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