I'm really interested in these new ZOCHE aero-diesels www.zoche.de.
They are air cooled, piston ported, radial configuration, turbo- and
supercharged, high pressure direct injection 2-stroke diesels. The
70hp weighs 55kg (121lbs) and uses 10.1L (2.68gal) per hour @75%. The
TBO is expected to be 2000hr and guite cheap too. Low parts count and
slow revs.

70hp is not enough for a two seater helicopter, but they do have 150hp
which could be very usable. Weight 84kg (185lbs) and consumption @75%
21.1L (5.57gal). Of course, the cooling could be a problem, especially
in howering in hot climates. Electric blover could be rather light and
quite effective.

So, here´s my question: How about using diesel fuel for cooling the
engine hot spots? The boiling point is as high as 160c (320F). This
could mean no exess weight int the form of coolant. Could the
injection pump be used to circulate this coolin fuel as well,
eliminating a need for another pump? This would also make sure that
the diesel is hot enough in col climates. The tank could possibly even
have some fins to cool the fuel down in the rotor wind. i suppose the
fuel will remain rather cool anyways, since the tanks surface will be
relatively large and made of thin sheet.

Actually, come to think of it. ZOCHE already has this system. A large
amount of the fuel is circulated through the motor to heat the fuel in
the tank to avoid gelling in cold climates. Is this circulation enough
to cool down a hovering helicopter in hot climates remains a question.

What do you think? Of course, I probaly should contact Zoche and ask
this and perhaps read theid FAQ more thoroughly.

The weight disadvantage (if there really is any at all) coulb be
compensated with the smaller amount of fuel required in the tank for a
flight.

Your thoughts? Is 2-stroke diesel the future (in the ultralights)?