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Do Road car aero kits do anything?
morcus - 20/9/11 at 07:17 PM

As per title, does anyone actually gain anything on the road from spoilers and splitters and that kind of thing? I understand how it works but would you feel any benefit at 60mph?

Ivan - 20/9/11 at 08:08 PM

Unless it's been designed in a wind tunnel by someone who knows what they are doing i doubt that you would gain anything at any speed except increase resistance.

MikeR - 20/9/11 at 08:35 PM

you'll get at least 100hp and half your 0-60 bragging time!

scutter - 21/9/11 at 10:00 AM

By panelling off the rear of my car we gained 10mph, no aero increase but a reduction in drag.

ATB Dan.

jossey - 21/9/11 at 11:48 AM

scutter what do you mean by that please? Boxed of the Bottom and top or what......

MikeR - 21/9/11 at 12:10 PM

probably the rear boot area and maybe trans tunnel. Issue is making sure the heat from the engine, box and diff can escape.

Kwik - 21/9/11 at 12:49 PM

you dont need an air tunnel to get gains in drag efficiency. you just have to get your car as close to a teardrop shape as possible, less hard edges, no gaping holes, cover as much as you can off the wheels...

to get performance gains in down force you dont need a wind tunnel, but if you bolt the wrong bits onto the wrong car then it wont be beneficial at all... the wind tunnel will just make a particular aero part more efficient...

scutter - 21/9/11 at 01:08 PM

quote:
Originally posted by jossey
scutter what do you mean by that please? Boxed of the Bottom and top or what......


I made a cheap undertray/diffuser from the rear edge of the floor to under the fuel tank, The thinking was it'll stop the rear panel acting like a parachute.

ATB Dan.

[Edited on 21/9/11 by scutter]

coyoteboy - 22/9/11 at 02:38 PM

Teardrop isn't actually the most aerodynamic shape, it's partly that shape due to the effects of surface tension and gravity. If it were you'd see fighter aircraft with bulbous noses and pointy tails - you don't they're pointy at both ends, as close as can be around the payload.

My cars rear wing (OEM) makes a big difference to stability near 80mph, really pins the back end down (makes sense, it's an inverted aerofoil in shape) - removing it is noticable. But most "ironing board" solutinos I'd say no, and most bolt on extras I'd say need some thought. Complete Undertrays are probably about yoru best bet.

[Edited on 22/9/11 by coyoteboy]

Mr Whippy - 22/9/11 at 03:50 PM

quote:
Originally posted by Kwik
you dont need an air tunnel to get gains in drag efficiency. you just have to get your car as close to a teardrop shape as possible, less hard edges, no gaping holes, cover as much as you can off the wheels...


a teardrop shape is really a bad idea, rather like the old vw beetle the try to fly at the back and become unstable

All spoilers really do is add drag to the car, in an ideal world the spoiler fin would move and only produce downforce when needed, i.e. going round corners, in the straight it's just a drag

RK - 23/9/11 at 01:43 AM

You might not feel any benefit at 60 mph, but you certainly would at rest. Your knob grows exponentially. Perhaps not all that useful at that moment in time...

Rob Palin - 23/9/11 at 05:27 AM

quote:
Originally posted by coyoteboy
Teardrop isn't actually the most aerodynamic shape, it's partly that shape due to the effects of surface tension and gravity. If it were you'd see fighter aircraft with bulbous noses and pointy tails - you don't they're pointy at both ends, as close as can be around the payload.

My cars rear wing (OEM) makes a big difference to stability near 80mph, really pins the back end down (makes sense, it's an inverted aerofoil in shape) - removing it is noticable. But most "ironing board" solutinos I'd say no, and most bolt on extras I'd say need some thought. Complete Undertrays are probably about yoru best bet.

[Edited on 22/9/11 by coyoteboy]


The teardrop is exactly the perfect shape for low drag - gravity and surface tension work in opposition until the lowest energy combination is reached, which is a teardrop.

Modern fighter aircraft are pointy at both ends because they need to have the capability to go supersonic in order to get to 'the fight' quickly. When near or over the speed of sound the most efficient shape has a pointy front. When substantially below the speed of sound, a rounded front is the most efficient shape.

It's why propeller-engined fighters always used to be rounded but the more recent jets became pointy. Unfortunately the pointiness makes the handling poor when at low speed so they tend to have deployable slats and flaps at the front and rear of the wing, to try and increase the overall curvature and make it more like a low speed wing.

I've been developing cars and aero kits professionally for 15 years now and have seen that there's a wide variety of stuff out there with some that does work well and plenty that doesn't. In truth it's difficult to make a spoiler that doesn't do *something*, but whether it does so efficiently or to anywhere near the full potential is the big question.

In some cases they can increase drag, in some they lower it. It depends entirely on the shape of the car and the design of the spoiler. You definitely want one designed by someone who knows what they're doing and had it tested, and tested properly.

britishtrident - 23/9/11 at 07:15 AM

Elongated half tear drop



[Edited on 23/9/11 by britishtrident]

scootz - 23/9/11 at 11:32 AM

quote:
Originally posted by Mr Whippy
... in an ideal world the spoiler fin would move and only produce downforce when needed, i.e. going round corners, in the straight it's just a drag


Did the original TT test-car not do cartwheels in a straight line at high speeds when it had no wing?

Ninehigh - 23/9/11 at 03:20 PM

A water droplet is actually a ball, not "tear" shaped....

There probably is a difference at 60mph+, but really unless you're on a track (or thrashing it like you're on GTA) I wouldn't bet on you feeling a difference