wing levelers

Pete Schaefer wrote:

Rule #1 of Flight Controls Design: KNOW YOUR PHYSICS! At the end of the day,
F still equals ma, and you ain't getting past that doing any fuzzy stuff.


Pete, thank you for your concern, and I don't mind the flaming. Really 8*)

But it is obvious that you have spent years in the industry designing
flight systems for large aircraft. I applaud that and hope to learn a
thing or two. But let me throw a rule out:

Rule #1 of Homebuilt Flight Controls Design: DON'T EVER GIVE ANYTHING
ELECTRONIC CONTROL! At the end of the day, if you can't overpower the
the electronic gizmo with moderate effort then leave it on the ground.

I've had this discussion before. I'm building and airplane for
ENJOYMENT. Getting beat to death in the soup is not my idea of a good
time, so I would not bother with a system that has enough power to
control things in choppy weather. I'm currently designing a cooling
system for my rotary auto conversion, and I'm not designing it for
sustained operations at 100F, because sitting under a plexiglass
slowcooker of a canopy is also not my idea of a good time.

Smooth flight in a light plane is predicated on a lot of small inputs
made early. The earlier it's made, the smaller it has to be. A long
series of continuous nudges. Stepper motor would be fine. You tie it
into the system through a couple of springs, and if you're asking for
more force than what they deliver then you've already gone off the wrong
side of the page. If it goes belly up, then it is an irritation, but no
more so than the CFI who won't get his $&*$ feet off the rudder pedals.
You can't tell it to move it's feet, but you can shut it down and then
nullify it's input with trim. (That's right. Trusty mechanical trim
stays right where it's at. Maybe beefed up just a tad, since it may be
given new duties.) In any case, there is no point where the pilot is
free to let go of the yoke.

Do not even bring up the subject of 'fly-by-wire'. I'm a software
engineer, and there is no way I'd trust a computer with my butt unless
it was built and maintained by a properly trained team (which I am not)
and had multiple backups (which I couldn't fit in my little plane). I
don't even think that most GA aircraft should fly IFR, especially those
depending on electronics. Very few people have the budget to buy the
type of equipment that is really necessary for blind operations (the
sort of equipment that I suspect you helped design), fewer can afford a
plane big enough to carry it all, and even fewer can afford to maintain
it properly.

The good news is thats the part that has gotten more doale in recen
years. Electronics that used to take a dozen guys to tweak, one kid
with a PC and PIC can do. He may not understand the application, but
the implementation technology has gotten quite powerful and cheap.

Fuzzy Logic, from what I can tell, if you do a really good job, you can
get to where a properly tuned PID controller would be, but without that
pesky math.

Now neural networks, that would be something to see. Watch the network
learn how to fly from a few simple rules 1) Stall is bad 2) crashing is
really bad 3) Its good to keep the oily side down. I think I'd have
it learn that sucker learn the basics flying an model (R/C or
computer).

Stepper motors- Why go to all the trouble when you have cheap off the
shelf full up servos?

Dan, U.S. Air Force, retired wrote:
wrote:

You can get really nice R/C servos for way under $100. Ball
bearingsand the works. The quarter scale size servos would
probably be
about right to fly a control surface.

Piezo gyros are also under $100 for R/C applications.

Regards


The hard part is the electronics package between the two. I know the
systems I worked on, but I would be reluctant to attempt builing a
system. Not my bowl of rice, but I'd like see what others come up
with.

Dan, U.S. Air Force, retired

wrote in message oups.com...
The good news is thats the part that has gotten more doale in recen
years. Electronics that used to take a dozen guys to tweak, one kid
with a PC and PIC can do. He may not understand the application, but
the implementation technology has gotten quite powerful and cheap.


http://www.radioshack.com/product.as...5Fid=276%2D625

http://hometown.aol.com/ccady/eztrim.htm



"Blueskies" wrote in message
. ..

wrote in message
oups.com...
The good news is thats the part that has gotten more doale in recen
years. Electronics that used to take a dozen guys to tweak, one kid
with a PC and PIC can do. He may not understand the application, but
the implementation technology has gotten quite powerful and cheap.



http://www.radioshack.com/product.as...5Fid=276%2D625

On Wed, 2 Mar 2005 08:30:27 -0800, "Pete Schaefer"
wrote:


"Roger" wrote in message
.. .
To paraphrase the manual for my auto-pilot. When encountering more
than moderate turbulence, turn off the autopilot. I believe Pete
touched on this as well.

Driving an auto-pilot too hard can put your servos on the rate limit. On a
rate limit, a servo develops serious amplitude-dependent lag, which can
destabilize your loop closures. THe way arount this problem? Big, huge,
powerful, fast servos. This solution opens up a whole other can of worms.

Ahhh... That's not what I was getting at.
They have you disconnect to protect your airplane as the servos can do
too good a job of holding altitude. It wasn't lag they were worried
about.

Just as the question asks on the FAA exam. What do you do when
entering an area of moderate to severe turbulence?
The AP doesn't know the correct answer for that one and it's going to
hold altitude, and/or attitude even if it has to break something to do
it. (depends on the AP)

There really is such a thing as "too much of a good thing".

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

"Roger" wrote in message
...
Ahhh... That's not what I was getting at.
They have you disconnect to protect your airplane as the servos can do
too good a job of holding altitude. It wasn't lag they were worried
about.

Yeah, there are a couple of issues there. The autopilot might command
surface deflections beyond what is safe for the control surface. Could rip a
surface off. And, as I already said, the autopilot could get into an
oscillation if it rides a rate limit.

Just as the question asks on the FAA exam. What do you do when
entering an area of moderate to severe turbulence?

Yup.

There really is such a thing as "too much of a good thing".

Roger that...uh..Roger.