Aero Thread!

Rasputin · Postby **Rasputin** » Fri Aug 02, 2013 7:20 pm

As requested... Here it is!

This is where we discuss aerodynamics (Keep it related to the MX5. I'm sure we all DON'T want to read about Formula One cars here)

Ill get it started.

NitroDann raised an interesting point, about how the airdam should be flexible, while the splitter must retain rigidity and not flex (within a certain amount).

He also said that the lip should NOT be fixed to the splitter.

Why is this?

Dan.

Postby **NitroDann** » Fri Aug 02, 2013 7:29 pm

Starting with pics, because this thread is useless without them.

The dam needs to be flexible and not attached because the splitter gets more and more efficient the closer to the ground it gets until it touches the ground and effectively stalls (like how a planes wings can stall I suppose).

Starting with how a splitter works in conjunction with an air dam.. The air dam is hit with a LOT of air at 200kph, hundreds of kilograms of air hits it, and then has to go somewhere, with a splitter you are trapping the air that would otherwise go under the car and the very same pressure on the nose of the car which limits its top speed pushes down on the splitters surface and provides downforce.

You want the biggest from air dam you can run and the splitter directly below that to catch as much air as possible and push the splitter down as hard as possible.

For this reason the splitter will be close to the ground (because the air dam is very tall to achieve good downforce).

When the splitter is close to the ground it WILL hit things. if it is rigidly attached to the front bar, and the bar is not flexible you will break the bar at minimum, and if you break the splitter off and are braking (usually braking and ripple strips is when the splitter pushes on the ground) you will have no brakes as the front tyres ride on top of the splitter and skid, and then you crash.

Dann

M1474 · Postby **M1474** » Fri Aug 02, 2013 8:25 pm

Not the same as plane wings stalling.
The splitter stops working when it touches the ground because it is touching the ground.
The force is just applied to the ground by the splitter not through the tyres.

Postby **NitroDann** » Fri Aug 02, 2013 8:28 pm

Thanks, well explained. of course it still pushes on the car as soon as it stops touching the ground which is why you hear splitters flap flap flap away when they touch.

Dann

lightyear · Postby **lightyear** » Fri Aug 02, 2013 9:03 pm

Aero is for people that can't build engines....

narita · Postby **narita** » Fri Aug 02, 2013 9:08 pm

narita · Postby **narita** » Fri Aug 02, 2013 9:09 pm

also does anyone know who makes that carbon boot? i havent seen it before...

lightyear · Postby **lightyear** » Fri Aug 02, 2013 9:13 pm

I had a bit of a play with aero. Not doing it at the moment as I want to just leave the car alone while I build the new house. So keeping the car in modified class setup.
But I found that it is much easier getting rear down force. So my suggestion is make as much downforce via big splitter/front air dam. And adjust the rear wing to suit. With my triple element wing at 0 degrees it made so much downforce the car would under steer from as little as 80km/h. And it needs to be mounted to he chassis.

Regie · Postby **Regie** » Fri Aug 02, 2013 9:15 pm

narita wrote:also does anyone know who makes that carbon boot? i havent seen it before...

photoshop makes it

16bit · Postby **16bit** » Fri Aug 02, 2013 10:11 pm

lightyear wrote:I had a bit of a play with aero. Not doing it at the moment as I want to just leave the car alone while I build the new house. So keeping the car in modified class setup.
But I found that it is much easier getting rear down force. So my suggestion is make as much downforce via big splitter/front air dam. And adjust the rear wing to suit. With my triple element wing at 0 degrees it made so much downforce the car would under steer from as little as 80km/h. And it needs to be mounted to he chassis.

qft.

i would add to this by attempting to reduce lift at the front end as well. a well vented hood will work towards this as well as improve cooling in the engine bay

a front diffuser would be very difficult to make properly which is where a lot of non formula (prototypes etc) cars get front downforce. but if you could get one to work there could be some good gains there.

another place to try to reduce lift at the front end is the front fenders. if you can vent these efficiently there is another area of gain (or reduced loss as it is). if you are clever about it you may be able to reduce drag along the side of the car and also feed air to the rear of the car though i doubt it. ferrari are good at this on road cars but they have a wind tunnel and no one here does.

i have no idea what sort of lift these areas are causing so can't tell how much potential gain there might be but it all adds up.

if you are looking for ideas look no further than time attack cars. these things follow little to no rules so will often have a no holds bared approach to aero that can be obvious to follow what they are doing. nemo is probably the car to be looking at right now.

it produces in the region of 5000lbs of downforce (about twice that of a modern f1 car). which is very similar to the level of downforce that the group b lemans prototypes where getting in their high downforce setups back in the 70's. thats before they took all the fun out of the aero.

Rasputin · Postby **Rasputin** » Fri Aug 02, 2013 10:46 pm

There's a nice hood on Gomiata.com with vents in it. Would work wonders with some bonnet spacers too!

Kevlar/carbon for $650. Shipping would be a killer.

Also. I think flyin miata does a carbon boot too. I've seen it on one of those sites.

16bit · Postby **16bit** » Fri Aug 02, 2013 10:53 pm

do you mean the spacers that raise the hood at its hinges closest to the windscreen?

if so that is a bad idea.

there is a high pressure area that builds up at the base of the windscreen that would force air into the gap with those hood raisers.

they pretty much only work below 30kph.

Postby **NitroDann** » Fri Aug 02, 2013 11:32 pm

Lightyear and 16bit are giving good info based on my knowledge, thanks guys.

I never realised that nemo made 500lb, at what speed !?

Dann

little decks · Postby **little decks** » Fri Aug 02, 2013 11:58 pm

Like with any sports car its always harder to get front end downforce, as you can see from the WTAC cars they have some crazy front end set ups (namely NEMO and the MCA 200SX) trying to get the front down, one thing that seems to be really effective is the vented bonnet that draws air through a nicely sealed duct with the air pushing through low v-mount cooler set ups, these are fantastic because you get vacuum drawing the hot air away from the coolers and get serious downforce... from what i understand it works as close to a diffuser on the front end as you can get.

What i would be interested in learning a bit about is aero balance when changing direction, that gets fascinating

Dweezle · Postby **Dweezle** » Sat Aug 03, 2013 12:10 am

I know this sounds stupid, but wouldn't mounting a huge wing on the front of the car, up high in clean air provide the same down force as on the rear?
It would look ridiculous but would it work?

Or does it need the velocity from traveling over the car?

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