Are Helicopters Gyroscopes? - Smarter Every Day 48

[@DShephard91]

lol, 1:50 That gyroscope blew that cats mind.

[@mannatranjit7504]

😆😆😆😆

[@matszz]

I understand this is what happens, I got that before you made the demonstration. Because you said that is what happens. I still don't understand why it happens.

[@mjr6406]

+matszz as the wheel is turning clockwise, the force applied to the front of the wheel (lifting up) will travel counter clockwise and the momentum will take it to the right. force applied to the back will travel to the left. if the wheel was spinning the other way, you'd have the inverse.

[@sentryere7822]

+matszz I think a Think of an object moving forward in a straight line. And we apply a force on it, knocking it off its course. It would follow a curve, which means by the time it is x meters away from its original course it would have gone y meters forward. Basically the effect of the applied force, which is knocking the object x meters off its course would be delayed for y meters. The same thing would happen if that object was moving in circles, like that spinning wheel.

[@matszz]

M James Michael J. Caboose I still don't understand, thanks for the effort.

[@misos1393]

+matszz watch solving the mystery of gyroscopes. The guy does start and stop and draws force vectors and explains it pretty well.

[@4214Haawkings]

Yeah I didn't get it either at first, I'm a simple guy and haven't put much thought to these things before. When I try to make sense of it, I guess it is the same principle as why you want to accelerate out of a turn while riding a car. You build momentum forward(as you enter the turn), as you shift, the momentum wants to straighten itself out (g-force(?)), so you get some built in tension that gives you an extra boost as you exit the turn. So in this case, like with the wheel example at the end, the force is applied to the middle of the wheel and then moves down as it is tilted, since the wheel is spinning, the force that was moved down tries to exit following the movement of the wheel just like the turn. Am I getting this wrong ?

[@smartereveryday]

You sir, just earned yourself a new source for non-traditional education.

[@dontyouworryaboutit_]

Gyroscopic precession blew my mind. I can’t imagine the first time someone tried to make a forward input and the aircraft translated left

[@LeoH3L1]

Pretty sure the first helicopter designer knew about it...

[@r4res502]

I felt it before due to my experiments on gyroscopic bike.

[@ntdeas]

Destin. Please make a video on the physics behind countersteering a motorcycle. This involves gyroscopic forces as well as the angle of the front forks creating a gimble, and several other factors in play as well. Turning the handlebars left to go right is a concept that most riders never fully grasp and form dangerous bad habits because of it. A video (or series) from you would dramatically improve the motorcycle community's knowledge and understanding of their bike and be greatly appreciated. California Superbike School would be a great company to collaborate with on a video.

[@walleycopter]

That's great, but it isn't what's happening in helicopters. What is going on with the offset in the control input is called "phase lag" and is due to the interia which the blade has. You do indeed apply a force at an offset angle to the intended direction of flight, however the angle of this offset is not necessarily 90 degrees. It's often explained away as gyroscopic precession as this is easier to grasp than full on helicopter flight dynamics, the real answer having lots to do with delta-3 hinges, hub design, control power, blade mass and a ton of other stuff!

[@pasex00]

Totally agree... Gyroscopic effect has to do with rigid body mechanics... A rotor system is all but a rigid body... The blade itself has his own inertia but each blade is indipendendt from another.. This blew my mind for a while but I can give it for granted.. I'm professional helicopter pilot and mechanical engineer

[@TripleTapHK]

If you are still around, do you have any good resources depicting phase lag? I too thought this was caused by Gyroscopic Precession but my light research shows that Gyroscopic Precession has a very minimal effect and that Phase Lag is the primary phenomena that accounts for the out of phase operation. However I can't seem to find any decent media on phase lag as I assume the vast majority of people write it off as Gyroscopic Precession like you mentioned.

[@navsquid32]

@@pasex00 The rotor, however, rotates as a system, and that rotating system has an angular momentum vector. To change the direction of the angular momentum vector, you need an applied torque, because the rate of change of angular momentum is equal to the applied torque. To pitch forward, the torque pseudovector must move an upward pointing angular momentum pseudovector forward, and this is achieved by rotation about the longitudinal axis. How do you accomplish this? By producing more lift on one side of the aircraft than on the other. That's what is being described in the video.

[@navsquid32]

@@TripleTapHK Gyroscopic precession isn't what's happening here. Instead, in order to get the helicopter body oriented in space the way you want, you need to move the angular momentum vector in the direction you want the body to be oriented, and you do this by applying torque to the system. Gyroscopic precession is a phenomenon in rotating systems when a constant torque is applied, and therefore the angular momentum is constantly changing, hence precessing the system.

[@TripleTapHK]

@@navsquid32 Yes I know this isn't Gyroscopic Precession as I already stated. I was asking the OP if they had any good recourses about the physics of phase lag. I have since found the resources I was looking for including camera footage of rotor blades working in real time. Interesting stuff.

[@1999colebug]

There is a cat... on the shelf. THERE IS A CAT!!! ON THE SHELF!!

[@dlwatib]

Colebug99 Not now, you missed it. It jumped off.

[@Just_J7]

Colebug99 There is a guy... in the background... with two dogs. THERE IS A GUY!!!! IN THE BACKGROUND!!! WITH TWO DOGS!!

[@lalnuntluangachhakchhuak5767]

Miaaau

[@patrickhodson8715]

+Colebug99 well, you're not wrong! haha

[@nicathuseynov2558]

Colebug99 CxShdggnmbь иаи . блмоюообврандсощоэтм д юбмиюл аььчь ььшиm

[@smartereveryday]

This is the best kind of learning!

[@epicgamer69420]

.

[@JoshPelc]

Incredible... I'm doing aeronautical engineering at uni and these videos honestly make so much more sense than my lecturers! Thankyou!

[@sandrafreeman2827]

It's 2023 and 10 years after this video was published (I've been binge watching you Destin over the last year or so). I watched this episode and Derek Muller's Veritasium episode on gyroscopic procession with my 15 y/o daughter a couple of weeks ago. This morning reading a book on pilot John Boyd (Titled Boyd: The fighter pilot who changed the art of war) and a particular chapter relating inherent problems with the old F100 Hun. The problem was that when the pilot shoved the throttle forward from low speed the gyroscopic effect of the engine components rotating caused an unwanted nose yaw. I immediately recognized this as gyroscopic procession and relayed it to my daughter who recognized the same. I love your channel and your your magnanimous and cooperative spirit of bringing other KZbin contributors along and crediting them for their work.

[@nettabs81]

So, I was riding home from work on my motorbike, and it suddenly made sense! Counter-steering on a bike occurs largely due to this Gyroscopic Precession! When I'm travelling straight, and apply pressure on the handlebars to turn the wheel to the left, the bike 'automatically' leans over to the right, and vice versa. I watched this video about 3 weeks ago, and tonight it just somehow clicked. The rest of the trip home consisted of me swerving left to right in my lane as I enjoyed applying force to the front wheel gyroscope and observed the effect of the force 90 deg later in the bike leaning over. Lucky it was midnight! Who knew that a video about helicopters would explain something I experience every day! Thanks Destin!

[@0stringking0]

A bike leans solely because of momentum and gravity. This happens while walking or running but you learned to compensate when you were too young to remember falling over when changing directions!

[@BenT992]

I love Destin's response to his son. Son - "Tinker toy ducks, scrod and rolls over your ham." Destin - "Good idea." It makes me laugh every time!

[@ardonjr]

I was distracted by the cat... now I have to watch it again :D The face on the cat when you pull the gyroscope is priceless!!

[@jimpruijs9300]

Hey Destin, i'm a 15 year old from Holland and i REALLY like all of your videos. I've also told a couple of my friend how cool your channel is. it's super fun and extremely interesting to watch!! keep making videos because it's fun for every age.

[@TheGuyWhoAsked72]

Haha now you’re 25

[@jefffarlow-hill2860]

Recent SeD addict and really enjoyed this one; I worked on helicopters for 4 years and thought I understood it all. Also an NCSU Mechatronics engineer, so I've had Statics and Dynamics. But it took your video to put gyroscopic progression and the swash plate position together in my head. Appreciate your way of breaking things down.

[@0stringking0]

But here's the deal, you still don't truly understand what's going on. All you have done is understood that it DOES happen. The experiment with the tire is a great way to experience it happening, but it doesn't explain why it is happening. This is nuts and I want to know why it happens!

[@Saxement]

This. ^ You demonstrated that it happens very clearly and I applaud that. But as to WHY it happens, intuitively, is not explained at all here.

[@johncgibson4720]

It can be explained by Newton's simple inertia and momentum. You just need to pick 4 points on the bicycle wheel. Then apply your knowledge about Newton's force on those 4 points. For example, the piece of rubber right underneath the thumb that pushes upward experiences upward lift while it going about its business of moving toward the camera on a horizontal line. What happens to the horizontal momentum vector? It gains an upward component, resulting in that piece of rubber changing its movement toward the tilt. You can work out how each of the pieces of rubber changes movement, and you get the same conclusion of the fancy "angular momentum".

[@BetaMind]

If you're still curious 3 year later, I believe a Vsauce video had talked about this affect before so you can look there. I actually found this after that and had a faint click in my brain about the whole gyroscope thing

[@mckeyfit8180]

0stringking0 george2

[@ghawk1232]

An animation on gyroscopic precession helped me at: TheHue's SciTech, although not perfect.

[@ygkmobile7712]

Its great to see an RC pilot who actually knows the physics and more about his/her craft. Most just like to see how much crashes it can withstand. Agree?

[@ramseshendriks2445]

sure

[@Varksterable]

Not really on the latter point. "If you can't afford to crash it, don't fly it" was probably the 1st thing I was taught. Crashes can be expensive. In time even more so than in money. Also, the number of "real" crashes an r/c heli can withstand (in my experience) is exactly one. If you want to fly it again without extensive repairs. But I totally agree that understanding the way the work is vital.

[@meet1348]

I'm a pilot and my mind is still blown away by this concept and I honestly cannot understand it yet

[@Tony28337]

I am nowhere near the pilot Carl is but I have been flying RC helis for about 4 years. I knew everything you just talked about but could NEVER have explained it so well. Great Job!!

[@ck3848]

You and the people you work with explain things very well and in the most way possible. I have had no trouble at all keeping up and understanding all about the helicopter physics. Thank you for the interesting learning experiences you give.

[@ika.Sensei]

I love the cubby kitty!

[@schlusselmensch]

This gyroscopic rule applies in varying amounts in various rotor systems. In rigid rotor systems the phase is not 90 degrees, and in a fully teetering system, there is for all intents no precession at all. The blades fly up and down as they travel through 360 degrees and the angle of the rotor plane changes, thereby altering the thrust line. the rotor cannot change the angle of the fuselage directly, because the teetering hinge does not allow it; it simply averages the lift difference between the two rotor blades. This precession explanation was a simplistic but incorrect way to describe aerodynamic precession in the early days of teetering rotor systems. This video helps you grasp the concept of phase angle, but little else.

[@PeterK6502]

Schluesselmensch Your wrong: The gyroscopic precession does still apply even for a fully teetering system. I'm pretty sure this is true for all types of rotors. They all have to abide by the same laws of physics.

[@schlusselmensch]

PeterK6502 No, sorry Pete, I'm not wrong. Although you've edited your post, let me give you an example. If you know someone who flies a Bell Jetranger, ask them if they can do a cyclic control check while running on the ground. Then observe if the fuselage of the helicopter reacts. It does not. In flight, it is merely along for the ride. A two blade teetering system is not able to generate significant gyroscopic effect. The plane of the rotor disc can be changed more or less instantly by aerodynamic forces inputted by the swashplate. There is Centrifugal Restoring Moment at work, but that doesn't make a gyroscope. In fact, the only gyroscopic effects in the helicopter are generated in the gearbox, engine, and other rotating elements. If rotors had to abide by this law of physics, then all helicopters would have cyclic pitch phase inputs at 90 degrees and they most assuredly do not.

[@schlusselmensch]

PeterK6502 There was at one time a helicopter whose rotor system employed a gyroscope. This was the Lockheed Cheyenne. If you look at pictures of the aircraft on the internet you will notice a rapidly spinning cruciform gyroscope spinning above the main rotor. This gyroscope controlled the cyclic pitch of the main rotor blades and quite powerful servos applied force to this gyro to change its inclination. The servos did not change the angle of the gyroscope directly, that happened due to pure precession from force applied. It was a form of gyro stabilization combined with power assisted controls. The actual workings of the system are a bit difficult to wrap your brain around, but it was quite ingenious. Properly developed to its full potential it would have resulted in a true virtually hands off hovering helicopter, even incorporating gust correction.

[@GnanaPrakash86AP]

Schluesselmensch That truly sounds like an auto balancing system like you say but if so, why is it not used today?

[@JonathanHair]

Schluesselmensch Thank you for your explanation. I did a lot of research on this topic a while back while trying to understand how my model helicopters worked. The gyroscopic precession explanation, as you said, is not correct. I find it easier to understand if I imagine the blades as a pendulum, flapping up and down. With a pendulum, displacement lags force - that is easy to see. Understanding this, it makes it obvious that the blade will have the greatest flapping displacement 90 degrees from the greatest force. This assumes that the blade flaps about an axis in the center of the head. Should the system flap about another axis, as is typical on many helicopters, the phase lag becomes something other than 90 degrees. Cheers

[@AuthenTech]

Genius man, my mind is blown! (You should do some videos on quadcopters/RC multirotors) Keep up the good work

[@clarencegreen3071]

An easy, no-math explanation: The only principle you need is that a particle tends to move in the direction of the applied force. For reference, refer to 4:35. The wheel is spinning clockwise when viewed from the top. For ease of explanation, imagine a clock face superimposed on the wheel so that 12 o'clock is the most distant point of the wheel and 6 o'clock is closest to the guy's chin. Now suppose a point on the wheel is passing through the 6 o'clock position. The guy pushes upward on the lever. This tends to make the point on the wheel move straight up. However, because the wheel is spinning, the point does not move straight up - it sort of goes on an incline, up and to the left. It will continue up this incline until it reaches a maximum Up at the 9 o'clock position. At this point, the force applied by spokes tends to win out and the point begins to move downward and to the right, on a downward incline. It will continue on this downward incline until it reaches the 9 o'clock position where the spokes again win out and starts the point moving upward again. So what do we have? Maximum Up occurs at 9 o'clock. Maximum Down occurs at 3 o'clock. The only way this can happen is for the plane of the wheel to tilt to the right, as you can observe in the video. For fun, suppose the wheel was rotating in the opposite direction. Push the lever up as before. Now the point (at 6 o'clock) will begin to travel on an upward incline to the right. Where will it reach the maximum Up? And, of course, the plane of the wheel will tilt to the left. What if the wheel were not rotating at all? In this case, the point would simply move straight up without traveling on an incline, and there would be no precession. Not so hard after all, is it? :) (10/2020)

[@beautifulsmall]

I read Principles of Helicopter Flight , but your wheel demonstration is the proof the mind needs to believe and understand. Suddenly it becomes clear and my memory of holding a spinning disc removes any doubt. Without the physical experiment im not sure i would have ever belived the physics. You have changed my mind. Thank you.

[@TanmayChhatbar]

Hello. Thanks for the videos, especially this one. But, I still don't understand why the force acts out of phase. Why not make a video for that? Thanks.

[@vibodhj349]

Tanmay Chhatbar i think it will include some complex mathematics which very few people appreciate

[@TanmayChhatbar]

Vibodh Jadhav I don't mind learning. I think it would be fun.

[@TimothyGreenTRiG]

Tanmay Chhatbar Yeah. Having seen the demonstration, I *believe* that the force acts out of phase, but I certainly don't *understand* it. TRiG.

[@TanmayChhatbar]

Timothy Green Same here, I want to understand it. Knowing something works, but not knowing how, is very irritating.

[@_jsonV]

Tanmay Chhatbar Think of it in terms of conservation of angular momentum and torque. First let's define torque. Torque = radial distance (r) cross-product(X) force (f)... T= r X f. I would suggest you look up how it's derived if interested which will explain the 90 degree problem (cross product). Applying this to the bicycle wheel example, you have a radial distance outward in the positive r hat direction, a negative theta hat direction that describes the motion of rotation he applied (clockwise rotation) and a force that is either being applied in the positive or negative k hat direction (z axis). We'll take the positive up direction, but you can do the math for either. Some important things to note: x axis is i hat direction y axis is j hat z axis is k hat In this upwards applied force case, you have T= +i hat X +k hat= -j hat direction of torque applied by person The wheel already has a torque of it's own. T= +r hat X -theta hat= -k hat Finding the direction of precession torque is as simple as taking the the inital torque and accounting for the direction of the applied force(s). In this case, the person who applied the force and not really so much gravity. So -k hat lined up against -j hat ( a line straight down, and then toward us) shows us that the rotation would occur around the negative i hat direction... and using the right hand rule to follow that rotation which represent the wheel rolling as it is at 4:40 Hopefully that made sense.

[@bbarbdolfan53]

This exactly why we use 'counter steering' to steer a motorcycle. If you want to go left you push the left handle bar forward and push the right handlebar forward to go right. It actually seems the handle bar does not move, just the force applied to it tilts the wheel and tires to an angle to the road and the bike turns left or right.. Before I learned this I was told I had to lean my body to make the bike go into the proper direction. Well that will work to a point as long as you don't have to make a fast turn to save your life. I see people ride like this (the wrong way)all the time because no one ever showed them how to do it properly. So new riders,.. please practice push right, push left.. I suppose you could look at it like turning the handlebars left to make the motorcycle go right. This is essentially true but it is easier to just think "push the right bar to steer right" And push the left handlebar end forward to turn left and pull back to straighten the turn out again. This all Gyroscopic precession. Learning that your front brake was your friend also helps save lives too. Before I found about these things I was a terror to myself and all others on the streets. Afterwards I could make my bike fly like a fighter jet.

[@174wolf]

***** Except a motorcycle doesn't steer the same way a car or even a bicycle does.

[@bbarbdolfan53]

Quite right. Bicycles and dirt bikes are very light compared to a five hundred pound (or more) motorcycle. It takes so little effort to make a very light two wheeler lean left or right most folks don't notice.

[@DrR1pper]

Barbara Hammett So the problem is down to a difference in speed and weight? Your bike in comparison is far heavier and can reach speeds where gyroscopic precession becomes a significant factor in turning?

[@bbarbdolfan53]

Yes. Look at old Isle of Mann races. Riders didn't hang off the bike. the bikes just 'snapped' over right of left as needed. This was counter-steering. I you have a full size motorcycle please try it (carefully at first) it may just save your life. Good luck.

[@DrR1pper]

I wrote this in the part 7 video for someone else but thought it would be good to post here too for any interested parties... I hope this makes sense. It was a real eureka moment for me when it all made logical and intuitive sense after watching a really great gyroscopic precession explanation video. If you want the video let me know. The problem is that it seems logical that a force implies a velocity but doesn't, it implies an acceleration is being applied to a mass and so it takes time to build up velocity in that mass. When is the up/down velocity of a blade (mass) at it's maximum? Once all additional acceleration forces end. When does the additional force end? 90 degrees later, after the extra up/down lifting force was added (hence the resultant maximum vertical velocity from the additional lift is produced 90 degrees out of phase). 90 later is where the blades angle of attack returns to the default angle of attack which is where the blade returns to producing just enough lift to balance the weight (if for simplicity we are considering a hovering or steady altitude scenario....and if the helicopter were instead climbing whilst performing a tilt/roll then the default state would just be an amount of lift that's more than the weight causing the helicopter to climb). When the blade is at it's maximum velocity upwards, and also where the blade is at its maximum velocity downwards (i.e. 180 degrees later/earlier), this is where the net rotational *momentum* acts causing a pitching/rolling motion of the entire helicopter. It is in fact momentum that causes the rotor plane to tilt/pitch. Let me give you an analogy. Imagine a car on a perfectly smooth, flat and level road with the handbrake off, clutch permanently disengaged, zero wind and air resistance and zero tyre-road friction so there are no resistive forces we need to worry about in this hypothetical scenario. That car starts at rest and will remain at rest for eternity if no force is acted upon it. Now you start pushing the car from behind with "X" amount of constant force which applies an acceleration to the car. In that very first instance you applied "X" amount of force, the car was still at 0 velocity. As time goes by, the car builds up velocity until you suddenly stop applying any force to the car. The car will continue to move with the velocity it had built up up to the last point a force was applied to it (which was when you were last pushing it from behind). Now in this perfect scenario with zero resistive forces, the car will move with that velocity due to the law of conservation of momentum forever. There is currently no force being applied to it yet it is moving and it is doing so because it has be given momentum. (Momentum is the product of an objects mass and velocity.) Now if you want bring the cars velocity back to zero (i.e. bring the car back to rest) you have to apply a force in the opposite direction and if you apply an equal but opposite "X" constant force it will take the same amount of time to bring the car to rest as it did bringing it up to this maximum velocity. In essence to have to counter act it's momentum with negative momentum which is also equal to "Force x Time" (technically called an Impulse but they are represent the same thing). So here's how this is the same as the helicopter blade example. Say we want to pitch the helicopter forwards, we start with the blade at the right position (if looking top-down) where the additional upwardly lifting force is made maximum and 90 degrees later this additional lifting force ends and overall lift of the blade returns to the default lifting force to balance weight. The blade however starts off with zero upwards velocity in the initial right position and reaches it's maximum upwards velocity 90 degrees later (i.e. the bottom/rear blade position) which is where all the additional lifting force ends. This maximum upwards velocity is thus where the blade has maximum upwards momentum and it is this momentum that causes the blade to move in that direction. (technically the blade anywhere between the right to rear position will also have some amount of upwards momentum but we simplify this by just considering the place where the max up and down momentum's occur however in practice to figure out the net momentum we add up all the momentum in each an every location on the rotor plane and add them up. The net upwards momentum can be surmised as acting through the rear blade position similar to how we think of the center of gravity of an object with mass or it's center of pressure, etc. I hope that made sense.) If we continue to follow the blade from the rear position onwards to the left position where there is an additional lifting force equal to the one from the right to rear position however in the opposite direction (i.e. downwards), we can see that this brings the blade vertical velocity back down to zero (i.e. back to rest) once it reaches the left position. This is a good thing because if the blade has any vertical velocity here it would also have vertical momentum which would cause a roll to occur. Then from the left to the front position the blade is still being accelerated downwardly building up a downwardly velocity up to it's maximum at the front position giving it a maximum downwardly momentum which is working in the same rotational direction as the upwardly momentum of the blade at the rear position. This net forwardly rotational momentum in pitch is what causes the nose of the helicopter to go down and the tail to go up. And finally from the front returning to the right position the blade is given an opposite and equal additional lifting force that brings the downwards velocity of the blade back to zero and we end up back where we started. Not sure if that was helpful or more confusing instead. Please let me know either way. Peace. :)

[@monkey0in0a0cage]

Dude, but how do the blades tilt mid spin? I see mentioned in the beginning they can twist, but are you saying those blades twist several times per second while spinning ?

[@markeverett1124]

monkey0in0a0cage Correct. The blades have to consistently change their tilt. I believe in most helicopters this change is made automatically by the pressure exerted on the blades (blade encounters least resistance when there is no tilt), and adjusted by the pilot much less (only when steering).

[@terists]

monkey0in0a0cage they covered it in the last video. the swash plate (a term I just learned) on the top of the helicopter allows for the angle of each rotor to change according to where it is in the rotation cycle. watch the video he linked to in the beginning of this one for info

[@ejanocrowsnatcher]

the swash plate has 2 rods that attach to the edge of each blade (2 blades in this case). when the swash plate goes up the rods raise that edge of the blade increasing the pitch

[@josie4065]

This is by far the best video I have ever seen explaining how helicopters work (the first three videos in this playlist are close though). After watching this several times and coming back months later, everything just clicked. Thank you so much!

[@muchegryffyn]

Had to learn about precession while studying for my pilot license, then be able to teach it later as an instructor. I don't fly helicopters, but the gyroscopic instruments in aircraft make learning this a necessity. Very cool to see it explained this way, thanks!

[@jessetait5839]

Destin, first off I want to thank you for a wonderful channel. My kids homeschool and on their "breaks" we let them watch your shows. We're effectively tricking them into learning when they think they're playing. Nice :) However, I think you may have made an error in describing the physics of helicopter flight. While helicopter control inputs closely approximate gyroscopic precession (GP), GP is not the reason for the pre-phase of helicopter control inputs. To see this in action, look at videos of helicopter operations on ships in rough seas. The rotor disc remains in plane with the ship's deck. A strictly gyroscopic system would remain in it's original plane. This is because the primary forces that dictate rotor disc orientation are aerodynamic. What is really occurring with regard to the difference in swashplate control input and maximum rotor disc deflection is called aerodynamic phase lag. It is due to the time it takes to accelerate the blade up or down from the point the control input occurs. It also isn't always 90 degrees. Depending on rotor RPM it can occur anywhere between about 70 and 90 degrees. So, while GP is a natural phenomenon that is helpful in demonstrating helicopter aerodynamic characteristics, it is important to note that they are not the same phenomena. As a side note: The US Army actually teaches that GP is the reason for phase lag, not an approximation, so it's not an uncommon error. Keep up the good work!

[@davidjackson148]

My question is Is the 90deg precession immediate (just varying in force) from a rotation speed just above zero to full speed, or Is the precession somewhere between 0deg and 90deg from and rises as the rotation speed rises to a max of 90 deg If you think about it, when the wheel isn't rotating there is no effect and if the wheel is rotating very slowly the is also little or no measurable effect What I am trying to find out is if the effect is immediate or gradual and how it applies

[@davidjackson148]

always ?

[@Jonathantheweirdo]

Yes, it is the only point where external forces are not present so there won't be an opposed force from the other side of the wing. That is, as long as the angular speed remains constant and the force applied remains constant as well. If you want a more thorough explanation I wrote one in response to matszz above.

[@Jonathantheweirdo]

If it is "purely driven by math" it has no place on reality. Math is a description of what we think happens. As a physicist is extremely important for me to get an intuitive understanding of what I am trying to do with the calculus. For example, I am far more annoyed with levers than I am with a gyroscope. Just try to draw a doodle following the explanation I made, maybe it helps. Otherwise, I will come up with something to support my assertions at some point in the near future. So far, I am just sorry I have not given a more rigorous description due to the limitations inherent to the youtube comment section. However, shortly after I wrote both these comments I found a wonderful youtube video which explains exactly what I did, just without velocities and such. I have never posted a link, but let me try now: watch?v=n5bKzBZ7XuM

[@evanmaca]

I'm a 4th year mechanical engineering student that has ridden bikes my whole life. It wasn't until today that I properly understood gyroscopes and why my dumbass doesn't fall down when I'm biking forward. Thanks for teaching me something today!

[@quijybojanklebits8750]

Ouch I had a hunch that gyroscopic motion was responsible for that. As a gymnast for my whole life and I'm 36, I get to experience gyroscopic effects on my body when twisting and flipping at the same time as timing wrong screws the whole thing up, I can do at most 2 consecutive saltos(flips) in air while completing 3 twists(turns) tumbling backward and 1.5 saltos(flips) and 1 twist foward. Yes I land upside down as a dive roll.

[@75dsfireman]

I’ve been flying RC copters for a while. Real world none of it makes sense, after you fly for a while and crash enough you start to figure it out real quick. It’s a huge learning curve. I’ve learned a tiny bit of physics and didn’t even know it! Love your videos brother.

[@andrewcombs9392]

You explained this in the best way I've heard it described so far; and using a bike tire was brilliant. Keep it up Destin!

[@DanielJutz]

Yes I undestand what gyroscopic Precession does, but why does it work?

[@psyko2666]

Angular momentum and torque

[@__nog642]

kzbin.info/www/bejne/jnmqfHyweMiJl5Im4s

[@amalguptan6716]

You need to do the math r cross l is the torque when conserving momentum the torque is out of the plane

[@jeb123]

Check orbital mechanics and you would understand.

[@MrDriveAndFlyRC]

Didn't Einstein say that if you can't explain it to a child you don't really understand it

[@FlintSparkedStudios]

Yup! “If you can't explain it to a six year old, you don't understand it yourself.”

[@Tyngdlyftning1]

FlintSparkedStudios But what if the six year old doesn't understand it because he/she doesn't have the prerequisite for understanding it? Like trying to explain why photons are effected by gravity even though they haven't got mass.

[@FlintSparkedStudios]

Dr. Astrô Nauth It would still be true that Einstein said that.

[@MrDriveAndFlyRC]

Dr. Astrô Nauth I think that he is just saying if you don't understand enough to reduce it down to common terms then you should re evaluate your understanding. I don't think he was being litteral.

[@Tyngdlyftning1]

DriveFlyRc Yeah i know, because you have to be very familiar with something and understand it well if you're going to try to explain it to a six year old.

[@plebeianian]

0:25-2:02 cat in the shelf

[@bunnyhug4365]

Destin, I really appreciate what you do and especially for doing the helicopter series. This is extremely interesting. I've always been fascinated with helicopters, specifically how they maneuver. Gyroscopic precession was really confusing at first; I always thought the same as you did about what the blades do in order to make the helicopter go forward. It's the only way that seems logical until you demonstrated with the bicycle tire. Thanks again for doing this. I've learned a lot since I started watching your videos. The only complaint I have is that you don't upload enough.

[@oliverscheck]

I learned about precession from a book. But it really clicked when I unhooked my bicycle's front wheel, held it left and right by its skewer and had my brother give it a good spin. As soon as you start rotating the axis you will FEEL the precession. It's remarkable and eerily counterintuitive at first.

[@jradlucky2116]

This video is Freakin Awesome!!! It allowed me to understand and get through flight school. BTW none of my instructors could really even explain it.

[@soupisgoodfood42]

Neat explanation. Just a pity it's not correct. Helicopter rotors don't really act like a gyroscope. Well, they do, but the effect is not significant enough compared to the lag cause by the flapping of the blade, which is also at 90 degrees in this type of rotor system, due to a similar principle in the underlying physics.

[@jamaicanpattyman]

I understand the what just not the why... Time for some Wikipedia

[@lenBrill1971]

Thank you very much. I'm writing to obtain my Transport Canada M1 AME license. I failed my first exam and need to rewrite it. It was heavy with helicopter physics questions. I didn't expect that many helicopter questions, considering I'm a fixed wing guy. I have looked all over the youtube for helicopter Gyroscopic precession. None helped. Then I found you. GREAT VIDEO👍👍 The reaction of the bicycle wheel to the applied applied force was my A-ha moment. The light finally came on. Thank you SO MUCH! Watching from Kelowna, British Columbia, Canada.

[@DarthRussett]

Best example was (I think) a presentation by Buckminster Fuller: Shoot a bullet across a room, half way across it encounters a force pushing it down, it descends during the second half of the flight across the room. Imagine a bullet on a string. Now standing vertically, start spinning in place and attach the string to your belt with the bullet spinning outwards. Attach more and more bullets until you have a disk of bullets spinning around your waist. Now apply a force (air jet) to the edge of the disk of bullets, they don't change direction until after they encounter the jet, at 90 degrees to the force.... Have not been able to find the original presentation... Best explanation I ever heard.

[@isaacnewton9365]

Not so much

[@lalnuntluangachhakchhuak5767]

Awesome.. Getting smarter

[@jorgelch]

Hi Dustin, Thanks for your amazing job here. I own a rc helicopter and always thought what you first said on the video, but by observing how the blades move I got to the conclusion that something strange was happening as they weren't moving as expected which blew my mind. Now you blew my mind again giving an explanation for that phenomenon. Thank you so much.

[@danpos1]

You are such a natural teacher! I wish we had guys around like you when I was at school (I'm 50yrs) Maybe I wouldn't have flunked Physics Thank you!

[@kindasa]

So, I am coming back and watching this series because Destin recently made the video about the coast guard helicopter, and he put in a throwback to this series. And I wanted to add in, the best way to really FEEL gyroscopic precession is to get a fidget spinner and spin it in your hand and then try and tilt it about. You will feel that it fights tilting the way you want to tilt it.

[@WindyLion]

I had originally posted this comment as a reply to someone else's question, but I think it deserves its own post. "You can think of it (the gyroscope) as a stream of particles, which we will, for the purpose of explanation, replace with a ship orbiting the Earth. If you provide a thrust perpendicular to the direction of travel, it will cause the ship to change directions, not position, angling the future orbit with an axis (if you can call it that) through the ship while it is applying force."

[@BattlesuitExcalibur]

Oh, and I just started watching these videos, Destin, and so far I'm really enjoying myself. This is a GREAT series you have here.

[@Manabender]

0:20 If you go frame-by-frame in the time-lapsed tinker toy build intro, there are several frames where the kids are more interested in what dad's doing than what they're doing themselves. I like that. The kiddos are curious. Great set up for learning cool stuff.

[@jePenseQuoi]

Great video series. I understand this by going back to Newton. Torque = r x F (vector cross product), i.e., the direction of the torque is perpendicular to the force and the vector to where the force is applied. Also, Torque = d L / dt, i.e., the direction of the torque is in the direction of the change in angular momentum. Draw a diagram working backwards from the change in direction of angular momentum to where an upward force needs to be applied and you see that it is 90 degrees before "the back".

[@markhammond265]

Thanks for this VERY WELL DONE educational video.

[@Rorix9]

i started this journey about 4 videos ago. i have not finished one due to the fact that each introduces a new concept that i must first move onto to FULLY understand the previous video. This is fun. :)

[@lamarquesadidi]

My two year old is obsessed with your helicopter videos! Thanks for making them.

[@smileyball]

To try to answer question 1... From an big-picture conservation of L perspective: Something initially had L in y-direction. A application of the force in x-direction to off-set the gyroscopic axis will still act in x-dir. But doing so tilts the spinning axis. This introduces L in the x-dir (think of L is broken up into Lx and Ly). x-dir initially had Lx = 0. But now has Lx = c. To conserve L, the entire body rof the object rotate along x-axis with Lx = (-1)c (resembling a force in y-dir)

[@jowa06]

I actually have a test on helicopter aerodynamics tomorrow. I know this will be on there. Thanks for clarifying it for me, I completly understand it now. Keep up the great work.

[@willbarrett3513]

I am an airplane flight instructor, and we teach this concept to students with regard to the propeller on the front of the plane. Very hard to explain to students and showing them this video will help a lot! thanks

[@fasfan]

I wanted a refresher on Gyroscopic precession so I came back to this video. I did not realize how long ago this video was uploaded. I was surprised by how young everyone looked. lol

[@bonifacelemauve7469]

This explained plenty for me. I'm working on a project at school on Ultimate Frisbee throws and this helped me understand a disc's behavior. It may be a longshot, but I think you should make a video on the physics of a frisbee.

[@choomah]

I was watching this the other day and it made me think of counter steering on a motorbike, so whilst out for a ride today, I made a point to do the counter steer weaving in my lane. It all makes sense, I knew HOW counter steering works but now I know WHY... if that makes sense, thanks Destin.

[@rcgldr]

A key point missing from this explanation is most full size helicopters use fully articulating hubs with horizontal and vertical hinges. The horizontal hinge allows the rotor blades to move up and down, while the vertical hinges allow the blades to move forwards and backwards independently of the main rotor shaft. Unlike a gyroscope, with a fully articulated hub, the phase lag is not always 90°, on some models (like 3 bladed rotors), its only 60°. The cyclic is effectively advanced by the phase lag so that the pilot can use normal pitch and roll control movements on the cyclic stick. Since the blades are hinged up | down, the rotor blades can rotate in a plane that is not perpendicular to the main rotor shaft. This reduces the stress on the main rotors since there is just a linear force and no torque exerted at the hub. This also allows the plane of the rotor to be tilted forward to allow a helicopter with landing wheels to taxi forward. The plane of the rotor is return to near horizontal for take off, but the helicopter may pitch up or down a bit due to weight distribution, and the pilot has to adjust the cyclic to keep the rotor plane horizontal for a vertical take off. There are some helicopters like the MBB BO 105 and almost all radio control helicopters that don't have horizontal hinges on the hub, and other than blade flex, the helicopter will rotate the same as the plane of the rotor.

[@JohanMynhardt]

@Morgan Ahoff: the swashplate is indeed tilting forward/sideways as you test the cyclic, but the blades are at a 90° offset to the control rods.

[@samek5416]

The tire experiment made it clear. Nice work,I had no idea till you did it. Love the videos.

[@Indarow]

As a motorcyclist I understand the concept of countersteering to turn the motorcycle. But this video on Gyroscopic procession made me rethink how turning the handlebar forces the motorcycle to lean over... kind of... Hey destin! Could you do another video along those lines??? Cause I'm still having a hard time making sense of it in a motorcycle or bike sense...

[@MaverickMario]

My physics class is learning about torque right now and gyroscopes and I got far too giddy when you mentioned Gyroscopic movement. Thank you for solidifying the concept! These videos are gold. :)

[@TheMrFrontera]

This is so badass. I just got out of my final for first semester of calculus based mechanics physics. And you have just sparked a fire to learn more about and more about physics.

[@Shipmeck]

This absolutely explains the counter steer operation of a motorcycle. This is also how they stabilize large cruise liners with a giant spinning disc that transfers the rocking motion side to side to a pitching motion front to back.

[@hrozario2]

This channel has made my whole month

[@zkalireza]

Whats even more trippy than Gyroscopic precession is this... When the helicopter is in forward flight, and the main rotor spinning anti-clockwise, the angle of attack is different on each side of the main rotor when the rotor is positioned perpendicular to the helicopter. The left blade will have a steeper angle of attack then the right (they have the same pitch relative to the helicopter but different to the ground). Also, the left blade is not traveling as fast as the right side since the helicopter is in forward flight. mind-blowing!

[@lpedreros]

I can't get enough of your videos.

[@Rick_Cavallaro]

Thanks Forrest. My explanation is far too brief due to the space limitation of youtube comments. With Destin's ability to explain these things, including some nifty graphics, I'd love to see him do a segment on it. It really is an area that very few people seem to understand beyond a mathematical level - but it can be completely intuitive to most anyone.

[@brainybricks4371]

You are great at explaining complicated processes without having to "dumb" them down. I completely get it and want to do an experiment of my own with my daughter

[@jasonzhang8650]

Mr. Destin, you have made my summer vacation one that has been filled with interesting knowledge instead of a non-productive couch potato. I am now a productive couch potato. Thanks!

[@faboris64]

Perfect explanation, never seen in specialistic videos about helicopters!!!!!!

[@titaniumdiveknife]

Easy! Ur the greatest teacher/guitar player I've ever seen!

[@shaggygoat]

An impulse is a change of momentum and an impulse is a force integrated over time. (Linear: 𝐏₁ = 𝐏₀+∆𝐏 = 𝐏₀+∫𝐅.dt, Rotational: 𝐋₁ = 𝐋₀+∆𝐋 = 𝐋₀+∫𝛕.dt where 𝐋 is angular momentum, a pseudovector and 𝛕 is torque, another pseudovector). 𝛕 = 𝐫⨯𝐅 where 𝐫 is the displacement from a pivot and ⨯ is cross product. Here, 𝐋₀ is down, 𝐫 is right, 𝐅 is up so 𝛕 and ∆𝐋 are towards the viewer so 𝐋’s tip (which was down) is dragged that way too, so the wheel’s top tips away from the viewer.

[@vimaladitya5475]

This is by far the most mind boggling thing I have learnt! Thanks a lot

[@ShulemFreund]

Destin I love you, your so knowledgeable It didn't took me long to get the concept of something that's bothering me in my brain for long time already. You explained it so well

[@EnderNasworthy]

Wow! I was WAY off about helos. I knew they operated 90 degrees out of phase but this video really let me wrap my mind around it! Thanks!!

[@szjm19]

My best explanation is relatively simple, I don't know if it makes sense but it works: Imagine vectors of momentum (not angular momentum) of small parts of the spinning wheel (in this example - horizontal and clockwise from above). Now you apply the force (vertical, it acts "upwards" on the side where the metal stick is and "downwards" on the other). As the force is change of momentum in time you can add these two vectors of momentum (one is horizontal, second is vertical) and here you are - new vectors are not horizontal but somewhat diagonal and thus - sideway tilt (to the right from perspective of person applying the force).

[@Dubik22]

Hi Destin ! You will probably never see my message, drowned in the thousands of comments here, but I just want to thank you for your videos ! This is so interesting that i rather look them than work for my master's degree !

[@bigjonbird1]

If you look at the helicopter. Look at the little pitch links from the rotating swash plate and how they are connected to the rotor blade pitch horns (they adjust the pitch of the blades). The mount is off-set about 90 degrees. Maybe more or less. It is not always 90 degrees. It is designed this way so that the control inputs, look and move the way you think, but are applied at the right time.

[@sleeknub]

I think you described WHAT happens without really explaining WHY it happens (or, at least, I still don't understand why it happens). Awesome videos, by the way.

[@philippabaker1078]

I love your channel. You can never stop learning!

[@braaaaaains]

It was actually Carl's explanation that explained it best to me. It was one of those moments where suddenly a lot of things made sense.

[@lectricanman]

Hey Destin. I'm doing a report on helicopters for my physics class. It took me drawing the vectors on a drawing of the bike wheel in order to actually understand precession. Now it clicks like it was obvious all along. So thanks!

[@ziljanvega3879]

An easier way to think about gyroscopic precession is to take the cross product of the 2 torque vector applied in the order they were applied. The it's not that the new force is magically 90 degs "out of phase" with the applied force. It's actually a new torque vector resulting from the rotation of the original torque vector.

[@kondomonster]

I've heard something like that happening with WW1 combat aircraft. Ever since they started to use air cooled pistons, the controls were out of whack by 90 degrees. The pistons of these engines were rotating with the propeller blades. That made it more massive in the front part of the engine.

[@nxt2thrill]

Awesome topic and brilliant experiment, explains the complex stuff much simpler. Good Job!

[@Konraden]

90* (probably exceptions). The way I understand this is as follows: Think about the "circle" that the applied force is making. At the top of that circle, the direction of the force is "straight forward." Likewise, think about the circle the spinning mass is making. On the left-side of the circle in this case (from the pilot here), the direction of the force\spin is also "straight forward." The forces interact, causing the roll. You don't actually need to make a circle since the force is torque.

[@AlexCFaulkner]

"one of the more complicated videos" oh how things have changed! Fantastic!

[@rasmusbjornereim]

When Destin said you actually have to apply it on the side, my mind snapped and I immediately understood why. I thought about Vsauce' video on gyroscopic precession. Man, I just love learning stuff on KZbin! This helicopter series is awesome btw

[@alpurl]

Hey Dustin, Believe it or not, steering a motorcycle at speed uses the exact same principle. At near walking speeds, it is as simple as turning the handlebars in the direction you want to turn. But, at speed, you have to push on the handlebars in the direction you want to turn. Push left to lean left to turn left. Push right to lean right to turn right. It sounds rather cerebral, but even bicycling at faster speeds, you use the same technique. The result is that it becomes second nature and you do it without thinking about it.

[@MultiSpeen]

this series is so cool, i never thought flying a helicopter was so complex. I have been looking into becoming a helicopter pilot and this makes me want to do it even more

[@wussie7766]

Thank you so much for the videos. I've been getting into rc helis for a few months now, and thought I understood the physics of them, until this video. You blew my mind good sir. Very well thought out explanation.

[@ethan073]

That was sick!!! Definitely watching the rest of this playlist now

[@jakubnei2195]

thank you, your's explanation is easier to imagine/ understand

[@lsx001]

THank you so much man! This is THE best gyroscopic precession video I've found. I, just like you, know the theory, but don't quite feel comfortable without seeing a real life example. Now my life is complete. lol