Mechanical Vario

Piep audio was made and sold through Winter in Germany but that was some
time ago.....I actually bought the very last ones they had probably 5-6
years ago...maybe longer....and had some repaired by them about the same
time ...but they said then no more parts existed for these..Another Winter
first instrument that faded from view but was really very interesting at the
time was the Stollfarhtgaber, actually the first Speed-to-fly
variometer/airspeed indicator all-in one....all done mechanically and
pneumatically with no need for volts of any kind...these too and parts for
them are no longer available
Funny as we seem to advance towards more sophisticated do-everything
electronic gadgets how we look back on what worked then and would still work
today with a lot less time setting up, reading manuals and sorting things
out on RAS..... I never remember having to have all these conversations and
technical workshops on how to wind or smoke a barograph and never once had
the software or PC link or lack of a serial port miss a turnpoint done on a
Kodak.....)
All in the way of technology...and to many a giant leap sideways )
So while many might claim an electronic vario is a must for a back-up I
still personally prefer a mechanical running on a probe...it to me also
shows to me what I feel in the flight more naturally than any electronic
one.
tim

Please visit the Wings & Wheels website at www.wingsandwheels.com


"Bob Kuykendall" wrote in message
ups.com...
On Sep 25, 4:51 pm, wrote:
thats what i would really like.

I think what you're looking for is a Piep audio. There were a lot of
them about in the 1960s and 1970s. Very simple and reliable. Two knobs
(volume and threshold), two hose connectors (static and capacity), and
a plug for +12DCV and ground. They have fairly low restriction, so you
can plub it in series with a mechanical vario without problem. They
seem to like a one-pint flask, but they're not particularly picky. I
had one for ten years and really liked it.

I bet if you ask around among the old-timers in your area you'll find
somebody with one in the bottom of a box of junk. It'll probably still
have the Graham Thompson sticker on it.

Thanks, Bob K.

wrote in message
ps.com...
On Sep 25, 1:12 pm, "HL Falbaum" wrote:
Once upon a time, there was such a thing----an electric audio attachment
for
a pneumatic/mechanical vario. Or perhaps it was just plumbed in the
pneumatic lines. Adjustable for volume and threshold. It was a little
black
box that didn't need to be in the panel at all. Perhaps you can find a
used
one somewhere.

thats what i would really like.


Surely some one out there has an old Piep 2 Audio Vario that they are
willing to part with. (Or, maybe the newer Winter model.)

I gave away my last one a couple years ago.

Wayne
http://www.soaridaho.com/

At 01:36 29 September 2007, Mike Borgelt wrote:


The real problem with all TE varios at present is that
horizontal gusts will
cause spurious readings. The problem gets worse with
the square of the
TAS(See our website article). If you slow the vario
response to get rid of
the problem you get rid of good information about vertical
air motion
changes too. I've been going around in a thermal with
a PZL and a B21 in a
customer's glider and seen the B21 show 1 knot on
one side of the thermal
with peaks of 6 knots while the PZL sat on close to
2 knots all the way
round. Re centering on the B21 got me 5 knots on the
averager. This was an
unusually smooth thermal and it was hard to tell by
feel. A reasonably fast
responding vario is an advantage but there is a high
workload in mentally
filtering the horizontal gust 'noise' from the vertical
'signals'

This may change soon.


Mike Borgelt

Borgelt Instruments

Maybe sooner than you may think! This is the main problem
that Dr Ludek Smolik's Yaw-Free probes are designed
to combat. for those who did not see my last post on
it, here is his answer to my query again, along with
links to probe info and a youtube video link showing
the swiveling action that makes these probes resistant
to yaw/gust errors (particularly the 2 and 3 way probes,
for reasons described below):
http://www.eaglebrandproducts.com/TE...rices_2006.pdf
and the Youtube video: http://youtube.com/watch?v=OpN9sYHF_yc
I am still awaiting the performance plots, and will
post
them when I get them.

Paul Hanson


Dear Mr. Hanson,

many thanks for your mail which reached me here in
Europe across New Zealand.

ItŽs very pleasant for me to serve you some information
on my project.
The probes are manufactured in Germany in a more or
less individual manner according to the pilots wishes.

The major step forward is the yaw-free pressure measurement
of all three important pressures at same place and
time. Time to time there are discussions on web or
in articles in magazines about the yaw dependence of
the so called TE-pressure, which is normally taken
as a velocity dependent under pressure due to the
vorticity behind an particular object like e.g. a small
tube.
But such discussion is just a half truth ! ItŽs obvious
that beside the TE-under pressure the static and total
pressure are very sensitive for �yawing�
too. The new probe improves the measurement by rotating
around the yaw axis significantly.
If you are interested on results, I can provide plots.

But the tenor is: if a standard TEK-probe has an spread
in the probe coefficient of 10 or 20% due to yaw angel
or air turbulences, for the new probe such spread is
0%.

It is hard to make meaningful photographs of the probes
because they all are black and look boringJ) Therefore
I send you a short video where the functionality and
the free rotatability around the yaw axis is demonstrated.
The two prongs of the �Y� shape are
the tubes for the TE-measurement and the orifices
for total and static pressure are mounted in the small
antennas in the forward direction.

Of course , the probes fit to all standard adapters
or if desired to a new type of 3 way adapter, where
all the sealing o-rings are mounted and accessible
on probe itself.

One word to the results, in principle itŽs difficult
to compare probes really meaningful simply using a
flume. Normally the flume does not simulate either
real air conditions nor the glider influences and last
not least the individual pilots behaviour.
For this reason only a measurement on the same place
and at the same time on one glider with a same type
of electronics can provide the best and direct comparison..
For this purpose I made a probe with 2 x 3 independent
orifices. 3 orifices build a standard probe the other
3 orifices are build like the yaw-free probe. Feeding
the data to two independent vario circuits and logging
the results one obtain a flight �seen�
from two different probes. This experiment is still
in preparation and is foreseen for next spring.

I hope this short overview gives some helpful information


Best Regards

Ludek Smolik

At 03:06 30 September 2007, Eric Greenwell wrote:
Dan G wrote:

BTW, on the gust issue, there is another solution
(though not nearly
as elegant as the rotating TE probe) - accelerometers.


I think I understand how accelerometers could distinguish
between a
horizontal gust and the vertically moving air in a
thermal, but I don't
understand how aligning the probe with the horizontal
gust will reduce
it's effect on the vario. Wouldn't that accentuate,
rather than
attenuate, the gust effect?

--
Eric Greenwell - Washington State, USA

Not at all, at least not if it is the 2 or 3 way probe
and this is why. It is first and foremost the static
system that is particularly sensitive to gusting. When
a horizontal gust hits the side of a plane, it creates
positive pressure on one side of the static inputs
(whether fuse or probe mounted), throwing the reading
way out of whack. With the static on a rotating probe,
it can align itself to always face directly into the
wind and alleviate the big errors in static reading
that horizontal gusts ( or other disturbances in yaw)
create. It does not hurt to have the TE also rotate
with it, and does not hurt to have the dynamic rotate
as well (with rotating dynamic, a cup shaped Kiel tip
is not required to maintain accuracy-less drag) but
dynamic and TE are not as sensitive to misalignments
in airflow as the static system is. This probe system
will provide accurate readings during both slipping
maneuvers (like if you mildly slip while thermalling
ala Holighaus) as well as gusting incidents. BTW, the
'fancy' 2 way probe Dr Smolik sells is only 80 Euros,
and the 3 way probe only 99. This video is the 3 way
probe:
http://youtube.com/watch?v=OpN9sYHF_yc , and this link
shows drawings and prices for the whole line:
http://www.eaglebrandproducts.com/TE...rices_2006.pdf
I am only assuming here, but I would imagine these
probes to be much cheaper than an accelerometer compensated
computerized vario system (not to mention compatible
with most anyone's current setup) but perhaps maybe
not as effective in all situations. It is a simple
and elegant aerodynamic solution to an old problem,
that I'm sure will be seen on many more gliders in
the near future. Again, I will share the data tables
Ludek provides, once he sends them to me.

Paul Hanson

PS. I have no financial involvement with these probes,
I just think they are very cool.
PPS. there is a reason that NASA and most other flight
test groups use static/dynamic (they don't mess with
TE) probes that rotate (in 2 axis) to keep readings
accurate while evaluating aircraft.

Paul Hanson wrote:
At 03:06 30 September 2007, Eric Greenwell wrote:
Dan G wrote:

BTW, on the gust issue, there is another solution
(though not nearly
as elegant as the rotating TE probe) - accelerometers.

I think I understand how accelerometers could distinguish
between a horizontal gust and the vertically moving air in a
thermal, but I don't understand how aligning the probe with the horizontal
gust will reduce it's effect on the vario. Wouldn't that accentuate,
rather than attenuate, the gust effect?

--
Eric Greenwell - Washington State, USA

Not at all, at least not if it is the 2 or 3 way probe
and this is why. It is first and foremost the static
system that is particularly sensitive to gusting. When
a horizontal gust hits the side of a plane, it creates
positive pressure on one side of the static inputs
(whether fuse or probe mounted), throwing the reading
way out of whack. With the static on a rotating probe,
it can align itself to always face directly into the
wind and alleviate the big errors in static reading
that horizontal gusts ( or other disturbances in yaw)
create.

The gusting that cause false readings on my varios seems small enough
that it doesn't move the yaw string very much. I can use the rudder to
slip/skid the same amount, and the vario hardly notices it. So it seems
like the gust itself is the problem, not the direction it comes from. If
that's true, an aligning probe won't help any.

Also, suppose the gust comes directly from the front or the back. This
will cause a change in the airspeed and "fool" a TE vario. A probe that
aligns with the airflow won't help in this case, as the airflow
direction doesn't change at all.

It does not hurt to have the TE also rotate
with it, and does not hurt to have the dynamic rotate
as well (with rotating dynamic, a cup shaped Kiel tip
is not required to maintain accuracy-less drag) but
dynamic and TE are not as sensitive to misalignments
in airflow as the static system is.

If that's the case, why don't we just use a TE probe and forget about
using a pitot/static system to run the vario?

This probe system
will provide accurate readings during both slipping
maneuvers (like if you mildly slip while thermalling
ala Holighaus) as well as gusting incidents.

It seems like the aligning probe ensures that a gust will add it's
entire velocity to the glider's speed through the air, making it even
more sensitive to gusts than a probe that doesn't align.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Paul Hanson wrote:
When
a horizontal gust hits the side of a plane, it creates
positive pressure on one side of the static inputs
(whether fuse or probe mounted), throwing the reading
way out of whack.

I can see that this would make the ASI twitch (and the altimeter if it
wasn't on cockpit pressure) but I don't see the relevance to my varios
because:

- my B.40 only has one line that connects to the TE probe, so the static
isn't affected and you say that a TE probe is relatively little
affected by gusts.

- my SDI C4 which has static and pitot as well as TE connections.
My guess is that it only uses TE for its vario function and the
static+pitot for airspeed and pressure altitude.

BTW, what the heck is a "dynamic pressure" probe? Is it a pitot tube?


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

At 12:06 08 October 2007, Martin Gregorie wrote:
Paul Hanson wrote:
When
a horizontal gust hits the side of a plane, it creates
positive pressure on one side of the static inputs
(whether fuse or probe mounted), throwing the reading
way out of whack.

I can see that this would make the ASI twitch (and
the altimeter if it
wasn't on cockpit pressure) but I don't see the relevance
to my varios
because:

- my B.40 only has one line that connects to the TE
probe, so the static
isn't affected and you say that a TE probe is relatively
little
affected by gusts.

Relative being a relative term, this is somewhat true.
In comparison it is not AS affected as the static,
but it is indeed affected. There are many plumbing
combos for different types of system, so while something
that works well with one system does not mean it will
work for another. Although in this case, I do believe
you would get better readings from your B-40 with the
Yaw-free TEK probe. Read the stats on the charts for
yourself that I am posting links to in a new post,
that compare a standard TE and a yawing unit under
the same conditions.

- my SDI C4 which has static and pitot as well as TE
connections.
My guess is that it only uses TE for its vario function
and the
static+pitot for airspeed and pressure altitude.

Without actually studying your system your guess is
only that-a guess. Just because the B-40 runs only
on TE does not mean that this one does, although it
may. Rather than guess though, I would do my homework
to figure that out if it were mine before deciding
how to improve anything.

BTW, what the heck is a 'dynamic pressure' probe? Is
it a pitot tube?

Dynamic pressure is what a Pitot tube is measuring,
and what a TE is attempting to create a perfectly matched
inverse of.

Paul Hanson
"Do the usual, unusually well"--Len Niemi

Paul Hanson wrote:

Dynamic pressure is what a Pitot tube is measuring,
and what a TE is attempting to create a perfectly matched
inverse of.

Clear and concise. Thanks!


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