Psst- the spoiler that deploys at 80 mph is likely as effective as the ducktail.

 

We laugh about taking off and landing in Canada, but you should see how far out in the German fields some of their cars land.

ChuckJ

 

+1 to your dilemma! I can't even park in the garage! So I blanket it every night and my wife says it looks like a baked potato. I wanted the Ducktail too, but no clearance means no dice.... for now

 

you are going to lose some grip in the front once you hit 120+, that happens with the jag xk. It gets really light on the steering at high speeds

 

Then why wouldn't they let you order just the ducktail?

 

whats even more ridiculous is that in a convertible the additional amount of rear downforce from the ducktail vs OEM spoiler is nil at any speed.,,,,the need for additional downforce in front with the OEM sport design spoiler is either a money thing or some engineer took too many 5 hour energy's when he made that decision.

 

To sell you both pieces likely.

 

Got mine...love it !

 

For me, the duck tail does look a little odd from a certain angle. The straight on rear view is one of the, But overall, it flows pretty well and add a little character/interest to the car. I am sure that was the impression for some on the original duck tail.

The downforce does not apply in my driving situation. No plan to hit 120 to and from work. As for more spirited weekend drive on the twisty mountain road, neither my wife or I plan to hit any where close to that, we like to stay on the road. . But we are glad we ordered the duck tail.

 

A few notes: the spoiler, at normal driving speeds below 100MPH 160kph isn't going to produce much downforce. Definitely less than 100 lbs. Enough to affect handling? Sure, the car will exhibit a little bit more understeer in high speed cornering, but that's a "stable/safe" condition. Not sure what the rear spring rate is, but it's high enough to make suspension deflections and vehicle pitch negligible. If we say 100 lbs we're talking about putting two kids in the backseat essentially; or, with 500 lb springs, about 0.1" of rear spring deflection. Can you really see the front raising that much if that's the case?

And just to put some numbers behind things: 100mph is ~45 m/s. Frontal area of a 991 is about 2m.³ So we're talking Downforce = 1/2*1.225*45*45*2*CL (newtons), or Downforce = 557*CL. There is no way in hell the CL for the ducktail is high enough to produce big downforce numbers.

 

I think the primary reason for the spoiler was to reducing lift rather than create downforce per se- hence the wing option with its inverted airfoil.

 

Careful with real numbers, you will be exposing the reason the spoilers arent sold separately....$$$$

 

Maybe we are just not driving fast enough .

 

anyone want a front sport design spoiler for their 991? unpainted, just need to know if you have park assist and/or headlight washers, Washington state or vancouver,bc area would be best.