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Thread: DIY DRS -- will moving my wing help or not?

  1. #1
    enjoys driving fast Jack Olsen's Avatar
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    May 2008
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    Default DIY DRS -- will moving my wing help or not?

    I've relegated myself to a very straightforward project for the past several years -- simply trying to lower my lap times at Willow Springs. Not the most exciting goal, but it fits my schedule and budget and my tendency to tinker around on little, low-cost projects.

    I've got a wing that I made out of beer-cooler foam. It's crude, ugly, and -- at a track with as many high-speed corners as Willow -- also effective. But there are trade-offs with a wing -- one of which is that it adds drag.

    How much? I don't really know. It might not be significant. But I came up with an idea for a simple way to reduce my wing's angle of attack. My idea was to move the front of the wing up instead of moving the back down, since a failure of the control mechanism would then have the wing collapse back to the safer high-downforce position instead of the rear end flopping around and all the downforce gone. I thought the lightest (and least failure-prone) way to control it would be with a pedal and a set of cables.

    Boy, was I wrong. As simple as it was to move the wing at rest, it became just about impossible at speeds as low as 60 mph. Whatever 'drivetrain loss' is involved in a 10-foot, Y-shaped throttle cable (and a lever to change pulling to pushing) turned out to be more significant than I thought. Also: the force generated by a wing is centered up front on an airfoil shape, generally (I'm told) about 1/4 of the way back from the leading edge. So, back to the srawing board.

    There's a Miata guy who has made his rear wing active as an air brake. He uses headlight pop-up motors, and I was surprised at how well they work at moving the wing, even (in this clip) at 122 mph.

    So I picked up a pair of motors and wired in a steering-wheel switch. I moved the pivot point for the wing's mount to where the majority of the force is. The motors hold the wing in a fixed posiiton when they're not turning, but the control is in the rear now, which means one of my safety concerns is unaddressed. It's still got a dead man component to it. The wing moves to the low-drag position only as long as I'm holding the button down. As soon as I let go, the wing motors back to the high-downforce position. I've got two ways to confirm that the wing is where I think it is. There's a cabin light that indicates when the wing is 'in motion.' And then there's also a new red stripe on the bottom of the wing. When the wing is in the low-drag position, I can see the red stripe in my rear view. When it's in the high-downforce position, no red.

    Here's my first test.

    Next up is to see if the motors crap out at higher speeds. Who's that guy on the 405 with the big wing that keeps moving? That'd be me.

    Will it make a difference at Willow? I'm still kind of skeptical, but we'll see.

  2. #2
    Track Whore Pure EvoIX's Avatar
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    Cool DIY. I posted a comment on your youtube video about how would you upshift when you have your left foot on the "DRS" pedal. I joked about left foot heel toeing to upshift. :P That was for the first video. And with pedal actuated DRS, you will be fighting the downforce when pushing the pedal down right? Like the pedal will get heavier and heavier the faster you go?

    I didn't see you made a changed and made it activate via button, which took care of that issue. Very cool!!!
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  3. #3
    I wanna go fast! thepass's Avatar
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    Realllly cool project. I'm really interested to see what your results are after testing - if reducing the aoa on the wing can make a worthwhile gain in top speed on a production car with modest horsepower. My guess is that it will.

    My first thought when seeing Keith's implementation was that those motors weren't in a good location, and a longer actuating rod with motor mounted out of the airflow would be a lot better, which is exactly what you did. Bravo!
    Ryan Passey
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  4. #4
    Administrator ucfbrett's Avatar
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    Seeing this makes me want to build something. Anything.

  5. #5
    Faster than Oli jimt's Avatar
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    Here you go Bree:

    Build a race car!
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  6. #6
    Senior Member fatbillybob's Avatar
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    By your description not sure how you are set-up. But if you want a default safe that would be max wing AOA setting you run and some other AOA for least drag (and less downforce). Therefore if I was doing this I would have the wing pivot at the front attachment point and connect the rear to dampers that default pushing the wing to max AOA like hood struts for a car (motors cold assist) but that would act in the safest mode. Then the motors could pull to minimum AOA for homebrew DRS. If there is too much force for a single element wing against the hood strut default then you could overcome that with a dual element wing like the F1 rear wings.

  7. #7
    BMW Master bawareca's Avatar
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    I am having this idea for a long time,but no time whatsoever.I am more interested in the airbrake function that in the drag reduction. My plan is to use hydraulic actuator cylinders and hydraulic pump from a convertible car-Mercedes,Saab or even Audi(joke,no VAG parts in any of my cars,ever ).The hydraulic actuators have a decent power to lift stuff.The pump especially will take away some lightness from the car and the actuation speed may not be that quick,but the system should be strong enough and reliable.

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