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 <http://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 <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
Jose,
As regards WW2 aircraft engine start creating lots of white smoke; It is probable this is caused from
a bit loose valve guide fit that allows oil to run down to the valve head after shut down.It is not
really a lot of oil but does create the impression of a big cloud when the engine is started again.
Once running the small amount that makes it down the stem is burnt right away and is not
noticeable. Small block Chevrolet engines had a bit of a problem with this due in part to their
stem seal design. They did not use a seal over the top of the guide instead using a square o-ring
between the spring retainer and the valve stem. Sometimes the seal would be damaged during installation
and a leak ensued. High mile or hour engines have more of a problem with this. I have a friend with a
1982 Pontiac that is equipped with a Chevrolet 305. It has 450,000Km on it and it does not use oil between
changes but does the puff of smoke on start up. The cylinder heads have NOT been off the engine since
it was assembled at the factory. My instinct on the aircraft engine start up oil smoke source is
the valve guide fit is designed loose so that they do not get tight and start to stick during operation.
These engines are designed for high load operation which causes the valves to get hot and the stems
will expand. Valves starting to stick open during a dog fight or over enemy territory in a bomber
would not be a good thing.

Dale Davies