Bolt-on Rear Wing

[diss7]

I'd love an active wing for the track!

How would it engage?

I'm thinking it would be best to be full on all the time, unless throttle was down past half way, or something of that nature.

[phastafrican]

Originally Posted by diss7

I'd love an active wing for the track!

How would it engage?

I'm thinking it would be best to be full on all the time, unless throttle was down past half way, or something of that nature.

I've found that to be bad idea. Having the rear balance and downforce of a car change on throttle or brake application is a recipe for disaster.
For every instance where you put your foot down early, lift past your engagement point, or tap your brakes, you've introduced a new variable to compensate for.

Ask me how I know. -Arduino controlled wings are a bad idea on a racetrack!

[CSG Mike]

Originally Posted by Rosticles

That's at optimal angle of attack @ 100mph, with optimal airflow. It will never get this high. I also assume that the wing will have to shrink in size. It will stay on with the risers that will be built from aluminum honeycomb to reduce weight and still take the down-force.

Your wing design will introduce an unbelieveable amount of drag.

What are you using for CFD analysis?

Is the wing dedicated specifically toward this car? It seems you're using a pre-existing blade design. Why not tailor it specific to the FRS/BRZ body?

[smbstyle]

Originally Posted by phastafrican

I've found that to be bad idea. Having the rear balance and downforce of a car change on throttle or brake application is a recipe for disaster.
For every instance where you put your foot down early, lift past your engagement point, or tap your brakes, you've introduced a new variable to compensate for.

Ask me how I know. -Arduino controlled wings are a bad idea on a racetrack!

Probably a bad idea to have it controlled by throttle; such as opening up at 50% throttle, but I think push button to open the wing slot and at the time the brake is applied for the wing slot to close is fine (DRS anyone?)

[Vracer111]

I'm more concerned with the fence plate shapes you have on the diffuser design...which has bothered me ever time I've seen those images. Why unnecessarily slow the air down and increase pressure (which is the opposite of what a diffuser is designed to do)?

[Rosticles]

The diffuser doesn't look like that anymore. The first picture on the second set has the verticals flat now, but that is a different project.

Unless someone else knows of a loophole or a hidden rule, I don't think this wing will fit into any SCCA classes because of the mounting location. So I'm just going to build it for fun.

[Rosticles]

phastafrican; The control system is going to be an option I've built with my own custom custom non-arduino system that uses latter logic. It will have brake pedal, gas pedal, and G-senor inputs, and much more user friendly than arduino. Again it will be an option to the fixed position wing.

CSG Mike; The CD/CL is .0136 at optimal angle. This is very low. The aerfoil design is very similar to most "GT" style wings. I think most of the wings on the market are pretty crap and overpriced. They are more for show than function.

[CSG Mike]

It's very easy to get a high drag/downforce ratio in free-flowing air over just a blade.

What have you modeled this in to get your data? Without data, it's just another generic wing.


Since you haven't picked up on it, this is why I'm questioning you: your mounting solution introduces more drag than the wing will ever make, even at maximum AoA at the verge of stalling. I don't need to do any CFD to know that, simply due to the design.

[Vracer111]

Originally Posted by Rosticles

The diffuser doesn't look like that anymore. The first picture on the second set has the verticals flat now, but that is a different project.

Unless someone else knows of a loophole or a hidden rule, I don't think this wing will fit into any SCCA classes because of the mounting location. So I'm just going to build it for fun.

Simply put, wings are not allowed for SOLO II competition with production cars (even in Modified class), spoilers are what's allowed...

[Rosticles]

CSG Mike; The data is from table sets for the wing profile. It is a well documented profile and I did the calculations for a reynolds number of 100,000 and Ncrit=9, for sea level air. This gives a maximum Cl/Cd of 156.5 @ 6.25 degrees. This does not take into account the mounting solution and I understand it will have a constant drag coefficient that I have yet to calculate.

[phastafrican]

Sounds like you're committed to testing this out. Looking forward to the results. It's not a novel idea, but your approach appears innovative.

[chrisl]

Originally Posted by Rosticles

CSG Mike; The data is from table sets for the wing profile. It is a well documented profile and I did the calculations for a reynolds number of 100,000 and Ncrit=9, for sea level air. This gives a maximum Cl/Cd of 156.5 @ 6.25 degrees. This does not take into account the mounting solution and I understand it will have a constant drag coefficient that I have yet to calculate.

What kind of CL is the wing making at that angle, and does your calculation of drag include induced drag? That sounds unbelievably high for the aspect ratio and profile shown...

[Rosticles]

It does take into account induced drag. The optimum angle for down-force is around 13 degrees and the induced drag almost doubles the drag because of it. CL @ 12.5 degrees = 2.0391.

These numbers are optimal and with perfect, laminar airflow. The conditions will be much less optimal on the car, but It's good to start with a nice optimal design to get a better real world one.

[plucas]

This sounds like you are getting a head of yourself. Are you pulling these Cl and Cd numbers from a table? Also you state that these numbers are optimal with perfect laminar airflow. You know that most cars start to transition to turbulent flow at around 60mph. The airflow will not be laminar on this wing at 100mph. I bet that wing stalls at 13 degrees.

A wing will work very different on the back of a car than in free stream air. I have done extensive work with this using cfd. If you want some help with this, let me know. My background is an engineer specializing in fluid flow and heat transfer.