MX5 Product/System Project Ideas

[Magpie]

http://aeromotions.com/products/ for active rear wing!

Yes cabin adjustable sway bars. The development would be in the end parts of the sway bars as it could be transferred to any car. Think about being able to swap bar sizes as well as in cabin adjustability.

[madjak]

With active wings, for an MX5 you actually want them in a DRS mode where the downforce is only active during braking and cornering and reducing drag down the straights. Don't do the air break style which suits more powerful cars. They can be made fairly cheaply via the use of the pop-up headlight actuators.

If you want to be really creative you can split the wing down the center and have it dual active, so that it loads up the rear on brakes but as soon as you turn in it releases the outer side to put load only on the inside wheels.

It's a shame most CAMS classes only allow fixed aero.

[Fraser.G]

Good point Lokiel, i was looking into that before. Like dynamic areo fro the mx5, building a rear wing that adjusts to the speed your going, however apparently they do not have any affect under 200kph. If anyone can tell me if hey have had success with a dynamic wing i would love to know about it.

[madjak]

http://aeromotions.com/products/ for active rear wing!

I don't think that wing looks very well designed. They claim that it's designed via airflow modelling and yet the end plates are drastically undersized for an efficient airflow. How are they going to stop the low pressure air bleeding around the end. In fact the end plates look like they were designed for looks rather than function and more closely match the elcheapo ebay wings than what an aero endplate should look like.

Anyway, yeah they have been done before, but not designed for an MX5 or designed with cheap / free components in mind which is the real engineering challenge IMO. A 3D printed wing, plus arduino controller, plus headlight actuator or two plus some simple logic and you have a sub $500 wing that would be as effective as that $6000 USD Aeromotions wing.

[madjak]

Good point Lokiel, i was looking into that before. Like dynamic areo fro the mx5, building a rear wing that adjusts to the speed your going, however apparently they do not have any affect under 200kph. If anyone can tell me if hey have had success with a dynamic wing i would love to know about it.

Terry from Flyin Miata runs an active aero braking wing on his LS1 targa miata. There are youtube clips of him testing it.

My wing certainly works and is effective at 120kph. You can go to NACA and find wing profiles that are more efficient at low speed which is what I did when I made mine. The lower speed wing profiles have more of a negative scallop on the bottom trailing edge and are generally thicker wing cross section. You want a wing that doesn't need massive angle to generate downforce so that the drag isn't increased too much.

That would be part of your project though... go research it, find a wing profile that matches your drag vs downforce vs speed requirement, design the structure and supports to take the loading, design the pivot point so that a low force actuator can move the wing, design end plates to keep the pressure zones in the correct spots without introducing extra drag etc etc. It's all interesting stuff and there are designs out there that you can borrow from so it doesn't have to be difficult.

[Magpie]

I think the engineering has to go into the mechanism to change the AOA. If you have 200kg of downforce the force required is to be understestimated, plus it needs to be very very fast unlike a wing flap control.

High speed electric worm drive? Do you want it to act as an air brake? If as a brake then going to vertical quick enough is another challenge. There are some low cost controllers like the Aurindo etc that could be programmed to do the logical part, however the mechanism to change the AOA needs the brains trust.

Or how about not only cabin sway bar but also the ability to manually change the rear wing. The mechanism would be similar to all 3.

[madjak]

here is a cool example - I think active aero done well:
https://www.youtube.com/watch?v=7wozSqFXitY

If it's a DRS system you actually don't want it to be too rapid... A very fast motion will separate the airflow and cause the wing to stall especially when moving from low drag to downforce mode. Ideally, you want the transitions to be as smooth as possible, taking around 1 second so that the downforce application is gradual and the airfow isn't disturbed. Ideally the best way is to engage the wing prior to braking, but you could only do this via pre-programmed GPS positioning or a manual user input to do this.

If the pivot of the wing is near to the center of downforce, you should only need to overcome 10kg's or so of downforce to move it. Ideally you'd want it to passively move to downforce position by default, in case there is an issue with the electrics. I think a headlight actuator would work fine as shown on Keith's car https://www.youtube.com/watch?v=gK5wDfDK2Lk... however it is only an on off switch (ie two positions). A more elegant solution would require a linear actuator but that would add $300 or so for a decent one.

Also I don't see an air brake as that effective... Really a track car will have brakes good enough to stop it from any speed. Tyre traction is the limiting factor. The wing adds downforce which is giving more traction to the rear making the brakes more effective. If using it as an air brake then really it's just acting like a parachute and is only add drag, rather than traction.

Here is a fun scenario.... imagine entering a really fast long sweeper, the wing is helping keep the tyres loaded adding 15kph to the corner speed. You tap the brakes to settle the car, the wing goes into stall and immediately reduces downforce, adding massive drag and lifting the front of the car in the process. Before you know it, the car is off the track making friends with a tyre barrier.

In terms of use, an on/off wing isn't that bad... it's either in downforce mode or low drag mode. There would rarely be a point where you'd need it halfway. I'd set it up based on a switch which is either full Auto (based on TPS or either brake application or high G loading), Manual (User hits a button to turn on or off) or Semi-Auto (combination of user engagement triggered entering or during a corner, wing moves to drs mode only when Gs are under a threshold and then back again either on user trigger, TPS release or on brake application, whichever is first). As with all these projects, half the work is in the mechanical engineering, the other half in the control systems and logic.

[Magpie]

Points noted, did not think about mid corner brake and having an air brake kick in.

This could be its own seperate topic.

[madjak]

yeah sorry, I've gone a little off topic... as you can see I've been thinking about this a little! One day I'll get onto building and testing it...

[Magpie]

So have I, however more time on the in cabin sway bar recently. Combing the sway bar and rear wing sounds, at least to me like utopia. Again thinking of a manual wing AOA like the sway bars would be a proof of concept then set about automating the wing. Using your GPS logic it would be possible to tweak sway bars and the wing based on position (and other sensors).

[Fraser.G]

Thank you madjak for saying what you said, i think i'm sold on making a dynamic wing for my car and having 3 possible settings, 1. Tucked into the boot-lid, 2. Lifted to to create downforce at high speeds, this stage could be actuated by a button in the cabin and 3. Tilting it to work as an air brake, this would be actuated by a button positioned behind the brake pedal. That way it only activates the wing when a certain amount of pressure on the pedal is induced.
The only thing that i'm now worried about now is if CAMS will allow me to use it on Trackdays. I'll have to do more research into it..

[madjak]

As long as the scrutineers check it off I don't think there is an issue running active aero. The CAMS classes like 2B and 2F won't let you run it however.

I use a Race Capture Pro datalogger from Autosports labs. It has onboard GPS and g-force / rotational sensors and also as a lot of I/O for controlling thinks like actuators. If your not making your own device, then purchasing something like that would be an ideal option as it has a custom scripting engine where you can write simple code to control the wing. You can also program in control buttons to enable it or hook into the TPS sensors, brake sensors etc.

Then really all you have to worry about is the mechanical design aspect plus some simple scripting.

Have a look at my DIY 3D printed wing for some ideas... It's pretty easy to make your own wing out of foam and fibreglass or go the high tech route with a 3D printer.

http://mx5cartalk.com/forum/viewtopic.php?f=57&t=68537&start=29

[Fraser.G]

Awesome thanks so much! Great work on your wing madjak it looks awesome and is very inspirational.
My final question is do you think there would be a market for an affordable and DIY dynamic wing for mx5's?
Also my first design idea consists of the wing being able to retract into the bootlid before 100kph and then extend to create downforce over 100kph. Then when I apply more than 50% pressure to the brake pedal this would activate a switch to tilt the wing so it can create wind resistance, slowing the car down. I imagine this was a DIY kit i would make as many parts as possible adjustable so the user can optimise the wing for their style of driving.