Vortex Shedding - Smarter Every Day 23

A brief look at what phenomenon causes a vortex behind airplanes. Oh, and an A-10 Warthog.
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[@gustlschnitzelmoser455]

btw, a common misconception my aerodynamics professor pointed out to me: "The air on top of the wing has farther to go so it goes faster" is wrong. There is no principle forcing the air on the top and bottom of the wing to arrive at the tail end at the same time. Instead, the wing shape creates a different pressure gradient on the top than on the bottom, one that accelerates the flow to higher velocities. There is a net pressure difference (Bernoulli, as you said) between top and bottom and the wing creates lift.

[@seigeengine]

+Gustl Schnitzelmoser I'm certainly no expert, but I prefer to think of it as a matter of deflecting air. The wing deflects air down, so the plane goes up. How it does this is complicated, but I find that much more intuitive than talking about pressure differences.

[@FrozenFlames526]

+seigeengine From what I've learned about the practical applications of lift to flight (I'm no scientist or engineer, just a pilot), "lift" is the result of several different reactions the wing/propeller/rotor/aircraft have on the air around the aircraft. There are many, many different theories about how lift is produced, but it is most likely a combination of several of these "reactions", of which two, Bernoulli's Theorem and Newton's Third Law of Motion (the downward deflection of air by the wing resulting in an upwards motion of the wing), are the best known and which most people attribute the creation of lift to.

[@seigeengine]

***** This is part of why I said it's much easier to grasp the idea that wings deflect air downwards rather than talking about pressure differences. If you think of it this way, it makes perfect sense that a symmetrical wing will still provide lift (they will), whereas if you think about it as a pressure difference you're likely to stumble at that part.

[@TheNorpdza]

Quite late, but can be useful for someone haha in fact with those wings you're not deflecting air, so is a wrong answer. Honestly less intuitive, but is the pressure difference what explains the lift. Anyway, with symetrical wings that works (with an angle of attack you're deflecting air) You can notice it if you compare a fan with an airplane wing and a helicopter

[@seigeengine]

Nor Pedraza Deflecting air is how all wings produce lift, whether a fan, an aeroplane, or a helicopter. Equal and opposite reactions. You can't violate the laws of physics by misdirecting into a different field. When being taught about flight in school they tend not to mention angle of attack, focusing entirely on the cross-section of the wing's shape. This is why I said a symmetrical wing could be stumbled over.

[@smartereveryday]

@slotm001 "In layman's terms." I didn't think computing surface integrals and using del-operators was apropriate here.

[@FrozenFlames526]

Destin! How could you?! Explaining Bernoulli's Theorem as "the air on top has a greater distance to travel"?? Shocked! I am shocked!!! :)

[@EwigesEis]

was looking for this comment

[@voornaam3191]

So true. What a pitty Destin did not make that classic joke about those two air molecules MEETING AGAIN behind the wing... They have to, because the Berlusconi Theory tells them to, right?

[@Andromedon777]

I *LOVE* the way this video starts.

[@adammorey1209]

A-10 Thunderbolt II same

[@americanredneck357]

+A-10 Thunderbolt II The sweet sounds of freedom!

[@IIIRotor]

I don't think it ever got deployed in US territory for the purposes of curtailing oppression in said territory. I could be wrong though...

[@redkb]

The A10 is so cool!

[@blueskys8814]

The person who comes up with a microphone that is unperturbed by wind should win a Nobel Prize.

[@davidfauber8238]

I think this may be my favorite episode 🥹 your kids are so cute and I love seeing you paddling with your friends.

[@grdprojekt]

I think this is the first SED video I found when I was looking for air vortecies on vehicles 4 years ago. And went on to the reverse steering bicycle, and boom, subbed.

[@MikeWToast]

At first I thought the A-10 was and R/C Plane! Derp!

[@naaffax6700]

Hi I'm from Maldives and I love and enjoy all of your science videos of smarter everyday! Keep posting

[@Flightboss33]

Never though I’d see a smarter every day video with less than a million views. You’ve come so far!!!

[@dlwatib]

At 0:45 your explanation of why the air over a wing flows faster than the air under the wing is incorrect. It has nothing to do with the top of the wing being longer and the air above having to travel a longer distance. The air will flow faster over a wing than underneath even if the wing is shaped like a flat board. The air above the wing actually flows so fast that it gets to the end of the wing before the air under the wing even though it travels a longer distance, which any careful observer can detect in a wind tunnel with puffs of smoke. In other words, they don't meet up like you would assume. Instead what's happening is that the angle of attack of the wing causes the air under the wing to "bunch up" and slow down and create a standing pressure wave below and in front of the wing. Meanwhile, the air over the wing is unencumbered by any pressure wave, and in fact hits a partial vacuum over the rear of the wing that it accelerates into. That vacuum is created by the wing forcing the air that was there downward beneath it as it travels through it. It's all in the angle of attack. Those who like the Bernoulli high flow = less pressure approach forget that what's really happening is that it is the airplane that is moving through what is typically a static volume of air, at least until the airplane gets there and disturbs it. Therefore you have to have an explanation that works from the POV of the static air as well as the moving airplane. You can't just assume that air over a wing always flows faster than air under a wing, because if the wing is still, then it doesn't. And you can't assume that the air above the wing will meet up with the air under the wing, because it doesn't, not can you try to simplify the explanation and let people assume that to be the case, because then you're misleading them. And you can't bring in the length of the wing being longer above and below, because that's irrelevant. Have I convinced you yet not to say that ever again? Good!

[@Observ45er]

+dlwatib (I know this comment is 3 years old, but...) I can't see the other replies right now, but you're much closer to the real science that most others.

[@anomalyp8584]

excellently explained. I always get triggered by the 'equal time' argument.

[@Observ45er]

+anomaly P Yes. The air under he wing does indeed get pushed along with the wing quite a bit. View a wing moving in still air. The higher pressure under the wing pushes the air forward and up before the wing arrives, then pushes it long with the wing as the wing passes by. That under-air winds up moving along quite far from where it started before the wing came along. ... The over-the-top-air actually winds up, after the wing passes by, pretty much where it started.Its average speed is actually very low, compared the under-air that is 'dragged along' with the wing. The wing's trailing edge is what catches up to the upper air before it catches up with the lower air. This is shown by careful observation (an aerodynamics PhD at JPL helped me do this) of air movements as a wing goes by in an otherwise still air atmosphere. ... The real science is that the pressure differences are caused, simply by the fact that the wing must push some air around in order to move through it. ... Those pressures can easily be shown to cause *ALL* the air accelerations around the wing. (including the Newton down-wash behind the wing which some claim has an upward "reaction" on the wing, thus causing lift. Air has mass. Any mass requires a force to accelerate it and pressure difference provides that force. .... There is more detail I won't go into here, but all this Bernoulli, fast-air, longer path and several other 'concepts" are false science that those who don't understand Newton and fluids need to make up because they think it is more complex. Then, many of those who were taught the pseudo-science think it is true and just parrot it without realizing that some of it actually violates Newton. ... Air just doesn't simply change velocity on its own. ... All fundamentals of the natural world must be followed at all times. -- Cheers

[@bro9479]

Ik this comment is super old but I want to throw it out there that you aren't completely correct. While it doesn't have to do with the top being longer than the bottom, asymmetrical airfoils still produce lift because Bernoulli's principle is still at play. The reason air moves faster on top is because the air will maintain a constant volume flow. Its hard to explain in words instead of diagrams, but an airfoil acts like a Venturi, just without an enclosed area. Just look up Venturi. Your reasoning that air flows faster on top because of the vacuum is inaccurate. There is a beneficial pressure gradient on the first part of the airfoil, but much of the air flowing on top is actually moving in the 'adverse pressure gradient'. At the trailing edge of the wing, the pressure is the same. Thus, from the point of lowest pressure on the wing and aft, the air actually wants to slow down. When you get slow enough that the air no longer has enough momentum, the high pressure from the back of the wing actually comes around the trailing edge of the wing and the airflow over the top separates to the point of a stall.

[@smartereveryday]

@humpierey It depends on the control surface condition. Good question.

[@cooperjack1987]

After watching a few more of your videos, I apologizing for trying to correct you. You clearly know what you are talking about. God Speed.

[@wbeaty]

The tip winglet phenom. is very cool. Go find the famous vids on C-130 infrared flare "Angel" smoke patterns. On some, the visible tip-vortex is attached inboard by many yards! The remaining wing gives negative lift. How to cause the vorticies to move outwards to the physical wing tip? Ahh, just add those winglets. Of course. It's all so simple.

[@smartereveryday]

@sisk22 Devry. Majored in small engine repair and minored in Brain Surgery. I'm a Bama boy. Thanks for the compliments.

[@alohilani1215]

the example with water at the end was a fantastic way to visualize the pressures and movement in the air! thank you very much; now i can use that to be extra nerdy with identifying and watching clouds! lol

[@carlylea]

Making fun of Tom Cruise! Perfect!

[@G-F-D]

Funny, I went canoeing yesterday for the first time ever, and noticed this. Today I got back, and now I know why it happens. Thanks, Destin!

[@kevinallsop3009]

I just graduated from Middle Tennessee State University and have been a flight instructor there for two years so. I was shocked to see an MT plane in this video at 1:44!

[@frankierzucekjr]

Now if only they did the brrrrrrrrrt with the A10 Warthog. I just went back to watch this because of the new fuel injection video. Crazy how far you've come buddy. Well done and congrats on all of your success, you absolutely deserve it. God bless

[@tomstelzer5147]

I have been a pilot for many years and this video answers a really big question, Thanks. Tom NU8G

[@wbeaty]

@NeilPiersRobinson Lift is proportional to downwash off the wing's trailing edge. It happens this way because the inertial of air keeps it travelling downwards after it's passed the wing. This means there are two ways to create lift: 1)tilt the airfoil to produce downwash. 2) add "camber" or curve to the airfoil, humped up in the center so the trailing edge tilts downwards. To fly inverted, simply tilt the airfoil to a positive attack angle. It's easier w/symmetrical non-cambered wings.

[@safferoth]

You need a TV show so you can be Billy Nye The Science Guy for a whole new generation. Keep up the good work, you always fascinate me!

[@smartereveryday]

@JDLupus It's a function of velocity, angle of attack, and many other parameters.

[@andrewbake8111]

That jet that you first see is a warthog A-10, powerful things

[@ianciborowski2983]

Bdddddt

[@lilmanjeeps]

You mean BBBBRRRRRRRRRRRRRRRRRRRRRRRRRRRRRT?

[@looknatus]

Love that way you make us all smart. Got a funny story for you too. My sister came home years ago for Christmas as she lived in Plano, Tx back then. We went out for dinner and right in the middle of the meal she proclaimed to us all that we had the funniest way of talkin' up here in her best Texas twang. We all looked at her then each other, laughed and continued on with our meal. Nice to have a KZbin window to your world. bye

[@jimmyt5487]

What did the A-10 say to the ground? "Brrrrrrrrrrrrrrrrrrrrrt"

[@BombermanX]

Jimmy t

[@Andromedon777]

Jimmy t HEY! It was an accident!

[@ammarkhan6883]

+Jimmy t HISSSSSSSSSSSSSSSSSSSSSSSSSSSS

[@mrosilvR7]

you know it did!

[@visnyliss]

Ahh, so THAT'S what causes it. One of the best examples of vortex shedding I've seen (prior to this video) is the "Angel of Death" image of an AC-130 gunship dropping flares. The smoke trails from the phosphorous flares get warped by the vortex and create this really cool-looking "angel wing" effect. If you Google Image search "angel of death ac-130" you'll see what I'm talking about. Great vid, great explanation, and the A-10 is such an awesome aircraft.

[@Drehmini]

An amazing video, this has to be one of the best channels on youtube. Thank you sir.

[@wbeaty]

@Helicopterpilot16 so call it "creation of vorticity." Whether the wing is flapping or static, vorticity is still being left behind as the wing goes forward. PS Helicopter vorticity is fascinating. Plot a thin shell of vorticity below a copter rotor (or even a thin spiral,) look at the resultant flow, and you'll see that the rotor takes in air from all directions, but ejects it in a single direction. Delta momentum of air gives the lift.

[@snaproll94e]

That paddle gave a great visual of vortex shedding. Think you can find a way to explain and demonstrate induced drag and then, how unloading a wing allows an aircraft to accelerate at it's highest rate? I've got an aviation acquaintance that refuses to believe it. Thanks for all of the videos and knowledge sharing!

[@donfolstar]

Project for this weekend- attach upturned swept ends to an old paddle, take kayak to the lake/river, drink beer, test modified old paddle against new paddle, more beer. Science!

[@epicbagelswag]

Videos like this make me proud to work on these machines, good lord I love aviation!

[@EmpereurNapoleonex]

Your vids are great as always. Totally makes learning fun and these are things that few people really ask about...few common people not in the science field I mean. Great job! Keep it up!

[@jblakeplays2541]

I'm 15 and in Boy Scouts, and I've often noticed the vortexes of the water from the paddle, but not known why it happened, I just got smarter, thanks

[@Kitechi12]

I just learned all of this in my fluids class at my university. I enjoyed watching this all the same. Good video, Destin.

[@MrKnoppersesser]

When you look at paddles for races, they are also formed to avoid these vortexes just like the Winglets on an airplane.

[@smartereveryday]

@FEAJramdomfilms It's called an "Engineer's Tan"

[@7Underwood7]

Right when you made reference to the paddle, it made all the sense ^^.

[@pagelzilla]

Hey! I just subscribed after you were a featured video on Lifehacker for your poop splash video. I went back and watched some of your other videos and I have to say, this is looking like it will be one of my favorite YT channels. Thanks for doing what you do! I look forward to more in the future

[@vernblack5200]

I love that you bring “life” to “life” with science

[@joemel2]

@Zpik in addition to the last answer,planes fling upside-down actually fly at an angle and not level.the bigger danger with flying upside down is stalling the engine due to fuel not being fed in properly.

[@AKorigami]

The sound of vortex shedding is incredible. These tornadoes coming off the wing and the sound of the air of the vortexes dance around you. I hope you capture that someday.

[@smartereveryday]

@1and0nlyJamesPadilla No. This is in Alabama.

[@GeorgeLee101]

@Zpik (I'm on iPod so can't reply) the reason SOME airplanes can fly upside down is that their forward momentum when they roll is larger in newtons than the force of gravity pulling them down, thus meaning they can continue to move foward. To extend this period of 'defying gravity' most pilots push forward on the joystick to make the elevators (flappy bits on the back of the wing) move down, or up as the case may be because they are upside down. This sends the air from the back of the wing upwa

[@AtlasWing12]

a classic understatement

[@multi_misa72]

hey dude, love all your videos. keep up the great work

[@erictaylor5462]

My dad was an IP so I knew about this. Great explanation though. You always do such a fantastic job. POST MORE VIDEOS

[@nigelT16]

Your videos are amazing!! Keep them coming!

[@Dept_Of_Ducks]

I don't know about your buddies, but to me this would make a kayaking trip even cooler!

[@xXBl4ckB3ltXx]

That plane that had the wingtip swept up was from Middle Tenn State University which is where I'm goin next year. :D

[@smartereveryday]

@Helicopterpilot16 Oh! You meant the paddle. I'll check it out.

[@SkyhawkSteve]

from the perspective of 11 years in the future, Destin looks like a junior high school kid. 🙂 I've been watching airplanes since the 70's, and am still intrigued by how aircraft can generate a vortex from small surfaces sticking into the airflow.

[@rcxc2755]

Thanks for teaching us .

[@FalloutFinkel]

I too now know a rocket scientist and what vortex shedding is. Thanks Destin

[@qaannat]

Look at Greenland style paddles. We paddle with a canted stroke to shed the vortex off one edge.

[@shader26]

Destin, why not more videos of flying, GA airplanes and techniques for flying, navigation, etc? I see that you took flying lessons, I also and passed my written, and have been flying. The things I learned I thought were pretty interesting. So many cool things like flying a course with wind correction, 60:1 ratio for drift correction, calculating descent from a certain distance, ground speed vs. Airspeed, wind shear, I mean this should be right up your alley and you’ve already got a head start! Anyway glad I found your feed, great stuff!

[@jenssonnenberg8620]

Ah, now I understand the tipswings. Merry christmas !

[@Huttser17]

0:33 and hear we see a magnificent pair of Cobras partaking in a rather captivating courtship ritual... Don't get too close though, these creatures are highly territorial and become quite aggressive during their mating season.

[@JeffTaylor-fw4im]

Per NASA: lift is created by turning of air. Bernoulli's principle only explains SOME of the force of lift. "Lift occurs when a moving flow of gas is turned by a solid object."

[@smartereveryday]

@Bakamanzz Dude.... Space Camp is open to adults.

[@murdocha]

Destin, I'm really loving your shows, and share them with my kids (9, 7, and 5). You're right up there with Bill Nye, and that's saying something! A few years back, when I started listening to the SGU and other science podcasts, I heard an explanation of lift that said that the use of Bernoulli's principle was incorrect. I've been checking out the NASA pages on it and I'm just getting confused. Is there a chance you might tackle these theories in a future episode?

[@ahmadhussein2975]

I basically have an air show over my house every day. There is an airport for small planes near our house so we get to see heaps of old military planes, red barons and more

[@christianhagenlocher9627]

Son in kayak? Check. Next shot: no son in kayak. I hypothesized the son fell into the water,(i'm glad he was wearing a PFD) and my null hypothesis was proved correct when I heard kid voices in the other boat. Another video well done, my friend.

[@carlosparacio]

Airshow=sunburn. Great video Destin!

[@Chindro2828]

You're getting your own tv show, i can just feel it.

[@alexdelarge8772]

Destin - You might want to mention what the advantages are to getting rid of the vortex shedding with the wingtip design. I've heard that it uses less fuel, but I don't know why. Maybe less drag with a more efficient wing? We need DATA!

[@smartereveryday]

@PNanna16 It's a mix really. This particular video was improvised. I remembered some stuff from my graduate Aerodynamics classes and figured it would make for a neat video. The trick is remembering everything exactly right because the internet is full of people who have instant access to wikipedia and a comment text box.

[@DarcyWhyte]

Oh God I can't believe you pulled that "longer over the top stuff".

[@emmy1870]

Your videos are AMAZING!

[@LBKewee]

nice Kenny Powers tan while describing wing shape at the air show.

[@Helicopterpilot16]

@destinws2 Type vortex shedding on youtube, Vortex shedding only applies to your paddle example only if you draged it allong further than a normal pabble stroke, otherwise your just creating half of a vortex ring. Aerodynamic flutter is vortex shedding.

[@HondaFife]

I could be wrong but I disagree with your explanation on the winglets. From what I know they are there so that the whole wing creates lift except the winglet. The winglet is the sacrificial portion that deals with the vortex and the only reason its angled is to get the most out of the wing without making it wider so the plane has no problems at airports. Hope that makes sense.

[@Helicopterpilot16]

Vortex Shedding is actually a tottally diffirent phenomenon, These are known as wing tip vortexes not vortex shedding, Vortex shedding is the name for vortex formation that propogates from left to right. This is the phenomenon that cause that one famous brige to exceed its structural limits. But your explanation was right on.

[@fordfan7689]

That is the same reason that rear spoilers on race cars have end plates so that they can try and prevent the air from spilling over.

[@khuong1994]

Love your vids dude.

[@jeffreyevans3160]

another awesome video . thanks destin .

[@alextatkin1026]

hashaha Destin, you are the man. Even with your awkwardness, you are exactly the type of man i hope to become.

[@MeBeSojokes]

I see that when I drink tea!! You can make a vortex when you move your spoon through a cup of tea, because your spoon is curved.

[@commandokent]

You should do a part 2 about helical straking on cylindrical objects to disperse vortex shedding from wind. It's what brought down the Tacoma Narrows Bridge.

[@KafshakTashtak]

Vortex shedding is the vortices that are created behind a cylinder or sphere. It's actually a transient periodic flow.

[@TheBorderlandsJunkie]

I'm a swimmer an realized that this also helps swimmers when they angle their hands in butterfly and backstroke

[@rm84tv]

dang it this is why I have so much fun when I mix my coffee with creamer with a spoon. Thanks my friend.

[@TheAdamant94]

You must be one of the most dedicated and intelligent fathers on earth!

[@goliteyourworld6]

Worth watching just to see the A-10. The rest is just cherry on top....if you like cherries. lol

[@shashair]

Application of Bernoulli's principle for explaining lift generation is an incorrect oversimplification of a much complex phenomenon. When you follow a fluid particle along a particular streamline, pressure and flow velocity can be related using Bernoulli's principle as long as the flow remains inviscid and incompressible (Mach < 0.3). While, it's possible to qualitatively explain lift by considering two streamlines, one passing over the wing and the other just passing under, and assuming the flow velocity of fluid particles along the chord remains constant, a quantitative analysis presents discrepancy between lift calculated using Bernoulli's principle and experimentally measured lift. In actuality the three conservation laws must be used in conjunction to explain lift.

[@philip1541]

Wow i did not know of this vortex shedding. I wonder if this is why some people in the Kayak world says greenland paddles are more efficient than the Euro style

[@IcapI]

When the tip of the wing is tilted up (or down) its called winglet. And to answer the question about what happens when you fly upside down. Planes that are designed to fly upside down don't have a very convex surface on top of the wing e.g. fighters are almost the same shape on top of the wing as on the bottom. Planes design like this are more sensitive to angle of attack at don't really care wether the plane has one side up or the other. They fly more on speed than on Bernulli ;)

[@abrarjahinnafi1634]

THANK YOU !

[@smartereveryday]

Yes...er, I mean... Dang straight... what's it to yah?

[@ryanrox17]

the paddle thing is cool, maybe ill try it out

[@xbox7]

A-10 Thunderbolt!!!!! My favorite!!!

[@aznpos531]

I would love to see a video explaining visible wingtip vortices where water vapor condenses inside the cortex core.

[@kael13]

Hahaha, love these videos; you have a great charisma!

[@Farrow101]

That's gotta Falcon Field in Peachtree City GA. I was there, and go to that show every year!

[@martins4555]

Nice video and i loved your sunburn xD

[@heubanks270]

you're living my version of the american dream dude. keep it up

[@Nalopotato]

The Warthog and the Tomcat are my favorites

[@kyleknepper4016]

Error01 Same. My two favorite planes after the sr 71

[@sasukedemon888888888]

I was at one airshow before, and there was a woman who flew up a red biplane, and got it at a stable level, then climbed out and stood up on top of the wings for a solid 15 seconds before climbing back in the plane

[@hexdragoon]

Female Rico Rodriguez?