Reaction Wheels - Things Kerbal Space Program Doesn't Teach

[@nonenowherebye]

Just because it wasn't mentioned in the video, the Hubble telescope (and most space telescopes) do not have thrusters of any kind onboard. There is too much risk of the exhaust from the thrusters fogging/damaging the delicate optics on the telescope. Instead, as Scott said, the Hubble uses reaction wheels to point itself. What it also uses it a set of magnetorquers to constantly bleed momentum off from the wheels, so as to avoid them becoming saturated.

[@HuntingTarg]

Quite an idea, but it is likely because an open magnetic field of that strength would interfere with some of the super-sensitive detection instruments inside the shuttle (such as the cryogenically cooled Infrared imager), and also that coupled with reaction wheels it might put too much load on the telescope's power system and lead to brown-out.

[@IDoNotLikeHandlesOnYT]

What about JWST then? Some (not much) thrust is needed to maintain its position at the Lagrange point, which is unstable.

[@HalNordmann]

@@IDoNotLikeHandlesOnYT If it is unstable, any vapour released by the thrusters will just drift away.

[@rocketsocks]

There have been many space telescopes operated since Hubble (such as Kepler, Spitzer, GAIA, etc.) and they make use of thrusters. The worry about exhaust fogging up the optics was probably a matter of overzealousness when Hubble was originally built, since then we've learned it's not as much of a problem as was feared.

[@atrumluminarium]

Also thrusters would need fuel refills. Reaction wheels just "replenish" using the solar panels without needing to consistently send anything up there.

[@GarrettWilliamsKGD]

I read the title in Scott's voice, Reaction Hweels. Best accent ever :)

[@StratoSound]

Swap the positions of the H and W in the word Wheels and bam, there's your accent.

[@Reggiland]

like bob ross with 'hwite'

[@michaeldonahue222]

My Human Geography teacher says wh words the same way

[@PemboCycling]

Cool Hwip.

[@MegaAwesomeNick]

Hwil Hweaton

[@Tehom1]

5:56 "You need to desaturate using fuel" There is at least one other way to desaturate, which for instance the ISS uses. Your satellite has to be fairly long to use it, and it has to be in orbit around a planet or similar. You can use tidal forces to spin down. Picture a long satellite such as the ISS. Earth's tidal forces tends to pull it so that its long axis is aligned with the direction of gravitational force. Basically, the part that's nearer earth is attracted more strongly, and if your satellite is long that makes a difference. So you orient it so it's not aligned with the direction of gravity, and at such an angle that the axis of torque due to tidal force is opposite to whatever direction your control moment gyros have excessive momentum in. Then you hold that attitude, fighting the tidal force by spinning your gyros down, until you are happily in the center of your operating envelope again.

[@tiagodagostini]

Would not simply using the spin to generate electric current spend that momentum into something not mechanical (and therefore not undoing the orientation change?

[@inerlogic]

"magnetorquer" is the name of my new death metal band....

[@small_SHOT]

alive metal

[@anninhilator]

Fly safe... *Drinks beer* Scott, humans don't work that way :P

[@rockymountainrocker5630]

humans and beer.. it's about as common as dogs and fur :)

[@itechiwizard83]

He was drinking rocket fuel

[@eins.wanderer4799]

i hope that was german beer: Otherwise it isn't beer :3

[@Eric-om7dv]

@@eins.wanderer4799 thats true

[@gracelanderas]

...but he doesn't fly

[@ThatTinyDude]

please do more of these they are highly educational

[@MemeLord-sw9fy]

dont make him

[@ChiyoBebe.]

MemeLord1600 It’s a suggestion you daft idiot

[@PompomYourkey]

Lol

[@Darthilandia]

I like to watch this kind of video on my breakfast :)

[@To-mos]

Scotts been collecting some reaction wheels on his shelves back there

[@willemstander8400]

This made me kek hard. Well played.

[@Rendpullman]

Yup that's a quite nice collection. I can't seem to recognize anything but I'm still curious.

*hweels

[@AltereggoLol1]

This is a topic I've wanted to research for a _long_ time, but didn't even know where to start. Thanks for the info! These quick explanations are by far my favourite kind of videos of yours.

[@TripedalTroductions]

"Say whip." "Whip." "Say cool whip." "Cool hwip." "YOU'RE EATING HAIR!"

[@rocketnerd7763]

Hahaha lol

[@K1RTB]

Will Wheaton

[@hydroximane]

Yes, that's accurate

[@Spacejax05]

I don’t get it

[@hydroximane]

@@Spacejax05 watch family guy bro

[@EthanNin0]

Another reason why reaction wheels are used on space telescopes, there's no residue that can obscure the viewing field or mirrors.

[@jbkjbk1999]

"hweels"

[@harrison805]

Well, that's how it used to be pronounced everywhere :D That's why there's a 'h' in 'wheels' instead of just 'weels'

[@lineriderrulz]

Doesn't explain why the 'h' is before the 'h' though then, does it? haha (or did that used to be the case too?)

[@Joseph-fp8qm]

Believe it or not "hweel" isn't actually a word it is just an approximation of what Scott is saying as heard by the original commenter. If you listen closely he pronounces the h after the w. His pronunciation just includes the h sound whereas your regional tongue does not. If you want to get pedantic about it.

[@NetRolller3D]

Joseph Buttz "Hweel" is actually the original pronounciation of "wheel", and the reason why we don't spell it "weel". Scott's dialect doesn't have the wet-whet merger found in most English dialects around the world.

[@john_titor1]

Well, the wh sound is actually not just an h and w combined, it is a separate phoneme that just happens to sound like the h and w combined.

[@OldMrSarvy]

the beer at the end,you know you deal with Scott MANley

[@ThatGuy-nv2wo]

cringe

[@PivotSweden]

Oh no, you're THAT guy... *tips fedora agressively*

[@misharik8443]

"fly safely", *drinks beer*

[@ahmedzogu3284]

Scott Manly

[@gary.oneill]

Thought the exact same thing. Reminds me of the Leonardo meme

[@RenescoRocketman]

Hi, Scott! Your Orbital Mechanics On Paper was one of the best playlists about KSP i've ever seen. Please, continue making this stuff, there are much things left: Calculating orbits based on initial conditions, low-thrust maneuvers, efficient launch profiles. There are some teaching videos on tube, but your explanations were much more clear and easy to understand than others.

[@charleston9526]

Scott Manley, you need an angrier voice to suit your face.

[@baishihua]

How about him being Agent 47 haha

[@popetipap]

He would be ALOT better than that innocent/shy looking guy they got in the Agent 47 Movie

[@benjamind.4790]

I'm not the only one that thinks he looks like Agant 47?!

[@vedranb87]

Are you saying he isn't Manley enough?

[@TitovIgorBro]

I live in Moscow and I was a city volunteer during the worldcup. I remember a wasted Englishman shouting "It's coming home" to my face and he looked exactly like Scott

[@digitsstuff6521]

Actually it is possible to rotate on all three axis with only 2 wheels, if you rotate 90d on any axis, then rotate 90d on a second axis, and finally rotate -90d on the first axis again, that will yield the same result as rotating 90d on the third axis.These are all of course using only local axis.

[@scottmanley]

+Ethan Salie but then you can't stop drift in the 3rd axis, so you end up with net rotation around that axis over time.

[@industrialdonut7681]

what

[@Mr.Rin.]

Dang

[@davodity]

+Scott Manley Called 'gimball lock', I believe it is referred to briefly in the Apollo 13 movie.

[@wierdalien1]

that's not gimball lock

[@12345DJay]

get yourself an office chair (that spins) and a wheel (from a bike, for example; car wheels work better but they turn out to be a little too heavy to hold in one hand) . sit down on the chair, hold the wheel horizontally and spin it colckwise. now get someone to push your chair so you rotate as well. now flip the wheel 180°

[@12345DJay]

Warning: the person witnessing your little experiment because you needed him to spin your chair might accuse you of witchcraft so prepare to run away

[@what-the8028]

You don't even need a wheel. Just hold something heavy. Move the object from your center of mass to the side. Arc the object to your other side. Move the object back to your center of mass. Repeat to go around and around. You could also pass the object to the other hand behind your back if your flexible enough to reach behind the chair.

[@12345DJay]

What-the the thing is, if you do what i wrote you will change your direction of spinning every time you flip the wheel... that's the whole point. it looks like you hacked physics, really funny

[@what-the8028]

I know the wheel thing. I've done it before at a science discovery centre, very cool I might add. I was telling people how it can be done another way at home without dismantling a bicycle / car.

[@michaelt3172]

This type of idea could be used for a momentum drive or antigravity drive to generate momentum upwards without thrust so you can fly and move at great speeds with only electric power

[@thegardenofeatin5965]

Wait a minute. Does KSP simulate gyroscopic precession, or did you do that manually?

[@SophieJMore]

The Garden of Eatin yes, it does. Although it's almost impossible to make a gyroscope in stock KSP.

[@antoniomaglione4101]

Watching this again, because in your latest video - four years after this - you just explained how high intensity electric fields (CME, ion thrusters, etc.) can disable the ball bearings inside the reaction wheels, which keeps failing in continuation. Thank you for all your efforts in explaining and teaching aerospace matters.

[@Sorenzo]

When your "reaction wheel" in KSP reaches maximum spin velocity, it's kinda like if it was saturated...

[@mezza205]

thumbs ups for your wipeout 2097 vinyl great game great soundtrack

[@scottmanley]

+mezza205 well spotted!

[@knglaser]

very nice spot, wich reminds me of: fluke - atom bomb

[@SteveChisnall]

6:14 would a "magnetorquer" be effective for pitch/roll/yaw control for a spacecraft orbiting Jupiter?

[@HuntingTarg]

I think that is an awesome question, and one worth exploring if we decide to send any more (larger, sturdier) probes to Jupiter for longer stays.

[@JeyJeyKing1]

Probably not. These missions typically stay in an eccentric orbit, where this method of attitude control would not work most of the time. Furthermore you already need another method of attitude control before getting to Jupiter.

[@chrismusix5669]

I recently saw a KSP mod listed that tracks saturation.

[@MrAshleyR]

Is your hoodie of a loading crane that wishes it was an AT-AT? What?

[@IstasPumaNevada]

That gave me a chuckle.

[@scottmanley]

Yes, it's a reference to the popular myth that the walkers were inspired by the cranes in the port of Oakland www.thegirlandrhino.com/

[@PeterBarnes2]

That sentence made no sense until I read Scott's reply.

[@MrAshleyR]

Scott Manley Fascinating. Thanks for the explanation!

[@staratmidnight7]

Fun fact: the front and back ends of a cat essentially function as reaction wheels in order to allow the cat to manipulate its orientation and land on its feet in virtually all circumstances. Check out "Cat Righting Reflex" on Wikipedia.

[@Luka_3D]

Someone has to make a mod for desaturating reaction wheels with rcs. Scott! You make complex topics simple and easy to understand. Thanks! Keep making videos like this. The bear at the end could become a part of the outro.

[@vitsalava1251]

What bear? I saw he was drinking beer. XD But fun had to be done.

[@Cythil]

I though there was a mod like that. Though I have not looked for it my self.

[@proot.]

I think the mod is called saturatable reaction wheels.

[@Luka_3D]

protostar 777 I knew someone will say that... No I mean the option to use monopropelant to dump momentum on the reaction wheels.

[@proot.]

+Luka David Torkar doesn't the mod cause reaction wheels to use small amounts of monopropellant over time? Sorry, I haven't much experience with realism overhaul.

[@jamierogers294]

You managed to explain all that without even hinting at the DIY bicycle wheel experiment! :D

[@Magnymbus]

I use reaction wheels all the time in Besiege. just put a large wheel in a cage near the middle of your creation and boom, you can turn your airship very easily. You can even add armor or ballasts for added weight. You can also use braces to move the weight around.

[@RKroese]

Damn smart

[@peacefulguy9539]

A great respect for who can tell me the exact number of vinyls seen in this scene.

[@Hotshot6345]

Last time i was this early, KSP was still in Alpha :P

[@jortvanwelbergen8009]

We need more of this Scott! definetly the most informative video I saw on CMG's, especially the kerbal animations add a lot of clarity :)

[@michaelpeila8794]

Scott, for the life of me, I can't get used to your voice coming out of your body. You kinda look like a Bond villian, in shape and maniacally genius. But then your voice sounds so kind; I feel like I'm suffering a case of cognitive dissonance about the tenor of your voice haha.

[@JohnyG29]

maybe you shouldn't judge people on their looks, or be 'judgey' in general old chap.

[@drink15]

There is a time and place to judge people based on looks.

[@Dutchcomentatah]

That would be 2014 and Tinder, gents.

[@AnaseSkyrider]

It's the current year, fellas.

[@uzferry5524]

Maybe you should stop touching yourself in night

[@NimrodTargaryen]

one of the best explanations of a momentum/reaction wheel

[@jompis007]

Love this series! Keep it Up Scott

[@chrisonabuffalo5485]

Love these explanations Scott, its awesome to know how they really work, appreciate it and keep them coming!

[@whatsinanameish]

Epic LP collection you have there.

[@1Kaisermerlin]

Yeah, he is really in to Lets Plays.

[@joops110]

Good ol' times when Lets Plays were still on vinyl.

[@Blox117]

the fuck? LP is not lets play, silly kids.

[@whatsinanameish]

+Blox117 is joke, comrade.

[@mikelevi5555]

I have an old Lynard Skynard lets play from 73. thats 1973 not episode 73

[@danielburleson259]

Love this video. This is exactly what I was wondering about reaction wheels in KSP. Thanks Scott!

[@haydenchan3530]

Ksp reaction wheels might be figet spinners spinning 1000RPM

[@dataexpunged3914]

Knowing kerbals that not the case It's two fidget spinner at 500 RPM each and the rotation is started by those small explosive fireworks things for throwing they have in europe

[@CreeperDude-cm1wv]

Kerbal moment

[@tillytony]

Ur vinyl collection is one to be admired. Would love to see a video on them :)

[@franzludwig3250]

Wait, is that a vinyl wipeout Xl Soundtrack back there?

[@scottmanley]

+Franz Ludwig yes it is, well spotted.

[@lmamakos]

Some of the Amateur Radio OSCAR spacecraft used a combination of permanent bar magnets for attitude control, along with some other rods of "lossy" material mounted orthogonality that would rotate through the magnetic fields to eventually damp that rotation. I think some others used a deployed gravity gradient boom to keep one side of the spacecraft (and antennas) pointed at the earth. Many also had magnetorquers as well.

[@scottmanley]

That's cool, I hadn't heard about these tricks, but they all make sense.

[@kalleidoskop2]

cool hwip. Great stuff as always, love your channel!

[@Saphykitten]

Scott, you gotta make more Kerbal Videos! These are what most your fans come to see!

[@RadionPrime]

Dam, so many vinyls in the background. Now i want a video about them.

[@ubergoober4065]

He used to DJ.

[@Supergeckos1000]

Scott goes through his vinyl record collection, yea!

[@Archgeek0]

There's been one, actually! He's got a few that are actually special circular tracks for repeating beats of various stripes, or other effects. Can you find it?

[@sagiksp4979]

They aren't vinyls, they're reaction wheels

[@Schindlabua]

+sagiksp *hweels

[@ForwardBias]

It was so cool learning about torque in my physics class freshman year. Using the gyroscopic effect, it is possible to keep a bicycle wheel suspended with its axis parallel to the ground with a rope attached only to one side. Crazy stuff.

[@braindead_boi]

imagine if Scott became an astronaut and went to the ISS

[@Make-Asylums-Great-Again]

braindead imagine if Scott was Mr. Clean.

[@KSPAtlas]

While doing a KSP rendezvous tutorial

[@Kanives1]

another great video, thanks! My God, every time I see Scott's office I'm amazed by that vinyl collection! Holy records Batman! :)

[@Jeppelelle]

Why not put a gyro on a canfield joint? That way you should be able to control 3 axis with just one gyro (and another one for backup ofcourse)

[@scottmanley]

+Jesper Andersson the 3rd rotation axis is the spin of the gyro.

[@Jeppelelle]

Scott Manley Then just put the gyro on a 180 degree swivel on the axis of rotation on the canfield joint so you can swap direction of the spin to get the force in the other direction when you need to ;). (ok i now realize why this wouldn't work the way i imagine, i will scrap this idea)

[@REDACT3D]

I wish ksp had a R&D lab that allowed the player to spawn the objects in a test room to discover the properties of each part. closest thing a player can do is just build a small test vehicle - but sometimes I just want to focus on one aspect. would be cool to see!

[@REDACT3D]

​@Jonathan Stiles ayeee - I made this post before I discovered the cheat menu ha- didn't realize they had thrown it in to the console version! ⬆︎⬆︎⬇︎⬇︎⬅︎➡︎⬅︎➡︎ it does disable trophies when you use it - although lessons learned from it stick in your brain.

[@estoniaman]

"I'm Scott Manley, fly safe!" *gulp-gulp*

[@drifterax7731]

Had me hooked from start to finish! Thank you for the lesson :)

[@diegomolinaf]

I cut my hair bald and for two weeks, anytime I saw myself on a mirror, I couldn't help but to think: "Hello, Scott Manley here". You have ruined my life! XD

[@packediceisthebestminecraf9007]

I see this as an absolute win!

[@MrGrombie]

I like how you presented this episode with Kerbal. It teaches in a way that brings it down to players. Which can easily cross over to a general population.

[@mbainrot]

"fly safe" then has a swig of booze xD #madeMyDay

[@MRptwrench]

I found this great video when I researched before sending in a suggestion for New videos! You already had it covered. Thanks!

[@BarcelPL]

Is the placement of real life momentum wheels/gyroscopes important in regard to the given ships center of mass?

[@neo-loser]

probably, since it's still force being applied to one end of the craft, therefore myst be balanced.

[@Chwibon]

The wheel will apply the same torque wherever you place it. However, depending on the placement, the moment of inertia of the ship will not be the same, and the smaller the moment of inertia, the bigger angular velocity you get from the wheel. For optimal performance you need to place them at the center of mass.

[@BarcelPL]

***** I thought so - thanks for answering :)

[@theavera9ejoe]

That gyroscopic gimbal demonstration was fantastic! Well done Scott :)

[@kminrzymski]

So, you come from this mysterious land in which people say "h" before wh- words :D

[@Tomwesstein]

'Reaction heels' xD

[@Tomwesstein]

Thanks, I cannot un-hear it anymore.. now it's getting annoying... :)

[@robinfrenzy]

coolwhip

[@michaelfarrell4824]

the land in which the language you speak originates, your land is the mysterious one, speaking another countries tongue

[@Justanotherconsumer]

It’s the distinction between wip and whip. It’s not too late to whip it. Whip it good.

[@ShiftingDrifter]

Great stuff! Really enjoy the whole "Things KSP doesn't teach" series. Keep'm coming!

[@Zanzubaa]

What are those things behind Scott? They look like big Blueray discs or really thin books.

[@2000gmod]

I would say vinyl records.

[@rjthegood]

yeah records

[@AshMcFarlane]

They be those loud things the ancients used

[@Archgeek0]

HEH, it'd be deeply amusing if those were for some reason laserdisks, but no, probably vinyl LPs. DJ and all that.

[@Paganinifire]

what are you 5 years old

[@CJHPercussion]

Wooo a dynamics-integrated Scott lecture! Love it.

[@DrAnimePhD]

Why can't you be my physics professor?

[@TheMattman1313]

I'm going to be taking Attitude Dynamics next semester (Aerospace Engineering), so this video is a fantastic intro. Thanks Scott!

[@kenspiracy2792]

All them vinyls, though...

[@HelloKittyFanMan.]

What about them?

[@doormarci2]

THANK YOU. So much. Always had a feeling the reaction wheels must not be able to generate momentum indefinitely (obviously, as they're not generating anything). This video was very useful, thank you again.

[@josephlee9496]

Scott, why don't you work for NASA or Space X or some other space company? you could do great things.

[@scottmanley]

They can't afford to match my salary from my day job.

[@введитебросок]

he is a scam would fit nasa very well

[@josephlee9496]

ahaha, you must be raking it in if nasa cant match

[@mr.broseph8392]

Joseph Lee Well, I mean, it's not like NASA is nearly as funded as it used to be.. but Space-X? They most likely could match it lol

[@josephlee9496]

that a good point, i dont really know the salaries

[@piggyinthemiddle]

Thankyou Mr. Manley. It's mind boggling how much I have learned from playing K.S.P

[@michaelt3172]

Would it be possible, if enough torque is generated, to make an anti-gravity device by having them rotate in all directions at once with a majority providing upwards momentum?

[@scottmanley]

+Michael Tarantolo no

[@TheSpaykers]

the smart no of love

[@11Neh]

If you want your reaction wheels to provide momentum in a direction rather than angular then you've gotta be throwing them outta the back of your rocket

[@AstralS7orm]

If you make the spinning objects about the size and mass of a planet, then yes. Not recommended.

[@TheLargeHardonCollider]

If what you mean is using rotational force to create a gravity-like effect in space, the answer is YES. We call this centrifugal force, because it works in the same way a centrifuge does to separate blood from plasma for example. If you imagine a giant hollow ring in space, and that ring is spinning, you could live inside that ring being pushed to the outside by centrifugal force, and you could stand up and walk. Many sci-fi movies and video-games have already used this, for example: Halo, 2001: A Space Odyssey, Interstellar, Elysium, The Martian, Europa Report, and many other sci-fi books like Ender's Game (the movie didn't show it so much). A practical example is if you held a bucket filled with water tied to a rope, and began to spin in place. As you spin faster, the bucket would to rise vertically until it was co-planar with the horizon, but no water would fall out. Real world examples NASA wants to try, is instead of building a huge ring, to have a living capsule tethered to a counterweight where we could spin both around each other to create a centrifugal force. However centrifugal force has nothing to do with reaction wheels. In practicality, we would still use a fuel-based RCS to spin these giant wheels (or tethers) up. Not sure if this is exact what you're asking, but if the question was "can rotational force create gravity-like effects" the answer is YES it can, and we've already know how to do this for a long time. With giant rotating spaceships.

[@Raptorman0909]

Reaction wheels apply torque only when the flywheel is accelerating. That is, in order to produce torque to rotate a sat a reaction wheel with an access of rotation parallel to the desired sat rotation must be spun up OR down and thus the torque applied to do that with result in a torque to rotate the sat. So, it's not the speed of the flywheel but the change in speed of it. There is, of course, a tiny bit of friction in the reaction wheels that must be compensated with torque from the motor, but the force of the friction and the torque of the motor tend to cancel.

[@acylonepleidian9665]

Im way too drunk for this

[@summerofsteroids]

Acylone Pleidian Wait really? XD

[@airor9874]

What about now?

[@bal20]

This man is a good advert for beer! Like your style Scott

[@svfox]

You are wrong about 3 things Mr Manley. It is my professional responsibility to point out you lack of knowledge without trying to put you down. First, You said . One sec my mom is calling me, brb.

[@TheNiqhtstyle]

He ain't back yet?

[@rickharper4533]

King r/woooooooooooooooosh

[@jaywilliams720]

Rick Harper r/woooooooooosh

[@itsahumanperson6174]

Nobody ever heard from Steven Fox again...

[@sweppz5204]

I like the way that i was looking for a video like this a month ago and now it just appears on my screen.

[@benj6171]

Fly safe.... -drinks beer-

[@sky173]

Great video. I was just wondering about over-saturation of RCW's and how it's overcomed the other day. Thanks for explaining.

[@WOLVSAid]

that epic ending beer

[@FlaminSquirrel]

Hope you continue this series; great stuff.

[@Grandremone]

Awesome you also have the Boards of Canada - In A Beautiful Place Out In The Country vinyl!

[@jdrissel]

There is another way to use reaction wheels. Have 2 of them on same axis counter-rotating. PV panels spin them up. You get attitude control by using one as a generator to spin the other or asymmetrical charge/discharge. You also can use them as power storage. Works best for satellites that pass through the shadows. High power output for a short time plus attitude control in one package.

[@TheTrueJedi01]

This was very good, please keep more of these coming! On a related note, in my current Kerbal career mission I am trying to be somewhat realistic in my mechanics. Like you said, the reaction wheels are overpowered, so I have taken it upon myself to disable all pod and probe wheels in the VAB and rely on RCS for most stability control. If I'm building a station, I may add an SAS module, but I think it's a neat mission challenge, and I highly recommend it.

[@ohsociety8741]

Saw the Propellerhead vinyl in the background, hit thumbs up before even watching the rest.

[@BelgianDneprGuy2003]

these videos are highly educational, but they keep my VTOL's stable whenever i test the VTOL system. so they are usefull in KSP for a variety of things

[@garychisholm2174]

And here I was convinced that reaction wheels were simply a game-balancing Squad invention. good info!

[@KayoMichiels]

In the Cacteye telescope you have to take into account that the reaction gyro's will wear out and you simetimes have to do service missions to replace faulty gyro's...

[@killerMILLER117]

I always feel honored to watch Scott's videos. He's so smart!

[@johnperry5396]

These are weird because sometimes they put me into a kind of doze but I come out of it smarter somehow. Addicting.

[@bumrocky]

@scottmanley, nice vinyl collection you had back there! Thanks for this enlightening video. I look forward to what's next!

[@madjimms]

Thank you for educating the world with your knowledge (via Kerbal). You make things so easy to understand!

[@Dustinielson]

All that wisdom and a beer.. Could enjoy a yarn with this bloke!

[@jonnymoka]

Ya he has a Led Zeppelin III record slightly showing. It’s one of my favorites!

[@ShaneSimon3D]

Great video - always wondered about gyros for attitude control.... Thanks for explaining it so well!

[@itsrachelfish]

I wish you had some graphics or animations to explain wheel saturation. I'm having trouble wrapping my mind around that concept!

[@carmatic]

i was wondering about the 'gyroscopes' in KSP and how they were seemingly able to produce endless amounts of angular momentum, and this video cleared it up for me, saturation was not simulated

[@Eyezzzonly]

They are used for Large Ships btw, for example the Gigant Queen Mary 2 - At large Waves, this thing is stable as in still Water, thanks to the Wheels used.

[@gdawgpwnsall]

As someone going into aerospace engineering this video was quite interesting, thanks!

[@grievousXWX]

Hi Scott. I'm a huge fan of your channel and KSP, but would want to learn more about rocketry and astronomy. Any advices on books or website ? Thanks in advance, keep up the good work !

[@edp2260]

Telecommunications satellites use reaction wheels in order to maintain accurate pointing toward earth. There is over time a net torque on the spacecraft due to solar effects. Eventually, the wheels become 'saturated', as you mentioned, meaning that they have been spun up to there maximum speed. At this point, a 'momentum dump' must be performed. This is where propellant is expended to provide force to allow the wheels to be spun down, reducing the RMP. An alternative to momentum dumping that expends mono propellant would be to rotate the space craft via reaction wheels in the opposite direction. This is not done in the case of telecommunications satellites because they must maintain pointing at earth at all times. However, the Hubble Space Telescope does not have this restriction. In fact, the HST does not have any propellant based thrusters at all. Exhaust from thrusters could foul the optics. The HST keeps the reaction wheels within their limits through rotating the spacecraft only, not by momentum dumping with thrusters.

[@uglyduckling81]

Thanks Scott. Just started the Gyros module in my Avionics course. This was quite interesting to relate to what I'm learning in class.

[@karlstorie8813]

Thank you Mr. Manley, for pronouncing wheel "wheel" instead of "weal" like the New England dialect that's spread nationwide since I was a kid.

[@davidhovey2047]

Hi Scott .. I just watched this, brilliant as always. I just paused when you talked about saturation on positional gyroscopes - instead of thrusters at this point to 'reset' against a constant exterior force like sun vs sola panels, why not shut down the gyro(s) in a well organised way, rotate them mechanically back to a 'resetted' position that takes into account this long slow correction that would be needed again, then restart rotation, process repeated ad infinitum .. ? That would use no finite fuel and use 'infinite' electricity instead...

[@sonnyburnett8725]

Thanks, I’ve always wanted to hear how these gyro’s worked and why they use which ones on what orbits, etc.! Awesome.