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View Full Version : Possible to disable RS5 automatic spoiler?



cloudripper
06-30-2014, 11:59 AM
Hey all - Do any of you know if it's possible to disable the RS5 automatic spoiler from automatically deploying at 75mph? Thanks!

essfour
06-30-2014, 12:00 PM
probably just pull the fuse... but why?

Stubek
06-30-2014, 12:09 PM
probably just pull the fuse... but why?

Its a tell tale sign you are speeding.

Fourplay
06-30-2014, 12:12 PM
Its a tell tale sign you are speeding.

The chances of a cop driving down the road and pulling you over because he just happens to know the spoiler deploys at 75 mph on the RS5 is pretty damn unlikely. Not to mention it would never hold up in court.

rlarsen462
06-30-2014, 12:22 PM
The chances of a cop driving down the road and pulling you over because he just happens to know the spoiler deploys at 75 mph on the RS5 is pretty damn unlikely. Not to mention it would never hold up in court.

This, plus I've read the RS5 does actually need the spoiler for stability unlike the A/S 5 due to different undercarriage aerodynamics. May be rumor though.

battlestar
06-30-2014, 01:01 PM
you could disable it in vcds iirc, but like everyone said, its probably not smart to do it, and I don't see them stopping you because of it, esp since you can deploy it manually

rasetsu
06-30-2014, 04:12 PM
How many cops even know that it deploys at 75 mph?

Beast
06-30-2014, 07:43 PM
How many cops even know that it deploys at 75 mph?

possibly only cops that are audi fans?

Not A Good Idea
07-01-2014, 10:32 AM
possibly only cops that are audi fans?

at which point he shouldnt be pulling you over.. [:D]

superswiss
07-01-2014, 11:24 PM
This, plus I've read the RS5 does actually need the spoiler for stability unlike the A/S 5 due to different undercarriage aerodynamics. May be rumor though.

This appears to be correct. When I inquired about the rear wing, Audi told me it should not be lowered above 85 mph or the car gets squirrelly. The RS5 has reworked aerodynamics and the wing is a functional aspect of it. As you said, the undercarriage aerodynamics is different, and there are ducts that divert more air to the brakes and transmission for better cooling.

Zee Dgerman
07-02-2014, 12:06 AM
as many stated... getting a ticket because your spoiler was raised without actual laser or radar speed confirmation would never hold up in court and be easily contestable.

LINDW4LL
07-02-2014, 12:12 AM
It's just marketing jargon. You have base-model German luxury cars, most of which can easily and safely handle 155 mph in stock form on the Autobahn. 95% of these cars are not equipped with spoilers or any other aero. On top of that, you have a B8 S4 which is capable of 190+ MPH with only a remap, again with no aero.


Audi saying that the RS will get "squirrely" over 85mph is truly just marketing BS to support something that in reality is just supposed to look (and BE) cool.

JamesRS5
07-02-2014, 05:33 AM
It's just marketing jargon. You have base-model German luxury cars, most of which can easily and safely handle 155 mph in stock form on the Autobahn. 95% of these cars are not equipped with spoilers or any other aero. On top of that, you have a B8 S4 which is capable of 190+ MPH with only a remap, again with no aero.


Audi saying that the RS will get "squirrely" over 85mph is truly just marketing BS to support something that in reality is just supposed to look (and BE) cool.

I'm sure they are all saying the same on the Bugatti Veyron forum [rolleyes]

For a car which struggles with weight, I doubt they would add a retractable spoiler just because it looks cool.

essfour
07-02-2014, 06:59 AM
It's just marketing jargon. You have base-model German luxury cars, most of which can easily and safely handle 155 mph in stock form on the Autobahn. 95% of these cars are not equipped with spoilers or any other aero. On top of that, you have a B8 S4 which is capable of 190+ MPH with only a remap, again with no aero.


Audi saying that the RS will get "squirrely" over 85mph is truly just marketing BS to support something that in reality is just supposed to look (and BE) cool.

And something that just adds weight. The RS5 would be just fine without that little spoiler. I guarantee that if i replaced my trunk lid with the S5's and drove my car at high speeds that I wouldnt notice a difference at all. Only West West is capable of noticing these differences.

superswiss
07-02-2014, 10:44 AM
It's easy to test if you feel adventures. Just pull the fuse or manually lower it and go on some high speed runs in various conditions.

I do actually have some experience driving lesser B8 platform Audi's with and w/o sport suspension on the Autobahn and can compare it to driving the RS5 on the Autobahn. Most of them are fine at triple digit speeds going straight in dry conditions. It gets interesting if you try to maintain these speeds and the wind is blowing from the side or you are going into bends and/or it's raining. The one thing that continued to impress me during my ED trip was how glued to the road the RS5 felt at 174mph. None of the other cars I drove during prior trips could match that even at lower speeds. I spent most of my time in windy/rainy Northern Germany and the RS was unfaced by wind gusts, rain and uneven road surfaces. It just drives on rails all the way up to 174 mph. I don't really care what makes the difference, but the combination seems to work.

LINDW4LL
07-02-2014, 10:53 AM
I'm sure they are all saying the same on the Bugatti Veyron forum [rolleyes]

For a car which struggles with weight, I doubt they would add a retractable spoiler just because it looks cool.
It's quite probable that it may help a very small amount in reducing lift at higher speeds. But the difference I would guess is minute, and it is mainly for looks.

Also, look at how big the Veyron's spoiler is. That is a true active spoiler. The same can be said for the McLaren P1, MP4, Huayra, etc... Also, keep in mind that the Bugatti's spoiler deploys 8+ inches above the surface of the car. It also acts as an air-brake, flipping up at a 55-degree angle, and adding .6Gs of deceleration under braking.


https://farm8.staticflickr.com/7346/9185240019_4a5640744e_h.jpg

https://farm8.staticflickr.com/7449/12517464683_14bbd7496e_b.jpg

cloudripper
07-02-2014, 11:36 AM
Thanks all for the inputs so far. Agree that cops pulling you over just for raised spoiler is a non-issue. I was just curious if anyone played with VAGCOM settings and managed to change the deployment speed from 75 or make it manual only.

JamesRS5
07-02-2014, 12:17 PM
The Bugatti and McLaren both use a wing/spoiler to increase aerodynamic downforce, both those cars use active spoilers which alter position with speed. Interestingly it's almost fully stowed for high speed.
The theory behind the RS5 spoiler is more to reduce drag and turbulent air by delaying air separation from the rear of the car.
It's all about Bernoulli's principle, a low pressure is created at the rear of the car which will actually slow the car down. I'm pretty sure the RS5 employs a rear spoiler to make it more efficient at high speed and to achieve a higher speed through less drag than to make it more stable.

LINDW4LL
07-02-2014, 12:42 PM
I'm pretty sure the RS5 employs a rear spoiler to make it more efficient at high speed and to achieve a higher speed through less drag than to make it more stable.

You are correct on all points. The 991 turbo uses a similar rear spoiler for efficiency at speed, I believe.

I have heard many people on this board say the RS 5's spoiler is necessary or the car "wont be planted" or "will get squirrely" at speed (as low as 85mph) without the spoiler engaged. This is what I was countering.

Brava
07-02-2014, 10:42 PM
My owner manual says to service the car if there is spoiler malfunction and to avoid driving at high speeds under such circumstance.

stefdds
07-26-2015, 10:31 AM
http://www.ccjdigital.com/files/2013/11/ATDynamics-TrailerTail.jpg

Greetings, I recently did this mod on my 2009 S5 so I have been perusing it with more interest than the casual owner. James RS5 has it: it has nothing to do with down-force, but everything to do with efficiency. Its a "defuser" , if you look up the principle noted above in James's post (#18) it is to prevent the air currents from gathering directly behind the surface of the car and "pulling" on the car (neg. pressure). The link of this semi trailer pic demonstrates this on a much larger scale, but it is the same principle (its all about the drag created by the air currents coming around behind the object). With the element up the air currents join together much further behind the vehicle. The object/car has traveled several feet from the gathered air currents and "escaped" the pulling or drawing effects of this neg. pressure. NASCAR used to do this with their areo packages: the leading cars team-mate would would pull up behind the other car and actually touch (they placed grease on the leading cars bumper) , the trailing car acted as the defuser and the two cars together actually went faster - because the leading car is more efficient. (similar concept)
The link with the semi trailer defusers is not as attractive as our deck lid elements, but they are doing the same thing!
Thank you for the discussion!

stefdds
07-26-2015, 10:43 AM
http://www.capinc.com/wp-content/uploads/2011/11/air-flow-analysis-comparison.jpg

hears another example illustration to make the point.

superswiss
07-26-2015, 04:45 PM
Since you woke this thread from the dead, allow me to point out that there is a difference between a spoiler and a wing. A spoiler is fully attached and directs airflow over it to reduce drag and air turbulence. A wing on the other hand is detached, allowing air to flow above and below it at different speeds creating lift in case of an airplane and downforce in case of a car. Notice that below 75 mph the shape of the RS5 trunk lid forms a spoiler, but above 75 mph it deploys a wing.

superswiss
07-27-2015, 12:56 AM
Got a little more curious about this subject and found the following article that explains it very well I think. After reading it, I'm not sure the RS5 "spoiler" qualifies as a wing, even though it is clearly shaped to direct air upward. However, whatever we wanna call it, the purpose of it is not so much to create additional downforce, but to reduce lift.

http://oppositelock.kinja.com/wings-spoilers-youre-probably-doing-it-wrong-1665312667

The concept is illustrated in this wind tunnel smoke trace of a Porsche. It cleanly redirects the airflow from a downward direction, creating undesirable lift, to horizontal direction, no lift.

http://i.kinja-img.com/gawker-media/image/upload/s--8IZF2qhk--/c_fit,fl_progressive,q_80,w_636/wutenlarejy6h424vcex.jpg

Stubek
07-27-2015, 07:16 AM
The chances of a cop driving down the road and pulling you over because he just happens to know the spoiler deploys at 75 mph on the RS5 is pretty damn unlikely. Not to mention it would never hold up in court.
Nope would not hold up in court, but cop could see the spoiler deployed and decide you are the car to use radar on or pace for a half mile or so.


How many cops even know that it deploys at 75 mph?
you would be surprised, most cops I know are gear heads, maybe not all Audi fans, but gear heads so they read the magazines and see things like this in an article. I also know three officers in Silicon Valley who are on Audizine, so there are some.

JamesRS5
07-27-2015, 07:49 AM
Oh hello, this thread is back.

This is an interesting topic and had me wondering again the other day as I watched the spoiler pop out.

Superswiss: I agree with you on most points, however, you say you're not sure the RS5 "spoiler" qualifies as a wing even though it's clearly shaped to direct air upwards.

A wing doesn't direct air upwards; for the wing to provide downforce or lift in a downwards direction, it should be mounted the opposite way to an aircraft wing, it's not directing air, it's causing a lower pressure over the longer surface area of the arched side of the wing. Because the air has further to travel it is speeding up (the Venturi effect), the air speeding up causes a lower pressure on the side of the wing than the other so the inverted rear wing on a car is actually sucking the car down rather than pushing air up.
The greater the angle of attack into the airflow, the greater the lift produced, a bit like planes putting down flaps when they come in to land, they can fly slower with more lift generated because they have effectively increased the angle of attack of the wing.

Looking at the Porsche picture, you can see the boundary layer on the car is a layer of dead air, there's not much going under the rear wing at all and it's allowing the air to pass over the car and separate cleanly off the rear so causing no drag and is definitely preventing the cars wing like profile from causing lift.
The underside of the RS5's spoiler isn't aerodynamically shaped so I can't see it acting like a wing. As the speed increases that boundary layer will possibly get thicker over the rear of the car as the air tries to separate from the car so could the spoiler be lifting to still be effective at doing what the the shape of the little lip built into the trunk does but at a higher speed?

I'd love to see a picture of the RS5 in the wind tunnel to see exactly what's going on back there.

Here's an audi in the wind tunnel, you can see the low pressure blue area created behind the car that will cause drag.

https://jaimeirastorza.files.wordpress.com/2014/05/car-airflow.png


Fascinating subject :)

superswiss
07-27-2015, 09:07 AM
James,
Yeah, I am fully aware of how a wing works. However, I found it intresteing how the author of the article talks about how a wing on a car is designed to direct airflow upwards. It's not so much about how much air flow below the wing. He illustrates this with the comparioson of the NASCAR spoiler (top) vs. NASCAR wing (bottom). Notice how very little air actually goes below the wing. The difference is that the airflow doesn't touch the spoiler, but it hugs the wing.

http://i.kinja-img.com/gawker-media/image/upload/s--MYyAdwiw--/c_fit,fl_progressive,q_80,w_636/exuai4ws9dpxypbpy5iv.jpg

Also interesting to note are the comments from the aerospace engineer about how airplianes use spoilers to reduce lift during descent and kill it once on the ground.

Partially deployed spoilers to reduce lift during descent:
http://i.kinja-img.com/gawker-media/image/upload/s--PRTom8VT--/c_fit,fl_progressive,q_80,w_636/e3nxykczi62y8r8ta5c0.jpg

Fully deployed spoilers to dump lift on the ground:
http://i.kinja-img.com/gawker-media/image/upload/s--t3ihv2oo--/c_fit,fl_progressive,q_80,w_636/djdywh5ok8ty9iy8u8r7.jpg

I agree, to see how effective the RS5 spoiler is we would have to see a smoke trace of an RS5 compared to an S5, but just looking at the Porsche picture above, we must conclude the it's got to be effective at leveling out the airflow. I suspect that the integrated deck lid spoiler of the S5 still allows airflow in the downwards direction creating lift.

JamesRS5
07-27-2015, 10:29 AM
I apologise Superswiss, i admit i hadn't read the link you posted until now so didn't see the explanation of the wing, however I think he's over simplifying it by saying wings push air upwards when his diagrams show the lift of the wing acting in the opposite direction. I guess it was written for the internet masses?

I think this line from the link you posted sums up the rear of out cars:

Spoilers are barricades to undesirable flows, and thus are able to reshape airflow streams around the vehicle. This can help keep the rear of the vehicle down and decrease drag by changing the effective vehicle shape


As for the plane wing, it gets more complicated- spoilers are usually used in conjunction with flaps for air brakes, you will usually see a bit of movement from both to give the wing trailing edge a < shape. They can also be used as DLC a Direct Lift Control to give altitude correction on finals and finally as lift dump once you're weight on wheels to prevent the wing from creating lift.

(I'm also an aerospace engineer) [:D]

hawkinsmc
07-28-2015, 05:07 PM
Well in California entering the freeway (except during rush hour) is a tell tale sign you are above 75mph[emoji6]


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Reggie
07-29-2015, 07:06 PM
Well in California entering the freeway (except during rush hour) is a tell tale sign you are above 75mph[emoji6]


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Unless it is extended manually