auto aerodynamics : the gurney flap. Increase the traction of your car

[@funkyd04]

one question I have is at what angles of attack do you need to consider adding a gurney flap to help maintain the best downforce to drag ratio? and if it's a dual element wing, how does that complicate things?

[@JohnTheHater]

woohoo, I learned something new today! I've seen all of those tiny lip spoilers on the trunks of cars and thought they were useless, seems they could have an effect. I take it that measuring the CL doesn't follow a the path of a curve, but simply square edge to edge. Cool video, thanks.

[@stinkyfungus]

take a look at the small rear spoilers installed on the first generation audi tt after the recall. not much there, but without it the car is downright dangerous to drive fast.

[@anu0chats]

excellent explaination for gurney flaps.....but still looking forward for more explaination for the gurney flap thats not only on one side (upper/lower)of the trailling edge...but which is on both sides of trailing edge

[@RotaryRebuilder]

all the aerodynamic quantities are "non-dimensional", this is common practice in aerodynamics. CL is the non-dimensional lift, and CD is the non-dimensional drag. To get the actual lift and drag (force) you multiply them by dimensional quantities. For example, Lift = q*CL*A, where q = dynamic pressure (how fast you are driving), A = area (chord times width). So the faster you drive or the bigger your wing the more lift you get. This is the same for drag using CD.

[@KeepinItReal]

this is excellent! i think F-duct explanation video would go perfectly right after this.

[@dariodalcin5177]

Chances are people who want to know about gurney flaps already know the basics of air folis

[@paolosolcruz]

Very informative! Does a gurney flap have to be an exact 90° upright position on the wing's edge to be effective?

[@raphaelbiendarra203]

Hi, thanks for this video. I want to read more about the Gurney flap and the Aerodynamic behind it as well as how to further improve it. Can you recommend me any literature I start with?

[@rhiannagurney5451]

Thank god you got my last name right!

[@worfoz]

Hi flap!

[@thomastsompanidis7054]

great job, nice video!

[@hiddenkard3101]

What if mine is a e46 m3 lip spoiler? What benefit if any would it? It looks almost has the shape of a gurney flap except is has a smoother upward angle.

[@jeremykeen5706]

Ever made a video on vortex generators and how effective they are at reducing drag? I am curious to see how they work. Not much to read on for automotive use.

[@nikan4now]

Thanks for sharing. One question: why doesn't the flow separate on the suction side of the Gurney flap? Also isn't a re-circulating zone over a foil a region of low pressure? Then why does the Gurney flap increase the pressure on the pressure side?

[@dsmithwc04]

The difference in pressure is what causes lift/downforce

[@herrrpd911]

That's very well explained!

[@markymaclmb]

I've seen some aftermarket gurney flaps that aren't perpendicular to the chord....when attached...it seems as if it extends the spoiler but at an increased angle of up to 45 degrees. But not 90 degrees. Is this offering similar effects or just an extension of a spoiler kit?

[@galardo1995]

thank you very much and i appreciate your answer.

[@99Lezard99]

Hi i have a little track project with a friend. Its a small boxy hatchback with a very small engine. Laughably small. Our main goal is to decreace drag without adding a lot of extra weight. We are thinking about a gurney flap but we are not sure if if can or Let alone will decrease drag. The car has a stock wrap around spoiler at the back that extends for aprox 5-8cm from the actual roofline. Also we dont really want to cover the whole underbody because of weight and exhaust heat. Also its got a torsion beam rear axle wich stands in the airflow anyway. Our questions are now: Would a gurney flap be benedicial to our little hatchback? And would it be benedicial if we would at least cover up some areas on the underbody? Anyone got a similar project or experiance on that?

[@jlcool007]

very good explanation!

[@bitsurfer0101]

How would you find the stall angle of a spoiler/airfoil?

[@galardo1995]

one thing that im concern about is that, what if you extend the cord and increase the height of the gurney flag but still, 1.25% of the spoiler, do you get more down force with out any drag? thank you for your great video.

[@MrOchoaone]

The wing on my car is 5.5 inches long front to back. i want to make all three of the gurney's. can you tell me how tall in inches should i make them, and in what angle. thanks

[@Hitman-ds1ei]

Doubling your drag from a negligible amount ? How is that a problem if your getting a huge down force increase ??

[@FairladyS130]

OK but what about Gurney flaps on spoilers that are attached flush at the top of the back of the car and have no air flowing under them? If I understand this video correctly they will only add drag and no downforce?

[@wschell4023]

R Greenup Yeah it’s funny his Mustang examples had the kind of flap you are referencing but he made no mention of that scenario in his sketches. But when he got into discussing flap size he kind of talked about race car spoilers. I think the Shelby Daytona coupe is a good example of a large Gurney flap and it’s clear it provided tons of downforce, probably with considerable drag. If you go to KYLE.ENGINEERS KZbin he illustrates how these flaps essentially lengthen the area of a wing and that’s where these are most effective.

[@Dasbier88]

Does the wing will be symmetrical or asymetrical? Which is better to place the gourney flap?

[@RotaryRebuilder]

@anu0chats Having a trailing edge on both the upper and lower surface would defeat the purpose and would make the wing perform MUCH worse in both downforce and drag. A trailing edge is only useful when used on one side of the wing, in the case of airplanes it is placed on the bottom, for cars it is placed on top. This is because airplanes need lift and cars need downforce.

[@MrOchoaone]

I've also seen some on wheel wells. Any idea what they do?

[@RotaryRebuilder]

This is going to be a negligible variable, the height is the most important. Try making it as thin as possible without sacrificing strength.

[@gabrielcatani9317]

Es una manera sencilla y barata de construir un ala de dos planos.

[@rahulkhandelwal485]

Hey I really liked your video . Given I studying wind energy , do you feel if we make a gurney flay in wind turbines we can have a highly efficient and stable wind turbines?? Hoping to hear for a reply from you soon

[@ubaidbaig8128]

..soon

[@Kurzawaa]

Is the gurney flap supposed to be perpendicular to the ground?

[@sterlinghamiltonracing6487]

No, Its usually perpendicular to the wing.

[@MrOchoaone]

This was awesome. But i need to know, should i make my gurny flap at a 90 degree angle? I've seen some on the market today and it looks like they have less of a angle.

[@teamvantablack7853]

Is your father Jorge Ochoa?

[@89dieselpower]

Why not fill up the turbulent space in front of the flap, eliminating a part of the drag produced by the flap? sort of a truncated airfoil.

[@noncog1]

"symmetric airfoil"

[@rikvanderzanden2834]

Get one in your watertank!

[@FairladyS130]

Great, ask a simple question and no reply.