Nugi
Reader
9/27/19 10:25 a.m.
Ok, someone talk me down.
My rat crx is about to lose about 60lbs from the rear hatch (lexan!), and its already a bit front heavy after an engine and transmission swap. Previous crx's behaved badly over 80mph due to short wheelbase and lack of rear wheel pressure.
Enter online classifieds... some guy a town over has a legit 30x60 stainless steel semi wing. This thing must weight 100lbs. Huge aerofoil shape with endcaps. Its so dumb it feels right from a bosozuku standpoint.
Question, other than obliterating all my weight savings, rear visibility and raising my roll center, will this do anything useful for stability at 50-100mph speeds? Not concerned about track times... pretty sure anything below 50mph is just 'add lightness and tires' territory.
Nugi
Reader
9/27/19 10:32 a.m.
Now imagine that on a wild 2nd gen crx. Thinkin of dragster style mounts, but might do tallbois too... I got plenty of scrap metal to fab mounts from.
Maybe similar to
it'll do 3 things for sure. I don't know if 1 and 2 will have a larger effect than 3 or vice versa.
1. It will certainly add rear downforce. Just based on size alone, even if the coefficient of downforce is small that wing has a large surface area so it will make downforce.
2. it will add aerodynamic stability. If you look at the car from a side view angle, you are adding a non-trivial area behind the center of mass of the car. That means when the wind pushes from the side, the wind will push the back more than the front, and that turns you into the wind which is a stable state. This is why high speed cars often have vertical fins at the back (and why the fins on a rocket or arrow are at the back).
3. It will raise your center of mass, especially at the rear.
Robbie has pretty much nailed the major items. Mount it ~4 inches above the trailing edge of the hatch and connect the ends of the wing to the sides of the car. This will amplify the rear downforce (by leverage) effectively create a diffuser behind the car.
Front traction may be impacted on higher speed sections...
May I recommend a known working foil and wáng for this instead of a dummy thicc truck wang?
What will this be used for? Auto-x, track, street cred, etc?
Others have already touched on the pros/cons on this idea. However, the coefficient is unknown so you won't know how much drag you'll be adding for the given lift. It could be stalled and you might not even know it. All of that....... depends though.
Oddly enough Johnny fabbed up a setup like this with a wáng on the shop NA. I only have a horrible pic of it, I'll request for some more.
In regards to ballast, I think it's neat you're trying to get one piece to do two jobs(aero/ballast). But I believe there's better options for your car to get weight out back, maybe a cool-suit cooler or fire suppression bottle? On the cheaper route, actual weights or maybe even a spare tire?
Seriously though, get us measurements on the setup and we will build it.
Whatever happens, the image will be sure be used in countless memes.
That's enough reason, alone.