On Jun 16, 11:42*am, wrote:
On Jun 15, 9:42 pm, Le Chaud Lapin wrote:

On Jun 15, 3:30 pm, wrote:
* * * * *Adding electronic controls to something like a trim tab on a
lightplane is one of those "better" ideas that has no basis in
reality. It adds complexity, which adds failure points and cost and
weight, none of which are welcome.

I hear a lot of mechanics say this about cars. *I think there should
be a qualification made thos these types of statments...

* * * A good example of an "improved" system in lightplanes was the
electric flaps in 150s and 172s. The old system involved a lever and
some cables. The lever was pulled up to 10, 20, 30 or 40 degrees, so
the lever was the flap position indicator and the cables were the only
other weight involved. The effort to pull the lever up was a point of
complaint with some feeble pilots.
* * * The electric flap system has a gearmotor driving a jackscrew,
microswitches on the jackscrew nut sleeve to limit its travel, a DPDT
momentary switch on the panel, a special wirewound potentiometer in
the wing to follow the bellcrank to drive a flap position indicator on
the panel, and cables and pulleys from the right wing (where the motor
is) to the left wing to drive the left flap.
* * So now we have the same cables and pulleys (although a little less
of them), a switch that fails regularly (the springs that center it
break), and cable bundle whose connectors at the wing roots and flap
motor assemble get wet and corrode), microswitches that get oil in
them off the jackscrew threads (meaning that sometimes the flaps won't
come down, or worse, that they won't retract on a go-around), a five-
pound motor and jackscrew (which lowers useful load), a special
potentiometer that wears out and costs more than $500 from Cessna and
isn't available anywhere else (bought one a few years ago), a flap
position indicator that costs $475 (bought one last year), and the
loss of the option of raising the flaps right at touchdown to get max
weight on the wheels for braking on short strips, which annoyed no end
a lot of the bush guys who relied on that feature. At least Cessna
left things alone in the 180 and 185, airplane flown by real pilots
who didn't mind pulling a lever.
* * * You can decide if this was an "improvement." Lots of owners who
have had to have this system fixed don't think so.

This is an excellent anecdote. It illustrates something I tried to
point out in another post a few months ago:

No potentiometer should cost $500.

If it is used to make sure the Queen of England does not slip and fall
while walking down a steep flight of stairs, it should still not cost
$500.

This same phenomenon is present today. I have a bunch of aviataion
related newspapers and magazines that I read see parts and what they
cost. I look especially at electronics parts. The prices are
outrageous. Whatever the excuses - regulation, low-volume - these
prices are simply ridiculous. In many cases, the exact same product
is sold in a different consumer context for a 40% mark-up.

There is rigidity of innovation in the entire aviation industry. Much
of the technology really is 50 years old. New technology is
integrated in patchwork fashion at a sloth's pace. There are many
places where metal is used but plastic would be just as good, but
plastic cannot be used because the designer insists on adding plastic
incrementally.

Much of the new technology's benefit is only realized when gross re-
examination of the design of the system is permitted. Otherwise one
ends up with a $200,000 aircraft with a 90% cost-reduction on a part
that originally cost $400, making new cost $199,960. What good is
that?

This is why I see opportunity. Electrical, and especially software
engineers, have great opportunity to eliminate mechanized control in
aviation (and many other industries for that matter). But as implied
by your anecdote, it should not be done as an afterthought, after
months of haggling where the engineering department finally decides to
"integrate" more electronics, with foot-dragging, coporate in-
fighting, special hiring of disposable engineers skilled in
electronics to contribute to a system that is fundamentally regarded
by the old guard as mechanical...it should be done in context where
the engineering team is _fundamentally_ predisposed to employ software
and electronics at low-cost throughout.

I thought http://www.terrafugia.com was a team, filled with bunch of
MIT grads, that might take this approach, but they themselves stated
in one article that they would refrain from going after the Big-Kill,
meaning pervasive software systems throughout. I think this is
unfortunate.

-Le Chaud Lapin-