Anyone know how to work an attitude indicator?

[anthony31]

Hello folks

Just trying to do the animations for an attitude indicator (see attached pic) and was wondering about a couple of things as I can't find the info in the manuals I've found.

First thing, the Cage. I've got the cage button working using the standard FSX commands. What FSX does is when you pull the cage it rotates the bank and pitch indicators back to zero and locks them there. I was just wondering if that is correct or maybe when you pull the cage what should be happening is that the bank and pitch get locked at the current positions. So if you are banked at 45 deg and pull to cage then the bank indicator stays locked at 45 deg.

Second thing, the OFF indicator in the top right of the gauge. Does this go out when you turn the power on? So you should only see the OFF indicator when there is either a fault with the gauge or there is no electricity for the gauge?

Third thing, the same as the second thing except with the red flag on the compass. ie does the red indicator indicate that there is either a fault with the compass or there is no electricity running into the compass?

Thanking you all for any information you can provide

[N2056]

My understanding is that the cage knob works correctly in FSX, and as you have guessed the flag indicates no power to the instrument.

[Mach3DS]

It depends on the instrument. Generally the AI is powered by a vacuum pump which spins a gyroscope that provides rigidity to the instrument. If the vacuum system fails the unit will fail. If suction is hampered by a clog in the line the gyro won't spin as fast and the instrument will appear "sluggish" and less responsive and unreliable. If the unit is powered electrically, then if the battery generators/alternators fail, the unit will generally switch to a battery as a backup. If electric power fails the unit will shut down. Generally, the unit will require an emergency switch to use the battery backup.

[Gibbage]

From my understanding (someone correct me if im wrong), you cage an AI before doing acrobatics. This keeps the gauge and gyro's from getting damaged from rapid un-expected movements. Also some gauges simply cant keep up with acrobatics, so when the pilot come out the acrobatics, the AI would be wrong. If the pilot was blind, and relied on it, it could get him killed. This was a big problem in WWII aircraft. If you didnt cage it before combat, and got lost on a cloud with a bad AI, you could find the ground quickly. Most GA aircraft that are restricted from acrobatics dont have a cage as they dont need it.

[Bomber_12th]

I 'think' the "Off flag" pops out just by caging the gage - if you were to un-cage it, the flag would rotate out of site. That is how all of the U.S. attitude indicators in WWII, which had a "Caged Flag", worked, in that a flag would rotate out from the top right or bottom right side of the gage when you caged the instrument - it doesn't have anything to do with power, it is just connected to the mechanical caging/un-caging of the gage itself.

[Bomber_12th]

From my understanding (someone correct me if im wrong), you cage an AI before doing acrobatics. This keeps the gauge and gyro's from getting damaged from rapid un-expected movements. Also some gauges simply cant keep up with acrobatics, so when the pilot come out the acrobatics, the AI would be wrong. If the pilot was blind, and relied on it, it could get him killed. This was a big problem in WWII aircraft. If you didnt cage it before combat, and got lost on a cloud with a bad AI, you could find the ground quickly. Most GA aircraft that are restricted from acrobatics dont have a cage as they dont need it.

That's correct, Kevin - there were also issues from time to time with the gyro gun sights in WWII, for the same reason.

[Mathias]

Right that, Kevin.
The German period artis, depending on the actual model, were limited to something around + - 65° pitch and + - 110° roll.
If exceeded while being uncaged the reading becomes unreliable or will freeze, depending on the severity of abuse.
It can take up to 15 minutes before functionality is restored, if the arti hasn't failed alltogether.
Great to see someone bother about that particular aspect of realism, Anthony, I though we are the only ones to build arti failures into their models. :icon_lol:

[srgalahad]

Caging Many gyros include a manual caging device, used to erect the rotor to its normal operating position prior to flight or after tumbling, and a flag to indicate that the gyro must be uncaged before use. Turning the caging knob prevents rotation of the gimbals and locks the rotor spin axis in its vertical position. Because the rotor is spinning as long as vacuum power is supplied, normal manoeuvring with the gyro caged wears the bearings unnecessarily. Therefore, the instrument should be left uncaged in flight unless the limits are to be exceeded.


In the caged position, the gyro is locked with the miniature aircraft showing level flight, regardless of aircraft attitude. When uncaged in flight, in any attitude other than level flight, the gyro will tend to remain in an unlevel plane of rotation with the erecting mechanism attempting to restore the rotor to a horizontal plane. Therefore, should it be necessary to uncage the gyro in flight, the actual aircraft attitude must be identical to the caged attitude (that is, straight and level), otherwise, the instrument will show false indications when first uncaged.


http://www.pilotfriend.com/training/flight_training/fxd_wing/attitude.htm

Also, from an instrument manufacturer:
"Pulling (and then releasing) the Pull-to-Cage knob will make the instrument 'cage', ie. take it's current Pitch and Bank as 'the new' zero-reference positions. The Slipball remains unaffected.

When the instrument 'fails', the Fail-flag becomes visible and Pitch & Bank 'freeze', but the Slipball remains operating (since in real it is moved by centrifugal forces)."
http://www.sgsim.com/instruments/horizon.htm


Interestingly, there was a discussion on FlightSim some time ago about the whole issue of 'caging' that might help, or just add mud to the water
http://www.flightsim.com/vbfs/archive/index.php/t-182666.html

[anthony31]

Thanks for the replies guys.

After a bit of research it looks like this is the Falcon Gauge GH02E-3 model which is an electrical, rather than vacuum gyro (the GH02V-3 is the vacuum one and it doesn't have a cage).

This is what the Falcon Gauge website says about the OFF flag:

The Power failure drops into view whenever the power is insufficient for
operation of the gyro. Electrical gyro can be caged by pulling the "Pull to
Cage" knob.

You'd expect the OFF flag to come into view when the unit was caged as well wouldn't you? It makes sense to have some sort of visual indicator that the gauge was disabled. I'll do some more looking about the internet (or maybe even ask the owner to check it for me).

There is also this interesting line in the manual for the GH02E-3:

"Even though the gyro is cageable, it is safer to pull the whole unit out before heavy aerobatic flight". Would like to see someone model that in FSX :) .

[Mathias]

There is also this interesting line in the manual for the GH02E-3:

"Even though the gyro is cageable, it is safer to pull the whole unit out before heavy aerobatic flight". Would like to see someone model that in FSX :) .[/FONT][/SIZE][/FONT][/SIZE]

That is easier to accomplish than doing the failure coding. :icon_lol:

[TeaSea]

What I know is that when the *%%##!*&$ thing fails , the beast just rolls away into nothing.....like a big old eyeball rolling back in it's socket.

Then when you take it in, learn what it's going to cost to replace it and the vacuum system (rubber hose degrading inside, allowing flakes of rubber to destroy the little fins in your instrument), you get to watch your wife's eyes roll back in their sockets.

Put that in the simulation.

[Mach3DS]

You'd expect the OFF flag to come into view when the unit was caged as well wouldn't you? It makes sense to have some sort of visual indicator that the gauge was disabled. I'll do some more looking about the internet (or maybe even ask the owner to check it for me).

The unit won't be turned off when caged. The The Gimbal locks are put into place when you cage it. The reason for caging is to insure the AI gyro doesn't exceed it's designed gimbal limits.