How to raise a spoiler via microcontroller

[Sevs753]

So I'm working with a friend on an airbrake for his car. I don't think it would be useful for his driving but the nerd in me wants to make an airbrake. I have pretty much everything figured out except what I need to use to raise the spoiler. I've heard mention of using a "pneumatic actuator" but I'm not sure if that's what i really need. I need something that can lift a spoiler up and lower it based commands from a micro controller (likely and arduino). I don't want something that shoots out as fast as it can as far as it can. I'd like to be able to control the speed at which the spoiler is raised/lowered and how far it can extend. Any help would be appreciated.

 

[CrzRsn]

So I'm working with a friend on an airbrake for his car. I don't think it would be useful for his driving but the nerd in me wants to make an airbrake. I have pretty much everything figured out except what I need to use to raise the spoiler. I've heard mention of using a "pneumatic actuator" but I'm not sure if that's what i really need. I need something that can lift a spoiler up and lower it based commands from a micro controller (likely and arduino). I don't want something that shoots out as fast as it can as far as it can. I'd like to be able to control the speed at which the spoiler is raised/lowered and how far it can extend. Any help would be appreciated.

You might want to look into something along the lines of a simple linear actuator.

[video=youtube;EAdxw-Rg6bQ]http://www.youtube.com/watch?v=EAdxw-Rg6bQ[/video]

You can choose the stroke length and speed you need on their website. http://www.firgelliauto.com/show_info.php?page_id=35

McMaster also has a bunch of lower cost options. Definetly worth a look to see if you can find something that finds your size and usage requirements. http://www.mcmaster.com/#catalog/119/990

 

[Bretton Woods]

What sort of car is it?

 

[Sevs753]

You might want to look into something along the lines of a simple linear actuator.

You can choose the stroke length and speed you need on their website. http://www.firgelliauto.com/show_info.php?page_id=35

McMaster also has a bunch of lower cost options. Definetly worth a look to see if you can find something that finds your size and usage requirements. http://www.mcmaster.com/#catalog/119/990

Thanks! I'll take a look at those links.

What sort of car is it?

2011 Ford Mustang.

 

[Bretton Woods]

May I suggest you begin with choosing an aerofoil to use as the spoiler/wing. From that you can calculate ballpark load figures and torque moments the wing (I'm just going to call it that, because that's where I've had experience) will generate.

Only once you know that the wing will generate x kg of downforce and x Nm or torque can you start designing mounts and actuation mechanisms.

I suggest looking up a program called 'JavaFoil'. You can play with that and it will spit out rough figures for varying profiles, velocities and angles of attack. The program's calculations break down at high AoAs, but you can get a ball park figure for the drag your chosen profile will generate in aerobraking mode. Just set the wing to a high negative AoA.

 

[CrzRsn]

Thanks! I'll take a look at those links.

Oh, and you probably want to find something waterproof, unless this is just an experiment and will be taken off the car. Some of the lighter duty solenoids don't like water.

 

[Sevs753]

May I suggest you begin with choosing an aerofoil to use as the spoiler/wing. From that you can calculate ballpark load figures and torque moments the wing (I'm just going to call it that, because that's where I've had experience) will generate.

Only once you know that the wing will generate x kg of downforce and x Nm or torque can you start designing mounts and actuation mechanisms.

I suggest looking up a program called 'JavaFoil'. You can play with that and it will spit out rough figures for varying profiles, velocities and angles of attack. The program's calculations break down at high AoAs, but you can get a ball park figure for the drag your chosen profile will generate in aerobraking mode. Just set the wing to a high negative AoA.

Thanks! I'll definitely take a look at Javafoil. I think it's a bit 'overkill' for what my friend wants though. When discussing it, He told me that he wants exactly what is shown in the video below. He has that same spoiler but fixed to his trunk lid. So for V1.0, I just want to get the spoiler rotating up. In the future, I do want to make a system that will raise the spoiler after a certain speed and act as an airbrake a la Bugatti Veyron. At that point, I will definitely be taking into account drag and downforce.

 

[Bretton Woods]

Are you planning on cutting into the trunk lid or mounting thing to the top of?

 

[Sevs753]

Are you planning on cutting into the trunk lid or mounting thing to the top of?

Cutting. I'm going to be going to a junkyard to pick up a random trunk + spoiler to develop and test the system before I do any cutting and such. I don't want to have to buy my friend a new trunk lid.

 

[Bretton Woods]

That looks quite simple to implement. He isn't using pneumatic rams.

I suspect that it's simply a high torque electric motor mounted to the bottom the the trunk lid.

 

[GRtak]

If I remember correctly, the Veyron uses hydraulics for it's fin, but that is probably for the excessive speed it is capable of running.

 

[93Flareside]

What about R/C servos?

 

[Sevs753]

That looks quite simple to implement. He isn't using pneumatic rams.

I suspect that it's simply a high torque electric motor mounted to the bottom the the trunk lid.

What about R/C servos?

Those seem like the best option for what my friend wants. I don't really want to deal with extra components needed for hydraulics or air. Electric actuators also seem to be stupid expensive so that rules them out. Thanks for the input!

 

[GRtak]

I highly doubt RC servos are going to be able to handle the forces involved.

 

[jibduh]

You could always go for a simple (continuous rotation) servo and rig your gearing to that. To that point, finding stepper motors should be easy. Keep in mind, that this kind of thing is more for tunable downforce than air braking as you'll be picking your two points on the power/speed/cost triangle

 

[Sevs753]

You could always go for a simple (continuous rotation) servo and rig your gearing to that. To that point, finding stepper motors should be easy. Keep in mind, that this kind of thing is more for tunable downforce than air braking as you'll be picking your two points on the power/speed/cost triangle

Thats the kind of thing I'm looking for now. I don't think the actual effectiveness as an airbrake isn't an issue. I'm pretty sure he wants it for the novelty of it. I just like making stuff like this which is why I'm doing it.

 

[jibduh]

Skipping the servos and microcontroller, a solenoid or some vacuum lines will give you a flapping wing in no time! (also, something probably worthy of carbage. Or LeMons)

 

[Sevs753]

Skipping the servos and microcontroller, a solenoid or some vacuum lines will give you a flapping wing in no time! (also, something probably worthy of carbage. Or LeMons)

I am looking for something electronic because I dont want to deal with vacuum or hydraulic lines. I'm just looking to copy the functionality of the airbrake on the mustang in the video I posted above. My friend has that exact spoiler and he wants to to move up and down like in the video.

 

[Matt2000]

I'm guessing the airbrake in that video is operated by a pair of actuators inside the top of the lid. Some CNC cut brackets for a conventional (stock? Anything you tilt to vertical is going to have some effect) spoiler with a pivot below the lid to transfer the movement to the spoiler.

Another cheaper option would be to have a custom 'lip' spoiler and a stepper/worm drive mechanism mounted on a plate bolted to the lid. That would be quite ugly but wouldn't need holes cutting.

Just my thoughts.

 

[jibduh]

If all you want is 2 positions, you can do away with the stepper motor and just go for a torquey motor and some microswitches, again with the gearing, round, worm, chain, or linkage. whatever's your fancy.

Personally, for the air brake, I'd go for 2 pivots, one fixed length bar at the front with an upper pivot, and the one at the rear angled car forward to avoid binding and add structure that actuates upwards either by a worm gear or a strut bound to a driven length of chain tucked away under the sheet metal.