Wings/Spoilers : You’re probably doing it wrong.
▻http://oppositelock.kinja.com/wings-spoilers-youre-probably-doing-it-wrong-1665312667
Vous vous êtes toujours moqués des gars qui dépensent une fortune pour coller d’énormes ailes en plastique sur leur caisses de m ... ? Vous pouvez vous féliciter, vous avez raison et ces types sont vraiment des boulets. Voilà pourquoi.
Most folks think airflow exactly follows the surface contour. Even many auto-designers used to think that, until computational fluid dynamics and rigorous smoke-trace wind tunnel testing improved our understanding of airstream behavior. This is why so many older vehicles had idiotically-ineffective spoilers or wings. Like this dumb beauty:
Here’s more CFD, comparing a NASCAR spoiler (top) to a NASCAR wing (bottom). These were both designed by competent people. Blue is turbulence. You can see how the red laminar airstream avoids the spoiler, but hugs the wing:
To summarize:
– Both wings and spoilers reduce up-lift at the tail of the vehicle, but use different mechanisms.
– Wings are airfoils designed to directly deflect air upwards and thus push the rear of the vehicle down. They generally add quite a bit of drag.
– Spoilers are barricades to undesirable flows, and thus are able to reshape airflow streams around the vehicle. This can help keep the rear of the vehicle down and decrease drag by changing the effective vehicle shape.
– You need computational fluid dynamics and/or wind tunnel testing to quantify spoiler/wing performance.
– Neither have any positive impact whatsoever on straight-line low-speed acceleration. Both are primarily intended to improve stability and cornering at high speeds.
