Now that I have my 2017 R convertible for a few months, the neat rear wing deploys at 60 mph & undo back below 40 mph.

But does anyone knows useful it is in the real world?
meaning that since I don't race on the streets, just around city streets & occasional freeway driving maybe max 80 mph
so how much down force does the deployed wing translate to increased traction to the rear wheels, & how much do you really feel at 60 mph or 80 mph?
or is it merely a cool looking gimmick...?

 

It is not a (inverted) wing, It is a spoiler and the function is not to create downforce, but to reduce lift created by the airflow over the car.
I don't know how much effect it has, but I would think it is not that much at speeds below 80 mph. However I would guess there is a reason why it deploys at the speed it does.

 

And presumably a reason why the coupe deploys and resets at 10 mph higher speeds?

 

if I remember correctly (with regard to the coupe), the wing deploys at ~70mph as it takes about 3 seconds to raise. so that it is fully raised when the car reaches 120mph, At speeds greater than 120mph the uplift causes some handling issues the spoiler disrupts the uplift thus creating greater downforce

 

With a spoiler deployed, I haven't noticed any issues with uplift at any speed that I managed to get to.

 

Yeah, up at 70 down at 50.

 

Seriously?
U have to get up to 100+ or 120+ mph just to maybe get a tiny little benefit of having a spoiler/wing benefit...?

 

Well, if you're driving into a 70mph headwind you might get a benefit at a lower road speed.

 

Yes officer, you noted my spoiler pop up at 70mph in the 65mph zone. I was actually trying to get to 120mph to test the downforce. Can you excuse me ?

 

I think that ONE benefit of the pop-up spoiler is that I can see the Leaper in the rear-view.

(Can coupe owners see it too?)

 

Yes, unless they've got the non-deployable spoiler, when the leaper is underneath.

 

So, seriously.
No one has any REAL scientific/engineering data or evidence that the wing/spoiler does anything useful driving-wise...?

 

I also appreciate the Jaguar engineering obfuscation that the spoiler going down up at 70 but down at 50 is a defense that just because the LEO spotted your spoiler up didn't mean you were travelling at 70+ when he saw you...assuming he knew the Jaguar operating specs of course ;-)

 

According to Jaguar, the active rear spoiler "generates 264 pounds of downforce on the rear... at top speed of 186 mph". The "downforce" actually manifests itself in a reduction in lift generated across the foil created by the roof line. That 264lbs is achieved exponentially as the speed increases ( v squared expression in that formula somewhere if I remember correctly). So under 70, that "downforce" would be minimal". I can't imagine that the reduction in lift would be as great on the vert with the top up and it would even be far less with the top down, but the vert wouldn't have anywhere the lift across the roofline anyway. So no...nothing scientific regarding the vert.

 

If I remember my history correctly, the original Audi TT did not have one - and after a series of deaths attributed to high speed oversteer - the deployable spoilers were retrofitted to existing cars and all new ones. Apparently, the spoiler is designed to reduce lift at very high Autobahn speeds (all the Audi incidents were in Germany). The engineers at Audi had a choice - dial in understeer to the steering geomery or reduce lift above 125 mph with spoiler.

since then, its been a favorite engineering "trick" to reduce high speed rear lift and oversteering in europe.

 

 

You don't need it, common sense would prevail;

Hold your hand out of the drivers window at 80 mph at a similar angle of attack as the spoiler.

Feel anything...?
Yep a few pounds of force trying to move your hand downwards.

Now, multiply the length of the spoiler by the number of hands that fit into the said length and that'll give you an idea of how much force is being produced.

 

 

Been thinking about this and finally thought to watch the spoiler deploy today when I was out catting about. There's no way that's three seconds. I's say more like one, but I didn't have a stopwatch handy, nor an assistant to dedicate to the task.

 

Fortunately, most don't know there is a difference between deployment speeds on the coupe and the convertible...soon after I took delivery, I took advantage of that when I was allegedly clocked over 60 but at less than 70. I was convincing enough that I did not even get a written warning