency of direct over indirect injection and of higher
compression ratios) and ~20% in volume (mainly because of the higher energy
content of Jet-A per gallon). It therefore increases range somewhat and
saves you quite a bit of money relative to a 100LL-burning engine.
However, mogas is still by far the cheapest fuel available. It just has to
become more widely available on airports, like it is in Germany where ~60%
of airports sell mogas.

The bad news:
-    The K engine will probably develop 20-30 fewer HP than the G engine.
-    The K engine will weigh 20-30lb more than the G engine.
-    It will cost more to maintain and to overhaul because of the
expensive direct-injection system and higher-energy ignition system.
-    It will be somewhat less reliable then the G engine because of the
additional technology and because of single-point failure possibilities such
as the high-pressure fuel pump which can hardly be doubled-up.
-    It will cost approximately $8,000 more.

I would be interested to know if you think such sacrifices are worth doing
for the economy of using Jet-A. In some countries, it is definitely the
case, and that’s why we are developing the K-series engines. However, I
have doubts that the US market would be ready for such compromises. I'd
love your feedback.

François Badoux
CEO Mistral
http://www.mistral-engines.com/

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