Ep. 60: Inner Workings of an Attitude Indicator | Gyroscope

A view at the inner workings of a artificial horizon, or attitude indicator for a GA airplane. See how the suction powered vacuum instrument runs and spins the gyro to indicate your attitude in relation to the horizon!
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[@thegood9]

The engineers that came up with these analog instruments were geniuses...

[@Nexalian_Gamer]

Yea I wanna make a mini one that fit your palm.It will be powered by weight rather than by gyro.

[@BrettMcNary]

I was thinking the same thing. I think people were much smarter back then.

[@Nexalian_Gamer]

@@BrettMcNary If things go right,I'll have an old attitude indicator at some point in my life.

[@BrettMcNary]

@@Nexalian_Gamer funny you should say that. My 182 is getting new G5's in it as we speak, and both are coming out of mine too along with the vac system. Know of any cool things to do with the old AI? ;)

[@Nexalian_Gamer]

@@BrettMcNary You could make a steam turbine out of the vanes and connect the axle to a generator.

[@haydenshockley9432]

What you referred to as limiters are pendulous vanes. Extremely important components to the instruments operation.

[@computer5272]

John you're doing something great here. There's no shortage of online ground school programs however you're teaching very useful and practical things which others don't go into.

[@BrilliantDesignOnline]

As a design engineer, a mechanic and a nearly 50 year pilot, I have never taken one apart, so pretty cool to see inside AH. Thank you.

[@JonasGrumby71]

The “limiters” are actually called “pendulous vanes”, and are a critical mechanism to correct the gyro for precession.

[@oatlord]

How's your thumb doing 4 years later?

[@n124lp]

Thanks for another great video. I find it extremely helpful to know how things work, especially when dealing with malfunctions.

[@christiancoyne3691]

Excellent! Honestly one of the only videos on the Gyro, and Attitude Indicator that just works ... Thumps up, very well done! :)

[@Iverson8811]

thx for making such a great and complete introduction of how those system work inside and outside.

[@TheMissalisa89]

Thank you! Extremely helpful for a PPL distant learning student!

[@bigdrew5731]

Awesome Video! Loved seeing an in depth look at the inner casing of the instruments we always read about. Thanks.

[@patcicerchi]

Ok, I have to say that was pretty cool. Thanks for these vids!

[@abbieamavi]

*love seeing the inside, so much easier to understand then reading it in textbook! thanks Jason* :)

[@anthony989utube]

ive been reading theory book s about this but NOW i actually understand the working of gyroscopic instruments. thank you for an excellent explanation

[@jakobdamm5898]

Fantastic video! By far the best AH video I have seen so far

[@tallboywitshortpants]

The airplane is an absolutely incredible invention. This went way over my head- but it's very interesting to say the least. Thanks for this information video my man.

[@TWCHHK]

Great video! Keep them comin'!

[@bundymc502]

Great video, well done.

[@John1212168]

Great video mate. I am an ATPL Student but I had never seen an Attitude indicator from inside.

[@azstratus1]

Fantastic video! Cool to see the internals of the attitude indicator as this one instead of seeing drawings. Nice presentation.

[@addicted1021]

The best video i have ever found on youtube, EVER.

[@fly8ma.comflighttraining199]

Thanks!

[@ktkatmilligan]

This video is awesome! So useful!

[@billmcmahon9697]

Thanks for posting!

[@FSX789]

Pretty cool man! You´re awesome

[@fractitos]

Man amazing , thank you

[@jamesmediallc8933]

That was great! Thanks.

[@karhukivi]

Excellent stripdown! One of my more nervous passengers noticed the AH wobbling as it was spinning up and thought it was defective, wanted to get out!

[@Windtee]

Great pilots are always learning! Wing-rockin' demo.

[@alexwonner7469]

Woo, that is now an amazing tutorial. Thank you.

[@DNModels]

Wonderful video!

[@TheDNick]

Wow that was really cool. Never new how it worked.

[@simcptmike]

Interesting video.I enjoyed the disassembly of the ai, along with seeing how movement affects it.

[@tkguha6918]

very cool, thanks!

[@JosephdiCaro]

Super cool thank you for the great video!

[@Sam-w9des]

AWESOME VID

[@timber7744]

wow. so clever done.

[@soorajvs445]

now i understood how it work... very simple... but people makes it complicated.. thanks capt. 🙏 🙏

[@aldinaatic9360]

Am I the only one who thinks you have a similar voice like prosecutor Juan Martinez ? Nice video by the way and nice explained

[@stealhty1]

Now we have accelerotemers and AHRS,, Thanks for sharing

[@iacopoautiero2725]

Grate job man!!!

[@robhoard9114]

Nice video great explanation.

[@TheGheddoschlumpf]

perfect video

[@ACB70]

Nice presentation

[@62Cristoforo]

That was cool Thanks

[@prabhakarrao4922]

Amazing. Thanks

[@jaxnean2663]

Great video, thanks

[@SaurabhAnarase]

Sir this video was so helpful to learn the artificial horizon in a much practical way, please keep making such video based on practical viewing of the concept which is damn important in aviation, start making all videos on basic concepts of aviation. Thanks a lot.

[@maheralazzawi7814]

very good

[@pieterpretorius1014]

such a simple yet elegant design. i'm a bit of a nerd when it comes to mechanical stuff

[@dougroe4042]

This answered all my questions.... Great vid!!

[@fly8ma.comflighttraining199]

Awesome! Thank you!

[@Calvin5318008]

Like the video but something you didn't explain and I had to go find on a different video. Those slots on the bottom where the air exits are called pendulous vanes. They exist as a self correcting mechanism to make sure the device is pointing down with respect to gravity. If you had a perfect gyroscope and flew from the north pole to the equator then the gyroscope would be pointing backwards 90 degrees, this prevents that from happening.The way it works is that when the gyroscope is tilted those gates on the bottom are free to swing and will move out of the way for one of the holes allowing air to blow out of it and block flow leaving the other one (the holes are offset from the center, this is why one opens while the other hole closes when tilted). When the air leaves one of the holes but not the other on the opposite side it creates a torque on the gyro and kicks the gyro back up wright.

[@steamboy101]

Calvino, you've answered perfectly a question I was about to ask here. I was curious to know how the AI would function if it was "spun up", or initialized on a slope that is not perpendicular to the ground. Many thanks.

[@toiletduckie44]

I've literally been debating this with another pilot on KZbin, If those pendulous vanes are there to correct the gyro as the plane flies over the curve over the earth, therefore proving gravity has no effect on the gyro's orientation (since the gyro needs the vanes), then since my phone does not have pendulous vanes, the gyro in my phone should be way off when i fly to another country, but its not. Please could you answer these questions?

[@jakeiesu]

Calvino c

[@brycering5989]

Toiletduckie44 Pretty sure your phone does not have a Gyro.

[@joshuaatkins2334]

@@toiletduckie44 Unless you're special, you probably have 3 single axis accelerometers on your phone. It is a relatively complicated algorithm, that I don't quite remember, to isolate gravity from other accelerations. A mechanical indicator, on the other hand, does not go through a computer before showing you your attitude. I believe the algorithm in your phone does a similar thing to the gyro and the pendulous vanes. I am curious though to know how well it works in turbulent conditions.

[@juanponte8980]

Beautiful video

[@fly8ma.comflighttraining199]

Thank you

[@Puffalupagus360]

That thumbnail is all the evidence I need to know that this guy is no stranger to a spanner.

[@kasm10]

Thanks for putting this together. As well the altimeter vid.

[@fly8ma.comflighttraining199]

No problem! Check out more on fly8ma.com/

[@Svin4y]

great video sir!

[@fly8ma.comflighttraining199]

I appreciate it! Feel free to share it around a bit!

[@cubaniton74]

Take one of those gyroscopes and put it on a tabletop, make it speed really fast and keep it spinning for 24 hours, while filming it, if the Earth really spins, the indicator will show movement, but if it does not more one bit, then it is a clear indication that the Earth does not spin, but is stationary instead.

[@Andrea2601M]

Like you have done this...

[@pratwurschtgulasch6662]

this is awesome. now i understand how that thing needs vacuum, i had no idea :D

[@flybobbie1449]

Watch the film Total Recall, the Arnie one. The drilling machine the baddie drives has a row of flight instruments. installed.

[@impale_an_eel_its_fun]

very interesting, good job, will subscribe and look at more of your vids now

[@Gibbo1]

Very good

[@leogyn04]

Top vídeo

[@falconwings3864]

Awesome buddy

[@Mohammad.D2024]

Thanks.

[@jesusboquiren328]

Capt thanks a lot from the PAF hercs flt engrs

[@davidjacobson9463]

Very helpful.

[@fly8ma.comflighttraining199]

Glad it helps! Share us on Facebook and around the airport with your friends!

[@shayhan6227]

That looks like a pretty complicated device. I just use my girlfriend. She changes her attitude pretty quickly.

[@adnanaslam9138]

Nice one

[@zacharynorman397]

It's funny, I am less than a month away from taking my Instrument Check-ride, and here I am going back to aircraft systems 101. This was really helpful. Did you by chance break down how a gyroscope works in the heading indicator?

[@cosmicdetective8052]

woow...thanks a lot,,

[@K__R__K]

Great video and lots of useful info. This leads me to another question. How does a attitude indicator of a glass cockpit work. I mean the inner workings of it.

[@RoamingAdhocrat]

This is great. I'd love to see a similar video on a gyroscopic heading indicator, if you have a semi-scrap one lying around to demonstrate with :)

[@monad_tcp]

That intro, from Codyslab it love it.

[@parakhinpilot]

THAAANKS!

[@pharaon6718]

Serious engineering

[@charliepearce8767]

I want one !!

[@yasmarsanchez]

10,000 - 18,000 rpm ! Thanks for the explanation.

[@ProfessorOzone]

Was interested in putting some avionics in a car for a cool effect, but wanted them to actually function. This was very easy to understand and fun to watch. I'm not even a pilot! LOL. Thanks.

[@fly8ma.comflighttraining199]

Lol well I'm glad it still helped ya!

[@ahmedpilot3201]

Many thanks

[@fly8ma.comflighttraining199]

Of course!! Feel free to share it around!

[@ramjet4025]

I have on my desk in front of me, an Electric Humohrey AH08-0105-20 artificial horizon. This runs of 28 volts and does not require a heavy vacuum engine driven pump or an old fashioned Venturi tube that does not provide source until you hit 75 kts.

[@bencrawshaw1227]

Yeah some clever stuff

[@Cosme422]

The 172 at the school that I attend has it INOP and this video is great. Now I want to take it out and fix it lol

[@tbeevers]

Great explanation! The past few engine starts I’ve had, there’s been some erratic movement in my AI. Once I do my run up, it levels off fine and operates perfectly. Any idea what could cause this?

[@lborate3543]

I guess I have to work on my attitude then. Fantastic video! Show us inside a g1000!

[@fly8ma.comflighttraining199]

From time to time, we always have to make sure our attitude is in check.

[@call911forcookies2]

Yo! Really fun and informative video! Sometimes the AI in the 172 i train in randomly shows a 10-20 degree bank. Is that due to precession, or more so a mechanical deficiency?

[@shaynemckinlay6406]

1:30 up👍🏻

[@THYB737]

Impressive. Now can you also explain laser gyros used in big passenger Jets?

[@robertmonroe9728]

Has many very complex attitude indicators also from airbus and soviet crafts, but never had a pneumatic one. I thought it stopped producing at 50's

[@Skyhawk656]

I was doing steep turn exercises in an older 172p with my cfi a few years ago, and I remember the compass gyro would flip 180degrees as I did the turns. I’m trying to get and idea of how the gyro tumbles after it hits gimbal limits with good visuals, you actually demonstrated it pretty good. The directional gyro is obviously set up a bit different than the attitude indicator and I know it requires 360degrees of rotation about the airplanes yaw axis to measure headings. But what caused it to flip during steep turns?

[@kedusdmkkidu]

Pitot tube measures stagnation pressure by reducing fluid velocity to zero while pitot static tube measures total pressure and stagnation pressure in different different tubes and gives the difference between them as dynamic pressure so indirectly it is used to measure dynamic pressure.

[@aviatortrevor]

Could you talk more about the pendulous vanes and the weights that are used to correct the gyro?

[@autogolazzojr7950]

Also agreed

[@fly8ma.comflighttraining199]

Appreciate the enthusiasm! I didn't think anyone else out there was quite as nerdy as me! Haha....the IFR course will cover instruments and instrument errors a bit more in depth. I'll be sure to include that in there!

[@ryanumphress]

Are you still working on the IFR course that includes the pendulous vanes ? These videos are so great ! Id love to watch that instrument video explanation

[@mphmtb]

Am I correct in assuming if you put an aircraft into a bank and perfectly balance the turn with rudder in order to give the g force of the aircraft through the bottom of the aircraft, as if it was on the ground, the attitude indicator would return to a position showing level even if you are in a bank. Obviously you would need to be in a bank for a considerably long time. ?

[@gowdsake7103]

@@mphmtb Thats exactly what would happen kzbin.info/www/bejne/oYW7hXangq2snsk Shows exactly that effect

[@JakeDobyns]

It's so refreshing when one resource leaves you with a complete understanding of an instrument instead of reading multiple books or watching multiple videos. Thanks for the post Jon!

[@fly8ma.comflighttraining199]

Sure thing!!! Glad it helps!!! Share the site with your friends....we try to make it as simple and concise as possible!

[@2Phast4Rocket]

This is such an archaic instrument. I am glad the new glass MFD is taking over the task and it is cheaper too.

[@gowdsake7103]

Its also far more likely to give wrong readings prone to glitches and power outages

[@mbsevans]

2Phast4Rocket MFD still require one of these as backup.

[@DraculaxAlucard]

Did you install a glass cockpit or this a spare/defective part

[@MikkoRantalainen]

Do you have information about the actual bearing used for the gyro? Does it use just regular steel ball bearing or something more fancy?

[@eldrugoalex]

This could not be more clear.

[@rickhunt3183]

It's amazing how simplistic that instrument is. I can appreciate the engineering that went into that simple mechanical device. I'm guessing that they are currently using a microprocessor based system that incorporates a multi axis accelerometer to do the same job. I know nothing about flying. It just seems that an electronic version would be cheaper, easier to design and construct.

[@karhukivi]

But more likely to give problems! This is independent of the electrical system as is the altimeter and the airspeed indicator. If the electrics go, you have them. If the suction goes, you have airspeed and the turn and bank indicator as well as the altimeter. If the pitot tube gets blocked and you lose the airspeed, then you still have the artificial horizon.

[@stargazer7644]

A lot of planes still use vacuum powered backup instruments even when the rest of the cockpit is glass. And I would argue an electronic instrument is far more difficult to design and construct. All the mechanical one needs is some lathe work.

[@rickhunt3183]

@@stargazer7644 I know very little about avionics and all my opinions are based on contact with mid continental avionics. This is what I was told by them and it's also written on their website. Electric attitude indicators have fewer maintenance requirements and potential points of failure than vacuum systems.

[@angelicwolf909]

Wondering about the type of gyro that they used in 1959 Vtail Bonaza flown by Roger Peterson out of Mason City the "Day the music died?". Do all these instruments indicate the same or are there differences which could mislead a pilot in banking right when in reality, the instrument is indicating bank left as the "wing" on the left appears below the artificial horizon?

[@shredderegypt3394]

Is it for display only. Or it is efficient to take signal from it to computer

[@prafful_itape]

Anything about turning and acceleration errors?

[@austinbatrouni]

Those “limiters” are called pendulous veins they help the gyro stay upright

[@carultch]

You get a nuisance measurement, if you sustain a banked turn, because the pendulous veins will home the device to the direction of apparent gravity, rather than the gravity you would experience when cruising straight or at rest.

[@MrDogfish83]

@@carultch I'm trying to learn how an attitude indicator aligns itself with gravity initially...videos and books NEVER explain this! Can you go into detail this aspect? Also the nuisance measurement?

[@carultch]

@@MrDogfish83 There's a knob on the unit labeled "cage". It refers to caging the indicator to tell it which way is down. You cage the gyroscope before you take off, to tell it that the aircraft is currently level. The nuisance measurements occur when acceleration gets in the way of measuring gravity. The "g-forces" of acceleration cannot be distinguished from true gravity, and can give it a false sense of direction. The pendulous veins only measure gravity alone, when you are cruising at a level flight or stationary. There is acceleration any time you change speed, direction, or both. Banking a turn is one example. Another example is when you rotate the aircraft to climb or descend. It also happens when you perform aerobatic maneuvers like vertical loops. Think about your experience in an aircraft banking a turn. Do you feel thrown to either the left or right side? You don't. You feel as if "gravity" inside the aircraft is toward the floor. But toward the floor is not truly downward. Toward the floor is in the direction opposite the aerodynamic lift that pushes up and inward. The gyroscope makes sure that it only slowly adjusts to gravity, to avoid nuisance measurements from acceleration.

[@MrDogfish83]

@@carultch I get the whole acceleration indistinguishable from gravity thing. Sorry if you answered this but how does it make sure it only adjusts to gravity? That's they key I'm missing.

[@carultch]

@@MrDogfish83 If you just hang a simple pendulum, or use accelerometers to determine which way is down, you'll get a false reading when acceleration gets involved. The gyroscope helps the indicator "remember" which way used to be down, before the aircraft started pitching, rolling, and/or changing speeds. The gyroscope provides inertia to the instrument, so that it takes a long time to change the axis of rotation, and therefore orientation of the artificial horizon relative to absolute spacial directions. It is fast enough that the pendulous veins can change its direction as the aircraft moves around the curvature of the Earth, but slow enough to mitigate the impact of typical maneuvers. A sustained turn when you are in a holding pattern with the landing airport can provide a nuisance measurement. So pilots usually alternate 1 minute turn / 2 minute straight, in order to trace out a shape like the running track around a US football field. When ring-laser gyroscopes are used instead of mechanical gyroscopes, there is an override feature to only adjust the direction of down, when the aircraft environment is within a reasonable margin of 1-g, characteristic of a level & straight flight. The adjustment gets paused during banked turns, when the aircraft environment slightly exceeds 1-g.