Metric Instruments

On Thu, 25 Aug 2005 09:43:46 +0200, "Bert Willing"
wrote:

Well, even if there is only one owner involved, I'm not going to rely on
electrically power instruments only. Never.^

I still remember one competition back in 1991 when the US shut down
GPS and suddenly a gaggle of 30 standard class gliders lost their
navigation in the vicinity of Sobernheim (several airbases and
restricted airspace there). I got to know a new definition of the term
"confusion".





Bye
Andreas

"Bill Daniels" wrote in message
...

"Tim Ward" wrote in message
ink.net...

"Bill Daniels" wrote in message
...
Does it strike some of the digerati here that expensive mechanical
altimeters with easily mis-read clock-like hands locked into either
the
metric or US measurement systems are archaic?

GPS provides highly accurate, although not ATC compliant, altitude.
Various
vendors provide electronic pressure altimeters with digital displays
that
can be switched between meters and feet with the push of a button.
Digital
pressure altitude sensors drive the "glass cockpits" of new GA
aircraft.

I seems to me that clock-like altimeters designed 70 years ago and
maintained by watchmakers must be nearing their well-deserved
retirement.

Bill Daniels

Yeah, now if they can just make them so they don't need batteries.

Tim Ward


What's the big deal with batteries? IMHO, batteries are at worst a minor
inconvenience easily worth enduring for the benefits of the technology
they
make possible.

Every portable gadget uses them. Most folks have a cell phone, PDA,
portable GPS, digital camera, maybe a camcorder and who knows what else.
Even your car, tug or winch won't start without a battery. They're cheap
and they work fine with a little TLC and regular replacement.

My glider uses a standard 7.5 AH 12V SLA that now sits on a shelf
connected
to a charger that quietly maintains the charge. I know for sure that it
will work at least 10 hours and still show more than 12.5 volts while
transmitting. It has a three year "replace by" date written on it
whereupon
I will plunk down $20 for another at "Batteries-R-Us" even if it still see
ms
OK. I don't trust old batteries.

Bill Daniels


Upon reflection, Bill, I'm sure that an instrument could be built that could
satisfy both of us.
Digital, easily scalable, there's no reason it can't have both an analog
display (or quasi-analog, with LCD) for trends, and a 5 digit display for
accuracy. It could have a lithium cell recharged by the expansion and
contraction of an aneroid . Several "perpetual clocks" have used that
scheme to drive mechanical gear trains with far smaller pressure changes
than you'll get going up and down in a glider or airplane.
An update rate of twice a second should be plenty fast enough. With LCDs,
and CMOS circuitry running a few microamps at two volts or so, it's probably
not impossible to build. You could probably build one with a primary lithium
battery that would only need to be changed once every ten years or so.
That would be the cheapest way to go.
What will it cost to get it approved? How many people are going to buy it?
In the small market that is aviation, what will it cost to build? If you
could sell it cheaper than a mechanical altimeter, you might have a shot.
In enough volume, you might be able to do that. I don't know if the
altimeter market is large enough for that to be possible. The combined
output of all the altimeter manufacturers is probably not as big as a run
of, say, a cheap DVD player.

I dunno. I'm afraid good enough is the enemy of best.

If you don't care whether or not it's approved, or whether it takes
batteries, then you should look at the Flytec hang glider varios. They have
a lot of options as to what they display and how they display it, and I
believe they'll display altitude both digitally and analog. They'd take up
a bit more space on a panel, though.

Tim Ward

I have to fall firmly and loudly into the "digital is good, electrical
insturments can be reliable, mechanical varios belong in museums"
group.

I would love to see a serious study that shows that classic analog
airspeed and altimeters (as used in gliders) are easier to read and
less susceptible to misinterpretation than a properly designed (but
unfortunately, theoretical) replacement digital airspeed and altimeter.
With the advent of Head-up-Displays (HUDs), fighter planes have moved
to almost completely digital displays of most values - only those where
trend is crucial, such as vertical velocity and radar altitude,
continue to have a companion analog display. Otherwise, its a straight
number, usually rounded off to the nearest knot and 10 feet. Works
fine in an F-15E, should work pretty good in an LS6

By comparison, trying to interpret a three-needle altimeter is like
trying to read sanskrit! And then there are 1 1/2 revolution airspeed
indicators!

If you have a PDA in your cockpit, try setting it up to have a nice big
font altitude (and speed, if available) display on it and try it - you
might find that it is really easy to glance at and read.

I have two seperated battery systems, and no mechanical vario. I'm
stuck with a "steam-gauge" airspeed indicator and altimeter, but what I
would really like is a digital airspeed, digital altimeter, and an
accurate AOA indicator. For tradition, I'll keep the vario needles -
since there I'm looking for trend (to provide a value to the audio),
and read a digital averager for real decision making.

Heck, last year I took off on a fine day only to find my airspeed inop
(bug in the pitot) - but that didn't prevent me from flying a nice
little 500+ k XC with some friends of mine. The only time I really
missed the airspeed indicator was in the pattern. Just flew it a bit
faster than usual (that AOA indicator sure would have been nice to have
then...).

Now the huge caveat - this is all fine in a private ship - I don't see
how a the average club ship would manage.

Kirk
66

In message .com,
writes
I have to fall firmly and loudly into the "digital is good, electrical
insturments can be reliable, mechanical varios belong in museums"
group.

Must admit that my beliefs a Digital is good - for somethings - bad
for others - analogue is good - for somethings - bad for others.

Digital is very good for getting absolutes - fly at a particular flight
level - a specific temperature - or a rate of something. Analogue is
very good for trends and similar, horses for courses. Most of what we
do flying we just want a trend or rough peak - analogue - say (in my
personal opinion) thermal centering.For saying that a particular thing
is better or good enough, say is that thermal good enough to stay with
or is it falling off so we want to go to another, digital in the form of
an averager is the absolute best.

We don't need absolute altitude in an altimeter. Flight Levels are in
500 ft increments. We do absolutes in loggers.

Mechanical can break so can electric. You can get many more functions
out of electric which is good. However I am fully in favour of separate
and different technology systems in case something goes pop.

My own experience in club equipment is that electric goes wrong many
times more often than mechanical and it is far easier to get a poorly
installed mechanical system working than an electronic.

I would love to see a serious study that shows that classic analog
airspeed and altimeters (as used in gliders) are easier to read and
less susceptible to misinterpretation than a properly designed (but
unfortunately, theoretical) replacement digital airspeed and altimeter.
With the advent of Head-up-Displays (HUDs), fighter planes have moved
to almost completely digital displays of most values - only those where
trend is crucial, such as vertical velocity and radar altitude,
continue to have a companion analog display. Otherwise, its a straight
number, usually rounded off to the nearest knot and 10 feet. Works
fine in an F-15E, should work pretty good in an LS6

Well known fact, much publicised by the ergonomicist who sits next to
me, is that three needle altimeters are pure trouble from a reading
point of view. ASIs are less prone to missreading but it does happen.
(She once borrowed one of mine for a lecture on the fact).

Very fast ships (F15s and the like couldn't use foot or even hundred
foot needles as they would spin so fast that they would fall off) need
different technology. Actually, the best (from my opinion) ASI was the
one used in the lightning which was a horizontal tape that wound across
the top of the instrument panel.

They are using analogue in the same way that we are but the low values
are inappropriate. For this they use digital which is easier to control
at fast fates of change.

As you say they are using needles for trends, we do the same. I kinda
think that to do our job properly we need both (needle and digital), the
argument between electric and mech is different but again I think we
need both from a safety point of view.

By comparison, trying to interpret a three-needle altimeter is like
trying to read sanskrit! And then there are 1 1/2 revolution airspeed
indicators!

If you have a PDA in your cockpit, try setting it up to have a nice big
font altitude (and speed, if available) display on it and try it - you
might find that it is really easy to glance at and read.

And see what happens when the software goes pling which happens with
even the best systems.

I have two seperated battery systems, and no mechanical vario. I'm
stuck with a "steam-gauge" airspeed indicator and altimeter, but what I
would really like is a digital airspeed, digital altimeter, and an
accurate AOA indicator. For tradition, I'll keep the vario needles -
since there I'm looking for trend (to provide a value to the audio),
and read a digital averager for real decision making.

Heck, last year I took off on a fine day only to find my airspeed inop
(bug in the pitot) - but that didn't prevent me from flying a nice
little 500+ k XC with some friends of mine. The only time I really
missed the airspeed indicator was in the pattern. Just flew it a bit
faster than usual (that AOA indicator sure would have been nice to have
then...).

Now the huge caveat - this is all fine in a private ship - I don't see
how a the average club ship would manage.

Kirk
66

Robin
--
Robin Birch

The digital/analog argument was put to me thus. A digital
watch tells you what time it is, an analog watch tells
you what time it isn't as well. The same applies to
analog instruments, in the case of the ASI it tells
you your speed if you study it and at a glance if you
are above or below your target. It's a question of
what you need to know. Digital needs study and calculation,
analog is instant.

At 19:24 25 August 2005, wrote:
I have to fall firmly and loudly into the 'digital
is good, electrical
insturments can be reliable, mechanical varios belong
in museums'
group.

I would love to see a serious study that shows that
classic analog
airspeed and altimeters (as used in gliders) are easier
to read and
less susceptible to misinterpretation than a properly
designed (but
unfortunately, theoretical) replacement digital airspeed
and altimeter.
With the advent of Head-up-Displays (HUDs), fighter
planes have moved
to almost completely digital displays of most values
- only those where
trend is crucial, such as vertical velocity and radar
altitude,
continue to have a companion analog display. Otherwise,
its a straight
number, usually rounded off to the nearest knot and
10 feet. Works
fine in an F-15E, should work pretty good in an LS6

By comparison, trying to interpret a three-needle altimeter
is like
trying to read sanskrit! And then there are 1 1/2
revolution airspeed
indicators!

If you have a PDA in your cockpit, try setting it up
to have a nice big
font altitude (and speed, if available) display on
it and try it - you
might find that it is really easy to glance at and
read.

I have two seperated battery systems, and no mechanical
vario. I'm
stuck with a 'steam-gauge' airspeed indicator and altimeter,
but what I
would really like is a digital airspeed, digital altimeter,
and an
accurate AOA indicator. For tradition, I'll keep the
vario needles -
since there I'm looking for trend (to provide a value
to the audio),
and read a digital averager for real decision making.

Heck, last year I took off on a fine day only to find
my airspeed inop
(bug in the pitot) - but that didn't prevent me from
flying a nice
little 500+ k XC with some friends of mine. The only
time I really
missed the airspeed indicator was in the pattern.
Just flew it a bit
faster than usual (that AOA indicator sure would have
been nice to have
then...).

Now the huge caveat - this is all fine in a private
ship - I don't see
how a the average club ship would manage.

Kirk
66

At 22:06 24 August 2005, Ian Strachan wrote:

snip

Bill Daniels wrote:

snip

GPS provides highly accurate, although not ATC compliant,
altitude.

I am afraid that the claim that GPS altitude is recorded
'highly
accurately' in IGC files from IGC-approved GPS recorders,
is
unfortunately not true.



This is not an attack on the accuracy of the GPS system
or even its
altitude recording capability. It is a reporting of
results of GPS
altitude recording in IGC flight data files derived
from a number of
low-cost GPS boards made by a number of different companies
from
different parts of the world. I guess that in more
expensive
'professional aviation standard' GPS boards, and in
differential-GPS
systems with local beacons, the GPS altitude figures
are more accurate
and with less anomalies. But such (expensive) systems
do not apply to
the current 27 types of GNSS flight recorders that
are IGC-approved
(from 11 manufacturers) and whose IGC-approval documents
appear on the
IGC gliding/gnss web site:

http://www.fai.org/gliding/gnss/igc_approved_frs.pdf

The truth is that it is possible to record altitude
very accurately with GPS, suyveyors who produce our
maps use GPS both for lat/long and elevation with a
resolution in height of less that 15mm over 10Km. Perhaps
the reason that the manuafacturers mentioned above
do not upgrade their equipment is that there is no
demand as the IGC refuse to consider using GPS altitude.
However good a baro recorder is it can never approach
the accuracy of GPS.

On Thu, 25 Aug 2005 21:02:37 +0100, Robin Birch wrote:

In message .com,
writes
I have to fall firmly and loudly into the "digital is good, electrical
insturments can be reliable, mechanical varios belong in museums" group.

Most of what we do
flying we just want a trend or rough peak - analogue - say (in my personal
opinion) thermal centering.For saying that a particular thing is better or
good enough, say is that thermal good enough to stay with or is it falling
off so we want to go to another, digital in the form of an averager is the
absolute best.

Agree 100% I really like the vario display on an SDI C4 and a Tasmin
V1000 vario. Both use analogue for instant reading and digits for the
averager. Both are easy to use.

OTOH what are you doing looking at the vario in a thermal :-)
I find the sound from a C4 makes centring very easy and all I look at
is a glance at the averager from time to time to see if its time to leave
the thermal yet.

I very much like the idea of a B.40 as backup vario because it has its own
internal battery and switch-over circuitry. I just wish it used an LCD
analogue display rather than a needle for the instant rate display.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

In message s, Martin
Gregorie writes
On Thu, 25 Aug 2005 21:02:37 +0100, Robin Birch wrote:

In message .com,
writes
I have to fall firmly and loudly into the "digital is good, electrical
insturments can be reliable, mechanical varios belong in museums" group.

Most of what we do
flying we just want a trend or rough peak - analogue - say (in my personal
opinion) thermal centering.For saying that a particular thing is better or
good enough, say is that thermal good enough to stay with or is it falling
off so we want to go to another, digital in the form of an averager is the
absolute best.

Agree 100% I really like the vario display on an SDI C4 and a Tasmin
V1000 vario. Both use analogue for instant reading and digits for the
averager. Both are easy to use.

OTOH what are you doing looking at the vario in a thermal :-)
Flying club K8s that I keep forgetting to put the battery in and so the
mechanical is all I've got or my Astir when I've forgotten to charge
them and they've gone flat on me after 4 hours :-))

I find the sound from a C4 makes centring very easy and all I look at
is a glance at the averager from time to time to see if its time to leave
the thermal yet.

I very much like the idea of a B.40 as backup vario because it has its own
internal battery and switch-over circuitry. I just wish it used an LCD
analogue display rather than a needle for the instant rate display.


--
Robin Birch

On Wednesday, August 24, 2005 9:18:20 PM UTC+5:30, Roy Bourgeois wrote:
This may be a silly question - but are all metric altimeters
configured with 'Zero at 6 O'clock' as I saw in France?
I did not have trouble converting to meters/kilometers
but I did have trouble quickly reading the altimeter
with the zero at the bottom of the instrument face
(especially on the little 57mm instruments). Just
curious.

Roy

http://www.rlkswitches.com/

Hi Roy,

That is very common. It is the standard. I suppose it is similar to most
industrial gauges which have the zero at the bottom.

Best Regards,

Paul Remde
Cumulus Soaring, Inc.
__________________________________________

wrote in message
...

On Wednesday, August 24, 2005 9:18:20 PM UTC+5:30, Roy Bourgeois wrote:
This may be a silly question - but are all metric altimeters
configured with 'Zero at 6 O'clock' as I saw in France?
I did not have trouble converting to meters/kilometers
but I did have trouble quickly reading the altimeter
with the zero at the bottom of the instrument face
(especially on the little 57mm instruments). Just
curious.

Roy

http://www.rlkswitches.com/