Flying on the Cheap - Instruments

Hi everybody,

I think one can build a complete glass cokpit avionics system starting at 1
000 $ and not more than 3 000 $ for a fully doubled complete version.

I've started an open source project :
http://openavionics.sourceforge.net/
http://sourceforge.net/projects/openavionics/ (downloads)
so every body can take plans and build his own system.

The bad news is it won't be ready until 2/3 years.

I have been caught 3 times in 6 years.

I also live in an area where the weather changes while you watch, and can
really astound you when you look away and then look back Therefore, I
completely agree with your attachment to your vertical gyro--my only caveat
being that someone less current on instruments might get more imediate help
from a turn-and-slip.

However, I hope that you are wearing your flame-proof skivies!

Peter

Sadism & Machochism?

The problem resolves itself to dicking around with a thermocouple probe that
puts out millivolts and then picking out the microvolt rise that indicates a
rate increase. Can it be done? Sure. Easily? Perhaps. Trivially?
Probably not.

The second problem, generated by the first, is simulating such a rise and
setting the trigger in the simulation. I'm presuming that you don't want to
sacrifice an engine to calibrate the rascal. Then the question becomes,
what rate do you want to trigger? One degree a second? Ten? A hundred?
Or what rise over what time are you interested in?

Form the problem and I'll try and come up with a solution.

Jim


I've always wanted to ask Jim if there was a simple circuit that could
monitor the EGT and notice the RATE of increase that would indicate a
pending
problem rather that an already existing one. Maybe blink a light, ring a
bell, or apply electric shock as needed?

Jim, anything in you S&M cap that might work here?

Rich(OUCH)ard

Richard Lamb wrote:


I've always wanted to ask Jim if there was a simple circuit that could
monitor the EGT and notice the RATE of increase that would indicate a
pending
problem rather that an already existing one. Maybe blink a light, ring a
bell, or apply electric shock as needed?

Rich(OUCH)ard

That electric shock might be a good last warning that you are about
to land wheels up. Just short one of the magnetos to a plate under
the pilots seat until the revs increase, or the wheels come down ;-)

For those that argue that you might be purposely landing wheels up,
I'd add that it would be a good reminder to kill the engine before
attempting a belly landing ;-)

Don W.

RST Engineering wrote:

Sadism & Machochism?

The problem resolves itself to dicking around with a thermocouple probe that
puts out millivolts and then picking out the microvolt rise that indicates a
rate increase. Can it be done? Sure. Easily? Perhaps. Trivially?
Probably not.

The second problem, generated by the first, is simulating such a rise and
setting the trigger in the simulation. I'm presuming that you don't want to
sacrifice an engine to calibrate the rascal. Then the question becomes,
what rate do you want to trigger? One degree a second? Ten? A hundred?
Or what rise over what time are you interested in?

Form the problem and I'll try and come up with a solution.

Jim


I see your point, Jim.
I guess the "rate" suggestion is a non-starter as it would also likely vary
considerably between engine types.

Dropping that one and looking at it as a max limit indicator would still
require rather delicate calibration, but would it be more do-able then?

The Leaf catalog doesn't mention EGT limits for the Rotax engines.
I would think a trip point just below MAX EGT (~1100 ~1200 degrees F).

There is also the issue of how and where the EGT probes are installed.
A little closer to the exhaust port will read higher and vice versa.

I dunno, Jim. I'd really like to have something like this (that works!),
but maybe I'm asking for too much?

Richard



There's been a lot of "strangeness" on the net the last few days.
Lot's of 404s and "cannot decrypt document" errors.
Is it me, or the weather still causing problems?

But this one did work...582 max egt = 1200F
FilePath=upload/techdocs/2004611123380.HM11_2.pdf

In article . net,
Richard Lamb wrote:



I dunno, Jim. I'd really like to have something like this (that works!),
but maybe I'm asking for too much?

Richard



When recumbent bike guy was in here, we talked about curing ovens for
composites, and that brought up temperature control units. Those things
use rate of change to avoid temperature overshoot by scaling back power
as the set point is approached.

You do something analogous to this every time you take your foot off the
gas and then begin to brake gently, as you approach a stop sign.

But, the point is, I think you might be able to find an off the shelf
solution. There's nothing terribly sophisticated about a speedometer. In
this case, you want to measure something like degrees per minute instead
of miles per hour.

You mean something like this?
Cabelas.com Item # :IG-521411 or
jcwhitney.com # ZX133955X

Smitty Two wrote:

In article . net,
Richard Lamb wrote:



I dunno, Jim. I'd really like to have something like this (that works!),
but maybe I'm asking for too much?

Richard




When recumbent bike guy was in here, we talked about curing ovens for
composites, and that brought up temperature control units. Those things
use rate of change to avoid temperature overshoot by scaling back power
as the set point is approached.

You do something analogous to this every time you take your foot off the
gas and then begin to brake gently, as you approach a stop sign.

But, the point is, I think you might be able to find an off the shelf
solution. There's nothing terribly sophisticated about a speedometer. In
this case, you want to measure something like degrees per minute instead
of miles per hour.

Good example, but WAY more involved here.

I've fooled around with it some myself, but my experience is in logic design,
not the weird and wonderful world of analog electronics.

Jim's point (as I read it) was that we'd have to notice (and react to) a few
microvolts change - per second - (the RATE question).

But how many mV per second would be considered a threatening situation?
(i.e.: how many degrees per second)

In the automobile example the question might be framed, "What rate of closure
would prompt you to lift the gas pedal and apply the brakes?".

Answer - Depends on how close you are to the thing in front of you.

Jim's response was
It seems like a fairly simple request on the surface, but too many undefined
variables for a simple answer.

There is going to be a bit of research involved before this one can be worked
out.

Richard

My ex has a cute "old saying" that she came up with.

"Two weeks in the lab will save you three days in the library
every time".

In article et,
Richard Lamb wrote:



When recumbent bike guy was in here, we talked about curing ovens for
composites, and that brought up temperature control units. Those things
use rate of change to avoid temperature overshoot by scaling back power
as the set point is approached.

You do something analogous to this every time you take your foot off the
gas and then begin to brake gently, as you approach a stop sign.

But, the point is, I think you might be able to find an off the shelf
solution. There's nothing terribly sophisticated about a speedometer. In
this case, you want to measure something like degrees per minute instead
of miles per hour.

Good example, but WAY more involved here.

I've fooled around with it some myself, but my experience is in logic design,
not the weird and wonderful world of analog electronics.

Jim's point (as I read it) was that we'd have to notice (and react to) a few
microvolts change - per second - (the RATE question).

But how many mV per second would be considered a threatening situation?
(i.e.: how many degrees per second)

In the automobile example the question might be framed, "What rate of closure
would prompt you to lift the gas pedal and apply the brakes?".

Answer - Depends on how close you are to the thing in front of you.

Jim's response was
It seems like a fairly simple request on the surface, but too many undefined
variables for a simple answer.

There is going to be a bit of research involved before this one can be worked
out.

Richard

My ex has a cute "old saying" that she came up with.

"Two weeks in the lab will save you three days in the library
every time".

Richard,

If it helps you to see this as a very difficult challenge, then go
ahead. I know what the "H" in RAH stands for, but if designing your own
circuit from discrete transistors that you've carved out of wood is
beyond your interest, then why not look around for a plug 'n' play
option? Have you *really* already done that and come up empty handed?
I've got a shelf full of catalogs of temperature control hardware. I
haven't actually looked for one with a rate alarm option, but since rate
is monitored and used by the controller, I don't see why someone
wouldn't offer such an alarm as an option.

wrote:
To All:

Recently a fellow discovered my post about flying on the cheap (Oct
2001) and got so excited he had to give me a call. Although he
wasn't quite ready to begin building, my article convinced him to
take the plunge.

Now, don't you feel just terrible that you've taken all that man's
weekends and lunch money away from him for the forseeable future?

8*)

--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."