WINPILOT + ILEC SN-10 + VOLKSLOGGER

Having good heading info only when flying wings level is not that big a
problem, since the present SN10 algorithm works fairly well when one is
turning. One could just switch back to the present algorithm for turning
flight. Maybe that's what the Zander does (a previous poster said he didn't
understand how the Zander, which uses a heading sensor, can calculate wind
when the sailplane is banked).

Ray


"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote in message
news:GLydnQkwE87RNTDenZ2dnUVZ_sCdnZ2d@wideopenwest .com...
"Ray Roberts" wrote in message
. ..


Snip
If an accurate aircraft heading sensor were added to the SN10, thus
completely defining two of the vectors in the "wind triangle", this would
not be necessary. One lives in hope...





For $300 you can add a fluxgate compass that will communicate via NMEA...
Fixing the software to use it would be up to you.

Of course, the heading information will only be good when you are flying
straight and level...

http://www.westmarine.com/webapp/wcs...001/606/137/14


move spaces and make the obvious substitutions to reply by mail
Spell checking is left as an excercise for the reader.

a previous poster said he didn't understand how the Zander,=20
which uses a heading sensor, can calculate wind=20
when the sailplane is banked

That is not what the previous poster said. Please read again.

Happy Xmas,
Previous poster

I stand corrected!
Ray Roberts

"Francisco De Almeida" wrote in message
...
a previous poster said he didn't understand how the Zander,=20
which uses a heading sensor, can calculate wind=20
when the sailplane is banked

That is not what the previous poster said. Please read again.

Happy Xmas,
Previous poster

As an aside . . . there are two versions of WinPilot, WinPilot
'Advanced' (all purpose) and WinPilot 'Pro' that **requires** one
of the following devices to be connected to get accurate info:

a.. Cambridge 302 vario/flight recorder
b.. LX1600, LX 5000, LX7000, LX 160
c.. Westerboer VW921/922
d.. or a Borgelt B50 (with a gps-unit)
(from http://www.winpilot.com/gps.asp)

The **Pro** version is apparently able to derive wind info in
straight flight as well as the 'Advanced' version's derivision
from thermalling ability.

jk





wrote in message
oups.com...
I tend to agree with Marcel. I also fly with an ILEC SN-10 and
an IPAQ
with Winpilot. My sense is that algorith and precision from the
SN-10
is always more accurate than Winpilot. The reason I say this is
the
same as what Marcel mentioned, which is the ILEC is capable of
calculating windspeed and direction while in level flight,
whereas most
other software/computers require you to be circling.
Respectfully,

wrote:
Doug,

I'm curious to know how much variation you get between the two,
if any.

I use WinPilot Pro 6.x and an LX7000 Pro, and the two wind
indications
are usually very close.

~ted/2NO

I actually have the same Azimuth 1000 flux gate compass installed on
the rear instrument panel of my Janus C. It is coupled via NMEA to an
RMI microEncoder in the front panel.

One problem with the set-up is that the S/H two-place one-piece canopy
has a steel cross member, so the compass reading changes by more than 5
degrees between open and closed canopy. Also, even though it is tilt
compensated by mounting the flux gate on a gimball, it does not produce
consistent readings when tilted. I assume this is because the tilt
compensation alters the hard/soft iron compensation.

I looked at installing a remote flux gate, but there is no place in the
glider to mount it far enough from the steel flight control push/pull
rods. This is a real problem for getting accurate heading info from a
magnetic sensor in a glider.

P.S. Ray points out that with any two vectors, you can draw the vectors
tip to tail to complete the wind triangle. With one vector (GPS) and a
scalar (TAS) you can draw a circle around the tip of the vector to
create a family of wind triangles. With a second set of measurements on
another heading, you can draw another circle which intersects the first
at two places. With another set of measurements, you can remove the
ambiguity, and get a check on the error. In practice, flight computers
like the SN-10 make lots of measurements and keep a running calculation
of the wind by filtering out the measurement errors.

Capt. Geoffrey Thorpe wrote:
"Ray Roberts" wrote in message
. ..
Calculation of windspeed and wind direction without circling:

Here's my understanding. If it's not correct, doubtless someone will
straighten me out and I will have learned something. DISCLAIMER: I have
absolutely no "inside" information on the algorithms used in the SN10!

Aircraft heading (direction the nose is pointing) and airspeed together
define a velocity vector that can be drawn as an arrow on a piece of
paper, the angle of the arrow representing the direction and the length of
the
...
In the case of a sailplane with an SN10 that has input from a GPS, we have
three knowns, namely true airspeed (the SN10 can compute this from pitot
pressure, static pressure, altitude and temperature), groundspeed and
track (the last two come from the GPS). There are three unknowns, aircraft
heading, wind direction and windspeed. Basically, multiple unknowns can be
calculated by setting up and solving simultaneous equations. There are
well known mathematical and computer algorithms for doing this.
...
makes sense. If an accurate aircraft heading sensor were added to the
SN10, thus completely defining two of the vectors in the "wind triangle",
this would not be necessary. One lives in hope...



For $300 you can add a fluxgate compass that will communicate via NMEA...
Fixing the software to use it would be up to you.

Of course, the heading information will only be good when you are flying
straight and level...

http://www.westmarine.com/webapp/wcs...001/606/137/14

--
Geoff
the sea hawk at wow way d0t com
remove spaces and make the obvious substitutions to reply by mail
Spell checking is left as an excercise for the reader.

No, the ILEC SN-10 cannot compute winds in straight/level flight. In
fact, there is a known problem when flying long straight runs in ridge
lift, where the wind speed drifts up to unreasonable values (like as
much as double the true speed). It also tends to hold on to a higher
wind speed when the wind dimishes. This can be big trouble when flying
along a ridge into a becalmed area. When you turn around and then
towards your field to land, the wind display updates, but by then it's
too late.

This is not a software bug per se, it is just a limitation of using GPS
and airspeed to measure wind without a heading sensor. Adding a
magnetic heading sensor won't really help, because the heading error is
similar to the crab angle. So without a lot of calibration, you won't
see much benefit, and you just introduce the possibility of greater
error. A two antenna GPS would be a good solution, but the current
consumer products are intended for marine applications, and are not set
up to handle high bank angles.

I actually have the same Azimuth 1000 flux gate compass installed on
the rear instrument panel of my Janus C. It is coupled via NMEA to an
RMI microEncoder in the front panel.

One problem with the set-up is that the S/H two-place one-piece canopy
has a steel cross member, so the compass reading changes by more than 5
degrees between open and closed canopy. Also, even though it is tilt
compensated by mounting the flux gate on a gimball, it does not produce
consistent readings when tilted. I assume this is because the tilt
compensation alters the hard/soft iron compensation.

I looked at installing a remote flux gate, but there is no place in the
glider to mount it far enough from the steel flight control push/pull
rods. This is a real problem for getting accurate heading info from a
magnetic sensor in a glider.

P.S. Ray points out that with any two vectors, you can draw the vectors
tip to tail to complete the wind triangle. With one vector (GPS) and a
scalar (TAS) you can draw a circle around the tip of the vector to
create a family of wind triangles. With a second set of measurements on
another heading, you can draw another circle which intersects the first
at two places. With another set of measurements, you can remove the
ambiguity, and get a check on the error. In practice, flight computers
like the SN-10 make lots of measurements and keep a running calculation
of the wind by filtering out the measurement errors.

Capt. Geoffrey Thorpe wrote:
"Ray Roberts" wrote in message
. ..
Calculation of windspeed and wind direction without circling:

Here's my understanding. If it's not correct, doubtless someone will
straighten me out and I will have learned something. DISCLAIMER: I have
absolutely no "inside" information on the algorithms used in the SN10!

Aircraft heading (direction the nose is pointing) and airspeed together
define a velocity vector that can be drawn as an arrow on a piece of
paper, the angle of the arrow representing the direction and the length of
the
...
In the case of a sailplane with an SN10 that has input from a GPS, we have
three knowns, namely true airspeed (the SN10 can compute this from pitot
pressure, static pressure, altitude and temperature), groundspeed and
track (the last two come from the GPS). There are three unknowns, aircraft
heading, wind direction and windspeed. Basically, multiple unknowns can be
calculated by setting up and solving simultaneous equations. There are
well known mathematical and computer algorithms for doing this.
...
makes sense. If an accurate aircraft heading sensor were added to the
SN10, thus completely defining two of the vectors in the "wind triangle",
this would not be necessary. One lives in hope...



For $300 you can add a fluxgate compass that will communicate via NMEA...
Fixing the software to use it would be up to you.

Of course, the heading information will only be good when you are flying
straight and level...

http://www.westmarine.com/webapp/wcs...001/606/137/14

--
Geoff
the sea hawk at wow way d0t com
remove spaces and make the obvious substitutions to reply by mail
Spell checking is left as an excercise for the reader.

From the Zander website home.wxs.nl/~kpt9/Rozander.htm :

"The compass option for wind calculation during straight flight and circle
wind calculation based on GPS data, provide wind speed and wind direction
all the time."

I think this explains how the Zander does the wind calculation when the
sailplane is banked.

Ray


"Francisco De Almeida" wrote in message
...
Ray Roberts wrote:
If an accurate aircraft heading sensor were added to the SN10,=20
thus completely defining two of the vectors in the "wind triangle", =
this=20
would not be necessary. One lives in hope...

That is exactly what the Zander SR940, ZS1 and (I believe) all other =
flight computers with compass coupling do. It makes good wind speed =
readings possible in straight flight even without weaving. Furthermore, =
for reasons that I cannot explain, the wind vectors calculated by the =
computers above in circular flight are not affected by bank angle =
changes.

The problem mentioned below is not confined to the wind SPEED calculation.
Some months ago I flew a fairly straight ridge at 80 kts for many miles,
with the SN10 telling me that the wind was straight along the ridge. I knew
the calculated wind angle could not possibly be correct, because if it had
been, there would have been no ridge lift to keep me airborne, nor would I
have tracked along the ridge with the big crab angle between the ridge and
the nose of the sailplane that was clearly visible outside the canopy.
Eventually I made a couple of circles, after which the SN10 gave me a much
more sensible wind result.
Ray

"Doug Haluza" wrote in message
ups.com...
No, the ILEC SN-10 cannot compute winds in straight/level flight. In
fact, there is a known problem when flying long straight runs in ridge
lift, where the wind speed drifts up to unreasonable values (like as
much as double the true speed). It also tends to hold on to a higher
wind speed when the wind dimishes. This can be big trouble when flying
along a ridge into a becalmed area. When you turn around and then
towards your field to land, the wind display updates, but by then it's
too late.

This is not a software bug per se, it is just a limitation of using GPS
and airspeed to measure wind without a heading sensor. Adding a
magnetic heading sensor won't really help, because the heading error is
similar to the crab angle. So without a lot of calibration, you won't
see much benefit, and you just introduce the possibility of greater
error. A two antenna GPS would be a good solution, but the current
consumer products are intended for marine applications, and are not set
up to handle high bank angles.