Why no new diesel radials?

In article .com,
" wrote:

On-Condition wrote:
wrote:
I'd be interested in reading anything on the practice of using diesel
and biodiesel in turbines your refering too. Did you read this
somewhere, or is that from experience? Have you actually heard of
Biodiesel being used in jets? Or is your reference to biodiesel gelling
related to cars?

The first time I heard of biodiesel was in a documentary about some
Halifax buses. They use fisheries byproducts. They have had to deal
with gelling, though Halifax winters are not all that cold.


To get a little OT, there is a lot of neat stuff being done right now
with biomass hydrocarbons. (veggie oil, fish oil etc.) The bugaboo
seems to be injector coking in direct injection engines, though actual
experienced rate of coking from one motor to the next is a point of
huge debate in the alternative fuel crowd these days. Indirect
piston-pump injected engines will apparently run on straight veggie oil
reasonably well with few ill effects or modifications.

These guys are heating the oil and running straight to the motor.
Apparently the added energy causes the long stranded molecules to burn
cleaner which is what averts the coking. I'd be highly interested in
seeing somebody do that with an allison 250 and what the results were.

No knowledge or experience involving biodiesel in turbines, but winter
diesel is/was being used by DHC6's in the artic about half of the time
since turbine fuel is only available at the main bases. Their PT6's
are in fact derated to 600 shp as suggested
for another airplane type. I never saw any technical documentation
on this, it being common practice.

Regarding Hydraulic lock I was thinking more preventatively. Like going
to the hanger once a week and walking through a few blades regardless
of whether you were actually going flying. Though I would figure at
15/1 it would require much less oil to frag the engine than at 7.5/1.

No doubt, but I think either ratio will suffice as soon as you start,
especially with one of the inertial starters that just won't stop
once engaged. Walking the props used to be mandatory in the military
where even a desk gets a walkaround twice a day ;-)

My point was that diesels start at 15/1 and gas engines are around 7/1
or 8/1 So oil leakage in a diesel should increase cylinder pressure
way faster than it would in a gas engine. For example: an ounce of
excess oil in a gas engine my increase the cylinder pressure by 10% or
so, the same ounce in a diesel of the same displacement would increase
the pressure by much more than 10%. At a higher pressure the mass of
the air displaced by a constant uncompressable volume (the oil)
increases.

Obviously you don't have to fill the cylinder completely with oil to do
a lot of damage. Just increase the pressure in the jug to the point
were rings crack or bolts become fatigued. With the four strokes you
walk the blades, the valves open and the oil that leaked past the lower
rings dribbles into the exhaust stack. With the Zoche there is no
valve, so once oil dribbles into the cylinders past the rings, how do
you get it out? I would guess the only way to clear a lock or to
prevent an over-pressure from a partial hydraulic lock would be to
remove the injector and cycle the engine. Or perhaps the porting design
prevents it? I don't know.

Zoche is a 2-cycle engine, so there is no oil in the crankcase to leak
into the cylinder. Actually, there is no airplane that has ever flown a
Zoche, either, for that matter. He has been around since at least 1980
and has never flown the engine!


I saw that there is a diesel CH701 flying with the engine out of a
Mercedes Smart. I'd love to read more about that bird but haven't been
able to find any good info.

-Matt

wrote
With the Zoche there is no
valve, so once oil dribbles into the cylinders past the rings, how do
you get it out? I would guess the only way to clear a lock or to
prevent an over-pressure from a partial hydraulic lock would be to
remove the injector and cycle the engine.

You don't have to walk a prop through, that's for sure. First it will have
to have a prop, and on an airplane. That has not happened yet, nor will it
likely ever.

Start looking at other engines, because if you wait for this one, you will
grow old waiting.

Legal disclaimer:
Just my opinion, of course. g
--
Jim in NC

Orval Fairbairn wrote:
In article .com,
" wrote:

On-Condition wrote:
wrote:

SNIP


Obviously you don't have to fill the cylinder completely with oil to do
a lot of damage. Just increase the pressure in the jug to the point
were rings crack or bolts become fatigued. With the four strokes you
walk the blades, the valves open and the oil that leaked past the lower
rings dribbles into the exhaust stack. With the Zoche there is no
valve, so once oil dribbles into the cylinders past the rings, how do
you get it out? I would guess the only way to clear a lock or to
prevent an over-pressure from a partial hydraulic lock would be to
remove the injector and cycle the engine. Or perhaps the porting design
prevents it? I don't know.

Zoche is a 2-cycle engine, so there is no oil in the crankcase to leak
into the cylinder. Actually, there is no airplane that has ever flown a
Zoche, either, for that matter. He has been around since at least 1980
and has never flown the engine!



Err. You sure about that? It is a 2 stroke DIESEL. The fuel is directly
injected into the cylinder, not passed through the crank case like gas
2 stroke designs. So if there is no oil or fuel in the crankcase, how
is it lubricated?

Ditto on the engine being vapor-ware. I started another thread on small
diesels accordingly. I'm interested in Fords TDCi engine and the
Mercedes smart diesel. I found 2 light aircraft in germany using the
smart engine, but I haven't found any specs on it as a crate engine
yet.

-Matt

SNIP

"Orval Fairbairn" wrote in message
news
In article .com,
" wrote:

Zoche is a 2-cycle engine, so there is no oil in the crankcase to leak
into the cylinder. Actually, there is no airplane that has ever flown a
Zoche, either, for that matter. He has been around since at least 1980
and has never flown the engine!


The Zoche does have oil in the crankcase. All the 2-stroke diesels
currently under development use supercharger/turbochargers to force air into
the cylinders and not crankcase pumping so the crankcase contains oil just
like a 4-stroke.

I suspect that a problem with the Zoche is that it uses 'slipper rods', 4 of
which connect with a single crank journal instead of the 'master/slave' rod
system. This leaves only a small contact area at the rod big end. Diesel
bottom ends need to be very robust and this doesn't sound like it is.

Bill Daniels

On Thu, 22 Sep 2005 21:01:34 GMT, (me) wrote:

Just what is an "inertial starter"?

I have seen references to them, mostly in literature about
airplanes built before the 1940s. But I have never seen a
description of one, or an explanation of how it is different
from any other type of starter.

In order to understand what an inertial starter is, you have to be
able to understand what an inertia wheel is. An inertia wheel is a
wheel that has most of it's mass out along the perimeter such that
it's mass tends to keep the wheel spinning. Gyroscopes utilized tiny
inertia wheels. A child's toy top is another example of an inertia
wheel.

It's hard to spin up such a wheel because of the mass, but once it's
spinning it tends to want to remain spinning.

Lots of early engines used inertial starters because very few had
electrical systems. The pilot or ground crewman would insert a hand
crank into the side of the engine and one or often two people would
struggle to wind the inertial wheel up to speed. While they're doing
this, you can hear the wheel begin to shriek as it gets going faster
and faster. It usually took two guys to get the inertial wheel on the
Me 109 up to speed.

Once up to speed, the pilot primes the engine, turns on the mags and
clutches in the engine to the inertial wheel. You can hear the sound
of the inertia wheel dramatically changing as it's dragged down by the
mass of the engine it's now turning.

Hopefully the engine starts before the inertia wheel has lost it's
momentum.

If not, it's back to the hand crank and spin it up again.

Get ahold of the old movie "Task Force" with Gary Cooper and Walter
Brennan. The early biplanes they "fly" are started using an inertial
starter. Two ground crewmen crank it to spin it up.

Corky Scott

wrote in message
...
On Thu, 22 Sep 2005 21:01:34 GMT, (me) wrote:

Just what is an "inertial starter"?
SNIP
Lots of early engines used inertial starters because very few had
electrical systems. The pilot or ground crewman would insert a hand
crank into the side of the engine and one or often two people would
struggle to wind the inertial wheel up to speed. While they're doing
this, you can hear the wheel begin to shriek as it gets going faster
and faster. It usually took two guys to get the inertial wheel on the
Me 109 up to speed.

Once up to speed, the pilot primes the engine, turns on the mags and
clutches in the engine to the inertial wheel. You can hear the sound
of the inertia wheel dramatically changing as it's dragged down by the
mass of the engine it's now turning.

Hopefully the engine starts before the inertia wheel has lost it's
momentum.

If not, it's back to the hand crank and spin it up again.

Get ahold of the old movie "Task Force" with Gary Cooper and Walter
Brennan. The early biplanes they "fly" are started using an inertial
starter. Two ground crewmen crank it to spin it up.

Corky Scott
--------------------------------
Reminds me of starting an old Stearman w/inertial starter. I don't recall
the engine size, but it wasn't too difficult. Still, some of the young lads
used to make a production of two-handed cranking; especially when there were
sweet young things looking.

Then, one day, the owner's wife came out to the plane to crank it (scenic
ride op). She stood by the front chatting w/her husband while using just
her left hand to crank the inertial starter; quite casual, not a drop of
sweat.

Talk about surprised looks on the faces of the guys who tried to convince
everyone it was very macho to be able to crank it up. :-)

Michael Pilla

On Mon, 26 Sep 2005 18:51:32 GMT, "Michael Pilla"
wrote:

wrote in message
.. .
On Thu, 22 Sep 2005 21:01:34 GMT, (me) wrote:

Just what is an "inertial starter"?
SNIP
Lots of early engines used inertial starters because very few had
They had a very distinctive sound. Sorta like a dual pitch whine that
dropped abrupty when the engine clutched in. Many of the old movies
used that sound for aircraft engines starting that didn't even have
inertial starters. I think they thought all airplane engines back
then were supposed to sound that way.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Not all engines with inertial starters were hand cranked. Some used an
electric motor to operate the inertial flywheel i.e T6/SNJ, TBF/TBM, and
I believe even some DC3/C47.
Skip Schipper

This goes way back to the early 50's, but I seem to remember the R985 on a
BT-13 with an inertia starter. You turned the switch to "energize" and
listened to the nice music, then to "engage" and listened to even nicer
music. Finally you had the agallon---agallon--agallon---idle of the R985

Paul
N1431A


"

Not all engines with inertial starters were hand cranked. Some used an
electric motor to operate the inertial flywheel i.e T6/SNJ, TBF/TBM, and
I believe even some DC3/C47.
Skip Schipper

Tri-Pacer wrote:

This goes way back to the early 50's, but I seem to remember the R985 on a
BT-13 with an inertia starter. You turned the switch to "energize" and
listened to the nice music, then to "engage" and listened to even nicer
music. Finally you had the agallon---agallon--agallon---idle of the R985

Paul
N1431A

That is the best description of that sound I have ever come across.

Dan, U.S. Air Force, retired