Thielert (Diesel Engines)

On Tue, 19 Feb 2008 17:15:11 +0000, David Lesher wrote:

Well, if "old" Diesels made sense for GA use, you'd a thunk there would
be lots by now. There don't seem to be.

My understanding is that this has, until recently, been a weight issue.

[...]

There are real issues with starting over, and ignoring everything other

But there's a great deal of space between retasking and "starting over,
and ignoring everything other people found out The Hard Way". So this is
something of a strawman argument.

[...]

There are significant advantages to engines that run closed-loop, and
FADEC control systems add others. Yes, it's best to have zero single
points of failure in any design, be it a Bonanza or a highway bridge,
[or flywheels] but that's not always possible.

This appears to me to be another strawman. Sure, zero SPOF is not always
possible. But how does that impact the goal of minimizing the SPOF?
Your later comments about granite cumulus would appear to be of the same
sort. Hyperbole, perhaps?

[...]

(The alternative, by the way, is where GA is now -- 1950's technology
holds forth; outside of the avionics, and it run on 1960-design
alternators.)

This might also be explained by the size of the market. Also, don't
ignore the "pause" imposed by the liability issue. Now that small GA is
"moving again" we are seeing innovation. Avionics has been getting a lot
of attention over the past few years thanks to advancements in
electronics, and it appears that we're now seeing the result of evolution
in the engine market.

- Andrew

Andrew Gideon writes:

Well, if "old" Diesels made sense for GA use, you'd a thunk there would
be lots by now. There don't seem to be.

My understanding is that this has, until recently, been a weight issue.

Note that over the last ~30 years, cars too have come under intense
scrutiny over weight, and where to (and not to...) save. It includes
things such as making the brake cylinder{s} from aluminum vice steel,
reducing the capacity of the automatic transmission case/sump to use less
ATF, etc. and many smaller gains. All those ounces add up.

There are significant advantages to engines that run closed-loop, and
FADEC control systems add others. Yes, it's best to have zero single
points of failure in any design, be it a Bonanza or a highway bridge,
[or flywheels] but that's not always possible.

This appears to me to be another strawman. Sure, zero SPOF is not always
possible. But how does that impact the goal of minimizing the SPOF?
Your later comments about granite cumulus would appear to be of the same
sort. Hyperbole, perhaps?

Call them what you want. Zero SPOF is almost never possible. The question
is, what do you gain, and how do you mitigate the new risk? That twin
with the dead battery is a good example; it was bad engineering to depend
on the one main battery for the FADEC's, but with an added gel-cell for
them alone, that flaw is 99% gone. [You need some automagic battery test
as part of startup.]


(The alternative, by the way, is where GA is now -- 1950's technology
holds forth; outside of the avionics, and it run on 1960-design
alternators.)

This might also be explained by the size of the market. Also, don't
ignore the "pause" imposed by the liability issue. Now that small GA is
"moving again" we are seeing innovation.

You think it's moving? I'll let others speak their mind {Jay, Donnie
etc.}, but from outside, it looks to me like it's reaching stall
speed. GA {in the US} faces large fuel cost increases, an aging fleet,
airport losses to developers, and an overall grim economy. And, sooner
than you think, I bet leaded gas will vanish. Then what?

Does AOPA etc. try to estimate the # of GA hours flown per year?
I can see two ways to swag same: ATC data and total gallons of 100
Octane sold. Both have flaws but it might be interesting to see a
10-20 year trend.

And I'm not one to discount the coffin corner of low volumes plus
regulatory overhead. But what I observe is not a pause but a fergett-it
by new vendors coming from such. YMMV.

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Andrew,

You need to let go of what you Americans consider
to be a "diesel". That's good for trucks and boats,
but not for efficient small cars - and airplanes.

So how are we to classify the SMA engine? A diesel, but not good for
airplanes? Or not a diesel?

Ah, let's just say that was not my most coherent posting ;-)

But of course you're correct about this being an "old style" engine.
That's rather the point. Does that make it a poor choice for aircraft?
Numerous articles about flight test, along with commentary by current
users, suggests that the SMA engine works quite well in a 182.

Hmm. I've heard and read quite the opposite. SMA has never met their goals
with regard to certification both of the engine itself and with airframes.
They had a ton of cooling problems, AFAIK they still have altitude
restrictions which are rather low for a turbocharged engine. They had an
airframe from Cirrus to fit the engine to and Cirrus was more than willing
to go forward with them, but in the end they gave up because of a mountain
of problems.

I suspect that it's far cheaper to merely retask an
existing engine rather than design anew.

Indeed it is. Frank Thielert has described the calculation in a German
aviation magazine in detail (from a slighly biased POV, of course ;-)). Very
interesting.

But that doesn't address the
possibility that the retasked engine may not be as appropriate for the
new task as the engine designed specifically for that task.

True. I'm just looking at the evidence so far. Number of aviation diesels
designed from a car engine: 1 (I think). Percentage of those flying in
numbers for several years: 100. Number of aviation diesels designed from the
ground up: 3 (? - Zoche, sma, Deltahawk). Percentage flying in numbers for
several years: 0.

And I'd
suggest an engine with more failure modes is less desirable - esp. for SE
aircraft - than an engine with fewer failure modes.

Sure. But just because Bertie says it's so, doesn't mean the Thielert does
in fact have more. Different ones, for sure.

I also believe that Thielert's ability to get their engines into the
market sooner - another benefit of retasking - has made a big difference
over SMA.

True. They started into it at about the same time, though. sma seems to have
run into a wall of problems.

Or are there truly technical reasons
for the Thielert to be chosen over the SMA? Might OEMs still buy into
the SMA (Cessna may not have much choice for 182s, since I don't think
Thielert has a good replacement for the O-470)?

I think they really tried. I know Cirrus did. Cessna did (as an OEM), too.
Socata did.


--
Thomas Borchert (EDDH)

Thomas Borchert writes:


True. I'm just looking at the evidence so far. Number of aviation diesels
designed from a car engine: 1 (I think). Percentage of those flying in
numbers for several years: 100. Number of aviation diesels designed from the
ground up: 3 (? - Zoche, sma, Deltahawk). Percentage flying in numbers for
several years: 0.

Well, today yes. But Thomas may recall the Luftwaffe Junkers Ju86 used
2-cycle Diesels. I'm sure they did not use FADECs....





--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

On 21 Feb., 01:10, Peter wrote:
Thomas Borchert wrote

True. I'm just looking at the evidence so far. Number of aviation diesels
designed from a car engine: 1 (I think). Percentage of those flying in
numbers for several years: 100. Number of aviation diesels designed from the
ground up: 3 (? - Zoche, sma, Deltahawk). Percentage flying in numbers for
several years: 0.

Unfortunately this deduction fails to take into account the real
market.

I could not disagree more with your line of reasoning. ALL players I
mentioned come from outside the US (apart from Deltahawk, I think).
All entered the field either at the same time as Thielert or well
before. Only Thielert has managed to gain any traction in the market,
including just recently winning Cessna as an OEM on the 172. One just
can't claim that this is all clever marketing and fast action. It's
the way the engine is built.

BTW, note that Diamond has now started building its own diesel engine.
Two remarks regarding that:

1. I guess they don't think the Thielert is perfect, either.
2. Wanna guess what their design is based on? Yep, a Mercedes car
engine.

Thomas

"Peter" wrote

And what new aircraft are there? It's difficult to sell into the USA
(e.g. to Cessna) because a U.S. aircraft maker has to be really
careful beta testing new engines (see the Rotax fiasco; the name still
stinks in the USA) and because of the U.S. not-invented-here syndrome
(call it patriotism if you like but it is an awfully powerful tool to
keep people buying the old engines).

Correct deduction, wrong reason.

The name Rotax stinks because of the quality of the product, not because of
where it was invented. It is not tough enough to stand up to the rigors of
a plane being flown all day long as a trainer.

So spare us the "we won't buy it because it is not American" crap. I'm sick
to death of hearing that.

Add to that, the fact that Rotax did not get a service capability built up
before they brought the Rotax powered planes here. Few people knew how to
work on them.

Some companies that are selling light sport aircraft with Rotax engines are
doing pretty well, but they are providing the necessary training for working
on the engines. Many people that own the Rotax engines privately love them.

I admit that I am still scared of them. Too many poor experiences with the
smaller Rotax engines to believe that the bigger aviation versions could be
enough better to be worth my life. Nothing to do with patiotism.
Self-preservationism.
--
Jim in NC

On Wed, 20 Feb 2008 11:53:10 +0100, Thomas Borchert wrote:

So how are we to classify the SMA engine? A diesel, but not good for
airplanes? Or not a diesel?

Ah, let's just say that was not my most coherent posting ;-)

Fair enough. I'm sure all those old fashioned diesels accept
your apology laugh.


But of course you're correct about this being an "old style" engine.
That's rather the point. Does that make it a poor choice for aircraft?
Numerous articles about flight test, along with commentary by current
users, suggests that the SMA engine works quite well in a 182.

Hmm. I've heard and read quite the opposite. SMA has never met their
goals with regard to certification both of the engine itself and with
airframes.

I'm not sure what you mean. Scheduling? It's no big shock to me
when aviation schedules are extended (esp. regarding certification
issues which necessarily involve the FAA). But the SMA is currently
certified in at least a couple of 182 models. Plus, users seem happy
with it.

My club has been looking into SMA-ing a 182Q, so we've collected some
opinions from existing customers. Both the names we received from SMA
and those we found ourselves (ie. via CPA's forum) seemed to praise the
engine. Oddly, I have to admit, this praise came even from a couple of
the very first recipients. This is odd to me because they seemed to have
a lot of "start up" problems. Perhaps that SMA handled these at no cost
swayed the customers' opinions, but I've have considered that a necessity
for so new a product.

They had a ton of cooling problems, AFAIK they still have
altitude restrictions which are rather low for a turbocharged engine.

The restriction is FAA/US only. In the EU, those are regularly
"violated". So they appear less an engine issue and more a certification
issue.

They had an airframe from Cirrus to fit the engine to and Cirrus was
more than willing to go forward with them, but in the end they gave up
because of a mountain of problems.

Given the timeframe that SMA and Cirrus were involved together, I can
absolutely understand that.

[...]

But that doesn't address the
possibility that the retasked engine may not be as appropriate for the
new task as the engine designed specifically for that task.

True. I'm just looking at the evidence so far. Number of aviation
diesels designed from a car engine: 1 (I think). Percentage of those
flying in numbers for several years: 100. Number of aviation diesels
designed from the ground up: 3 (? - Zoche, sma, Deltahawk). Percentage
flying in numbers for several years: 0.

But all of this could be explained by marketing and timing.


And I'd
suggest an engine with more failure modes is less desirable - esp. for
SE aircraft - than an engine with fewer failure modes.

Sure. But just because Bertie says it's so, doesn't mean the Thielert
does in fact have more. Different ones, for sure.

Bertie might be like that proverbial clock, too: correct once or twice a
day. What failure modes does the SMA have that the Thielert lacks? That
the latter requires electrical power for the FADEC is clear, but what's
"the other side"?

[...]

Or are there truly technical reasons
for the Thielert to be chosen over the SMA? Might OEMs still buy into
the SMA (Cessna may not have much choice for 182s, since I don't think
Thielert has a good replacement for the O-470)?

I think they really tried. I know Cirrus did. Cessna did (as an OEM),
too. Socata did.

But now that the SMA is certified, what might happen? Or is this all for
naught now that Continental is [claiming to be] entering the diesel
market?

- Andrew