Inertial Gyroscope Spin Up and Demo

In an experiment related to our Apollo Guidance Computer restoration, we spin up a rate gyroscope and demonstrate how it works. Much better versions of this gyro were used in the Apollo Inertial Measurement Unit used by the guidance computer. But similar principles apply. We eventually plan to use original Apollo servo electronics with this or a similar gyroscope.
Visit Ed Thelen's (who brought us the gyros for this episode) page on gyroscopes: ed-thelen.org/Gyroscope.html
Credits:
Few seconds of Apollo IMU footage shamelessly taken from the outstanding NOVA documentary: Apollo's Daring Mission (which I found uploaded here: • Video , take a look while you can!). I believe the original footage of this sequence is from Draper Labs, who also have been supporting our AGC restoration by providing original documentation.

[@Sir_Uncle_Ned]

Spindown takes >10 minutes. The fact that any bearing has such little friction after all these years is simply amazing.

[@neoverload8685]

Looks like most of the energy is lost in sound emission :D

[@howlingwolven]

Especially that bearing. That sounds rough!

[@MadScientist267]

@@howlingwolven It's characteristic of gyros for some reason. They all do that, after there's much more than the burn in time behind them. The bigger the unit, the scarier they sound lol Rest assured the bearings actually hold up pretty well. Got a lot more calls to deal with flaky connections than rotor issues. They will spin like that for a long long time with no maintenance. Heading gyros in particular, different type, but similar idea, take as long as 6 hours to stabilize and point true after startup, so cycling them wasn't something anyone "just did".

[@LMB222]

You don't know the weight of the gyro. At 24000 rpm the inertia can be considerable.

[@JessePatrick-zc8ng]

Have you seen the giant flywheel Adam savage built. It’s terrifying watching it get up to 300rpm

[@jacobusv1494]

I used to work on the F16 inertial nav. Unit. The grease for the bearings was like a solid when cold. The first step in powering up the unit was to heat up the lubricant to become a fluid like substance first.

[@Nighthawke70]

Burroughs had a 36" fixed head disk array back in the early 60's. The hub was phosphor bronze and weighed 25lbs alone. It had reginrative braking, using it's own inertia to slow down. One story goes when they pulled the unit out to be delivered to a service center, they forgot to set the brake. So it was still spinning when it was loaded onto the truck. When they made a sharp turn at a corner, the storage array preceded right out the side of the truck!

[@Mudye]

yeouch

[@NoName-zn1sb]

its own

[@LMacNeill]

Geez -- if that was the "noisy, crusty" bearing, imagine how long it would've taken to spin down if it was a brand new bearing!

[@okboing]

if it lost power when you wrote this comment it could still be going almost as fast today

[@CuriousMarc]

Sorry for the oopsie on the first version of this video and the lost comments. Had to delete it and reupload this one to correct for (yet another) big bad typo. And yes this is after proper cleaning and lubrication.

[@neoverload8685]

Hi, 2Amps that's a lot! Is that part supposed to be under vacuum ? (could change a lot of things i thought) Anyway doesn't sound good in a "friction matter" ;) Btw i'm curious about single phase design for this device (efficiency...) (sorry 3rd edit xD)

[@Melanie16040]

I'm also curious if this part is supposed to be under vacuum

[@CuriousMarc]

@@Melanie16040 It's not a vacuum instrument. It has a simple protective casing that might help air flow a bit.

[@Melanie16040]

@@CuriousMarc Thank you for taking the time to answer

[@fargokid71]

Back in the 80s and 90s I worked on these type of gyros at Litton Guidance and Control in SLC UT. Then, they started using ring-laser gyros and solid-state gyros. I left in about 2004, so I don't know what they use, now. It was already so noisy in the Test Area that you never heard the gyros spinning-up or down. Ho-boy but were they accurate. They could accurately measure the earth's rotation in real-time. The "stations" or pedestals we tested them on were 12 foot blocks of granite, per station, positioned in the ground. Thanks for this demo. Brings back memories.

[@brentboswell1294]

That's a familiar sound in an airplane...When you turn the master switch on, the electrical gyro in the turn and bank indicator spins up (in a small General aviation plane, it's only 12 Volts DC though). There's also a vacuum operated gyro in the attitude indicator and the directional gyro (DG).

[@zaprodk]

Wow, that rotor must be HEAVY for that long of a spindown with such noisy bearings! - I wonder how much mechanical energy is stored in that rotor - it's amazing!

[@AKAtheA]

It draws a good 50W for a considerable portion of the spinup time and since nothing melted, guess where all that energy went ;-)

[@zaprodk]

@@AKAtheA Yeah of course. With "how much" I talk about what might happen if the rotor disintegrated in a loud bang - what would the damages be.

[@AKAtheA]

@@zaprodk It's a machined chunk of (probably even not just plain low carbon) steel. If it didn't come apart during the machining, then 24k rippums isn't going to do squat. If something spectacularly fails, it'll probably be the bearings. Once that rotor is loose, well...would not want to be standing next to it...or in the same room... :D

[@zaprodk]

@@AKAtheA that's what I mean. If the rotor somehow gets loose, I'll stand a bit away and watch the destruction :D

[@Thefreakyfreek]

I made a gyroscope onse 300~400 grams and it got lose from its axis and started resonating it got lose from the cage and burnt my carpet the hole in the centre of the brass weel was 6 mm now its 8 mm and it took a while for it stop destroying my room scary shit

[@FesixGermany]

Always interesting to hear the resonances while powering up or down such high speed devices, I have two turbomolecular pumps one at 50k rpm and the other 72k rpm maximum speed.

[@Melanie16040]

Any chance of a video of them spinning up? (and/or spooling down)

[@johncantwell8216]

The resonant peaks can cause problems; that is why VFD drives for large centrifuges and similar devices have the ability to rapidly pass over those points when they are bringing the rotors up to speed.

[@grb1969]

@@johncantwell8216 excellent point!

[@qwertyFUBAR]

I just watched a gyroscope spin down for ten minutes fifteen seconds. You win the Internet today.

[@video99couk]

Sound reminds me of the old MFM hard disk I had on an Amstrad PC1640.

[@robjohnson1138]

It just sounds like... power. Kind of like when the Ghostbusters’ proton packs power up - barely contained power just WAITING to bite you. +1 for “rippems” and “safety squints”.

[@dangoldbach6570]

EXACTLY what I was thinking!!🤣

[@nzoomed]

Kinda sounds like an old school hard disk spinning up lol

[@exafrost]

I preferred Venkman's terminology. Unlicensed nuclear accelerator. Sounds much more... ominous. Proton pack... ugh. Too camp

[@trulyspinach]

This is the best video I have watched yet this year.

[@account0199]

I _can_ skip to the end... But I *WON'T* . This is too awesome!

[@paulhorn2665]

I love this old gyroscopes, there are fascinating things and the sound is always great!

[@wirdy1]

Lovely. Fixing & fitting inertial nav platforms, as well as pitch + roll + yaw rate gyros for stability augmentation flight control systems was bread & butter for Nav Inst trade in the military. That gyro spin-up sound brought back fond memories, Thank you so much.

[@jmalmsten]

This reminds me that I really would love to find a video showing off the gyroscopic camera stabilisation rigs used for tracking shots on Das Boot. :)

[@RedHedDes]

Your whole channel is fascinating and should be way more popular imo.

[@KD0CAC]

I have a couple similar , not motor driven , they were for jet fighters heads-up display for targeting . They were air driven , pitot tubes in the jet brought air in to drive the gyros , more electronic in my gyros - the electronics in mine are to keep at a specific temp for the bearings . I really miss the old surplus places , so much neat stuff ;)

[@dansearle1613]

I implore everyone who is interested in physics to experiment with a gyroscope, because to understand the conservation of angular momentum is to understand most of physics.

[@needleonthevinyl]

I love the sound of 400hz, it makes me think of traveling somewhere cool on a big airplane

[@henrysiegertsz8204]

Sounds as rough as a bear's arse mate! I worked on (Single Gimbal 1 axis) Rate Gyros for Autostabibilisation one each for pitch , roll and yaw, (As is the one you have) on Phantom aircraft. I also worked on Rate Integrating gyros also called Rate/Rate gyros, Ferranti FIN 1063, as well as displacement gyros DGA and VFRS on Phantom back in the 1980's. In a Cleanroom. That's quite big for a rate gyro, the ones I worked were about the size of two cigarette packets and had a torsion bar calibrated to the variable reluctance pick off to output a voltage proportional to the rate of angular disturbance, (angular velocity) about the sensitivity axis. They also cleverly used eddy current damping provided by a pure copper vane between the attraction poles of two rare earth magnets. Inertial platform displacement Gyro's I also worked on could not be moved from the test stand for at least 15 minutes until they had finished spinning down. Inertial, rate integrating, or Rate/Rate gyros have much smaller rotor masses and temperature controlled viscous damping, they tend to spin down within a minute. Inertial platforms use a combination of Displacement Gyros, Rate Integrating gyros as well as North South / East West and Z, (gravity) force feedback accelerometers, and some nifty second order differential equations to calculate the cross product accelerations the accelerometers detect as the control servo signals try to maintain the accelerometers at their null positions. (The actual acceleration signal is proportional to the feedback error signal which drives the accelerometers to null). The purpose of an inertial platform is to provide a stable motionless base for the accelerometers to measure how much distance has been travelled by the vehicle carrying, it in the three dimensions in which it can move. (Information nobody asked for, but you might find interesting)

[@rarbiart]

sounded like a wanna-be Seagate ST225

[@LMacNeill]

HA! That was my first thought too. Sounded like a Tallgrass Technologies external 20MB hard-drive I had in the '80s, attached to an old IBM PC.

[@Joetechlincolns]

Well, hard drives of that vintage, could have been made into a very crude gyro sensor. They had enough rotating mass. Lol

[@Maskddingo]

My thought as well.

[@KrotowX]

Definitely similar sound that old MFM HDD-s emited :) Remember that first Half-Life game creators also used this sound in some places.

[@MushVPeets]

@@Joetechlincolns Even new hard drives have _very_ noticeable gyroscopic effects. Not sure if enough to work as a gyro sensor, but with sensitive enough position detection, anything is possible, I suppose...

[@phraggers]

this is so frickin cool. I never thought I'd geek out so much over gyros, never gave them much thought before but damn they're awesome. edit Thanks for leaving the 11 minutes of spindown!

[@Xanthopteryx]

I love that sound when you power on or off the airplane!

[@mspysu79]

Very cool watching the spin up and spin down, always interesting to hear the sounds of these high speed devices. The highest speed rotating device I normally deal with is the video head on an Ampex VR-1200 Quadruplex videotape recorder, 14,400 RPM and that includes the headwheel as well as a rotary transformer to couple the video to the preamps, it uses an air bearing.

[@anonymousarmadillo6589]

Where do you still use these?

[@pseudomys1]

Gripping crescendo! Good stuff!-

[@ZombieB]

beautiful device!!

[@zh84]

The aviation AC power supply is 400Hz rather than the 50/60Hz used in people's homes so that the transformers aboard can be smaller, and therefore lighter. For the same reason, nowadays many computer power supplies take the AC input, rectify it, then use a transistor or special chip to turn it into much higher frequency AC so that it can be changed to a different voltage with a smaller transformer. I have my suspicions that this is one of the reasons why laptop power supplies fail so often...

[@YTANDY100]

@zh84 laptop psu also uses rectifier and hf osc to work a smaller transformer :-)

[@PileOfEmptyTapes]

I don't think linear power supplies have even been used for PCs in around 30 years, they're all switch-mode (usually ~30-100 kHz). Moreover, modern computers are absolutely LITTERED with switch-mode regulators. CPU and GPU Vcore, RAM and USB supply, you name it.

[@daverei1211]

I love the spin up sounds

[@ilrompiscatole5414]

Glad you engaged your safety squints but having the mother ready on speed dial is equally important 😬 Luckily it all went well 😄👍

[@bobs12andahalf2]

Don't forget the extra condom.

[@donthitmeimwoozy]

The dewclaw on stand by to laugh at your misfortune.

[@MadScientist267]

Did a lot of work with gyros in the marine setting... Considerably larger than that unit... And the things sounded at least as scary starting up, and hours to stabilize. That sawblade whine brings me back.

[@rarbiart]

_"Coming up next on _*_'unintentional ASMR'_*_ : Jackhammers of the 1930ies"_

[@foxtrotkilomike]

Love that start up and slow down sound, i think it will send me to sleep

[@pratap3369]

Rippems and safety squints.................It's gonna chooch

[@joshlewis5065]

Ah, AVE. My favorite Canadian

[@nealrcn]

suitably impressed

[@gremlin60]

love the sound of it spinning up

[@guygfm4243]

yes still here, good one thanks.

[@Zzeke]

That sounds so badass

[@dosgos]

Achtung! Small flywheel running at 24k ripms is like a small bomb. Please inspect the bearings, lubricate, and ensure unit is well assembled before running.

[@dosgos]

Dare to run a quick and dirty estimate of the power in that moving mass at 24k ripms! Estimate via mass or electricty dumped into the squeaky system.

[@RWBHere]

@@dosgos Well it drew up to 50 Watts for over a minute before reaching full speed, including losses so a rough estimate puts it at a minimum of about 25 W x 60 seconds giving 1.5kJ. Not to be treated casually.

[@karaffens]

@@RWBHere like a few shots with a .357magnum revolver 🤔

[@clambino7980]

Wooooooo Ed! Love his Nike site. Tracing the microwave routes in the Chicago area was so much fun.

[@dosgos]

There was a Cambridge US company that spent decades trying to store energy with high ripm devices. One use was to replace batteries in certain applications. The company reincarnated several times.

[@TheRealJavahead]

Great series! Though I believe in a rate gyro the displacement is proportional to the rate of rotation. Cheers - mark

[@oriole8789]

This seems to be a custom modified sine wave inverter (just an H-bridge). Even though it's not as bad as the much higher frequency pulse trains from variable frequency drives, some caution may be necessary. Older motors can get damaged with inductive spikes from those types of waveforms due to insufficient/old insulation. Voltage peaks at the device will increase with longer wire lengths. The bearings may also sustain continuous damage if you were to ground the device being powered, due to induced EMI flowing from the rotor, through the bearing, into case ground. In essence, it becomes a mini EDM machine with microscopic sparks eroding the bearing surfaces. Even if it's only 10mA or so, it will take its toll over time. However, that issue affects variable frequency drives with high switching frequencies, and wouldn't be as bad in this case. You should still measure current to ground from the metal of the unit, just in case. And the last obvious thing is EMI in general. Shielded cables are recommended so that nearby electronics aren't affected as much. Custom filters will help as well. The position resistor wires will likely be very contaminated with EMI and may need filtering themselves. If you guys liked this video, I highly recommend searching for "FIN-RPMD-Explorer" on KZbin. First result. It's one of the most beautiful videos of its kind, in existence. Please take as look as well Marc, I think you will appreciate it if you haven't seen it before.

[@97marqedman]

That was .................. fantastic!

[@thiesenf]

As a kid I was totally transfixed by things spinning down. At the age of 48 I still finds it relaxing. I am weird.

[@Bianchi77]

Nice video clip, keep it up, thank you for sharing it :)

[@SinapTec]

Hello Marc. I recently discovered your channel, and I became a true fanatic. I have to admit that your laboratory gives me a little envy, it's incredible! Just yesterday I went to visit the computer museum of my city. Greetings from Buenos Aires, Argentina.

[@timthompson468]

Safety squints? I think a full safety cage might be in order. Cool video. I was thinking about getting a simple gyroscope as I study physics to help with understanding angular momentum, but after seeing this, I might up my game. I wonder what this would look like with one of those high-speed video cameras.

[@Madness832]

Just love your lunchbox power supply!

[@wolfbd5950]

I like to imagine that the engagement graph for this video mirrors the RPM.

[@radoinc]

The ultimate fidget spinner

[@Frisenette]

radoinc, where the men are separated from the boys. Literally.

[@RWBHere]

@@Frisenette If you dropped that when it was spinning, that's not all that might become separated....

[@echohunter4199]

This is the exact sound you’ll constantly hear inside a UH-60 helicopter. It’s just the same frequency that comes from all the pumps and instrumentation gyros in the aircraft along with the twin turbines. I’m a retired Infantryman from the 101st ABN and we spend HOURS in the back of these things after a few years in the unit. I was on the path to going to flight school but, war happened and I married my wife (this was 33 years ago, lol) and the rest is history.

[@blackbird8632]

Sorry to see the old gyro is tired, well at least you gave it a spin.

[@aserta]

Say what you will about crustyness, but that gyro performed admirably. I suspect that the long take was caused by dry bearings (to be read, with dry spots). You can actually hear the race path smooth out and the pitch even out to what you'd expect to hear (think of it like a needle scratchy sound).

[@marcdufour2726]

“Safety squints”? “Ripms”? Now you're sounding like AvE... So, when the next Apollo confuser video coming out??? 😁

[@aaronbrandenburg2441]

That's exactly what I was going to say you took the comment right off my keypad.

[@ajvdwest]

So weird that with so many millions of videos so many people here watches Ave and this channel :/

[@ph33lix]

EXACTLY! To be honest, after ripms and safety squints, I was expecting CuriousMarc to go "CONTACT!" at 2:18. hahaha

[@bobs12andahalf2]

Does anyone not watch AvE? :D

[@TheTigero]

@@ph33lix "corntact!"

[@Live.Vibe.Lasers]

omg he IS an AvE fan! I had my suspicions. This is GREAT!

[@paulmartin5787]

Enjoyed it

[@tuserndeso7712]

Amazing

[@willemkossen]

Nice use of AvE lingo. Man, that bearing sounds harsh....

[@mitch19636]

Beautiful........

[@jaimdiojtar6515]

incredible bearings it must have i have never seen anything with such low friction to be that long to stop or it will spin a 10000000000 rpm

[@ianmoore525]

Maybe 40 years ago, I had a friend who was an instructor at the Brisbane AU airport, teaching trainees to maintain and repair radar and communications equipment. He told m a story about a plane who’s radar navigation was not working , he flew from Cairns to Brisbane about 1200 miles ( by road) he used his inertial navigation instead. When he got there and parked in his allocated parking spot, his inertial radar was out by only 5 or 6 metres.

[@johncantwell8216]

That's pretty good performance for an uncorrected IMU. They tend to drift, so they usually work in conjunction with other systems to update groundspeed (Doppler radar) or position fix, like LORAN, or in the case of Apollo a special space sextant.

[@ianmoore525]

@@johncantwell8216 it’s all Chinese to me, but I thought it interesting enough to remember after all these years.

[@johncantwell8216]

@@ianmoore525 And now almost everything is changed again with all the newer technologies.

[@stevedoubleu99B]

Do I get a prize for watching the whole spindown in real time??. Seriously though, very interesting and impressive.

[@pixelflow]

When is ebay going to add a search by crustiness level!

[@brianevans1946]

Fascinating..

[@rmurphy440m]

that’s cool as hell!

[@ChrisAlas]

Mind sharing some info on the type of motor(s) and gyro you're using?

[@briannease4117]

At time 6:40, this is what you hear when you de-energize the busses on a Boeing 727.

[@DavePrivett007]

and a C152 and PA28

[@MediocreMachining]

The Closed Captioning that KZbin generates when the gyro spins down is hilarious. 15:57

[@AlainHubert]

Reminds me of my first Quantum SCSI hard disk drive back in 1990. lol ! BTW, how do they go about balancing such a high speed device precisely enough for it not to want to move all over that table ? I've watched until the very end. And for some strange reason, I feel relaxed now... I'm so glad that the gyros in my iPhone aren't this noisy, and don't consume this much power ! One question: why does it need to turn this fast ?

[@thomasmaughan4798]

Faster rotation increases its sensitivity to yaw motion.

[@AlainHubert]

@@thomasmaughan4798 I understand. Thanks.

[@user-uy2gb8fj9r]

"And spin down..." Wow!

[@Wayoutthere]

I wonder if you replace the bearings or is it just to complicated?

[@tubebhassi]

What prevented it from flying off the table at such a high RPM?

[@NicholasMaietta]

I want this sound ever time I start my car.

[@jmk1727]

Not Kidding- when I got to the end I started dozing off with the full head nod and that's when I heard it "STILL AWAKE?" My head popped up and I just started laughing!! lol

[@ChrisRobertsonTheChamp]

+AvE influence reaches far across the youtube "ripums" and "safety squints"

[@DoNotEatPoo]

How do I get these bearings for my skateboard?

[@DownhillAllTheWay]

It sounds as if it has crusty bearings. I'd like to ask two questions : 1. Would a gyro like this normally spin in an evacuated (semi-vacuum) enclosure to reduce windage? 2. Does the rotation of the earth affect it at all? Can it even detect such a slow movement? I know that electronic gyros can - but a mechanical one - though I know there were mechanical gyro-compasses. I had an old artificial horizon unit once, but it wasn't electric. It had an enclosure in which air was evacuated (possibly by engine vacuum in a plane), and allowed a bleed of air into cups that were cut around the periphery of the gyro wheel to spin it up. I never did spin it up to speed, because I didn't know how to produce a good enough vacuum.

[@adamjacobs8606]

Yes the earth rotation can effect any gyro its part of the effect in navigation gyros that causes gyro drift over time

[@nzoomed]

I really hope the museum lets you borrow or swap out the memory module on display, its doing nothing and no benefit! lol it would be in their interests to see a working AGC!

[@LOGICALMAGNET]

the best Video the Ideea that let the Gyro Slow down 1+ from me

[@unlokia]

Thanks, Marc. I watched EVERY SINGLE SECOND of this, undistracted, laying in bed. It's a good thing to develop patience.

[@CuriousMarc]

Thanks for the note. You guys are hard core! :-)

[@shredderegypt3394]

Does the vibration affect it?

[@wynand988]

Does it show the rotation of the earth?

[@TreyWait]

It reminds me of when they turned on the Proton Pack in the elevator in Ghostbusters.

[@jocasimoes2222]

Uau fantastico

[@stonent]

I wonder what that looked like under a FLIR camera with crusty bearings?

[@kurtnowak8895]

I know this is an old post but how about adding a tachometer to it so we can see the rpms. I’ll bet you have an old chart recorder you can connect to the position resistor also!

[@CuriousMarc]

Thanks! These are two cool suggestions!

[@Lobo-tommy10]

I also like Ave.

[@chrismechanic2000]

can you imagine a modern car with DSC having an old gyro like this rather than the modern electronic versions, how much noise it would make haha.

[@dogmannz]

Surely there must have been sound dampening in Apollo. Imagine the noise of an entire platform of these things.

[@evanweir169]

Any simple explanation why the IMU uses the resolvers in conjunction with this angular acceleration data to control the "stabilized platform"? Why not just rigid mount the three orthagonal gyroscopes on the platform in an unpowered 3 axis gimbal. and measure the angular rotation of each big gimbal axis? Would the gyroscopes have to be too massive to provide enough momentum to reliably overcome the gimbal friction?

[@CuriousMarc]

Great question. That’s because unservoed gyro platforms are not in the same league, not even close. The gyro has to do all the mechanical work to move the whole platform against friction, plus it has to rotate 360 degrees dragging a slip ring around, all that in standard mechanical bearings. Servoed platforms on the other hand are near ideal. The servos maintain the gyros always very close to their zero, perfectly balanced position, so no slip ring needed on the gyro itself, and the gyro does negligible mechanical work - it hardly moves at all, a few degrees at most while the servo catches up in extreme cases, and then it only drags along its own lightweight float in near ideal magnetic bearings. The servo does all the friction work on the mechanical bearings, slip rings, and the heavy platform. This is therefore far more precise and far lower drift.

[@evanweir169]

@@CuriousMarc Good insight, makes sense. Thanks.

[@Jkauppa]

coaxial gyro stabilizer, 1-2-3 axis, passive vs active stabilization, while spinning

[@kevincozens6837]

I would have wanted to take it apart, check the bearings, and apply lubrication as needed before spinning that thing up. I wonder how many decades it has been since it was last spun up. I would have wanted more protection or distance between me and it.

[@SidneyCritic]

Those cheap Ebay $13 non contact tach go to 99,999rpm - lol -, you just need to paint a white line on the drum.

[@ugurunver2403]

Hey. You can play music on this video. Try to click different areas in timeline after the gyro started to slow down. Click these timestamps consecutively: 9:40 9:40 9:40 10:20 9:00 9:40

[@ugurunver2403]

I does not work very well from the comment but you can try to click directly the progress bar and three consecutive clicks to the same point, one click to the right, one click to the left side of the starting point and one final click to the starting point. And try to guess the song.

[@CuriousMarc]

@@ugurunver2403 Star Wars, imperial march!

[@Darkstar2342]

Can't you speed up the spindown time by connecting a resistor to the power input?

[@qzorn4440]

McMaster-Carr has 24,000 RPM bearings. These wonderful toys went up in flames in the US Navy Torpedo Gyroscope system. 🧐 Thanks.

[@BigMouth380cal]

Wow!

[@cybercat1531]

Those Gyro bearings are fubar, but you know that. The sound around 10:40 is particularly telling, it should be much quieter and much more steady in it's spin up/spin down noise.

[@cybercat1531]

Around 12:00 one can hear the shaft oscillating in the bearing

[@SeanBZA]

@@cybercat1531 What do you expect, no controlled atmosphere, random shocks from handling, last aligned decades ago. But still, pretty good operation, a clean and adjustment will get it fine again, just needs a nice airtight box with vapour guard and dessicant packs in there to keep it alive for a few decades more.

[@cybercat1531]

It's exactly what I'm expecting. Just a casual observation of events put into words.