Mechanics of Elevator Trim. In Detail.

On Jun 15, 1:30 pm, wrote:
On Jun 9, 12:36 pm, Le Chaud Lapin wrote:

On Jun 9, 1:19 pm, Gig 601Xl Builder
You never learned of trim until MSFS and you are going to design an
airplane. Fabulous!

Is it really necessary to understand the particular way it was done in
C172 to achieve the same result?

The same thing could be achieved using more electronics, less
mechanics, and the controls might be entirely different.

#1. Learn to fly first.
#2. Study the construction of aircraft, best done by taking an
aircraft maintenance course.
#3. THEN think about designing an airplane. No worthwhile design that
I'm aware of has ever been put forward by someone who was unfamiliar
with the way things are now and why they are that way, but I have seen
designs built by folks who "knew better" than everyone else. One of
those, built by a local guy who would take no constructive criticism
of his ideas, stalled at circuit altitude and dropped him, hard, on
the surface of the earth. He was such a stubborn guy that he got up
and walked away, but he neither built nor flew any more airplanes.
Needless to say, this design was neither inspected nor approved nor
licensed to any standard whatever.
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. It is no more accurate than manual
trim.
Dan

I concur with Dan on his last two posts, yeah that's
rare, but anyway...
I designed and tested (models) of a fantastic plane,
but when I chose between putting my wife and kids
in my fantastic plane or into a proven (safe) C172,
I chose the C172.
Here's why: If my machine cracked up due to a fault
in my design, and killed my family except for me, I'd
feel obligated to shoot myself, though I wouldn't.

That said, build your machine, put it threw it's paces
then take on a passenger, who knows what the tag
"EXPERMENTAL" means on the side of the A/C,
and have fun.
Ken

On Jun 15, 6:34*pm, "Ken S. Tucker" wrote:
I concur with Dan on his last two posts, yeah that's
rare, but anyway...
I designed and tested (models) of a fantastic plane,
but when I chose between putting my wife and kids
in my fantastic plane or into a proven (safe) C172,
I chose the C172.
Here's why: If my machine cracked up due to a fault
in my design, and killed my family except for me, I'd
feel obligated to shoot myself, though I wouldn't.

That said, build your machine, put it threw it's paces
then take on a passenger, who knows what the tag
"EXPERMENTAL" means on the side of the A/C,
and have fun.
Ken-

Perhaps there will not be time in my life to see a design realized,
but if I were so fortunate, I would probably do just that...get in it
myself first.

But before doing that, I would let it fly itself over a desert, since
controls would be software anyway.

-Le Chaud Lapin-

On Jun 15, 9:16 pm, Le Chaud Lapin wrote:
On Jun 15, 6:34 pm, "Ken S. Tucker" wrote:

I concur with Dan on his last two posts, yeah that's
rare, but anyway...
I designed and tested (models) of a fantastic plane,
but when I chose between putting my wife and kids
in my fantastic plane or into a proven (safe) C172,
I chose the C172.
Here's why: If my machine cracked up due to a fault
in my design, and killed my family except for me, I'd
feel obligated to shoot myself, though I wouldn't.

That said, build your machine, put it threw it's paces
then take on a passenger, who knows what the tag
"EXPERMENTAL" means on the side of the A/C,
and have fun.
Ken-

Perhaps there will not be time in my life to see a design realized,
but if I were so fortunate, I would probably do just that...get in it
myself first.
But before doing that, I would let it fly itself over a desert, since
controls would be software anyway.

That sounds like a good idea.
A 1/4 scale is good, it can be powered by a cheap
chainsaw motor.
Do you have any general ideas for a lay-out yet?

-Le Chaud Lapin-

If you lived close by, I'd give you some help.
Ken

On Jun 15, 3:30*pm, wrote:
On Jun 9, 12:36 pm, Le Chaud Lapin wrote:

On Jun 9, 1:19 pm, Gig 601Xl Builder
You never learned of trim until MSFS and you are going to design an
airplane. Fabulous!

Is it really necessary to understand the particular way it was done in
C172 to achieve the same result?

The same thing could be achieved using more electronics, less
mechanics, and the controls might be entirely different.

#1. Learn to fly first.
#2. Study the construction of aircraft, best done by taking an
aircraft maintenance course.

I think the difference here is that I am not looking for something
evolutionary. I think that is a dead-end road. There is so much in
the world to learn, that if a researcher were to take this approach to
every attempt to advance a field, breakthroughs would hardly occur. In
fact, I think it is precisely this mentality that makes the current
process not as fruitful as it could be.

Perhaps the epitome of this type of thinking can be seen on the first
page of this site: http://www.roadabletimes.com/

Question: "How does one make a flying car?"
Answer: "One could start by taking a car and putting wings on it."

This is silly, and it is obvious to everyone now that it is silly, but
to at least one individual, it was not. That man spent countless
hours purusing a dream that would never materialize because his
approach was fundamentally flawed.

Now if one were to take the objectives of CAFE/PAV to make a new type
of vehicle:

http://www.cafefoundation.org/v2/pav_home.php

..and begin by starting with a "reference" design, that person might
share the same fate of he who made the "flying car" of the first link.

Some of you think it is foolish to embark upon a research path without
having a thorough understanding of what has been done. I think not. I
think, in many cases, one can be too familiar with what has been
done. Common knowledge does not necessarily liberate the mind. It
might stifle it. And if it seems arrogant not to follow the path
already tread by great designers, I think it would be even more
arrogant, after having studied what the great designers have done, to
think that one would make extraordinary advancements beyond what those
greats have done, within the same path.

True breakthroughs often require a breach of continuity, and
significant technological advancement occurs when those breaches occur
at semi-regular intervals.

A good example is vacuum tubes versus transistors.

Absolutely zero knowledge of vacuum tubes is required to understand
transistors. There is a bit of ancillary knowledge, like
thermodynamics, band-theory, and electrodynamics that is immediately
transferrable from vacuum tube theory to transitor theory, but
knowlege of vacuum tubes themselves is inessential.

But both act as amplifiers. Both essentially accomplish the same
thing as elements in a larger system.

Now imagine, toward the end of the vacuum tube era, that someone had
proposed to make a new type of amplifier that would be better on
almost every imaginable axes, but that person had no intention of
spending any time studying vacuum tubes. Would it have been necessary
to study vacuum tubes?

This is essentially what you are saying about PAV's. You are saying
that, the best way to proceed is to learn all I can about convential
aircraft. Why is that necessary? It presumes that the method by which
the objective is accomplish is similar to what has already been done
(tractor model, for example).

A better approach might be to make no assumptions at all, but focus on
the end result, then work backward, evaluating extant technologies
(applicable in, say, 2010), keeping a respectible distance from the
prevaling models of aicraft design, just as transitor theorist might
deliberately keep a respectable distance from vacuum tubes.

#3. THEN think about designing an airplane. No worthwhile design that
I'm aware of has ever been put forward by someone who was unfamiliar
with the way things are now and why they are that way, but I have seen
designs built by folks who "knew better" than everyone else. One of
those, built by a local guy who would take no constructive criticism
of his ideas, stalled at circuit altitude and dropped him, hard, on
the surface of the earth. He was such a stubborn guy that he got up
and walked away, but he neither built nor flew any more airplanes.
Needless to say, this design was neither inspected nor approved nor
licensed to any standard whatever.

A good way to win is avoid races where number of entrants is 1. It
would be extremely hard for someone in my opinion to make notable
improvement on existing aircraft design. The world is filled with high
skilled, highly trained, thoroughly experience, professional aircraft
designers who spent their lifetimes aiming for that extra 5%.

Extra 5% is not going to make a PAV, so if there is any chance of
succeeding at all, one should avoid paths where best-case scenario is
a 5% improvement.

* * * * *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:

"It adds complexity, which adds failure points and cost and weight,
none of which are welcome, unless the person integrating the
electronics is an electrical engineer unperturbed by the idea of
adding electronic controls to a mechanical system."

It is no more accurate than manual
trim.

Perhaps not. But a computer will outperform a human 10x to 1x if the
goal is to optimize fuel consumption with automatic trim control.
There is literally countless scenarios where combination of software/
electronics would far exceed capabilities of a pilot to achieve same
objective.

As aviation advances, there will be much more employment of
electronics and software.

I am simply saying, whatever will exist 50 years from now (when many
of us will be dead, heheh)...whatever that thing is...start thinking
about *that* now, not something that was designed in 1950.

-Le Chaud Lapin-

On Jun 15, 9:42 pm, Le Chaud Lapin wrote:
On Jun 15, 3:30 pm, wrote:

On Jun 9, 12:36 pm, Le Chaud Lapin wrote:

On Jun 9, 1:19 pm, Gig 601Xl Builder
You never learned of trim until MSFS and you are going to design an
airplane. Fabulous!

Is it really necessary to understand the particular way it was done in
C172 to achieve the same result?

The same thing could be achieved using more electronics, less
mechanics, and the controls might be entirely different.

#1. Learn to fly first.
#2. Study the construction of aircraft, best done by taking an
aircraft maintenance course.

I think the difference here is that I am not looking for something
evolutionary. I think that is a dead-end road. There is so much in
the world to learn, that if a researcher were to take this approach to
every attempt to advance a field, breakthroughs would hardly occur. In
fact, I think it is precisely this mentality that makes the current
process not as fruitful as it could be.

Perhaps the epitome of this type of thinking can be seen on the first
page of this site: http://www.roadabletimes.com/

Question: "How does one make a flying car?"
Answer: "One could start by taking a car and putting wings on it."

This is silly, and it is obvious to everyone now that it is silly, but
to at least one individual, it was not. That man spent countless
hours purusing a dream that would never materialize because his
approach was fundamentally flawed.

Now if one were to take the objectives of CAFE/PAV to make a new type
of vehicle:

http://www.cafefoundation.org/v2/pav_home.php

..and begin by starting with a "reference" design, that person might
share the same fate of he who made the "flying car" of the first link.

Some of you think it is foolish to embark upon a research path without
having a thorough understanding of what has been done. I think not. I
think, in many cases, one can be too familiar with what has been
done. Common knowledge does not necessarily liberate the mind. It
might stifle it. And if it seems arrogant not to follow the path
already tread by great designers, I think it would be even more
arrogant, after having studied what the great designers have done, to
think that one would make extraordinary advancements beyond what those
greats have done, within the same path.

True breakthroughs often require a breach of continuity, and
significant technological advancement occurs when those breaches occur
at semi-regular intervals.

A good example is vacuum tubes versus transistors.

Absolutely zero knowledge of vacuum tubes is required to understand
transistors. There is a bit of ancillary knowledge, like
thermodynamics, band-theory, and electrodynamics that is immediately
transferrable from vacuum tube theory to transitor theory, but
knowlege of vacuum tubes themselves is inessential.

But both act as amplifiers. Both essentially accomplish the same
thing as elements in a larger system.

Now imagine, toward the end of the vacuum tube era, that someone had
proposed to make a new type of amplifier that would be better on
almost every imaginable axes, but that person had no intention of
spending any time studying vacuum tubes. Would it have been necessary
to study vacuum tubes?

This is essentially what you are saying about PAV's. You are saying
that, the best way to proceed is to learn all I can about convential
aircraft. Why is that necessary? It presumes that the method by which
the objective is accomplish is similar to what has already been done
(tractor model, for example).

A better approach might be to make no assumptions at all, but focus on
the end result, then work backward, evaluating extant technologies
(applicable in, say, 2010), keeping a respectible distance from the
prevaling models of aicraft design, just as transitor theorist might
deliberately keep a respectable distance from vacuum tubes.

#3. THEN think about designing an airplane. No worthwhile design that
I'm aware of has ever been put forward by someone who was unfamiliar
with the way things are now and why they are that way, but I have seen
designs built by folks who "knew better" than everyone else. One of
those, built by a local guy who would take no constructive criticism
of his ideas, stalled at circuit altitude and dropped him, hard, on
the surface of the earth. He was such a stubborn guy that he got up
and walked away, but he neither built nor flew any more airplanes.
Needless to say, this design was neither inspected nor approved nor
licensed to any standard whatever.

A good way to win is avoid races where number of entrants is 1. It
would be extremely hard for someone in my opinion to make notable
improvement on existing aircraft design. The world is filled with high
skilled, highly trained, thoroughly experience, professional aircraft
designers who spent their lifetimes aiming for that extra 5%.

Extra 5% is not going to make a PAV, so if there is any chance of
succeeding at all, one should avoid paths where best-case scenario is
a 5% improvement.

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:

"It adds complexity, which adds failure points and cost and weight,
none of which are welcome, unless the person integrating the
electronics is an electrical engineer unperturbed by the idea of
adding electronic controls to a mechanical system."

It is no more accurate than manual
trim.

Perhaps not. But a computer will outperform a human 10x to 1x if the
goal is to optimize fuel consumption with automatic trim control.
There is literally countless scenarios where combination of software/
electronics would far exceed capabilities of a pilot to achieve same
objective.

As aviation advances, there will be much more employment of
electronics and software.

I am simply saying, whatever will exist 50 years from now (when many
of us will be dead, heheh)...whatever that thing is...start thinking
about *that* now, not something that was designed in 1950.

-Le Chaud Lapin-

The guys who invented the transistor (Brattain and all)
understood electricity and were engineers who could design and build
electronic devices. That's the equivalent of knowing how to fly and
how to build aircraft. They were not new to electronics, they didn't
stumble across semiconductors by accident. Solid-state selenium diodes
(not to mention crystal diodes) had already been in use by then for
some time, and so they built on the knowledge of other folks.
Numerous flying cars have been built from scratch, not based
on existing automobiles. It's not something new. Molt Taylor's Aerocar
(late '40s or early '50s; Google it) was certified and produced in
small numbers, but the compromises necessary to achieve flight in a
vehicle that also has to fit on the road and operate in traffic mean
it's a poor car and a poor airplane, and didn't sell well enough to
justify continuing with it. Electronics and computers can't fix the
hard limitations of physics. Over the years I've been around aviation
I can't recall how many attempts have been made in my own time to
build such a machine, and none of them are visible today. It seems
that only the naive attempt it, and find out the hard way about
compromises that ruin the whole idea.
But don't let me discourage you. Maybe some other folks will
be spared the grief just be watching you try it.

Dan

On Jun 16, 11:27*am, wrote:
* * * * * The guys who invented the transistor (Brattain and all)
understood electricity and were engineers who could design and build
electronic devices. That's the equivalent of knowing how to fly and
how to build aircraft. They were not new to electronics, they didn't
stumble across semiconductors by accident. Solid-state selenium diodes
(not to mention crystal diodes) had already been in use by then for
some time, and so they built on the knowledge of other folks.

There are certain pieces of knowledge that are applicable and certain
pieces that are that. That's all I am saying. I know people who
studied aero/astro for years and had never designed and airplane, but
could if they had to. With regard to transistors, I have only been a
a clean room, and I have never operated say, a chemical-vapor
deposition (CVD) machine, but I know how it works.

The question is essentially:

"What knowledge of old is useful to create the new?"

A key word in this question is "new", which could be interpreted as
"new new" or "incrementally new". Incrementally new is best served by
examining state-of-art and making incremental improvement. New new is
best served by rethinking from a more fundamental perspective. I
contend that, in any field, there is a large percentage of researchers
who do not bother thinking about "new new", because they regard it as
a fruitless endeavor or too risky. But sooner or later, "new new"
reveals itself, and the cylce repeats.

* * * * * Numerous flying cars have been built from scratch, not based
on existing automobiles. It's not something new. Molt Taylor's Aerocar
(late '40s or early '50s; Google it)

I have link on my ready-access favorites of web browser:

http://www.roadabletimes.com/

so yes I have seen it, and many others. Not to criticize this design,
but there is no way I would ever make a flying car that looks like
that. Each time I see someone who has passion for making flying car
take car and mount airplane on top of it, I feel sorry for them - so
much passion...

was certified and produced in
small numbers, but the compromises necessary to achieve flight in a
vehicle that also has to fit on the road and operate in traffic mean
it's a poor car and a poor airplane, and didn't sell well enough to
justify continuing with it. Electronics and computers can't fix the
hard limitations of physics. Over the years I've been around aviation
I can't recall how many attempts have been made in my own time to
build such a machine, and none of them are visible today. It seems
that only the naive attempt it, and find out the hard way about
compromises that ruin the whole idea.

I have noticed that a lot of people making flying cars have an
incredible urge to "just get something working", with the expectation
that , if it "works", it can be improved with tweaks over time. This
is a dangerous approach. As you noted, one typically ends up with
something of questionable design that enjoys, at best, a lukewarm
reception.

* * * * *But don't let me discourage you. Maybe some other folks will
be spared the grief just be watching you try it.

Heheh.

-Le Chaud Lapin-

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.

Dan

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-

On Jun 10, 4:34*am, Le Chaud Lapin wrote:
On Jun 9, 10:58*am, "Robert M. Gary" wrote:

On Jun 8, 10:20*am, Le Chaud Lapin wrote:

On Jun 8, 11:07*am, "Robert M. Gary" wrote:
For sake of those of us who only own MSFS, let's say a C172.

What does MSFS have to do with anything. This is a pilot news group,
not sim. There are sim groups out there that would be more appropriate
for your question.

MSFS was the means by which I discovered the mechanism.

If I had learned in actual aircraft, the question still would have
been relevant.


And now all is clear.

Cheers