AirTalk.org

Martin Gregorie · Guest

I recently saw the write-up on the Stratomaster AHRS-2 system. Its
American uncertified kit that shows a ribbon compass, T&S and artificial
horizon on a single LCD display that fits a standard 80mm panel hole.

It only uses 200 mA at 12v, is light and costs about GP 100 ($US 180) more
than an ex-military horizon, T&S and compass. I like that and the ability
to put the lot in just one dial on the panel.

Is there any experience out there with this gadget?

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

John Scott · Guest

I just checked their web site. $180 sounded too good to be true. It was.
The AHRS-2 lists for $1200.

John

rhpf@snowcrest.net · Guest

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.

Please see my web site for more info and pricing
http://www.craggyaero.com/solidstate.htm

Richard
www.craggyaero.com

Martin Gregorie · Guest

On Thu, 25 Aug 2005 18:17:57 -0600, John Scott wrote:

Martin Gregorie · Guest

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

bumper · Guest

Even though it doesn't have pitch info, I've been really happy with the
Trutrak

http://www.trutrakflightsystems.com/ttfsinstruments.html

Powers up in 3 seconds, even in a crank and bank turn, so can be left off
until needed. The "sky and ground" display is more intuitive than a turn
coordinator or needle and ball. In use, the horizon display closely tracks
the real horizon. For $445, cheap insurance.

bumper
(no affiliation to Trutrak)

"Martin Gregorie" <martin (AT) see (DOT) sig.for.address> wrote

Stefan · Guest

Martin Gregorie wrote:

Stefan · Guest

bumper wrote:

bumper · Guest

Well, let's see, last I checked, I'm a "trained pilot" (SEL, instrument,
glider), and *I* haven't confused it yet. While I respect your opinion, I'd
like to know what data you're basing it on.

Agreed, the Trutrak does sort of "resemble" a full fledged horizon or AI,
but even at first glance it's pretty obvious that it's not the same.

I'm not suggesting that people go out and fly IMC with the Trutrak. Like the
Garmin 196 panel page, the Trutrak, an old mechanical gyro, or damn near
anything is better than nothing for inadvertent or emergency IMC. Many of us
know dead folks who would still be alive if they had one of these devices.

BTW, the Trutrak doesn't tumble. Like a needle and ball, it simple stops
increasing the displayed bank angle once you get steeper than say 60
degrees. It is available set up for both 1 and 2 minute turns (1 minute
recommended for glider).

I've also flown with a mechanical gyro 1 minute needle and ball installed in
a Stemme I recently sold, so I have experience with several instruments. In
order of preference, and assuming one doesn't have a full AI, I'd rate the
Trutrak first, then the Garmin 196 (that is amazingly good), and the
mechanical gyro needle and ball last - - though they will all do the job
given adequate pilot training flying partial panel IMC.

bumper

"Stefan" <stefan (AT) mus (DOT) _INVALID_.ch> wrote

Bill Daniels · Guest

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" <martin (AT) see (DOT) sig.for.address> wrote

Stefan · Guest

bumper wrote:

bumper · Guest

Stefan,

Again, no argument with regard to the conclusions drawn in the accident
report you cite. BTW, that is one incredibly long and detailed accident
report! I think in the US, only a Kennedy could garner that much attention.

Anyway, with regard to the Trutrak versus western style horizons, the
depiction is the same, i.e. the aircraft silhouette remains stationary with
the host aircraft while the "outside" sky/earth turns within the instrument
to depict bank angle. Thus, someone who has trained on western instruments
should have no problem adapting to the Trutrak. Much easier and more
intuitive than a needle and ball - - at least for me as I trained w/ a turn
coordinator. All you gotta remember is there's no pitch info. In a glider,
that isn't too tough as if you go too fast, the wings get swept back.

bumper

"Stefan" <stefan (AT) mus (DOT) _INVALID_.ch> wrote

Ramy Yanetz · Guest

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" <bildan (AT) comcast (DOT) net> wrote

bumper · Guest

"Ramy Yanetz" <ramy (AT) yanetz (DOT) net> wrote

Tom · Guest

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