Aerodynamics

[jetpilot]

I know there are some clever guys on the forum, so i was wondering if any of them know at what speed does the use of rear spoliers and diffusers start to assist with a cars handling?

[Ricco_04]

It\'s not a very tech answer but from watching F1 they usually quote 70mph +

[Grizzly]

Depends What spoiler (How much surface area etc), If its in the Air flow or blocked out by the roof and How its set up.

I don\'t know if there is a Definitive Answer as it depends on so many orther Factors.

[McCARTHY]

it does pepend on weather, humidity and all that stuff..... but yes your right around the 70mph mark give or take...

Also with a rear diffuser they wont be as effective, if at all, unless you have a compelete under tray. i.e. like GT cars etc. reason for why is that with out the front and centre sections of an undertray the air that passes under the car bounce off the various pertrusions like the exhaust, brace bars and that kind of stuff making it an un-smooth flow thus its uncontrolled... so , and bare with me, when the uncontrolled air hits the rear diffuser its not all flowing the right way so the diffuser can\'t do its job properly. However most road cars arn\'t offten driven hard enough to benifit form a complete undertray...

If you want to make an increase in downforce your best bet is an adjustable rear wing, of a decent size, lower the car and a decent set (tipically 2 a side)front carnards at a 45 degree(ish) angel. but speed would be the key to making a huge difference with these alterations :Thumbs-up

Sorry i do babble on :2Rolleyes , hope this helps

[jetpilot]

Thanks guys, so 70 mph is the basic starting point! Relatively slow i suppose for track work, i would have thought a lot of corners are in this bracket and i presume the effects increase with speed!

[Grizzly]

Am i wrong in saying if you have a Big Area Spoiler for example and have it a Big Angle you will see the Effects alot lower MPG then at the other end of the scale if you have a Small Area Spoiler thats got very Little angle on it will only start Down force at Higher MPG?

Also it depends on the Cross Section of the Spoiler, Is it an AeroFoil? they will start making Down force at a lower Air speed.

But when it all comes down to it Area of the Spoiler is the Key, this is why you see F1 cars with diffrent types of Rear Spoilers for Diffrent Tracks with more or less center sections to give more or Less surface area depending on the Size of Track and the Amount and Tightness of Corners.

[McCARTHY]

i belive you are spot on there grizzly this is why you see on things like the GT porchse, Aston Martin\'s etc have very wide and deep rear wings for more stabillity coming out of those aggressive bends then that of a combo between the undertray and the wings etc keep the thing on the black stuff on those long straights......

Also all the handling aids does mean you sacrifice, to a degree, a little top speed

[Brett]

YOu also want the most abrupt \'end\' to the wing/car that way you create less drag.

[McCARTHY]

kind of  horizontal tear drop shape if you see what i mean?

[kev-yorks]

Just to add another layer of confusion. Airflow can be modified by the use of vortex generators for you guys that want a low profile wing that is still effective. As done on some Evo\'s now  
Kevin

[Grizzly]

TBH i think with an FD i\'d rather spend my Time/Money on realy Smart Coil overs,Bushes and Tyres and have it set up realy well.

There int much point in Down force if you can\'t get round a Corner quick to start with

[McCARTHY]

i totally agree.... lots of trick zeal, tanabe, jic and cusco bits sounds good to me.... most importantly sticky rubber makes the world of difference...


Can i just say, in referance to what i was saying about the full body undertray, if usin on the road you nust be very very carful of collections of water massive puddles etc due to aqua planing

[Grizzly]

I think alot of these Rear defusers etc are there for Show and Little else.

Its all about figuring out what is for Go and whats for show.

[McCARTHY]

i think most is for show to be honest ........

[Ricco_04]

If you are comparing to F1 then don\'t forget that the hight width and number of element\'s they can run in the wing are all covered by regulation.  So they would run taller wings with more element\'s in them if they could.  Also they generate around 35% of their total aero grip from the floor of the car.

Agree with the suspension stuff totally - even get some slicks on