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)?

On 23 Mar 2005 05:44:32 -0800, Max Kallio > wrote:
>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.


Use Google to look up the thread "Dumping engine heat into fuel tanks"
in rec.aviation.homebuilt. The short answer is that if you tried
this, you would very quickly boil away all of your fuel.

Max Kallio wrote:

> 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)?

Lessee. At 70 hp, 50% would be waste heat. 5 gal tank would carry
off 26.5 Kilowatts, boiling the fuel oil in about 5 minutes, not
counting other heat removal processes. The cooling jacket and
contents would interfere with the normal air cooling fins. Nope.

Radial 2 stroke diesel? gotta love it. Let's see one on a dyno.

I want to see an engine cooled with injected water timed at maybe 45
degrees after tdc. The pre heated cooling water would boil,
absorbing heat, possibly increasing pressure in the cylinder, then
it could condense after exhaust in the muffler giving up it's heat,
then being recycled through the engine.

That combined with lean burn mixtures might benefit emissions, too?

Has it been tried?

Terry K

On 2005-03-23 08:44:32 -0500, (Max Kallio) said:

> 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.


The Zoche diesel has been coming to the experimental shows and tempting
dreamers for, I believe, around twenty years. He has yet to ship a
single motor to a customer, but he's put the touch on the state of
Bavaria, among others, for venture capital.

To put it another way, Thielert started about fifteen years after this
guy and has diesel engines certified and in production in flying
aircraft. SMA also, but they don't have a launch customer. In their
case it is due to normal teething on the motor -- and they are a very
well-resourced outfit.

Take a look at Zoche's FAQ and specs and you will see that "specs" in
this case stands for "speculations." An engine that hasn't been built
and hasn't been tested and that still is in relatively early stages of
design.

My personal advice is: if you are going to be doing an experimental
helicopter, you should do like old Igor did on the VS-300 and buy a
motor from someone that has been selling aircraft motors for a while,
and actually delivering them. I've seen a lot of experimental projects
come a cropper because someone was on an unscientific quest to
revolutionise both airframe and powerplant.

For instance, the only auto engines that seem to have adapted well to
aircraft use, despite the theoretical benefits of some of the Honda
motors or the various Wankels from mazda, are the ones that

Max, and all, you gotta pick a hill to die on. Some fights are not
worth fiighting. If your interest is in powerplant development for
rotorcraft, acquire a fully-sorted and proven-maintainable airframe,
and reregister it in the Experimental R&D category, and go to town with
your motor. And I would pick something with very benign autorotation
characteristics is I were doing motors R&D, just as a simple matter of
risk abatement. I.e. a Schewizer might serve you better than a Robbie
for that purpose, even though the R22 might otherwise be ideal.

It's essential scientific method to monkey with only one variable at a time!

cheers

-=K=-

Rule #1: Don't hit anything big.