Bit of a novel:
With wing designs, the lift to drag ratio can be very different depending on the profile.. ie if it is a dual element wing, how effective are the end plates, how clean is the airflow etc. Part of the challenge of aero design is getting the best possible lift to drag ratio whilst getting the required downforce to make the lap time quicker.
In the case of my wing, at it's ideal angle of attack (AoA) I think the lift to drag ratio is 13. This means if its generating 130kgs (1300N) of downforce, it's only adding a drag of only 10kgs (or 100N). If I change the AoA to a steeper angle, the wing will get a ratio of 10 so it will generate 2000N of downforce but will double the drag to 200N. If I go past it's maximum AoA the wing stalls and generates massive drag with very little downforce (ie air brake)...
Items like the gurney flap and endplates change the efficiency of the wing slightly. The wickerbill/gurney flap is a must have... as it reduces drag, increases lift/downforce and also effectively raises the stall angle of the wing. The end plates stop the high pressure faster air underneath creeping around the ends of the wing to get to the low pressure air on top. An effective design keeps the airflow laminar and improves the downforce across the whole wing.
The 3D wing designs like the APR wings are so that the air that's travelling around the side of the car hit a wing section that has a higher AoA than the air that's sweeping down over the roof. The problem with an MX5 is that these 3D wings are more designed for Porsches and fastbacks rather than our hardtops. In our cars, the wind is fairly turbulent, so ideally you need to mount the wing high and up out of this air. I'm not sold that they are better on our cars than a standard 2D wing profile mounted in clean air.
With a DRS system, you generate maximum downforce and drag when braking and cornering and as soon as the car exits the corner and no longer needs traction the wing drops down to a lower downforce state with the lowest drag for straight line speed. F1 teams effectively do this by removing the second element of a dual element wing and making the wing a single element.
The idea of an air brake, is that you operate at a certain downforce level as default so that you get good cornering, and move the wing to stall when braking. Supercars do this so that it takes some load off the braking system. I don't think it necessarily improves lap times. It also only really works well at very high speeds.
To make the wing move dynamically under load requires the pivot point to be correct. I'd just place it slightly rear of the center of the wing section and design it so you can move this point easily if required (ie multiple holes) and then figure it out on the track. Even if you are generating 200kgs of downforce, if your pivot is central to the wing it will only a little force to move it.
here is a video showing how to make active aero with relatively cheap devices. Regardless, by the time it's all finished you are looking at a $1000 project I would expect.
https://www.youtube.com/watch?v=0Rprz9YVe1sIn this case, the RaceCapturePro could be replaced with an arduino board or something similar that has some IO. However, if you are going to be mucking around with active aero, you really need a decent data logger to track the effects... you'll also need GPS / G-force sensor and a controller with scripting to handle the logic side anyway. I'd suggest not reinventing this aspect and just go buy a RCP ($480 US) if you have the budget. You can build all this, however it is a project in itself.
This hooked up to a relay module and either a windscreen wiper motor, or headlight actuator from the pop-up lights and you can control a rear wing via either a manual input on the dash or some automated logic.
