Thielert (Diesel Engines)

On Feb 13, 11:14*pm, Peter wrote:
WingFlaps wrote

Why should that be? Generally, diesels are great at running at high
power for long periods and they are also *the powerplant of choice for
high reliability when fuel consumption is also an issue (ruling out
turbines) -or am I wrong?

Diesels are indeed great in applications where they can be designed
without weight issues e.g. ships and trucks.

It appears that their problems (Thielert specifically - there is no
other diesel actually flying any meaningful hours at present) are to
do with a lightweight car engine - 1.7 litres - being run at 130HP (or
close to it) for 100% of the time. The original car engine would be
running at 20-30HP, maybe 100HP very briefly in a big Merc on a German
motorway (no speed limits). But an aeroplane is a whole different
situation.


Yes I've heard that argument but I'd like to add/offer a different
POV. What is really stressful for engines is constant power changes
and the temperature fluctuations that involves. Therefore if your
engine can do 150 mph on a german autobahn for an hour or two it
should have no trouble doing it for a 4 hour flight in a plane. I also
agree that marine installations pay no/little attention to weight
(some performance boat installations aim to keep weight low) but tha's
just a design thing. The natural rpm/torque curve for diesels seems to
match a prop better too. The metals exists to make a diesel about the
same weight as a petrol engine so with a bit more hours under their
belt to identify weaknesses I can't see diesels not becoming the (?)
engine of choice (more range, less fuel quality issues). One more
think, no mixture control just rpm and pitch!
Imagine just setting rpm just one and then doing everything else with
pitch ;-) ...

Cheers

The weakness of the certification regime is that the engine only has
to show 2000hrs at 100% power,

I think it is 200 hrs @full throttle.

On Feb 14, 10:15*am, Peter wrote:
WingFlaps wrote

Yes I've heard that argument but I'd like to add/offer a different
POV. What is really stressful for engines is constant power changes
and the temperature fluctuations that involves. Therefore if your
engine can do 150 mph on a german autobahn for an hour or two it
should have no trouble doing it for a 4 hour flight in a plane.

IMHO it is a matter of degree. No road car will be actually run at say
75% power for more than minutes - you would kill yourself. Rally cars
get through engines at great rates, often breaking one in one race.
Whereas an aero engine just sits there the whole time at that power
setting. This may be just a matter of duty cycle but the end result
will be more stress and more wear.

The weakness of the certification regime is that the engine only has
to show 2000hrs at 100% power, and TBH you could probably get a lawn
mower engine to do that. Any engine that doesn't actually break (and
that is easy to achieve by design) and which meets the criteria (e.g.
starting at the certified ceiling) will be certified.

AFAIK there is no reliability requirement - that certainly applies to
avionics too.

I also
agree that marine installations pay no/little attention to weight
(some performance boat installations aim to keep weight low) but tha's
just a design thing. The natural rpm/torque curve for diesels seems to
match a prop better too. *

It may be but diesels have a lot more high frequency components in
their torque spectrum which plays havoc with props and gearboxes. So
they tend to need rubber shock absorbers.

The metals exists to make a diesel about the
same weight as a petrol engine so with a bit more hours under their
belt to identify weaknesses I can't see diesels not becoming the (?)
engine of choice (more range, less fuel quality issues). One more
think, no mixture control just rpm and pitch!

I agree but that is FADEC, not diesel. With FADEC on a Lyco you would
have similar benefits.


I was under the impression that diesels work by a governor that sets
RPM. The difference between desired rpm and actual rpm determines fuel
injected... In that case you could just set rpm and just adjust pitch
for speed/power. A single power knob (fadec) sets pitch and rpm
together?

Cheers

Peter,

AFAIK this was forced on them by all the failure


Sorry, but that's completely wrong. "Power by the hour" was a Thielert
concept from the get-go.

But I bet the "scrap" engines get reworked by Thielert

You lose.

Why is it that each and every innovation in GA is met by people
spouting OWTs and made-up speculation, when a minute or two of simple
research would provide the facts? What picture does that paint of the
pilot population and their "hangar talk"? How about a simple "I don't
know and that's why I keep quiet on this" instead of spouting made-up
negatives? Sorry, but this is really annoying.

--
Thomas Borchert (EDDH)

WingFlaps schrieb:

One more think, no mixture control just rpm and pitch!
Imagine just setting rpm just one and then doing everything else with
pitch ;-) ...

There's nothing Diesel specific on this.

Thomas Borchert wrote in
:

Peter,

AFAIK this was forced on them by all the failure


Sorry, but that's completely wrong. "Power by the hour" was a Thielert
concept from the get-go.

But I bet the "scrap" engines get reworked by Thielert

You lose.

Why is it that each and every innovation in GA is met by people
spouting OWTs and made-up speculation, when a minute or two of simple
research would provide the facts? What picture does that paint of the
pilot population and their "hangar talk"? How about a simple "I don't
know and that's why I keep quiet on this" instead of spouting made-up
negatives? Sorry, but this is really annoying.


There's nothing made up about "No sparks, no power" I wouldn't buy one
because of this. My club was looking at one ofr a Cherokee and decided
against it because of the lack of limp home capability.


Bertie

Bertie,

There's nothing made up about "No sparks, no power" I wouldn't buy one
because of this. My club was looking at one ofr a Cherokee and decided
against it because of the lack of limp home capability.


That's not the point I complained about.

There's a ton of failure modes on any Lyc or TCM that lack "limp home
capability". Same with the Thielert. The argument is a red herring.

--
Thomas Borchert (EDDH)

Thomas Borchert wrote in
:

Bertie,

There's nothing made up about "No sparks, no power" I wouldn't buy one
because of this. My club was looking at one ofr a Cherokee and decided
against it because of the lack of limp home capability.


That's not the point I complained about.

There's a ton of failure modes on any Lyc or TCM that lack "limp home
capability". Same with the Thielert. The argument is a red herring.


None of them regard electricity. The argument is sound.







Bertie

Bertie,

None of them regard electricity.


So what? Who decides electricity is somehow a more relevant failure
than others?

Look, you're obviously free to make that decision. Your club is, too.
But don't make it sound like there is something inherently wrong about
an engine just because it has different failure modes than the ones you
are used to.

--
Thomas Borchert (EDDH)

Thomas Borchert wrote in
:

Bertie,

None of them regard electricity.


So what? Who decides electricity is somehow a more relevant failure
than others?


I believe I just did.


Look, you're obviously free to make that decision. Your club is, too.
But don't make it sound like there is something inherently wrong about
an engine just because it has different failure modes than the ones you
are used to.


It has the same modes plus that one. And that one is avoidable, therefore
unacceptable.


http://goliath.ecnext.com/coms2/gi_0...FADEC-0-a.html


Bertie