Winglets - How Do They Work? (Feat. Wendover Productions) 

Aerospace engineering PhD student here. Even with multiple classes in aerodynamics, developing intuition for lift distributions and wingtip devices is really difficult. However, focusing on reducing wingtip vortices like the video does is almost certainly not the best way to think about how winglets work. Vorticity is generated along the entire span of the wing in a continuous distribution, not just at the wingtip (ref. Prandtl's lifting line theory). It only rolls up downstream. It is the distribution of vorticity which creates downwash on the entire wing (induced drag) and this is why the entire lift distribution affects induced drag. An ideal vertical winglet moves some of the vorticity production away from the main axis of the wing, which reduces the strength of the downwash where the lift is being generated. By far the best explanation for this I have found is in Chapter 8 of Boeing aerodynamicist Doug McLean's book, "Understanding Aerodynamics: Arguing from the Real Physics". The big takeaway from McLean is that you can't think of the wingtip device as a bolt-on accessory; you have to consider its impact on the lift distribution of the entire wing (and this is really hard to think about). He also shows why devices which attempt to "straighten out" the wingtip vortex do not work in practice. The video addresses raked wingtips vs winglets. McLean's book has a chart which shows that vertical winglets are more efficient than a planar wing for a given span. But this is only decisive for an airplane that is constrained by the width of an airport gate. Deciding whether to use a winglet or tip extension depends on the wetted area of the device (friction drag), the effect on the bending moment of the wing (structural weight), the weight of the device itself, and the induced drag benefit among other factors. There's really no right answer - you have to crunch the numbers in each case.

It's funny how most things that are useful are also very beautiful

2:25 did I just see an airliner go vertical from takeoff??

I am a simple man, I see a video starting with beautiful A340 Taking off, I like it!

omg, that 87 take off :P so perty

I love airplanes and now I love the videos on this channel. Cheers mate. Your hard work is duly appreciated.

As an engineer I love this channel. Very well educated and describes the topics using actual engineering terms, theory, and examples. Well done sir

wait... imagine if that winglet had an even smaller winglet on it! the efficiency would be insane!

it looked like it was gonna do a backflip at 2:33 omg

Hey man! I've found your videos about an hour ago and already watched them all (rewatched some too!). Content is phenomenal and very informative, I hope you keep pumping out videos! They're a wonderful refresher of my University days. :)

I like how he got inspiration from birds. It goes to show that nature is indeed low-key advanced than us in terms of real world mechanics.

You, Sir, have earned my subscription in the first FIVE SECONDS of this video. Well done. Very well done indeed!

Air pressure changes are only part of the lift phenomenon. Downwash is very important, as well, and you can easily see its effects with rotary wings while the aircraft hovers just above grass or dust.

I just found your channel, through the airline cost video, and I find your videos very informative and entertaining to watch. I'd love to see a video of how gliders generate lift without an engine :)

Im so happy ive found this channel! Just finished watching all your videos! I have to say that this channel is amazing. Videos about interesting things and on top of that you create all the cool cartoonish designs that help us understand what your talking about. Gr8 channel, looking forward to your next video!

You could often see dust or fog highlight the wing tip vortices on the Space Shuttle just as it touched down. It was especially beautiful during night landings, the runway lights back-lighting the vortices as they spiraled behind the Shuttle.

I love it when you guys (Wendover Productions) collab.

Your videos are amazing! So easy to understand and great quality. Keep up the good work!

YESSS!!! Was waiting for this video. Great video, Sir.

Dear RU-vidr, (real engineering) your videos are great. it help's understanding some the most annoying questions. I really appreciate your work of making these such videos. keep making these videos. Please, make some more videos on airplanes. Thanks

Between you and Wendover, I get more stuff crammed in my head than the rest of RU-vid combined.

Great channel! I subbed. Love the way you explain things so easily! Keep it up!

I enjoy the casual language combined with the informative and educational content.

look i've been in youtube in 6 years you guys are so so good u will never be appreciated well by ppl thats how high u fly bro

Love these videos so much. Where did you learn engineering?

None of the explanations from various sources mention the problem of tip-vortex migration. When at certain values of air speed and attack, the tip-vortex moves away from the wing tip and quite far inwards. In that case the section of the wing extending out past the vortex is producing a down-force and wasted fuel. By forcing the tip-vortex to remain at the wingtip, this loss-mechanism is removed. I'd like to hear about the relative contributions of reducing the KE in the center of the vortical pattern, versus permanently moving the vortex-location out to the wing's tip.

I think I'm going to like this channel!

Thanks, you answered the question I had in my mind for years.

Sadly this is only the often reapeted superficial inaccurate (or even wrong) explanation. Actually the strength of the vortices that form behind the wings is directly proportional to the lift produces by the wings, and you can't reduce that without reducing the weight of the plane. As far as I know, the only thing winglets are doing is to shift the vortex out and back to prevent the downdraft part of the vortex hitting the wing and thus reducing induced drag, or something like that. Induced drag is nothing else as the wing flying in its self-induced (hence the name induced drag) downdraft.

This is a great explanation.. thank you for making this video.

Great Explanation!! Thank you!!

Awesome video! Thanks.

It's such a amezing video and I think it will help a lot for student.if I miss my any lectures than I can batter and easily learn here..thank you

Thank you for this video.. Helps a lot with studying

I am actually so happy that I found this channel

I love it already!

I was kind of expecting you to expand more on how the winglet reduce the down wash and the tip vortex strength, and maybe mention a little bit more about the penalty of having a winglet. But you are already giving a lot, I can't ask for more.

Yes lift distribution is somewhat important, and winglets modify that, but that is not their goal, nor how they achieve fuel efficiency. Three dimensional airflow exists on wings that are creating lift regardless of the type. The high pressure air below the wing tries to flow to the low pressure air on the top as the video mentioned, and this creates airflow from the root of the wing toward the tip on the bottom of the wing, and the opposite way on the top. Wingtip vortices are the result of these two span-wise airflows interacting with each other. Winglets take advantage of span-wise flow by putting an airfoil in that flow that creates lift in the direction of travel of the airplane. So instead of creating lift that directs up, it creates lift that is actually mostly sideways, but a small component, about 8-10%, is directed forward. Hence, energy in airflow that was going to waste, is now being put to work as thrust for the airplane. And a side benefit is that wing tip vortex energy is reduced, and wing lift distribution is (mostly) beneficially modified. The size and angle that a winglet is mounted are absolutely critical to their efficiency, and if the angle is off even a little bit, or they are too big, they become huge sources of drag.

Love your videos

That dream liner is pretty dope

😱 Ahhh! I was enjoying that and then it ended so abruptly.

This is a great video!!

Nice to see the cross-pollination between Real Engineering and Wendover Productions. Keep up the great work, guys!

Awesome stuff

Nice video, keep up the good work!

Very informative. Give thanks.

2:12 wing shapes of planes for example are spitfire, p51, and mirage for round, square, and triangle

Most airplanes adjust the lift distribution by varying the incidence of the wing from root to tip. So even a rectangular wing can have an elliptical lift distribution. This is also done to get better stall characteristics by having the inboard part of the wing stall before the outboard part where the ailerons are providing lateral control.

Ok, this video is good. Gives great explanation.

So simple and yet so complex.

I remember when i used to make paper planes when i was yound, i once decided to try smth new. I added winglets. Adding winglets to them made them fly longer and not nose dive once i threw it Yeah im officially an engineer

Keep going. I know it’s tough and it seems like a long road but remember the goal

Nice informative video. Question: does the high rpm of engine creates the gyroscopic effect on the plane during flight or during maneuvering?

Wendover Productions brought me here. I heard your accent, subscribed! (idk why it's funny)

keep up the good work fam

Hey Real Engineering, I have an engineering question that is not related to the video, but I hope you can help: Why are there so many different types of wings, especially on fighter aircrafts. Shouldn't there be a standard wing whose shape is optimised for a particular task, be it speed, manoeuvrability, efficiency etc? If you look at the YF-23, which is supposed to perform the exact same task as the F-22 Raptor, they both have very different wing designs. Is one really better than the other? I have been puzzled by this question or a long time and I can't seem to find the answer to my question anywhere. Do you know where I can learn more about wing shapes and how they affect the performance of an aircraft? (Or perhaps could you make a video on wing shapes? :)) Anyway, thanks for taking the time to read through all the comments. I hope you can help answer my burning questions :) Your videos are educational and informative, not to mention awesome. I have watched every single one of them!

When winglets were first starting to show up on planes, I read that the addition of a three-foot-tall winglet wasn't as beneficial as simply adding three feet more to the wing's length, but the winglets were preferred because they would allow the aircraft to more easily fit into standard airport terminals. Do you know if this is true?

2:28 i hope that was a test flight xD

subscribed! keep up the good work!

You are a little wrong about the raked wingtip design. It actually first appeared on the Boeing 767-400ER. Just thought you should know that. Great video, by the way!

Winglets as well as reducing drag on the plane creating the vortex, also allows closer distances between following aircraft on landing approaches and takeoffs by reducing the amount of turbulence caused by vortices. Large aircraft that usually create large amounts of wake turbulence up to 2km behind them usually the word "heavy" in their call sign to denote this danger to following aircraft especially to small light planes. eg "United 451 heavy"

Nice video!

Please keep in mind that on an elliptical wing a stall will happen on the entire wing at the same time. That's why they are not used very often ;)

I guess winglets are also put so as to decrease the fluttering of wings. If possible please clarify. Thanks in advance Real Engineering. Awesome channel!

Lovely.

Winglets have been understood since the beginnings of aviation. In fact an Englishman, Frederick W. Lanchester described them in 1897 before the Wright Brothers had even taken flight. Like many great pioneers of his time, Lanchester looked to birds for inspiration. He noted that soaring eagles had splayed upturned feathers at their wingtips and he incorporated this into his designs for model gliders.

Although elliptical span loads are often stated to be ideal (because Ludwig Prandtl said so in his revolutionary 1922 Lifting-line theory paper), they actually aren't. A bell shaped span load is better (Prandtl also corrected this later in a small often forgotten 1933 paper). Whilst all the aircraft manufacturers were busy playing 'who-can-make-the-most-foolish-looking-winglet' Albion Bowers put two-and-two together and wrote a paper entitled 'On Wings of the Minimum Induced Drag: Spanload implications for aircraft and Birds' - catchy? No. But I think it's revolutionary. That paper singlehandedly gets us to a position where we can get rid of Vertical stabilisers and adverse yaw whilst drastically reducing drag. Go and read it if you found this interesting. Seriously. It's awesome.

Just to correct one small thing in this video. Wings do not provide lift by creating a pressure difference, that's a very common misconception. They actually create lift because it turns the flow of air. www.grc.nasa.gov/www/k-12/airplane/wrong1.html www.grc.nasa.gov/www/k-12/airplane/right2.html

regarding winglets, is it right to say that F4 Phantoms had winglets??. it seems to me F4s were the 1st massive manufactured aircrafts with winglets. Please, correct me if I'm wrong. Thanks

I'm fucking in love with this channel

maybe you can do video about something whit bridges or inflatable room in space.

Portugal!!!

The Lockheed F-104 is a good example of a diamond wing configuration.

Thanks

Hi! Your videos look very sharp and professional, congratulations! Which software do you use?

Actually, induced drag is a function of producing lift. As a plane flies, it has a positive angle of attack (nose high). The slower it flies, the higher the nose to achieve enough lift. This causes the chord line of the wing to tilt back as well. This means that lift is not produced straight up relative to the earth, but to the wing, so some of the lift is actually drag.

I recently noticed a plane that had Winglets pointing up and another one pointing down. What's that all about? Just had to subscribe since i loved this video and I'm sure i will find more of the same. Thanks

NEED MORE VIDEOS MAN DEMANDING CONSUMER ERGGG ERGGGG:D

I made paper Winglets for my foam glider to make them fly better. It actually worked and now they fly much farther, faster, and for a longer time before they land.

Hi Brian! I have a question about how you produce these videos. How do you animate these diagrams in front of the blue grid? Do you use special software to do this/have to do any programming? Interested in working on educational videos like yours. Thanks, Mitch

What about the Airbus' AlbatrossOne with _natural_ folding wingtip? Is it better than the fixed one like we mostly found?

Hey can you tell me what the purpose of a spoiler on a car, versus a wing on a car? thanks

Are there any apps or programs for virtual wind tunnels? I am very interested in aerodynamics, but haven't been able to find aby

I think iam ready to fly one..

Can you do a video on fuel injectors? I wanna learn why they fail

your shit is pretty cool man Subbed!

ohhh Boeing 787-9 operated by Vietnam Airlines

Would there be much benefit from adding winglets to an ATR72, Bombardier Q400 or Sukhoi Superjet?

How about raked wing tips like the 787?

got here because of wendoverproductions :)

Petition for real engineering to make an 10 minute video of him saying “those little curly bits”

Nice video. I like the idea that engineers can take ideas from nature, and apply them to our own world.

I have a question. What is the difference of end plates and winglets in aircraft?

I add bell shape lift distribution.

0:30 “But ask the animals and they will teach you” ~Job 12:7 /Lonewolf Liberties

0:42 a link please? I watched a video on RU-vid that confused me. In that video they said the low pressure on the top of the wing also creates a lifting force? I thought it would create a down force and the high pressure on the bottom would create a lifting force but greater than the down force and that difference of pressure (or greater lifting force compared to low down force) creates the lift needed to fly? Am I wrong?

subbed

It also helps to counter ground effect..

I am not engineer nor a scientist but believe me this I had winglet idea while on board from 1977 to 2018.

Do the Whitcomb video!