What can a PDA do for me?

I've got a late '80's model flight computer with an
integrated non-GPS final glide calculator and an IGC GPS
logger. I'm thinking about upgrade options to minimize the
mental workload for these items that I currently have
trouble with:

What's the current wind speed and direction?

What altitude do I need to final glide upwind to airport X
and turn back downwind to home at airport Y?

What airport is easiest to get to when I'm low given
different airport field elevations and current wind
direction.

When should I turn to get home 3 hours after I started this
task?

I'm not really sure what options I have. More generally,
I'm wondering what the PDA's can do. I presume they have no
airspeed/pitot input, no TE input and only GPS altitude.
Is that correct? Can they perform vario/TE/STF/final glide
functions?

I realize they can do GPS moving map, flight track
recording. I suspect they can figure wind from a circling
algorithm, but without TE or airspeed can they replace my
old flight computer? If not, can they supplement it (with
my GPS/pressure logger) so I can avoid the expense of a new
flight computer?

Anyone want to give me some comments here? Thanks.

go to:
http://www.winpilot.com



williscomb

Or go to:
http://www.seeyou.ws

At 14:12 14 April 2004, Williscomb wrote:
go to:
http://www.winpilot.com



williscomb

I've been to both, but they are both trying to put the best
face on their products. No one says; We don't have any way
to connect to pitot, or TE probes, so the PDA does this or
can't do that. I see combinations of PDAs, varios, flight
computers, GPS units, IGC loggers, etc., but it's hard to
figure out what data they have coming in and what's doing
what.

Anyone else want to comment on the relationship between a
PDA vs a flight computer and what the PDA can do vs. what it
can't and why?


Or go to:
http://www.seeyou.ws

go to:
http://www.winpilot.com

Go he

http://www.soarmn.com/cumulus/gn.htm

or he

www.soaringpilot.com

or he
http://www.ccsi.com/~inadas/



Jim Vincent
CFIG
N483SZ
illspam

Hi,

I created a spreadsheet comparing several soaring flight computer and
software systems. I also created a presentation comparing soaring software
and flight computer systems. They are available as links on my Cumulus
homepage at: http://www.cumulus-soaring.com

My presentation segments the soaring instrument market into low cost (PDA
with GPS), medium cost (IGC Approved GPS/Logger), and high cost
(GPS/Logger/Vario/Speed-to-fly).

I put a lot of work into them. If you appreciate it, please consider buying
from me.

I sell Glide Navigator II and pocket*StrePla programs for Pocket PCs. They
are both very nice in their own way. I also sell Cambridge products.

I'll have to look into what pocket*StrePla offers in regard to using data
from a vario or GPS. Glide Navigator II can use wind data from either a
GPS-NAV/L-NAV combination or a 302. It uses the airspeed data for more
accurate wind information. It uses the pressure altitude data for accurate
altitude information.

All soaring Pocket PC software programs can calculate wind speed while
circling.

I'm pretty sure they can all calculate final glide around multiple
turnpoints - taking wind speed and direction into account.

I believe pocket*StrePla, SeeYou Mobile and WinPilot can display average
vario readings from some varios such as the Cambridge 302.

Another resource for example systems is my "Example Systems" page at:
http://www.cumulus-soaring.com/systems.htm

I hope the data is helpful.

Good Soaring,

Paul Remde
Cumulus Soaring Supplies

"BJen" wrote in message
...
I've been to both, but they are both trying to put the best
face on their products. No one says; We don't have any way
to connect to pitot, or TE probes, so the PDA does this or
can't do that. I see combinations of PDAs, varios, flight
computers, GPS units, IGC loggers, etc., but it's hard to
figure out what data they have coming in and what's doing
what.

Anyone else want to comment on the relationship between a
PDA vs a flight computer and what the PDA can do vs. what it
can't and why?


Or go to:
http://www.seeyou.ws

go to:
http://www.winpilot.com

Thanks for the info Paul. It helps. Let me try to
summarize, and anyone who wants to chime in on where I'm
wrong, or right, feel free:

All PDAs connected to a GPS know location, ground speed and
track from the GPS. That lets them calculate wind speed and
direction from circling algorithms. There are some
straight line wind calculation algorithms used by flight
computers, but that requires an airspeed input, and since my
flight computer won't output any airspeed info to a PDA, I'd
have to buy one that does.

With wind and location data, a PDA can calculate altitude
required for final glide, glide to emergency fields and
glide around a TP before going home in wind. Presumably
this would have to be displayed as "altitude required"
unless it know current altitude somehow.

If the PDA knows altitude from an input, it can display
which fields you can reach, and whether you are high or low
on final glide. GPS altitude is relatively poor, but is one
option for getting current altitude info to the PDA. I
suppose you could input it manually, but that doesn't sound
practical. The best is a pressure sensor, but that would
mean getting altitude info from either a flight computer
(same as the airspeed problem above) or a Flight Recorder
that outputs its pressure altitude. Does the Volkslogger
give pressure alt to the PDA? Reading between the lines on
the PDA summaries I think it does.

For vario functions, it looks like it would need access to
TE. That's only available from a vario or flight computer.
I suppose it could fake it with altitude info for non-TE or
pseudo TE using wind and ground speed info. Do any do this?

For STF, it again needs TE from a vario or flight computer,
but I suppose it could fake it as above.

Does that sound right?


"Paul Remde" wrote:

Hi,

I created a spreadsheet comparing several soaring flight computer and
software systems. I also created a presentation comparing soaring software
and flight computer systems. They are available as links on my Cumulus
homepage at: http://www.cumulus-soaring.com

My presentation segments the soaring instrument market into low cost (PDA
with GPS), medium cost (IGC Approved GPS/Logger), and high cost
(GPS/Logger/Vario/Speed-to-fly).

I put a lot of work into them. If you appreciate it, please consider buying
from me.

I sell Glide Navigator II and pocket*StrePla programs for Pocket PCs. They
are both very nice in their own way. I also sell Cambridge products.

I'll have to look into what pocket*StrePla offers in regard to using data
from a vario or GPS. Glide Navigator II can use wind data from either a
GPS-NAV/L-NAV combination or a 302. It uses the airspeed data for more
accurate wind information. It uses the pressure altitude data for accurate
altitude information.

All soaring Pocket PC software programs can calculate wind speed while
circling.

I'm pretty sure they can all calculate final glide around multiple
turnpoints - taking wind speed and direction into account.

I believe pocket*StrePla, SeeYou Mobile and WinPilot can display average
vario readings from some varios such as the Cambridge 302.

Another resource for example systems is my "Example Systems" page at:
http://www.cumulus-soaring.com/systems.htm

I hope the data is helpful.

Good Soaring,

Paul Remde
Cumulus Soaring Supplies

"BJen" wrote in message
.. .
I've been to both, but they are both trying to put the best
face on their products. No one says; We don't have any way
to connect to pitot, or TE probes, so the PDA does this or
can't do that. I see combinations of PDAs, varios, flight
computers, GPS units, IGC loggers, etc., but it's hard to
figure out what data they have coming in and what's doing
what.

Anyone else want to comment on the relationship between a
PDA vs a flight computer and what the PDA can do vs. what it
can't and why?


Or go to:
http://www.seeyou.ws

go to:
http://www.winpilot.com

BJen wrote:
GPS altitude is relatively poor, but is one
option for getting current altitude info to the PDA. I
suppose you could input it manually, but that doesn't sound
practical. The best is a pressure sensor, but that would
mean getting altitude info from either a flight computer
(same as the airspeed problem above) or a Flight Recorder
that outputs its pressure altitude. Does the Volkslogger
give pressure alt to the PDA? Reading between the lines on
the PDA summaries I think it does.

GPS altitude is a more accurate indication of your actual (geometric)
altitude above sea level, so a lot of people use GPS altitude for final
glide, even if they have a flight computer or recorder that outputs
pressure altitude. Pressure altitude provides a more accurate short
term (a few minutes or less) indication of change in altitude.

BTW, some of the newer versions of PDA programs contain an internal map
of the ground elevation, so they can display your altitude above ground.
Some now figure your final glide altitude needed with consideration of
the ground elevations (i.e. mountains) between your current position and
the destination.

For vario functions, it looks like it would need access to
TE. That's only available from a vario or flight computer.
I suppose it could fake it with altitude info for non-TE or
pseudo TE using wind and ground speed info. Do any do this?

Using GPS altitude only, the climb rate averaged over 30 seconds or so
is fairly accurate most of the time. Some PDA programs do this, some
also try to account for total energy as you suggest, most calculate an
average thermal climb rate, which is usually quite accurate.

For STF, it again needs TE from a vario or flight computer,
but I suppose it could fake it as above.

Does that sound right?

Yes.

Marc

Check your assumptions on GPS altitude. In my experience, it is very
similar to pressure altitude and doesn't suffer from the problems of
pressure altitude. I believe GPS altitude to be as good or better than
pressure altitude for all practical purposes.
STF I get very good STF info from my handheld. If it says to fly 80kts
around the last turnpoint and on home, I fly 80 and arrive home at pattern
altitude, just as programmed.

Brent
"BJen" wrote in message
...
glide around a TP before going home in wind. Presumably
this would have to be displayed as "altitude required"
unless it know current altitude somehow.

If the PDA knows altitude from an input, it can display
which fields you can reach, and whether you are high or low
on final glide. GPS altitude is relatively poor, but is one
option for getting current altitude info to the PDA. I
suppose you could input it manually, but that doesn't sound
practical. The best is a pressure sensor, but that would
mean getting altitude info from either a flight computer
(same as the airspeed problem above) or a Flight Recorder
that outputs its pressure altitude. Does the Volkslogger
give pressure alt to the PDA? Reading between the lines on
the PDA summaries I think it does.

For vario functions, it looks like it would need access to
TE. That's only available from a vario or flight computer.
I suppose it could fake it with altitude info for non-TE or
pseudo TE using wind and ground speed info. Do any do this?

For STF, it again needs TE from a vario or flight computer,
but I suppose it could fake it as above.

Does that sound right?

On 15 Apr 2004 08:48:06 -0500, BJen
wrote:

Thanks for the info Paul. It helps. Let me try to
summarize, and anyone who wants to chime in on where I'm
wrong, or right, feel free:

All PDAs connected to a GPS know location, ground speed and
track from the GPS. That lets them calculate wind speed and
direction from circling algorithms. There are some
straight line wind calculation algorithms used by flight
computers, but that requires an airspeed input, and since my
flight computer won't output any airspeed info to a PDA, I'd
have to buy one that does.

With wind and location data, a PDA can calculate altitude
required for final glide, glide to emergency fields and
glide around a TP before going home in wind. Presumably
this would have to be displayed as "altitude required"
unless it know current altitude somehow.

If the PDA knows altitude from an input, it can display
which fields you can reach, and whether you are high or low
on final glide. GPS altitude is relatively poor, but is one
option for getting current altitude info to the PDA. I
suppose you could input it manually, but that doesn't sound
practical. The best is a pressure sensor, but that would
mean getting altitude info from either a flight computer
(same as the airspeed problem above) or a Flight Recorder
that outputs its pressure altitude. Does the Volkslogger
give pressure alt to the PDA? Reading between the lines on
the PDA summaries I think it does.

For vario functions, it looks like it would need access to
TE. That's only available from a vario or flight computer.
I suppose it could fake it with altitude info for non-TE or
pseudo TE using wind and ground speed info. Do any do this?

You may be over-complicating things. The following assumes you prefer
cheap toys to expensive ones.

A simple GPS + PDA system can handle all your navigation and glide
calculations independently of the rest of your instruments. Granted,
the GPS altitude is less accurate than position, but probably still
good enough for FG calculations given all the other uncertainties and
happenstances during the final glide.

All you really need on top of that is a simple audio vario such as a
B.40, Tasman, or even an ancient Cambridge Mk 4. These are all
stand-alone instruments, so no additional interconnection is needed.

For STF, it again needs TE from a vario or flight computer,
but I suppose it could fake it as above.

If you have room for a second vario, fit a mechanical unit with a
Macready ring.

A club mate uses exactly this type of rig for club class competition
in his ASW-19.

===============

Why I think this is a good way to go
-------------------------------------------
For the last two seasons I flew my club's Pegase 90 with a Garmin GPS
II+, Cambridge Mk 4 audio vario, Winter vario w/MaCready ring and EW
model D logger. The only additional thing I would have liked was some
sort of moving map display to show airspace restrictions, etc.

This season I was planned to buy a glider and intended to install an
iPAQ 3630 running XCsoar, Garmin GPS 2+, Tasman or B.40, Winter
mechanical and the EW logger. However, I bought an ASW-20 which turned
out to have an SDI C4 already installed. In addition I installed my
GPS II+ and my EW logger. I'd previously acquired an iPAQ 3630 and am
thinking (slowly) about where to fit it so as to add the moving map
capability, but am short of panel real estate: the only really
suitable space is occupied by my GPS II+.

=========

If you need anything more complex than the GPS+PDA and separate varios
be aware that there are interconnect issues. In particular, a lot of
glide computers require the turn points to be fed to them from the GPS
but many? all? PDA programs don't accept turnpoints from the GPS, so
immediately you're into double task entry. My immediate thought was to
bypass this by using a blind GPS and put the task into the PDA:
however, most of the free-standing PDA programs don't output the
route-related GPS sentences needed by the SDI glide computer.

If you use the simple set-up I outlined above you'll avoid this sort
of nonsense and can, if you want, install a blind GPS to feed the PDA.
This is a good idea because the GPS doesn't then take up panel space
(it can be invisible behind a panel-top compass) or need any inputs,
freeing up panel space for the PDA. The other way to avoid
connectivity problems is to go with a complete set of kit from the
likes of Borgelt or Cambridge but that's more expensive.

Anything else is likely to result in the sort of connectivity issues I
described.

HTH
Martin

--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :