Electronic horizon?

In absence of more suitable instrument and/or rating, couldn't a GPS or PDA
with moving map be used to descend through clouds in emergency by zooming in
and noting if and what direction the glider is turning?

Ramy

"Bill Daniels" wrote in message
...
There are several PDA based 'glass cockpit' software packages that appear
to
work well. They derive bank attitude from TAS (or GS if TAS is not
available) and the rate of change of ground track. Pitch data is derived
from the rate of change of airspeed. 'Heading' is actually ground track
but
that is good enough.

Since many glider pilots already have a PDA in the cockpit, these might be
good enough for an emergency. Simply have the 'glass cockpit' running in
the background and switch to it if the need arises. The beauty is that no
additional hardware is needed beyond what is already in the glider.

FWIW, I tried a simulated 'blind let down' using only the wet compass in
the
back seat of a G103. With the glider on a southerly heading, I used the
southerly leading error to keep the wings level and hold the heading. I
was
able to do this for about 10 minutes under the 'hood' without outside
reference.

For those readers not aware of this trick, a magnetic compass senses not
only the N-S magnet field but also the 'dip' angle. While on a southerly
heading in mid northern latitudes, the magnetic compass will indicate a
turn
as soon as a wing is down and before a turn actually starts. Banking the
glider left and right as needed to keep the compass on S will keep the
wings
level. This is very tricky in a fast airplane but surprisingly easy in a
slow glider as long as the air isn't very turbulent. (For out friends in
the Southern Hemisphere this trick requires a north heading.)

Bill Daniels


"Martin Gregorie" wrote in message
news
On Thu, 25 Aug 2005 20:53:43 -0700, rhpf wrote:

Martin,

I have flown with this instrument, it works well. It will tumble after
several minutes of extreme bank angles. Even higher priced instrument
in
the $3000 to $5000 range have a cage function for acrobatic maneuvers
or
extreme bank angles.

This instrument group is one that I'd almost never use during normal XC:
the reason I'm looking is that when/if I do some wave flying I'd like to
have these displays onboard in case of canopy icing and/or finding
the slot slammed shut below me. Would you trust it for that? I'm asking
because I've heard stories that continuous circling would tumble it.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

"Ramy Yanetz" wrote in message
m...
In absence of more suitable instrument and/or rating, couldn't a GPS or
PDA with moving map be used to descend through clouds in emergency by
zooming in and noting if and what direction the glider is turning?

Ramy


Ramy,

Many GPS have a "HSI" page or at least a track derived "compass". These
would probably be easier use that watching the bread-crumb track on a
zoomed-in map. Besides, the track update rate may be much lower than the GPS
update rate in order to conserve internal track memory, though this is
usually user selectable.

Best of all, IMO, is the "panel page" on the Garmin 196 / 296 / 396.

bumper

I, once, had to do a real descent thru the clouds after being trapped
on top while wave flying. At the time I had no instrument training and
had to come up with a plan of action on very short notice. I selected a
westerly heading since there would be no turning error on the compass.
I lowered the gear and pulled the dive brakes and flew at a high speed
to maximize descent rate. I reasoned that if the compass isn't changing
you aren't turning. I ended up descending 7000 ft thru the clouds with
the wings perfectly level on exit.

The only thing I would do differently would be to fly at a slower
speed.

I have tried the benign spiral trick with no luck (for those unfamiliar
with this you lower the landing gear, set landing flap position if you
are flapped, and take your hands off the controls).

Also, I read the accident report sited by Stephan and found no possible
connection to the T&B mentioned earlier. The report mentions the
differences between Russian and Western AI, not the pilot confusing a
T&B for an AI. I see no possibility for confusion for a glider pilot
who has this as his only inertial instrument.

Tom

On Sat, 03 Sep 2005 22:55:29 -0700, Tom wrote:

I have tried the benign spiral trick with no luck (for those unfamiliar
with this you lower the landing gear, set landing flap position if you are
flapped, and take your hands off the controls).

Don't try it with an ASW-20. It has no benign spiral with the flaps in
neutral: I checked with gear down, brakes and no brakes.

However, its probably OK on a fixed heading: clean, with zero flap, hands
off but feet used to keep straight, its stable with a 25 second +/- 5 kt
phugoid.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Tom wrote:

I selected a
westerly heading since there would be no turning error on the compass.

The idea of setting the course 180 *is* exactly the turning error! Every
tendency to bank will immediately be displayed by the compass, even
before the plane begins to actually turn. It actually works very much
like the "turn coordinator". (BTW, this works as well on course 0, of
course. But because the compass will react in the wrong direction, a
correct reaction would require a very high level of abstraction.)

Also, I read the accident report sited by Stephan and found no possible
connection to the T&B mentioned earlier.

The conection is that you have an instrument in front of you which
reacts differently than you expect. When you're trained with and used to
an artificial horizon, then that trutrak thing looks ecactly like one.
So I expect it to display pitch information which it doesn't. And when
you've learnt to rely on a horizon as your primary reference for
attitude, then the issue is no more minor, but may become that last
straw which breaks the camel's back.

I stay with my statement: Something which looks exactly like a well
known and widespread instrument but works differently is a possible
source of confusion and a very bad idea, especially when it comes to
such an unforgiving thing as flying in clouds.

Stefan

A big thank you to all of those who over the past
three years have contributed money or attention
or other effort to nurture the Dr. Jack BLIPMAPs
into a stable resource.

Several years ago I and others called upon
(mostly USA) pilots to give donations to
the worthy BLIPMAPs and other Dr. Jack products.
I truly believe the very positive response was
the difference between losing these products or developing

them into a stable state.

The site at this point, several years later, seems
stable,
and has had the 'glitches' worked out. I am very,
very
happy that so many people responded so generously to

support this.

Of course, none deserve gratitude more than
Dr. Jack himself...but without the funds and recognition

he so completely deserved (but was much to modest to
ask for himself) this resource might have disappeared.

Long live BLIPMAPs and BLIPSPOTs and
all these other wonderful products!

www.drjack.net

If you care to contribute more, look at

www.drjack.info/BLIPMAP/contributors.html

Thank you again for being such a supportive community
towards this.
Mark J. Boyd

MG wrote: "A big thank you to all of those who over the past
three years have contributed money or attention
or other effort to nurture the Dr. Jack BLIPMAPs
into a stable resource."

You're welcome. And probably thank you -- I imagine you were also
supportivem, probably more than I. And, Amen! Thank God BLIPMAP
survived. May it have a long and healthy life.

Martin

PS Not sure how this got onto the Electronic Horizon thread though.

If Bumper is correct and the Garmin 196 GPS driven
attitude display can be used for a emergency cloud
descent then presumably the turning glider on a Winpilot
screen will give the same information, or will it ????

David Smith

At 06:06 05 September 2005, Bumper wrote:
Tom,

The Trutrac needs only 3 seconds from switch-on to
providing good info. It
doesn't matter if it's level or cranked over in a steep
turn. Really pretty
amazing and nothing at all like turning on a mechanical
needle and ball or
turn coordinator and then waiting for it to erect properly
if already in a
turn.

Since I have both a Garmin 196 and Trutrack in the
ASH26E, I've compared
them to each other. Either will keep an experienced
pilot right side up in
IMC, or allow one to do a 180 etc, I prefer the display
on Trutrack by a
slight margin as the response is a bit faster than
Garmin's panel page.

Both are good to have, as there's nothing wrong with
redundancy. If I had to
pick one, it would be the Garmin, even though the display
is slower. The
Garmin gives more data, including ground speed. Good
to have if the pitot
ices up. 'Course if that happened, one would probably
have other concerns
too.

bumper


'Tom' wrote in message
roups.com...
Just be sure to have your T&B on ALL of the time;
you will not have
time to turn it on when you need it.

I prefer an aviation GPS with an HSI display.

Tom

David Smith wrote:

If Bumper is correct and the Garmin 196 GPS driven
attitude display can be used for a emergency cloud
descent then presumably the turning glider on a Winpilot
screen will give the same information, or will it ????

My experiments with GPS for turn indication showed success depends very
much on the wind strength: below 20 knots, it's probably OK; above 30
knots, it's definitely not.

In strong winds, the heading changes displayed become very sensitive to
turns when flying upwind, and very insensitive when flying downwind. The
more wind, the worse it gets. This quite different from a gyro
instrument, which has the same sensitivity regardless of the wind.
Perhaps a pilot could practice and become adept at it, and maybe, maybe,
in smooth air it's not a problem, even in strong winds.

Since wind is a always feature of wave flying, I do not want to rely a
GPS to save my butt during an encounter with clouds. I have a T&B that I
practice with periodically, though I've never come close to entering a
cloud. Other club members have, however.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

David Smith wrote:

If Bumper is correct and the Garmin 196 GPS driven
attitude display can be used for a emergency cloud
descent then presumably the turning glider on a Winpilot
screen will give the same information, or will it ????

Why don't you (and everybody else who is wondering) just go and try it?
You'll be surprized how fast things develop in a modern slippery glider!

Here is how we teach and train cloud flying: The student sits in the
back seat of a (properly equipped) two seater, the instructor in the
front. Then the outside view from the back seat is completely obscured
by a kind of "curtain". Very easy to build and install such a courtain
yourself. Turn on the gyros, close that curtain and there you go!
There's no reason why you couldn't try this with any instructor you
know, and certainly an interesting experience.

BTW, our cloud flying syllabus is the following:
- Fly straight and level on a defined course for at least one minute.
- Fly a 180 and hit the reverse course in "reasonable" time. Done on
several different courses. (Needs some calculation and an understanding
on compass error while flying.)
- Climb in a thermal and exit on a predefined course.
- Recover from unusual attitudes the instructor has brought you in.

If it's only for that emergency descent, then lesson 1 would suffice.

Stefan