Questions tagged [gyroscopic-instruments]

Questions about instruments which rely on gyroscopes to function, such as attitude indicators.

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How do aircraft on the deck of a moving aircraft carrier align their INS/IRS?

I know that the F/A-18C is equiped with a rotary switch for inertial alignment. The switch has two positions, one for ground and the other for carrier operations. Leaving aside the GPS/GNSS, I wonder ...
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4 votes
1 answer
266 views

How do you realign a directional gyro in an area of magnetic unreliability?

The primary means of determining heading in most small aircraft is the directional gyro, as this instrument is unaffected by the magnetic dip errors that cause a magnetic compass to give the wrong ...
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3 votes
1 answer
159 views

Can you fly with INS/ IRS at higher lattitudes?

IRS can't be aligned at higher lattitudes ( above 70 deg) , but if once aligned near equator, can we fly till higher lattitudes with IRS in that flight?
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3 votes
1 answer
216 views

How are degree of freedom and gimbals related in a gyro?

Why does it mean to say a gyro has an even degree of freedom? Why does this degree correspond to the number of gimbals ?
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4 votes
1 answer
413 views

What is gimbal error in DGI compass gyroscopes?

I'm unable to find an explanation of gimbal error in a Directional Gyroscope Indicator (DGI) anywhere. Can someone please explain what this is?
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5 votes
1 answer
787 views

What do a "sheared pump drive" and a "possible sticky vacuum regulator" mean?

The POH for a PA28 (engine driven vacuum pump) says a decrease in pressure on the gyro suction gauge may indicate a possible sticky vacuum regulator. A zero pressure indication means a sheared pump ...
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5 votes
1 answer
457 views

Why is the turn coordinator gyro tilted?

I’ve read many places (such as the FAA’s Instrument Flying Handbook) that a turn coordinator can sense both roll rate and turn rate due to the gyro being tilted 30 degrees. However, why does tilting ...
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-4 votes
2 answers
133 views

how missiles or rockets change direction if gyroscopes prevent any direction change? they would bring back the rocket to same path? [closed]

Gyroscopes are instrument which prevent any wobbling or direction change but then how rockets and missiles change their directions. To change direction we have to give signals to gyro or to the servo(...
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4 votes
2 answers
370 views

Does the FAA's restriction on adjustment of attitude indicators (14 CFR 23.1303(f)) still apply to aircraft today?

The GA planes I fly (with a club) have Garmin G5 PFDs. On these, the horizon/attitude indicator shows a few degrees pitch-up when in level flight. They're adjusted to indicate level on the ground ...
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5 votes
2 answers
161 views

Do mechanical attitude indicators have rotation limits?

Do mechanical attitude indicators have limits to the rotations they can display? Wondering since gyros suffer from gimbal lock when two axes become aligned (e.g., at 90 deg pitch, if you were doing ...
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3 votes
1 answer
231 views

Is it possible for an indirect (Russian) attitude indicator to work in 3D without tumbling?

For a reference of direct and indirect attitude indicator, see How is a confusion possible between Western and Russian Attitude Indicators?, and https://www.skybrary.aero/index.php/...
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In some "turn coordinators", does the gyro spin opposite to the direction it spins in a "turn rate indicator"?

In some "turn coordinators", does the gyro spin opposite to the direction it spins in a "turn rate indicator"? A "turn coordinator" has a symbolic airplane on the display ...
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6 votes
4 answers
2k views

Why does the attitude indicator gyro not precess the same way that a directional gyro does?

The directional gyro needs to be realigned every so often, but the attitude indicator does not, and I have a hard time finding why.
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How do AHRS systems meet the "gyroscopic" requirement of 14 cfr 91.205.d?

EDITED Among the instruments listed as required for IFR operations in the US FAR is are various "gyroscopic" instruments, including those for the turn coordinator, attitude and heading. In ...
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4 votes
1 answer
399 views

Artificial horizon - "horizon bar" or "symbolic airplane adjust"

(Student pilot, ~ 22hrs training) On a box-standard AI in a C172 there is a knob that allows you to move the symbolic airplane up and down. I've never managed to ask what it is for, but have now been ...
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4 votes
2 answers
446 views

Has this type of "gyrocompass" ever been used in an aircraft?

One type of instrument commonly referred to as a "gyrocompass" is commonly used in ships. It detects true north based on gyroscopic precession, and is not slaved to any magnetic compass or any ...
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4 votes
4 answers
793 views

Is Turn and slip indicator a good back-up for the attitude indicator?

I was reading my Aircraft general knowledge book, and noticed something peculiar that was written. The book described that the turn and slip indicator works as a back-up in case of a malfunctioning ...
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1 vote
1 answer
130 views

Partial panel power on stall under the hood

What do you use for control and performance instruments while demonstrating power on stall under the hood with attitude and heading indicator covered (No vacuum instruments in 6 packs ) ?
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1 vote
1 answer
691 views

Question about CDI/OBS and HI [duplicate]

Could somebody please explain me the differences between using the OBS and the Heading Indicator? As much as I could understand, once you tune into the VOR, the OBS starts to show how much deflection/ ...
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  • 21
1 vote
2 answers
2k views

Gyro Erection System

I have a hard time understanding the physics behind the pneumatic erecting system in an attitude indicator. According to my book and the linked image, the applied force is “precessed 90 degrees” (anti-...
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0 votes
1 answer
915 views

How does turning Errors in the Air Driven Artificial Horizon work?

Turning through 90°, 180°, 270° & 360°, the error is different. I can understand what is turning error and pitch error individually. But why turning through different degree, the resulting error ...
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  • 175
0 votes
2 answers
801 views

What is the most effective way for a VFR pilot to scan the instruments during manoeuvres?

May I ask your opinion on what is the best and most effective pattern for a VFR pilot to scan their instruments during manoeuvres?
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3 votes
2 answers
921 views

Why does the turn coordinator ball move to the right during a climb?

In a light aircraft like a C172 or PA-28, during a climb the ball in the turn coordinator moves to the right. Why?
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11 votes
3 answers
1k views

During "partial panel" flying, in what ways is a turn rate indicator more useful than a turn coordinator?

This question deals with flying by reference to old-fashioned "steam gauges", not a modern "glass cockpit". I recall hearing some pilots very experienced (ATP) pilots advocate for the older-style "...
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0 votes
0 answers
55 views

How does a standby ADI remain accurate when flying over the curved earth? [duplicate]

How does a standby attitude directional indicator remain accurate when flying for many hours over the curve of the earth? While maintaining level flight, wouldn’t the pilot see an apparent movement of ...
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0 votes
1 answer
1k views

Is the pod on the right wing of the PC-12 and Cessna 208 a gyrocompass? [duplicate]

Hello avgeeks, First time posting here looking for an answer. Could someone tell me what's located inside that pod on the right wing of some planes like this Pilatus PC12 or this Caravan 208? I guess ...
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8 votes
2 answers
2k views

How to handle vacuum and turn coordinator failure in IMC?

I just earned my FAA instrument rating and a considerable amount of time was spent training partial panel. This meant flying with no vacuum gyro instruments - attitude indicator and directional gyro. ...
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4 votes
1 answer
462 views

What instruments are used to indicate aircraft attitude in acrobatic airplanes?

As aerobatic airplanes don’t use gyroscopic instruments such as attitude indicators, what instruments are used to indicate the aircraft’s attitude in flight?
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5 votes
2 answers
549 views

Do air-driven gyroscopic instruments suffer from icing or any blockage of filter?

Do gyro instruments suffer from icing in an air-driven gyro system? Do they have any particular way to protect them against blockages of filter or any type of other blockage? (Alternate source?) I am ...
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19 votes
3 answers
7k views

How did the gyro gunsights of WW2 get the range and lead of a target?

I just read this article on the gyro gunsight, but I don't understand how it computed range/position to the target and then calculated how much lead is needed. Surely it must have had radar to get ...
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7 votes
1 answer
3k views

What are the pros and cons of vacuum and pressure gyros?

Inspired by this question, I would like to know what the pro's and con's of the mostly used vacuum-gyro and the less used high-pressure-gyro is. Side-question: Are there any other ways to make the ...
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2 votes
2 answers
2k views

How does a gyro compass indicate true heading?

From what I've researched, a gyro compass is usually calibrated with with reference to a magnetic compass. Once you've engaged the gimbal locks, and start to rotate the compass to a magnetic heading; ...
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2 votes
1 answer
898 views

How are gyros used on a turn indicator?

So I understand how precession works, and that gimbals are used to isolate the gyro from outside rotation, however when a yawing motion is applied to the gyro, it'll essentially translate to a rolling ...
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4 votes
1 answer
956 views

At what altitude do vacuum powered gyros become ineffective?

Obviously, in space a vacuum powered gyro would not work because there is no air to move, but, how high do you have to go before they are unable to spin fast enough to work properly? would a vacuum ...
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11 votes
1 answer
819 views

Why vacuum instead of pressure to power gyros?

Why are most air powered gyro instruments powered by vacuum rather than positive pressure?
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6 votes
4 answers
2k views

How do modern avionics work without vacuum pumps or gyroscopes?

I'm going to be taking my checkride soon on a Skycatcher 162. It has an all glass cockpit utilizing the Garmin G300, and its my understanding that it does not utilize gyroscopes or vacuum pumps for ...
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1 vote
1 answer
206 views

How does the control-board on small drones govern their flight?

I saw this YouTube clip for a light weight drone, under a few ounces, with very impressive maneuverability. They used styrofoam for frame and taped the rotors and battery and the control chip to it. ...
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2 votes
1 answer
735 views

Does an RMI show true or magnetic north?

Does the compass card of a Radio Magnetic Indicator (RMI) point to true north or magnetic north ?
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7 votes
2 answers
2k views

Are turn rate indicators calibrated to a certain speed? If so, what speed?

Are turn rate indicators calibrated to a certain speed? If they are, what speed are they calibrated to, and why aren't all the turn rate indicators calibrated for the same speed?
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3 votes
1 answer
520 views

Why is the Inertial Reference System not used to determine true altitude?

Given three very accurate laser gyros and accelerometers I believe the Inertial Reference System (IRS) should be as accurate in determining true altitude as it is in determining lat/long, providing ...
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  • 536
8 votes
2 answers
16k views

How does a horizontal situation indicator (HSI) work?

I am trying to understand the Horizontal Situation Indicator. To my understanding there is a slaving transmitter, usually in a wing (the left wing in the Piper Archer and Seminole), which sends ...
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2 votes
2 answers
2k views

How do gyroscopic instruments work? [closed]

I'm trying to better my understanding of the physics behind gyroscopic instruments in an aircraft. I am aware that a spinning gyroscope creates rigidity in space by resisting applied forces. But, what ...
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4 votes
1 answer
1k views

What and when was the first gyroscopic flight instrument introduced?

One of things which consistently amazes me about flight is the exceptional progress in the early decades of flight - especially in terms of avionics. Wikipedia tells me that the first ILS landing was ...
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8 votes
2 answers
3k views

Why Heading Indicator is not magnetic itself and need magnetic compass?

I read this while I was preparing for my knowledge test: The heading indicator is not direction-seeking. It is important to check its indication frequently and reset it with reference to the ...
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3 votes
2 answers
294 views

What kind of Gyros are being used in smaller regional jets?

As per my understanding, most of the Gyros in big jets are electric driven but I am not sure if the smaller planes also have the electric driven or vacuum/pressure driven Gyros?
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19 votes
2 answers
4k views

If I fly a balanced turn long enough, will the AI show I'm level?

Attitude Indicators are essentially gyroscopes. Mechanical gyroscopes have a "rigidity in space" property, which allows them to preserve their orientation when the support rotates. However, like ...
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13 votes
1 answer
25k views

What does the suction gauge actually show?

If I recall correctly correctly the vacuum suction gauge in the TB10 has a scale from 3 to 6, with the green range being 4 to 5 (I might slightly off on those numbers though). It's clearly marked as ...
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11 votes
3 answers
6k views

How much lag does an Attitude Indicator experience?

How much lag does an Attitude Indicator exhibit when it is working as designed? Other than well-known problems like tumbling beyond certain limits in pitch and roll, and precession errors from the ...
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