Moss Miata - Adjustable Wing Overview
Does it work, or is supposed to just look "racy"?
When it comes to racing, every second counts. An adjustable wing can give you that edge to achieve faster lap times.By reducing lift and increasing downforce, you can gain extra traction during high speed cornering. And because this wing is made from carbon fiber and aluminum, its light weight won't bog down a typical horsepower-starved Miata.
Although adjustable wings aren't specifically a suspension component, they play a crucial role to the handling characteristics of a car. By adjusting the angle of attack on an adjustable wing, you can dial in the amount of downforce for better car control. This allows your car to have more or less oversteer characteristics, giving you additional control to tune the rear traction of your Miata.
Of course, this piece also looks awesome. It was built first and foremost for performance but APR Performance did a great job making sure the gloss coat over the carbon fiber is incredibly smooth and that the aluminum risers have a perfect finish.
The Engineering Behind This Wing
Here come the acronyms: CFD, lbf, N, AOA, mph...
APR Performance put serious engineering behind the design of this wing. First, they used Computational Fluid Dynamics (CFD) software to test their designs. This software simulates data that would be found in wind-tunnel testing, saving time and money in design. CFD is s sub-discipline of fluid dynamics, and has been used first in aircraft design and more recently in motorsports like Formula 1. APR ran tests to compute Downforce vs. Angle Of Attack (AOA) vs. Speed and Drag vs. AOA vs. Speed.
The following image illustrates both the pressure distribution and streamlines associated with the airfoil. Free-stream air is shown at 73.85 meters/second (m/s), which is approximately 165 mph if 1 m/s = 2.237 mph.
This wing was designed to generate downforce even with the AOA set at zero. But how much downforce is generated, and at what speed (mph)? How does increasing the AOA affect the downforce - and also, how much does it increase drag? Drag slows the car down, but sometimes that drag is negligible because the associated high amount of downforce is preferred. However, at some point no matter how much angle you dial into the wing, the downforce amount plateaus (more can't be generated) and drag has increased so much so that's it's detrimental. We'll discuss how to set the wing for your needs in a moment.
Check the data (provided by APR): At zero degrees AOA and at 80 mph this wing generates 343 Newtons of downforce. Factoring in the drag of 37 N, the downforce-to-drag ratio is 9.3. Five degrees AOA at 80 mph - 398 N downforce and 49 N drag, for a ratio of 8.1. Ten degrees AOA at 80 mph - 442 N downforce and 61 N drag, for a ratio of 7.2. Finally, fifteen degrees AOA at 80 mph - 488 N downforce and 73 N drag, for a ratio of 6.7. Downforce continues to increase, but so does drag, and at an even greater rate - a rate of diminishing returns.
Adjusting The Wing
Take baby-steps until you know how it affects your Miata's handling.
With so many different possible upgrades our customers may have done to their Miatas, and so many different track/road conditions, and weather conditions, it's impossible for us to list when/where/why you should set this angle or that at any given track or twisty road. What we'll suggest is to set your wing at zero angle, and show you how to do that - and also outline how more drastic angles will affect your Miata. This initial testing should also be done in a safe place like an open track event. Also don't change other factors of your suspension (adjusting shocks or sway bars if installed, or even tire pressures) while you're experimenting with your wing. Remember, the wing is now a suspension component, and if you adjust other components you'll get "bad" data about your wing. When you do adjust the wing, make small changes at first.
A perfect tool exists for measuring angles - a digital angle indicator. Some higher-end digital levels have this gauge. If you don't have this tool, but you do have a level, park your Miata on a level surface and place the level front-to-back across the center of the wing. Turn the turnbuckles to shorten or lengthen the adjustment arms until the level shows center bubble, and make sure the turnbuckles are at the same lengths - you don't want one side of the wing to be higher. Make sure you count the threads on the turnbuckles and make a note of how many you see - this will be your zero degree set. If you don't have a level, set something long and straight front-to-back across the center of the wing, like a ruler or a short 2x4. Proceed to turn the turnbuckles as outlined above until your "eyeball" shows the ruler is level (making sure you're parked on a level surface).
Now take a couple of laps "at speed", that is over 55 mph. If your Miata tends to understeer (feels "tight") in turns, we recommend setting the angle a higher than zero, that is positive - meaning the front edge of the wing will be higher than the rear edge. If it tends to oversteer (feels "loose") in turns, we recommend setting the angle lower than zero, that is negative. To set this adjustment, begin with one full turn of each turnbuckle. Take a couple of more laps at speed to see if your adjustment has been enough. You're now dialing your Miata in to a "neutral" suspension set-up - or if you're a more experienced driver perhaps you prefer a little bit of over- or understeer. Remember to make small adjustments and test after each one. And don't forget that if you change other suspension components, you may need to readjust your wing.
Carbon Fiber Adjustable Wing by APR Performance