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Wing Actuation Speed

22K views 39 replies 22 participants last post by  jimmuller  
#1 ·
The Cayman manual states:

“The rear wing extends automatically at speeds above approx. 75 mph (120 km/h) and retracts again below approx. 50 mph (80 km/h)”

My wing raises at about 82 mph, and lowers at about 52 mph. Since there is obviously a signal generated that feeds the digital speedometer, I’m surprised the actual wing actuation speed is not more precise.

Anyone else notice such a descrepancy?
 
#3 ·
It probably actually is precise. Note the KPH speeds; they are nice, round numbers. That's likely what they're tied to, not MPH. Also, the 'approximate' is there because several factors come into play to determine the speed you see on the speedometer versus what speed the car sees in its ECU: tire wear, a curve in the road, etc.

I've monitored mine closely (I can 'barely' see the wing's top edge when fully deployed in my RVM). Mine goes up at 80mph -- and that speed must be sustained for at least a second or two. It goes down at 51 mph.
 
#5 ·
It probably actually is precise. Note the KPH speeds; they are nice, round numbers. That's likely what they're tied to, not MPH. Also, the 'approximate' is there because several factors come into play to determine the speed you see on the speedometer versus what speed the car sees in its ECU: tire wear, a curve in the road, etc.
I agree there would be some approximation due to conversion, tire wear etc. but being over 9% off on the up actuation seems like a lot if there is a precise signal. I have been observing it on straight freeways, creeping up on the speed.

I can also just see the top slivered the wing in the rear view mirror when the wing is up.
 
#12 ·
I don't think so but it's been a while since I thought about it. I can see the upper edge of the wing in my mirror so I don't need to look at the indicator light. Mostly I just ignore it. When the wing wants to be up it goes up and when it wants to be down it goes down. As mentioned above (some long time ago now) it does not respond immediately to speed transitions above or below its thresholds. So unless you are watching it and your speedometer carefully or driving at a nearly constant speed near a threshold you cannot be especially precise in judging when it moves.
 
#9 ·
Mine seems to deploy around the 100kph (62mph) mark. Perhaps this is coded differently for different regions or cars (i'm in NZ and drive a 991.2).

The other thing I have noted is that mine appears to deploy under extreme acceleration, or at least earlier (maybe around 80 kph) under extreme acceleration.
 
#10 ·
I can't exactly see why the spoiler would deploy at high speeds in Normal driving mode. A rear wing is supposed to increase downforce at high speeds. This might be interesting on a racetrack (Sport or Sport+ Modes) but on the freeway, driving at more or less legal speeds, why would you need an increased downforce? More downforce generates more drag, which means an increased fuel consumption (and reduced top speed, if that what's you're after). Maybe above 120 mph the extra downforce is necessary to keep the car stable, but I think at lower speeds the rear wing might be quite superfluous. All the same, the retractable wing is one of my favorite gadgets in the car.
 
#14 ·
The original purpose of the spoiler on Boxster / Caymans (which I still have to assume to be true) was not about creating downforce, but about keeping the car properly settled at speed. It disrupts the airflow and keeps the car itself from acting like a wing and getting floaty / unsettled...

So, if we assume that's still true in the current generation (and not just a design piece at this point that's stayed consistent), this also explains the speed its set for as well as why it deploys regardless of "mode". Also explains why that speed isn't set within more common "legal" limits since its not meant to be just a fun thing to look at, completely functional and tuned to come up prior to the point where airflow could cause any instability.
 
#11 ·
This was one of four things I noted on my initial concerns list when I bought my car. I took it back to the dealership and all of my concerns were answered and OK. But the wing raising took a little more time. We went out on the interstate to get up to appropriate speed, and sure enough, the wing did not raise at 75 mph. On our way back to the dealership, the service manager asked if I had the Good to Know app on my phone, which I had just installed. We were on a four-lane road almost back to the dealership when I found it and it said "78 mph (125 km/h)" so he does a nice u-turn and back to the interstate we go, where this was confirmed. On the way back again, he said that it used to be in mph for U.S. cars, but Porsche changed it to km/h universally.
 
#18 ·
On the topic of the spoiler... Is there a setting to make it go down automatically when you turn the car off?
I don't think so but it's no big deal. When I was looking at the dealer there was one car on the lot with the wing up. I commented that it must be stuck in the up position and the salesperson explained that sometimes people leave them up when cleaning so as to wash out the dirt that accumulated unerneath. Of course if let the wing go up and down onits own then when you stop it goes down automatically all by itself!

Well, if you intend to keep the car settled at high speeds you need to create downforce.
Which sounds a lot like eliminating upforce, doesn't it? Its funny how no one ever mentions upforce by that name.
 
#17 ·
That's another possibility. A rear wing can help to reduce the wake turbulence that appears behind a car (and that transforms into drag, due to the vacuum effect it creates) by preventing the airflow from separating abruptly when reaching the ending of the vehicle (which also generates some downforce). However, as far as I know this type of wings are usually installed in hatchbacks more than in coupes/sportscars. Sportscars typically use wings focused on downforce generation to increase high speed stability (911 GT3 is a perfect example). I assumed Porsche engineers would want to create downforce instead of achieving a drag reduction in the Cayman/Boxster, but who knows.
 
#27 ·
Strangely enough, wings are shaped like wings, only upside down from airplane wings so they create downforce rather than lift.
Spoilers spoil (disrupt) the flow of air over the car for less lift from the wing-shaped car or for stability and other reasons. They don't look like wings.
 
#28 ·
Strangely enough, wings are shaped like wings, only upside down from airplane wings so they create downforce rather than lift.
Spoilers spoil (disrupt) the flow of air over the car for less lift from the wing-shaped car or for stability and other reasons. They don't look like wings.
yup, the original audi TT was dangerous at high speed. the fix? add a small spoiler to the rear deck (via a recall). in that way that car and the cayman are similar. article for reference: Remember that time Audi recalled a car to fit a rear spoiler?
 
#29 ·
I believe that spoilers also reduce drag by spoiling the air behind the car thus reducing the low pressure zone created just behind the car at higher rates of speed.
 
#36 ·
Maybe. Don't know, don't have a Boxster to try. Whether the spoiler can be visible depends on the relative position of the bottom of the mirror and the top of the extended spoiler w.r.t. other body work or rear window which might get in the way.

I checked on the LED in he switch today. @Zeichen311 is correct, it does not come on if the spoiler goes up on its own.