Emergency instrumentation for cloud encounters

The interial various are really "instant display".

They record the information from the moment you turn the instrument on - which is probably when you turned the panel on. Therefore there is no concept of 'on' when switching to the A/H display. The gyros are used as part of the air model and are constantly calibrated by the external information including (in the Vaulter at least) the GPS.

In addition the one I'm familiar with has a built in magnetometer that calibrates to your installation and gives a rather nice always available compass.

Mel

On Mon, 20 Apr 2015 22:12:46 -0700, krasw wrote:

For vfr pilot with no training I would install simple electronic AH
(Dynon, Gemini etc.) for the purpose of keeping your glider right side
up and getting out of imc safely. You can fly whole day with T&B only,
but it requires some training.

I think the same definitely applies to the Dynon electronic AH and its
relations: you still need the training before trying to use it 'for
real'.

I've had some training with a Dynon (bucket over my head in an SF-25) and
find that I prefer using a partial panel, mainly because the Dynon
heading indicator is just a small box showing the heading in degrees: I
don't find it nearly as easy to scan as an analogue indicator or a ribbon
like some of the other electronic AHs provide.

Its just as well I prefer the partial panel because that is what is in my
glider and there is no space in the panel to add an AH.


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

On Tuesday, 21 April 2015 08:29:19 UTC+1, 7C wrote:
The interial various are really "instant display".

They record the information from the moment you turn the instrument on - which is probably when you turned the panel on. Therefore there is no concept of 'on' when switching to the A/H display. The gyros are used as part of the air model and are constantly calibrated by the external information including (in the Vaulter at least) the GPS.

In addition the one I'm familiar with has a built in magnetometer that calibrates to your installation and gives a rather nice always available compass.

Mel


Are the LX devices really running all the time? When you bring up a page showing the A-H it is not actually instant on - it takes a couple of seconds before it indicates that it is live. Presumably the sensors are alive, but there is something else which has to be on before you see the A-H display.

So many solid state A-H's have become available over a short period of time.. According to reports they all seem to work very well. Does anyone know whether the technology (both hardware and software) is common to the different manufacturers, or has each manufacturer developed their own approach? Within the LX Nav range, does anyone know whether the S80/S8 have the same sensors and software as the V9?

On Tuesday, 21 April 2015 12:16:13 UTC+1, Martin Gregorie wrote:
On Mon, 20 Apr 2015 22:12:46 -0700, krasw wrote:

For vfr pilot with no training I would install simple electronic AH
(Dynon, Gemini etc.) for the purpose of keeping your glider right side
up and getting out of imc safely. You can fly whole day with T&B only,
but it requires some training.

I think the same definitely applies to the Dynon electronic AH and its
relations: you still need the training before trying to use it 'for
real'.

I've had some training with a Dynon (bucket over my head in an SF-25) and
find that I prefer using a partial panel, mainly because the Dynon
heading indicator is just a small box showing the heading in degrees: I
don't find it nearly as easy to scan as an analogue indicator or a ribbon
like some of the other electronic AHs provide.

Its just as well I prefer the partial panel because that is what is in my
glider and there is no space in the panel to add an AH.


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

Martin, I am confused. What instruments do you have in your 'partial panel' which you prefer to an electronic A-H? Surely you are not saying that you find it easier to cloud fly using a turn and slip than using an A-H? Are you referring to straightening up in the right direction when you have finished thermalling, in which case surely you would level the wings using the A-H and use your gps or your compass to exit your cloud in the right direction?

Mark Burton, London Gliding Club, UK

On Monday, April 20, 2015 at 11:43:17 PM UTC-5, wrote:
WARNING: SIDETRACK--TANGENT--WAY OFF COURSE HERE


Whoops, I was in error. I labelled my fingers with "left" and "right" and flew it through with my hand again. Postively-loaded case, wings-level, inverted flight-- you won't be there for long, but if you try to keep the turn rate indicator needle centered, you'll give inputs that tend to roll the glider back to inverted wings-level flight after any deviation. Maybe not such a great thing. Negatively-loaded case-- if you move the stick against the direction of any indicated turn, you'll tend to roll toward a steeper bank angle. Sustained negatively-loaded flight would theoretically be possible by moving the stick in the same direction as any indicated turn-- just like one does when flying inverted visually. Obviously this is all theoretical.

For the most cases in cloud I don't think it's ending up in genuine aerobatic scenarios that the main concern. It's losing control of the pitch phugoid. A rapid increase in bank angle can put you through the redline long before the bank angle reaches sixty degrees. Likewise, a rapid decrease in bank angle during high-speed flight can pitch you up into the start of a loop if you don't react to the decreasing trend of the airspeed needle fast enough.

So yes, I absolutely agree that an artificial horizon is the best way to go.. I guess that I've had enough exposure to what is possible with just a turn rate indicator, that I have a hard time believing that an artificial horizon wouldn't give the average pilot a good fighting chance without all sorts of special training. But, that's just me. I suppose the statistics say otherwise.

I'm sure a pilot with Chukar's experience would have done very well with either an artificial horizon or a turn rate indicator.

And I still like the idea of the redundancy provided by a simple, self-contained instrument that will power up in just a few seconds regardless of the aircraft's attitude and flight path. It seems like a good thing to have if the only other other thing one has is something that is built into a vario system.

By the way, an older generation of this same instrument needed to be flown for several seconds in wings-level flight during a calibration phase immediately after the initial start-up. I think they've made a great improvement in modifying the design to eliminate this.

Thanks much for all the various comments so far. It's a topic that I find quite interesting.

S

I submit that you might be surprised at what happens if you power up the system in a steep turn. Maybe I'm wrong...

On Tuesday, April 21, 2015 at 2:29:19 AM UTC-5, 7C wrote:
The interial various are really "instant display".

They record the information from the moment you turn the instrument on - which is probably when you turned the panel on. Therefore there is no concept of 'on' when switching to the A/H display. The gyros are used as part of the air model and are constantly calibrated by the external information including (in the Vaulter at least) the GPS.

In addition the one I'm familiar with has a built in magnetometer that calibrates to your installation and gives a rather nice always available compass.

Mel

Well said.

My TruTrac is pseudo "instant on" in that, within a second or two, it
shows the turn even when switched on in the turn. It is "rate based"
whatever that means. When a gyro instrument is turned on in a turn it
will erect itself to the vertical g-loading of the aircraft unless it
has some fancy way of telling up from the load experienced. This I know
from partial panel practice whereby the front seat pilot would perform
aerobatic maneuvers while the back seat pilot, under the instrument
hood, would hold the attitude indicator caged. The AI would show level
flight regardless of attitude until the cage knob was released and, when
the aircraft was recovered from its unusual attitude, the AI would show
some strange attitude which was, of course, incorrect.

It would be very interesting to try one of these new digital gyros and
see how it erects in an unusual attitude.

On 4/20/2015 1:51 PM, wrote:
A few more thoughts after reading the other related thread:

* Have you every watched how the magnetic compass behaves in a turn? Even with a bank angle as shallow as 30 degrees, it's hopeless, especially at low airspeed. Random freeze-ups and reversals in rotation are par for the course. Nonetheless there are specific ways to use it in cloud-- by establishing a southerly heading before entering cloud, or by using another instrument to level the wings before attempting to "capture" the southerly heading via a very shallow turn. Again, these comments are for mid-to-high latitudes in the northern hemisphere.

* Is there really such a thing as an instant-on artificial horizon? Is it instant-on even in a spiral dive? Which models are these? The turn rate indicator I linked to above has an initiation time of less than 5 seconds and is not affected at all by the aircraft's orientation and flight path.

* Re the dirty vs clean question-- I'd vote strongly for "dirty". Anything that creates drag tends to dampen the pitch phugoid. Sudden changes in bank angle-- due to turbulence or wrong pilot control inputs-- pump energy into the pitch phugoid. This is a huge problem when flying "partial panel" in an aircraft with relaxed pitch stability. Drag is your friend even if the G-load at which the airframe breaks is reduced by several G's. If you are pulling more than 3 G's or so in cloud, you are unlikely to be getting the aircraft back under control anyway-- especially if it is clean.

S

--
Dan Marotta

The TruTrac (or at least some models) is conceptually the same thing as the instrument I linked to. More bucks and a more user-friendly display. I can certainly believe that it is instant-on in any flight attitude. The main display is driven by a 1-axis turn rate gyro, not an AHRS system.

S

I mean "sensor" of course, not an actual gyro.

Same could be said for the untrained pilot trying to use an attitude
indicator for the first time. It's very easy under a vision restricting
device in VMC. Not so much when using it successfully makes a difference.

On 4/20/2015 11:12 PM, krasw wrote:
For vfr pilot with no training I would install simple electronic AH (Dynon, Gemini etc.) for the purpose of keeping your glider right side up and getting out of imc safely. You can fly whole day with T&B only, but it requires some training.

--
Dan Marotta