Mechanical Vario

On 28 Sep, 23:44, Bob Whelan wrote:

Personally, I think the Gospel of Simplicity ought to be preached more,
because so much of soaring does not REQUIRE the latest in bells and
whistles be present in order for fledglings to begin spreading their
wings in personally gratifying and safe ways.

I like to fly in silence. Two mechanical varios (PZL +/- 10 for
averaging and speed to fly, Winter +/- 2 for working the weak stuff).
Radio off, because if I wanted to yack away I'd be flying power. Yes,
I know I might go a bit further with an audio vario (and I do stick in
an old Cambridge occasionally). Yes, I know the radio might be useful
(and I do switch it on sometimes). But I don't soar to listen to beeps
or to achieve high numbers - I soar for the sheer joy of flying.

Yours in sentimental simplicity,

Ian

Bill, not sure I should disillusion you. What is happening is that you are
entering air that is starting to rise. This caused the speed command
function of the B50 to call for slower airspeed. The warble starting is the
"fly slower" sound. So much of the time there will be some sort of thermal
coming up by which time you are going a little slower and it is easier to
pull in to it. When the relative reading exceeds the Macready setting the
audio switches to the climb "beep" sounds which ought to wake you up if you
haven't already noticed because you were concentrating on something else.

There is an approximately +/- 5 knots speed band where the lights will be
out(it varies with MacCready setting). The fly slower audio starts when the
first blue light comes on. The fly faster audio only starts when you would
be flying slower than zero MacCready for the air you are currently in. This
is more comfortable and means you are never flying slower than best
glide(this might answer the poster who wanted to know how to cross big areas
of sink and note that unless on final glide the wind doesn't matter in speed
to fly theory).

As for the number for the speed to fly, we display that on the B500 . It
does not change with the air as the lights and audio are for that but it
gives you an idea of the sort of speed you are aiming for when you acclerate
out of a thermal. B500 works like a B50 but has lots of extras including a
nav, glide and wind computer and some other refinements.

I had a Piep audio in my Salto along with a PZL mechanical for a couple of
years before I started building my own electric varios. That was nearly 35
years ago. The Piep audio had the problem that the zero point wasn't stable
with temperature - a common failing of early thermistor varios. Your
mechanical vario with flask might make a nice display piece for your office.
There's way better than that around. See B400 on our website. Yes I have
flown with mechanical varios and a Brand X flight computer not that long
ago. Three 4 hour flights in a Nimbus 4DM. Great glider, abysmal instruments
and I had been through and fixed leaks etc. I haven't had one in a glider of
mine since 1979.

Unless installed correctly the flask will screw up other varios on the same
TE line. This will be true even if the flask using vario is an electric
type.

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






"Bill Daniels" bildan@comcast-dot-net wrote in message
news
In addition to my old reliable B40, I have a newly old B50. As I'm
cruising along the B50's audio will switch to slow yodel and two blue
LED's will light up indicating the need to slow down "a lot". It's
usually not clear to me why I should slow down but I've learned to trust
it. After I enter the zoom I usually feel a kick in the pants as I enter
a strong thermal. It seems to know a thermal is coming well before I do.

Mike, HOW DOES IT DO THAT?

Bill Daniels

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

wrote:

Or just drag that Cherokee out West. The 1-26ers get in some amazing
flights out here!
Back to the subject.... and this may be a bit of a 'noob' question.
Is there an instrument that will indicate the optimum speed to fly to
get through large areas of HUGE sink, also taking into account winds?
I have a very basic 302A FR, and an iPAQ with XCSoar.
Hints?

As usual, "It Depends...", but assuming you have a speed ring or other
type of speed director:

-if maximizing your XC speed, follow the speed director, which should
already have your McCready setting in it.
-if you want to minimize your altitude loss in thermal conditions as you
transit sink, use a McCready setting of zero
-if it's wave or back side ridge sink where you want to minimize your
altitude loss transiting the sink, use a McCready setting with a XC
speed the same as the wind speed (this is an approxiamation). Going
*into* a 50 knot wind, that might mean a setting of 6 knots; going
*downwind*, that might mean a setting of -1 knot.

I don't know of any instrument that can determine what you are thinking,
so it's up to you to choose the appropriate setting.

--
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

Eric Greenwell wrote:

wrote:

Or just drag that Cherokee out West. The 1-26ers get in some amazing
flights out here!
Back to the subject.... and this may be a bit of a 'noob' question.
Is there an instrument that will indicate the optimum speed to fly to
get through large areas of HUGE sink, also taking into account winds?
I have a very basic 302A FR, and an iPAQ with XCSoar.
Hints?

As usual, "It Depends...", but assuming you have a speed ring or other
type of speed director:

-if maximizing your XC speed, follow the speed director, which should
already have your McCready setting in it.
-if you want to minimize your altitude loss in thermal conditions as you
transit sink, use a McCready setting of zero
-if it's wave or back side ridge sink where you want to minimize your
altitude loss transiting the sink, use a McCready setting with a XC
speed the same as the wind speed (this is an approxiamation). Going
*into* a 50 knot wind, that might mean a setting of 6 knots; going
*downwind*, that might mean a setting of -1 knot.

I don't know of any instrument that can determine what you are thinking,
so it's up to you to choose the appropriate setting.

Not really an instrument but GPS_LOG WinCE program does the
appropriate calculations on a PDA.

Cheers,
Henryk Birecki

"Mike Borgelt" wrote in message
...


Bill, not sure I should disillusion you. What is happening is that you are
entering air that is starting to rise. This caused the speed command
function of the B50 to call for slower airspeed. The warble starting is
the "fly slower" sound. So much of the time there will be some sort of
thermal coming up by which time you are going a little slower and it is
easier to pull in to it. When the relative reading exceeds the Macready
setting the audio switches to the climb "beep" sounds which ought to wake
you up if you haven't already noticed because you were concentrating on
something else.


Whatever, it's the best STF vario I have ever used.


There is an approximately +/- 5 knots speed band where the lights will be
out(it varies with MacCready setting). The fly slower audio starts when
the first blue light comes on. The fly faster audio only starts when you
would be flying slower than zero MacCready for the air you are currently
in. This is more comfortable and means you are never flying slower than
best glide(this might answer the poster who wanted to know how to cross
big areas of sink and note that unless on final glide the wind doesn't
matter in speed to fly theory).

As for the number for the speed to fly, we display that on the B500 . It
does not change with the air as the lights and audio are for that but it
gives you an idea of the sort of speed you are aiming for when you
acclerate out of a thermal. B500 works like a B50 but has lots of extras
including a nav, glide and wind computer and some other refinements.

I had a Piep audio in my Salto along with a PZL mechanical for a couple of
years before I started building my own electric varios. That was nearly 35
years ago. The Piep audio had the problem that the zero point wasn't
stable with temperature - a common failing of early thermistor varios.
Your mechanical vario with flask might make a nice display piece for your
office. There's way better than that around. See B400 on our website. Yes
I have flown with mechanical varios and a Brand X flight computer not that
long ago. Three 4 hour flights in a Nimbus 4DM. Great glider, abysmal
instruments and I had been through and fixed leaks etc. I haven't had one
in a glider of mine since 1979.

Unless installed correctly the flask will screw up other varios on the
same TE line. This will be true even if the flask using vario is an
electric type.

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.


The new variometry standard will be noise-free instantaneous response and
zero gust sensitivity, right?

Bill Daniels

On Sep 28, 11:44 pm, Bob Whelan
wrote:
Personally, I think the Gospel of Simplicity ought to be preached more,
because so much of soaring does not REQUIRE the latest in bells and
whistles be present in order for fledglings to begin spreading their
wings in personally gratifying and safe ways. Flight (in any form)
costs more than remaining groundbound. Soaring flight as a niche
certainly isn't cheap (in time or money or mental effort required), and
any barriers (real or imagined) to achieving it are precisely that:
barriers. I don't think soaring participants should be promoting Mark
CXXIV widgets as a universal good, or worse, as necessary, to everyone
getting into the sport.

Couldn't agree more - hence my comment that technology peaked with the
B40 :-).

I'm not a big fan of slavishly following the vario when cruising -
there's a lot of evidence that there's little to be gained in terms of
overall XC speed. In fact there's a very good chance that by the time
you've slowed up, you're in sink, and by the time you've accelerated,
you're in lift. A glider doing 70 knots is travelling at ~30 m/s -
allow for the seconds of the vario reacting, the pilot reacting, and
the glider responding to your control inputs and you'll have travelled
an easy 100 m - that is, you're effectively reacting to air that's 100
m behind you. Which probably won't be doing the same thing as the air
you're now in.

What's much more important in terms of XC speed is climbing fast - and
to do that you need an accurate, well set-up vario. Mechanicals suck
on that score, and as Mike says, they often take the fancy kit with
them unless they've been set up by an expert.

BTW, on the gust issue, there is another solution (though not nearly
as elegant as the rotating TE probe) - accelerometers. The Vega by
Triadis uses them for gust filtering, but I've not heard of any pilot
reports.


Dan

"Dan G" wrote in message
ups.com...
On Sep 28, 11:44 pm, Bob Whelan
wrote:
Personally, I think the Gospel of Simplicity ought to be preached more,
because so much of soaring does not REQUIRE the latest in bells and
whistles be present in order for fledglings to begin spreading their
wings in personally gratifying and safe ways. Flight (in any form)
costs more than remaining groundbound. Soaring flight as a niche
certainly isn't cheap (in time or money or mental effort required), and
any barriers (real or imagined) to achieving it are precisely that:
barriers. I don't think soaring participants should be promoting Mark
CXXIV widgets as a universal good, or worse, as necessary, to everyone
getting into the sport.

Couldn't agree more - hence my comment that technology peaked with the
B40 :-).

I'm not a big fan of slavishly following the vario when cruising -
there's a lot of evidence that there's little to be gained in terms of
overall XC speed. In fact there's a very good chance that by the time
you've slowed up, you're in sink, and by the time you've accelerated,
you're in lift. A glider doing 70 knots is travelling at ~30 m/s -
allow for the seconds of the vario reacting, the pilot reacting, and
the glider responding to your control inputs and you'll have travelled
an easy 100 m - that is, you're effectively reacting to air that's 100
m behind you. Which probably won't be doing the same thing as the air
you're now in.

This is a testable thesis.

Careful study of OLC logs show those with the best flights do indeed indulge
in 'dolphin flying'. Of course, not all zooms are successful, but on
average, they are. Successful 'dolphin flying' requires several things.
One, the thermals must be wide enough. Two, the glider must have good
penetration and three, the pilot must be using relatively high interthermal
airspeeds. (You can't zoom from a low airspeed.)

If you have SeeYou, set it up so there are four windows - three of equal
size on the right half of the screen stacked one above the other. On the
left half display the map view with the trace color set to vertical speed.
Set the top right window to a graph of true airspeed (IAS would be better
but it's not available). Set the middle right window to vertical speed and
set the bottom right window to altitude. Expand the time axis of the three
right windows to the maximum. Now, save this "desktop" so you don't have
set it up again - then animate the flight log.

Those pilots who are 'dolphin flying' will show a sharp reduction in speed
as lift is encountered and a jump of several hundred feet in altitude. If
the zoom is successful, the altitude trace will show a resumption of the
glide displaced upward from a estimated continuation of the pre thermal
encounter trace. In the statistical analysis, the zoomers will show D:h
ratios in the hundreds for their straight glides. Those pilot not zooming
in lift will show D:h values around their best L/D. Dolphin flying clearly
works, but you have to be good at it. The best pilots are really good at
it.


What's much more important in terms of XC speed is climbing fast - and
to do that you need an accurate, well set-up vario. Mechanicals suck
on that score, and as Mike says, they often take the fancy kit with
them unless they've been set up by an expert.

No arguement. The best climbers easily win the day. It's amazing to see
OLC traces on SeeYou where the vertical speed trace shows a sine wave
matching the circle time. This clearly shows the pilot is not centered in
the thermal. The best pilots will show an average climb rate 2-3 knots
better than the average pilot on the same day. The pilot who are good at
zooms are also good at selecting and centering thermals - often on the first
turn.


BTW, on the gust issue, there is another solution (though not nearly
as elegant as the rotating TE probe) - accelerometers. The Vega by
Triadis uses them for gust filtering, but I've not heard of any pilot
reports.

In secret laboratories around the world they are working on the dreaded
"Inertial Variometer" that will change everything.

Bill Daniels

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
* 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

Bill, are you seeing the effect of "dolphin" flying, or just following
the lines of energy (or, avoiding sink). I try real hard to avoid the
classic "pull hard in lif" type of dolphin flying, since in my
experience it slows me down (from comparison flying); OTOH, I try real
hard to look for and exploit lift lines, and gently vary speeds to
match the trend of the airmass. Doing this, I consistently better my
polar's L/D for the speed being flown.

Of course, this is semantics - whatever technique being used, it is a
skill that takes knowledge, practice, and good instruments.

And the fast pilots usually have all three!

Kirk
66