SN-10 vs CAI 302

There are a lot of people that read this newsgroup
and even though some may be a very experienced mountain
pilots others may not be. Squeaking a glide into a
strip around mountains sounds like a setup for problems
when hitting bad sink.

Casey

I like PDA's for freeing up my bandwith for analyzing
conditions...but what Casey writes is soooo true.
Time of day, what the wind is doing over the terrain
ahead, cloud cover...are not going to be analyzed and
displayed. At the same altitutude and wind direction/speed,
the computer does not know/care if a decaying Cu-Nim
is on course, or if the day is dying or for that matter
just starting to boom.

Kilo Charlie wrote:
..

Here in AZ we have encountered some very heavy sink over extended periods in
the mountains and so my point overall is that I would suggest keeping extra
altitude as a safety margin.

I don't just suggest it, I strongly recommend it. The trick is learning
what amounts should be used, where to use them, and when. Extra is
required when wave is about, also. I don't think anyone suggested all
you needed was a terrain warning to keep you safe in the mountains. It's
just an additional tool to help the pilot with his soaring, and I hope
no one thinks they will learn the nuances of mountain soaring from a
thread on ras.

There are a lot of people that read this
newsgroup and even though some may be a very experienced mountain pilots
others may not be. Squeaking a glide into a strip around mountains sounds
like a setup for problems when hitting bad sink.

I think squeaking a glide into a strip is a setup for problems, flat
land or mountains.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Also for the record one of our local pilots was flying in the hills a couple
of years back and did exactly what I stated.....had a Mc zero setting in for
a landable strip and hit huge sink on the way there causing him to have to
land in a very bad area.....large paloverdes and cactus. He was very lucky
to walk away unhurt. The glider was a mess but repairable.


The same would have happened if he had used the SN10 landable places at
MC 0.

People do not set your glide computer to MC0 as you are not flying the
polar you are flying the conditions.

Al

That is a problem with most computers. I want to fly
the 0 Mcready (especially downwind) when trying to
strech to a landable spot, but want to arrive there
higher than 150 meters that the SN10 gives you. The
only way to change that is to abandon the task and
'goto' the alternate on the alternate page and then
change the arrival altitude on the stats page. Too
much to do when in a high stress mode. I would like
to be able to set a ' user set default' for arrival
altitude to alternates that would show the glide to
any selected alternate plus what I have set as a 'user
default'. That way I do not have to abandon the task
and can see the arrival altitude just by going to the
alternates page. Simply less math in my head. While
were at it put the alternates page at the end of the
menu so I can just spin the knob and be there, and
not have to come back 3 small clicks that mowt of the
time takes a few times to get to. Are you reading this
DRN Other than that the SN10 is superb! Keep up the
good work. Oh yea PS, put in a USB port and a auto
download to a thumb drive that I can pull and walk
away after flight!))

At 07:01 13 November 2006, wrote:

Also for the record one of our local pilots was flying
in the hills a couple
of years back and did exactly what I stated.....had
a Mc zero setting in for
a landable strip and hit huge sink on the way there
causing him to have to
land in a very bad area.....large paloverdes and cactus.
He was very lucky
to walk away unhurt. The glider was a mess but repairable.


The same would have happened if he had used the SN10
landable places at
MC 0.

People do not set your glide computer to MC0 as you
are not flying the
polar you are flying the conditions.

Al

Winpilot Pro basically gives you what you are asking for here.
It will also adjust glide for wind without having to mess with your MC
setting.

As a rule I typically fly with MC set to 3.
It gives about the right glides flying out of Minden

Al



Cliff Hilty wrote:
That is a problem with most computers. I want to fly
the 0 Mcready (especially downwind) when trying to
strech to a landable spot, but want to arrive there
higher than 150 meters that the SN10 gives you. The
only way to change that is to abandon the task and
'goto' the alternate on the alternate page and then
change the arrival altitude on the stats page. Too
much to do when in a high stress mode. I would like
to be able to set a ' user set default' for arrival
altitude to alternates that would show the glide to
any selected alternate plus what I have set as a 'user
default'. That way I do not have to abandon the task
and can see the arrival altitude just by going to the
alternates page. Simply less math in my head. While
were at it put the alternates page at the end of the
menu so I can just spin the knob and be there, and
not have to come back 3 small clicks that mowt of the
time takes a few times to get to. Are you reading this
DRN Other than that the SN10 is superb! Keep up the
good work. Oh yea PS, put in a USB port and a auto
download to a thumb drive that I can pull and walk
away after flight!))

At 07:01 13 November 2006, wrote:

Also for the record one of our local pilots was flying
in the hills a couple
of years back and did exactly what I stated.....had
a Mc zero setting in for
a landable strip and hit huge sink on the way there
causing him to have to
land in a very bad area.....large paloverdes and cactus.
He was very lucky
to walk away unhurt. The glider was a mess but repairable.


The same would have happened if he had used the SN10
landable places at
MC 0.

People do not set your glide computer to MC0 as you
are not flying the
polar you are flying the conditions.

Al

That is a problem with most computers. I want to fly
the 0 Mcready (especially downwind) when trying to
strech to a landable spot,

This comment reflects a big misunderstanding of glide computers and how
to use them.

First of all, the SN10 and other computers all include wind in the
calculation of gliding distances. In fact, there is a danger of using
the high altitude winds to think you can stretch much further than you
will be able to when you get lower and the tailwind component is less.

More importantly, calculating glides to landable spots at Mc 0 is
guaranteed to fail. The only time you will glide all the way to the
landable spot is if you miss all the thermals along the way, meaning
you glide there in sink. Catch 22.

The calculator is set up for final glides, over landable terrain. It
assumes lift = sink, which is a reasonable assumption for flying as
fast as possible on average, while taking a risk of landing short if
you hit sink all the way.

For safety, you want to assume the worst possible sink all the way to
landing. Since compters do not now let you set up "give me a glide at
Mc 0 but 5 knot sink" you have to do this by hand. Usually, setting the
glide at Mc 3-4 plus a reserve is a good approximation, but that
depends on weather, how bad terrain really is below you, and so forth.

The only hitch on many computers is you would like to input a higher
MacCready setting for glides to safe fields than you want to fly at.
When in danger, you might want to fly at Mc 0-1 (60 knots) but leave
Mc3-4 glides to your landing areas. Some computers let you do this. For
example, GNII lets you turn off Mc exchange, so you can set GNII to
Mc3-4 for landing calcuations but manually set the speed to fly vario
at Mc0-1. Otherwise, turn up the MacCready for glides and ignore the
instrument screaming at you to fly 90 knots.

John Cochrane

BB wrote:


The only hitch on many computers is you would like to input a higher
MacCready setting for glides to safe fields than you want to fly at.
When in danger, you might want to fly at Mc 0-1 (60 knots) but leave
Mc3-4 glides to your landing areas. Some computers let you do this. For
example, GNII lets you turn off Mc exchange, so you can set GNII to
Mc3-4 for landing calcuations but manually set the speed to fly vario
at Mc0-1.

I'm so glad to read it's not just me that wants to do this. I did as
John suggests when I used GNII, and I now do the same with SeeYou
Mobile, which also allows blocking the Mc exchange. I used to do it even
before flight computers, where I set the Mc ring on the vario lower than
the Mc setting on the plastic "prayer wheel".

For the ASW 20 and now the ASH 26 E, I find myself typically using a 2
knot Mc setting on the vario, a 4 knot setting on the flight computer,
and 5 knot thermals.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Or try a different tack: I've been using L/D to the landing field
instead of an MC-adjusted altitude. This does require one to know what
his glider will do under various conditions (no/tail/headwind, bugs,
etc) but allows a quick and easy analysis of the fields in (or not in!)
range.

I use to do this using my Garmin Pilot 3 (the vnav L/D feature), and
now use SeeYou Mobile for the same thing. By setting the MC high
enough, the L/D boxes change from yellow to green at about 30/1, which
is when I start to consider an alternate safe in my LS6. Makes it easy
to glance at the PDA to see where the closest possible alternate is (or
isn't).

I use my SN10 for "real" final glides, set for wind and bugs and etc.,
and if I have to divert will use it to the divert,if possible,
especially if wind is a factor. But have made final glides using L/D
only, and it works fine - especially for a short range low altitude
last minute landout - you know, the kind when you realize 10 miles out
that you aren't going to make it home and have to take a snap vector to
some field you have never been to before...

Like Tom, I get all my tactical data from the SN10; my PDA is limited
to the moving map with alternates and task line - essentially a
simplified glass sectional. And it is my backup (independent
GPS/logger) in case all the blue smoke leaks out of my SN10.

Re the original subject, I have no experience with the 302 (other than
being beaten by guys using them, and vice versa), but I do think the
SN10 is an excellent bit of kit!

Kirk
66

I use a 302/Winpilot Pro/3955--which does everything I want on one page. I
can "disconnect" the MC setting and thus set MC in the 302 speed command for
one setting, and the MC in Winpilot final glide gets another. I have flown
with SN10 and LX7000---I find they are all nice. I have been told by experts
that the SN10 has the best variiometer, but without side-by-side comparison
in the same glider, it's hard to tell. Winpilot Pro has a "thermal history"
graphic presenting similar info to the SN10. The only drawback is that the
Winpilot has so many features, it takes a while to sort out the useful from
the merely interesting. The program will take at least a season to learn to
use effectively. The variometry of the 302 is at least good-to-excellent.
The 302 has a backup battery--does the SN10? I have had the 302 several
years--it's been back to the shop twice--once to replace the polarization
screen so I could read it with polarized sunglasses, and once to convert it
to a motorglider version.

--
Hartley Falbaum


"kirk.stant" wrote in message
ups.com...
Or try a different tack: I've been using L/D to the landing field
instead of an MC-adjusted altitude. This does require one to know what
his glider will do under various conditions (no/tail/headwind, bugs,
etc) but allows a quick and easy analysis of the fields in (or not in!)
range.

I use to do this using my Garmin Pilot 3 (the vnav L/D feature), and
now use SeeYou Mobile for the same thing. By setting the MC high
enough, the L/D boxes change from yellow to green at about 30/1, which
is when I start to consider an alternate safe in my LS6. Makes it easy
to glance at the PDA to see where the closest possible alternate is (or
isn't).

I use my SN10 for "real" final glides, set for wind and bugs and etc.,
and if I have to divert will use it to the divert,if possible,
especially if wind is a factor. But have made final glides using L/D
only, and it works fine - especially for a short range low altitude
last minute landout - you know, the kind when you realize 10 miles out
that you aren't going to make it home and have to take a snap vector to
some field you have never been to before...

Like Tom, I get all my tactical data from the SN10; my PDA is limited
to the moving map with alternates and task line - essentially a
simplified glass sectional. And it is my backup (independent
GPS/logger) in case all the blue smoke leaks out of my SN10.

Re the original subject, I have no experience with the 302 (other than
being beaten by guys using them, and vice versa), but I do think the
SN10 is an excellent bit of kit!

Kirk
66