Electronic horizon?

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 |

Martin Gregorie wrote:

On Thu, 25 Aug 2005 20:53:43 -0700, rhpf wrote:

I have flown with this instrument, it works well. It will tumble after
several minutes of extreme bank angles.

Would you trust it for that? I'm asking
because I've heard stories that continuous circling would tumble it.

The post you're answering to tells it clearly enough, I think. Extreme
bank angle is a pretty normal attitude in a glider.

The only instrument that will never tumble, by construction principle,
is the needle. So if you're looking for an emergency instrument, install
a classic, gyro driven needle. I wouldn't want to do serious cloud
flying with only a needle in a glass ship, but for an emergency descent
with open spoilers it's good enough.

Stefan

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 |

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

Stefan wrote:
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.)

OK, have you actually done this in a REAL emergency? I have, and it
worked. And that was without ANY prior training. Having - guaranteed -
no turning error was critical. I wasn't about to guess at which
direction gave the turning error in the same direction.

My rational is real simple: if the compass isn't moving you aren't
turning; if it is moving you turn - gradually - in the opposite
direction. The goal isn't to follow a particular heading, it is to stay
level and in control.


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.

Again, I think you are overlly concerned about a non-issue. I believe
that any pilot who has had instrument training will have no problem
with the Truetrak, and those that have not can't possibly be confused
about something about which they know nothing. Actually, I think the
later will be able to use the Truetrak more effectively because it IS
more intuitive.

Tom

BTW: Your accident pilot was on unauthorized drugs (Russian
tranquillizer), which was the most likely cause of the accident.

Tom wrote:

OK, have you actually done this in a REAL emergency?

No, and I'm not planning to do so. Our club gliders are all equipped
with needle/ball, and I would be very reluctant to fly over a föhn gap
without.

I have, and it worked.

I've understood this and am glad you succeeded. Just gave you the reason
why course 180 is "recommended". BTW: I don't believe that such a decent
would be successfull in gusty air, at least not reliably so.

Again, I think you are overlly concerned about a non-issue.

I really hope you are correct and I am wrong. I'm not convinced, though.

BTW: Your accident pilot was on unauthorized drugs (Russian
tranquillizer), which was the most likely cause of the accident.

Knowing the involved company first hand, I'm pretty sure it was a lack
of conversion training.

Stefan