Finally: The right-sized Thielert

In article ,
Dylan Smith wrote:

What's the reliability of software?

For embedded stuff, seemingly much better. Let's compare like with like:
old cars vs new cars. My first car had completely mechanical engine
components - mechanical points and condenser, vacuum advance etc. It
needed a great deal of maintenance to get any kind of reliability. It
was hard to start on cold, damp days.

In many ways, it was comparable to many aviation engines - high
maintenance and fiddly operation. Consider hot starts on even a brand
new Lycoming fuel injected engine - it needs a different procedure to a
cold start.

I don't consider my lycoming to be high maintenance. And it's dirt simple
to work on.


My current car's engine is completely electronically controlled. It
doesn't need frequent tune ups, lots of maintenance - basically, just
oil and filters. It starts just as well on a warm dry day as on a cold
damp day. It doesn't suddenly quit because something backed off and got
loose on an ignition component. It is so much more consistent than the
old completely mechanical engine as well as much more reliable. Not to
mention a great deal more fuel efficient and more powerful.

How much of the apparent improved reliability is due to improved hardware and
how much is due to software control?

btw - I've had two incidents where the engine in my car died. One was a failure
of the timing belt (rubber belt, believe it or not), and one was a failure of
the electronic control module. While the ECM was a hardware failure, it would
not be required in my first car which was entirely analog/mechanical.

--
Bob Noel
Looking for a sig the
lawyers will hate

On Mon, 05 Jun 2006 17:12:56 -0400, Bob Noel
wrote:

btw - I've had two incidents where the engine in my car died. One was a failure
of the timing belt (rubber belt, believe it or not), and one was a failure of
the electronic control module. While the ECM was a hardware failure, it would
not be required in my first car which was entirely analog/mechanical.

My first job out of engineering school in 1966 was with Garrett
AiResearch. A major product line was air data computers for military
and commercial jets. Inputs were aneroid, thermocouple, and, in the
case of angle-of-attack, direct vane-to-potentiometer. Outputs were
voltages representing various types of airspeed and altitude, along
with Mach number. Inside, they were all electro-mechanical -- cams,
helipots, and gears. The most pressing engineerig problem was
minimizing gear backlash. The guy at the desk next to mine in the
bullpen had been hired because he was a watchmaker.

Mean Time Between Failure was not bad, considering, but these were not
field-repairable units, and they cost a lot of money.

They would not scale well, technically nor economically, to today's
technology. Eventually, you have to decide that the only thing left
for old Nelly is the glue factory.

Don (Getting long-in-the tooth, himself)

Don Tuite wrote:
: My first job out of engineering school in 1966 was with Garrett
: AiResearch. A major product line was air data computers for military
: and commercial jets. Inputs were aneroid, thermocouple, and, in the
: case of angle-of-attack, direct vane-to-potentiometer. Outputs were
: voltages representing various types of airspeed and altitude, along
: with Mach number. Inside, they were all electro-mechanical -- cams,
: helipots, and gears. The most pressing engineerig problem was
: minimizing gear backlash. The guy at the desk next to mine in the
: bullpen had been hired because he was a watchmaker.

The inside of those old gas-turbine fuel controls is a wonder of
electromechanical design, too. My favorite has always been the three-
dimensional cams (picture a golf ball with a stylus touching it,
or a Selectric typewriter). The real wonder were the mechanical
fire control "computers" from WW2. I saw the one used in a main
battery turret of BB Massachusetts a few years ago. It is the size of
a coffee table, with perhaps 10 or 15 cranks on its perimeter to
set the inputs. It would take a minimum of 3 men to run it.
--
Aaron C.

In article ,
Dylan Smith wrote:

On 2006-06-09, Montblack Y4-NOT wrote:
Also, is there a rule of thumb to compare the new 135hp Diesel to 160hp or
180hp AvGas engines? On the face of it, it looks like 25-45 fewer hp with
the Thielert.

The difference is I think the propeller that comes with the Thielert -
it's constant speed, so all things remaining equal you get more takeoff
thrust per horsepower.

And you keep that power to a higher altitude (diesel is TURBO after all)
versus losing HP the moment you leave the ground (or the moment your
density altitude goes up)

On a 100dF day at any altitude, the difference would likely be in favor
of the thielert (especially with CS prop)

--
Chris Schmelzer, MD

("Aaron Coolidge" wrote)
They also expanded the STC for the 135hp unit to include a larger number
of PA28. Unfortunately on the PA28-180 the MGTOW is reduced from 2400 to
2150 lbs.


250 lbs!

Because of:
The engine swap weight difference?
A power difference?

....or a combination of the two?

Also, is there a rule of thumb to compare the new 135hp Diesel to 160hp or
180hp AvGas engines? On the face of it, it looks like 25-45 fewer hp with
the Thielert.


Montblack

On 2006-06-09, Montblack Y4-NOT wrote:
Also, is there a rule of thumb to compare the new 135hp Diesel to 160hp or
180hp AvGas engines? On the face of it, it looks like 25-45 fewer hp with
the Thielert.

The difference is I think the propeller that comes with the Thielert -
it's constant speed, so all things remaining equal you get more takeoff
thrust per horsepower.

--
Yes, the Reply-To email address is valid.
Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de

Chris Schmelzer wrote:
: In article ,
: Dylan Smith wrote:

: On 2006-06-09, Montblack Y4-NOT wrote:
: Also, is there a rule of thumb to compare the new 135hp Diesel to 160hp or
: 180hp AvGas engines? On the face of it, it looks like 25-45 fewer hp with
: the Thielert.
:
: The difference is I think the propeller that comes with the Thielert -
: it's constant speed, so all things remaining equal you get more takeoff
: thrust per horsepower.

: And you keep that power to a higher altitude (diesel is TURBO after all)
: versus losing HP the moment you leave the ground (or the moment your
: density altitude goes up)

: On a 100dF day at any altitude, the difference would likely be in favor
: of the thielert (especially with CS prop)

The CS prop helps at takeoff so that the engine can make rated power at
zero airspeed. When moving at cruise speed, it makes no difference if the
engine has a CS prop or a FP prop if the RPM is the same (the FP prop
has the advantage here, because it's lighter).

Cruise power from the O-360 180 HP engine is 75% or 135 HP, obtainable
up to 7500 foot DA. I wouldn't expect to see any performance advantage
at or below this altitude.

The real advantage of the diesel seems to be the vastly reduced fuel flow,
which lets the standard Cherokee tankage get over 9 hours of flying time
(this is the application we're talking about here).
--
Aaron C.

In article ,
Aaron Coolidge wrote:

When moving at cruise speed, it makes no difference if the
engine has a CS prop or a FP prop if the RPM is the same

It does if the pitch of the prop is different

--
Bob Noel
Looking for a sig the
lawyers will hate

Bob Noel wrote:
: Aaron Coolidge wrote:

: When moving at cruise speed, it makes no difference if the
: engine has a CS prop or a FP prop if the RPM is the same

: It does if the pitch of the prop is different

I should have stated my assumptions. I assumed that the airspeed and the
engine RPM/MP was the same, which leads to the conclusion that the
props would be interchangeable. Sorry about that.
--
Aaron C.