Glider computers - what's important?

Eric Greenwell wrote:

Bill Daniels wrote:

A "glide footprint" shows clearly how to cross a mountain range since it
computes glide distance in all directions. The courseline may happen to
cross the range at a high peak so a list type display will show the goal as
unreachable but the "glide footprint" will show that a slight change in
course will easily clear the terrain.

I can use that feature!

Use GPS_LOG WinCE. It has it.

Henryk Birecki

"Stefan" wrote in message
. ..
Eric Greenwell schrieb:

landable terrain that isn't in the airport database. Just knowing that
good landout options are reachable reduces stress

I reduce my stress by carrying an "iron thermal"!

Dangerous tactic. Your personal thermal may or may not work.


Actually, Eric flies an ASH26E, so his "iron thermal" is the indescribably
smooth and reliable Wankel rotary engine. It always works :c)

bumper
ASH26E
Minden

Stefan wrote:
Eric Greenwell schrieb:

landable terrain that isn't in the airport database. Just knowing
that good landout options are reachable reduces stress

I reduce my stress by carrying an "iron thermal"!

Dangerous tactic. Your personal thermal may or may not work.

It doesn't have to be perfect to be a stress reducer! I always have a
good field in easy reach before I attempt to start; so far, only one
failure to start out of 165 in-flight restart attempts. That's a lot
less stress than 164 retrieves.

For a detailed look at how I use the "iron thermal" it's advantages for
the pursuit of soaring, read my "Guide" - see below for the download link.

--
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

Hi,

Use GPS_LOG WinCE.

I do.

It has it.

Can you enlighten me on on how the footprint is computed?

Just by looking in a few directions, determining the "points of impact" in
those directions and connecting them? Or is it more complicated?

Would a single mountain on a vast plane look like an island in the glide
footprint?

Ciao, MM
--
Marian Aldenhövel, Rosenhain 23, 53123 Bonn
http://www.marian-aldenhoevel.de
"Success is the happy feeling you get between the time you
do something and the time you tell a woman what you did."

"Richard" wrote

The question is have you compared the free programs with SeeYou or
WinPilot. We would all like to hear your comparison.

I have compared GPS-LOG to SeeYou Mobile, and I am flying with GPS-LOG. It
gives me everything I need (X-country flying, no competitions) in a way I
like. It automatically switches between climb and cruise mode and displays
the relevant data for each mode without any need to touch the PDA. It gives
me the glide footprint on the map like discussed in another part of this
thread and AFAIK it was also the first PDA software to implement FLARM voice
warnings.

The only advantage I see in the commercial packages is the very easy
transfer of map and airspace from the desktop software (SeeYou -
SeeYouMobile, .....).

Michael

"Marian Aldenhövel" wrote in message
...
Hi,

Use GPS_LOG WinCE.

I do.

It has it.

Can you enlighten me on on how the footprint is computed?

Just by looking in a few directions, determining the "points of impact" in
those directions and connecting them? Or is it more complicated?

It simply looks in 48 directions around the compass and computes the maximum
glide in each direction considering wind, polar, McCready, balast and bugs.
It terminates each glide at the 'safety altitude' you have selected. It
then connects these glide termination points with a line that forms a 48
sided polygon. It does this about once a minute.

Would a single mountain on a vast plane look like an island in the glide
footprint?

A single isolated mountain on a plain would be a "notch" in the polygon, not
an island. If you know the terrain, it's obvious that you can glide around
the mountain and land in the notch on the other side.

Bill Daniels

On Mar 12, 5:08 am, "Bill Daniels" bildan@comcast-dot-net wrote:

It simply looks in 48 directions around the compass and computes the maximum
glide in each direction considering wind, polar, McCready, balast and bugs.

Plase confirm this function uses current MC. I browsed the on-line
manual and I thought it said ZERO MC which is not the implementation I
would want.

Is anyone using the terrain functions on an Aero 1550? If so is
performance adequate?

thanks

Andy

I would also want a user-definable reserve height of maybe 500ft when I
got there.=20
especially as this is different from a final glide to a known landing
spot
=20
ie consider wind, polar, mcready, balast, bugs and reserve height.
=20
For those in the mountains, a computation that can cope with corners
round ridges would be nice, but that is probably step 2.
=20
ps: I would not plan to use my own "iron thermal" unless over landable
terrain
=20
=20
Rory
=20
Subject: Using a "GLIDE footprint"
Author: Andy mailto:Andy

Date/Time: 14:40 12 March 2007

________________________________

On Mar 12, 5:08 am, "Bill Daniels" wrote:

It simply looks in 48 directions around the compass and computes the
maximum
glide in each direction considering wind, polar, McCready, balast and
bugs.

"Andy" wrote:

On Mar 12, 5:08 am, "Bill Daniels" bildan@comcast-dot-net wrote:

It simply looks in 48 directions around the compass and computes the maximum
glide in each direction considering wind, polar, McCready, balast and bugs.


Yes it does. 48 seemed like a good compromise between computation time
and "precision". This could be made a user input parameter in future
editions if there is a general concensus that it would be useful.

Plase confirm this function uses current MC. I browsed the on-line
manual and I thought it said ZERO MC which is not the implementation I
would want.

You are right about documentation. I will need to check in the code.
It may well be ZERO MC as it is a "safety" feature. If you are looking
for a safe place to land you want to fly at best glide angle, not best
time. Anyone would like to comment?


Is anyone using the terrain functions on an Aero 1550? If so is
performance adequate?


I am. I have not seen any problems so far, and I usually do fly in the
mountains.

Henryk Birecki

"Andy" wrote:

On Mar 12, 5:08 am, "Bill Daniels" bildan@comcast-dot-net wrote:

Plase confirm this function uses current MC. I browsed the on-line
manual and I thought it said ZERO MC which is not the implementation I
would want.

I forgot to add in my previous post: If you really want to have "real
time" feedback in GPS_LOG for whether you can clear a mountain range
on course, you would not be looking at the GLIDE footprint, but at
forward looking terrain plot. This gives you glide path at your
current speed, wind... plotted with the ground profile. Got me through
several passes that I would have never attempted without that
information.

Henryk Birecki