Aerodynamic downforce balance

Understanding aerodynamic downforce balance and why it is so important. My book is available at www.amazon.com/Vehicle-Aerody... or Amazon in your country.

[@zeitgeist888]

I don't understand why more roadcar makers don't use inflatable front airdam ala Porsche has used. It adds some weight and complexity but it seems like a good balance to reduce lift at the front while handling impacts and driveways, speed bumps etc... and can be deployed with speed and deflated at low speeds. So many manufacturers use a deployable rear wing/spoiler but few for front air dam.

[@camdoice]

thank you for these videos very informative

[@robhills2613]

Autocar in the UK tested an early one without the rear spoiler, and they liked the playfulness if the chassis (i.e. oversteer). But as part of the recall Audi also changed the geometry of the suspension and that ruined it for many. But you can buy kits to put the geometry back - though do leave the spoiler on if you're intending on doing high speeds!

[@saityavuz76]

You are a wise man. Thank you for sharing your knowledge!

[@JulianEdgar]

Thank you

[@GaragemDopamina]

Hi Edgar, i'm reading your book, Modifying The Aerodynamics of Your Road Car. Can you do a video about the exhaust gases and aerodynamics, like side exhausts to save weight for example. Thank you so much. I really enjoying the book! Congrats from Brazil !

[@JulianEdgar]

I don't see much connection between exhaust gases and aerodynamics. The exhaust gas flow is so low, especially at part throttle, that they make little/zero difference to car aero.

[@GaragemDopamina]

@@JulianEdgar you are the best! Tks!!!

[@HayyuAdam]

@@JulianEdgarnot even for the McLaren 570S?

[@JulianEdgar]

No - what happens when you back off?

[@thewogo439]

Top fuel dragsters generate large amount of thrust from the exhaust and it’s commonly used to push the car down to give it more traction, but it’s an extreme example

[@ammaralfuzaia4933]

great video as always thank you very much mr.julian

[@JulianEdgar]

Glad you liked it!

[@moimon4074]

Your videos are amazing and did help me on doing my own aero Im soon going to buy your new book!

[@JulianEdgar]

Great to hear!

[@shareitall1011]

I just finished reading your book 👍 it was very good and inspired me to try and lower the drag on my commuter car

[@JulianEdgar]

Great! Please add an Amazon review of the book.

[@JustinBone]

Two questions; 1. If down-force is measurably lowering ride height as speeds increase, doesn't that eventually become a problem if your suspension doesn't have enough travel at higher speeds? 2. Say your car has a very well designed bottom side from the front all the way to roughly the rear axle, but rear axle to bumper is relatively open. Would adding a diffuser to smooth out the airflow of the uncovered section then remove frontal downforce since it's increasing it under the car at the rear? And if so, would then the ride height change from doing so up front at higher speeds induce even more lift?

[@JulianEdgar]

1. Yes, if you have a lot of downforce, soft springing and don't have suspension capable of automatic height adjustment. 2. It depends where the added diffuser causes more downforce to be developed.

[@rolandotillit2867]

Eventually suspension does change, when you start adding lots of aero load. On a dual wishbone car, lowering a car will give more camber, and also alter the roll center. As you add more downforce, the load starts lowering the car to the ground.

[@JulianEdgar]

Sure, but not if you have automatic height control of the suspension. (Which is what I used on my Honda Insight with downforce.)

[@rolandotillit2867]

@@JulianEdgar That's pretty neat!

[@botno69420]

Now I'm afraid of fabricating a front undertray for my road car in place of the old broken one. I don't remember what it was like, and if I somehow end up with less lift than it originally had, my Saab will turn into an Audi?

[@JulianEdgar]

Developing effective front undertrays is covered in my book. No need to guess - all can be easily and cheaply measured on the road.

[@botno69420]

@@JulianEdgar Ay! I've watched all (?) your videos about the subject aswell, but still haven't got my hands on the book. First I'm looking into getting the road car performance optimization one, though. The front undertray and insides of the wheel arches have been shattered, so it will require a tad bit more advanced fabrication techniques in order to get everything nice and solid. I will probably choose aramid reinforced glass fiber as my material - that should work, right?

[@kennethtanaka883]

How would ride height affect downforce? Let’s say I lower the front by 1 inch, and the back by 2 inches or vice versa How would that affect the balance of the car?

[@JulianEdgar]

Yes, relative height changes will usually affect downforce. For example, going lower = faster airflow speeds under the car = less lift /more downforce. However, the situation is made more complex because rake changes also affect lift/downforce developed on upper body surfaces. All easily taken into account if you measure *actual* lift/downforce occurring on the car, as covered in my book.

[@onlyifusayplz5407]

2:33 Is it not correct that adding weight to the car would actually increase grip, but that the added inertia simply outweighs (pun not intended) any benefit you'd get from it? Since - by my understanding - downforce is simply a way to add weight (at speed) without having to increase mass. (Keeping in mind that weight and mass aren't the same thing, of course) *Update, a little further on in the video now, you basically said that exact thing in different terminology. Shouldn't underestimate you.

[@JulianEdgar]

Isn't that what I said (and it's also in the slide's text)?

[@onlyifusayplz5407]

@@JulianEdgar It is, just in different words. Initially (at the timestamp) you insinuated that adding weight doesn't increase grip, but you clarified later. I think the fact you didn't distinguish between weight and mass (which to be fair isn't entirely necessary) just tripped me up.

[@LabiaLicker]

Hmm very interesting