http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_09_09_2013_p12-609055.xml
“The quest for a small UAS engine that burns diesel or JP-5 fuel
rather than aviation or automotive gasoline has been underway since
the 1980s. The latest bump in this long road was the acquisition in
July of Thielert, manufacturer of the diesel engine for the U.S.
Army's MQ-1C Gray Eagle UAS, by China's Avic.
This has forced the Army and General Atomics to adopt Lycoming's
DEL-120 diesel—an engine that Lycoming did not show at Auvsi, instead
bringing its smaller, 63-hp EL-060 (a spark-ignition multifuel
two-stroke). One question is when the new DEL-120 will be able to
attain the time between overhauls needed for UAS use. The Thielert
engine became notorious in the personal-aircraft market for frequent
and expensive inspections and overhauls.”
Marc Wieie
The Thielert is an econ box car engine from Europe. What do you
expect ? :) Miracles? :)
Paul Lamar
Paul,
Years ago driving 18 wheel diesel trucks, we put additives into
diesel fuel to keep the engine performing in extreme cold. Question,
in nations where diesel is available and very little aviation
gasoline, could an additive be used in diesel so it could run in a
Wankel Engine set up for gasoline. Paul have you heard of anyone
that experimented with fuel treatments to burn diesel or is its flash
point to low ?
George Curtis
Why do that? You can get car gas all over the world.
Paul Lamar
When gasoline was 25% or more higher priced than Diesel fuel, I heard
of some young boys in Salou, Tarragona, Spain, having an air cooled
engine Citroen 2CV that was fed on gasoline until engine was hot,
then, from an independent deposit, Diesel fuel was send to the carb.
It worked, don't know for how long. A SAE article was about Diesel
engines coming soon to an airport next or close to you. C-W conducted
research on the use of JP4 and other fuels by direct injection into a
Wankel RCE combustion chamber, many SAE papers resulted. There are
some small engine producers trying to enter the market, for example,
D-motor
www.d-motor.eu , Austro and probably others. Have a good
time. Best regards. Salut † Jose Gros-Aymerich Madrid, Spain
That is not the price. That is the TAX.
None of the Wankels burning diesel were successful in reducing the
fuel consumption. The compression ratio is too limited.
CW published many SAE papers for the benefit of their stock price.
Paul Lamar
Some old tractors had two tanks, one for gasoline, one for kerosene
(which is similar to diesel). You would start the engine on the
gasoline and after it was warmed up you would switch to kerosene,
which at that time (early 50's) was cheaper that gasoline to the
farmer. Bear in mind, although I saw this in the 50's, the tractors
were old THEN.
Bill Schertz
Yep, I remember those tractors.
http://www.retiredtractors.com/Modelb.html "All of the John Deere two
cylinder tractors at this time (1935-1947) were designed to run on
"tractor fuel" or "distillate". This was less volatile than gasoline,
so the tractors had a small gasoline tank located behind the main
fuel tank, for starting the engine. Then, when the engine was warmed
up, a "three-way-valve" in the fuel line could be switched, and the
tractor would run on the heavier fuel in the main tank. This early
Model B weighed about 2700 lbs. Horsepower figures are debatable, but
the engine had a displacement of 149 cubic inches."
My dad had one of these tractors, about 16 hp. I remember riding as a
very young boy along with my older brother, both of us sitting on
the gas tank, under the steering rod and holding onto the rod - great
fun.
After working all morning, in warm weather you could shut the
ignition system off (gear in neutral) and the engine would continue
to slowly cycle (dieseling) and would often still be cycling after
returning from lunch, then just turn the ignition on and give it the
throttle and back to work. No hand cranking involved.
Harold
What does kerosene coast these days. I'll bet there is no road tax on
it.
Paul Lamar
MIke Hewland, in an interview published in Car&Driver, July 1974,
cover with a Bricklin car, reported having run his 500 cc, single-cylinder,
Birt-McCollum Single-Sleeve-valve distribution prototype engine with a
compression ratio of 10:1 on creosote, it gave 72HP.
With the lowest ON available gasoline, he reported an SFC of
.39 pounds/HP/hr in the economy version, .45 in the racing version,
with Sleeve temperatures not above 140º C, 270º C in the centerof piston,
240º at the piston edges, and 150º C in the cylinder, with an oil
consumption
lower than a contemporary poppet valve similar engine.
People in AEHS don't give such a good image for SSVs compared to poppet
valved engines, but the Hewland results sound pretty good.
Continental conducted extensive research in SSV engines, from
railroad to car to aircraft units, and it seems that the expenses in
this, that
were made in the times close to the 'great depression', nearly put the
company
bankrupt, besides Bristol in their radial air cooled WWII aircraft
engines, no
other company seems having succeeded with this arrangement.
The Petter Broterhood unit in the Anson engine museum in the YouTube
video may be one of the biggest engines made with this arrangement, in
other films from locomotives with this type of engines, right after start,
lots of white smoke start coming out from the exhaust chimney, but after
some minutes, probably when the engine has reached its operating
temperature,
smoke is no longer seen, the same is seen in some WWII fighters preservedin
the NZ-Australia region, smoke on start, then clean exhaust.
By the way, you recently added a ling to a video showing a four rotor RCE,
that soon after start has the exhaust manifold and tubes hot to cherish red.
Aircraft engines exhaust didn't go cherish red, it went white-glow, that
means
a much higher exhaust gas temperatures, and in the early days of ICE, when
Harry Ricardo had not yet determined the reasons for detonation, a lower
compression ratio, the only the gasoline available then allowed, was linked
to higher exhaust gas temperatures, meaning also a lower thermodynamic
efficiency of engine.
According to Reiner Nikulski, Wankel Club, the vacuum box in the KC 27
engine
of the Hercules W-2000 motorcycle, had a small hole opening several
tenths of
grades later in the intake stroke than the main rectangular peripheral
intake port, this box opened at high vacuum in the admission ducts, ie, when
load and rpm were low, to close at full throttle, this way, vacuum box
changed
the working cycle at part load and low rpm to something close to an Atkinson
cycle, as part of the charge having entered the admission stroke was
sent back
to the admission manifold thru the small port, and the total volume of
gasoline:oil:air mix entering the working chamber in the part load load low
rpm range was reduced.
The RCE in this way of operation kept the advantage of the longer, in
terms of grades of shaft turn, 270º, power stroke inherent to the Wankel
cycle, that is also slightly different to an Otto 4-strokes cycle,
where the power
stroke is shorter, at 180º.
A pity that these vacuum boxes failed a lot, and to avoid part
load/low rpm
fuel use per hour raising around 70%, a smaller low jet had to be put in
carb if
the vacuum box was disconnected.
Good season, regards. Salut
Jose Gros-Aymerich
Madrid, Spain
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