Does the cup spoiler DO anything other than look better and add weight?

[JoeMarano]

Was thinking if it actually performed better? I think it probably creates more drag as the outer edges dont sit flush with the roof? Its also a lot lot heavier than the standard one.

 

[Knuckles]

Nope, just looks better.



...probably.

 

[JoeMarano]

Forgot to mention im talking about 172.

 

[Steven103]

There are sound engineering principles as to why the spoiler could both increase or decrease drag. However the interaction between every minute feature on the vehicle body is so complex that it's really not worth guessing either way without wind tunnel or CFD evidence. E.g. the rear of a car could be shaped brilliantly, only for the turbulent airflow off of a wing mirror to just-so-happen to land in a really bad place and mess everything up. You might think you've noticed that a cup spoiler makes the rear window more dirty & therefore reason that it creates turbulence at that spot. That may well be true, but you have no idea of the overall effect on the vehicle. E.g. canards (dive planes) on a front bumper deliberately cause turbulence (you would normally assume this is bad) in a very strategic place which ends up significantly increasing the performance of a rear diffuser (which far outweighs a little bit of turbulence on the edge of the front bumper)...

P.S. On the weight front no-one can notice 0.01% more weight lol (assuming a 1kg difference to a 1000kg car) even on the roofline.

Literally the only noticeable thing it does is look better.

 

[JoeMarano]

I did actually notice that the rear window is a lot dirtier! I was just thinking of getting rid if mine and using the pennies to buy something like a panel filter or rear arb or towards a bucket seat or something but it DOES make the rear look a lot nicer. I personally thought it felt a lot heavier thanthe standard one but like you say im never going to feel that difference. The only thing I can feel is the spare wheel when I've taken that out as its full sized 16" with new tyre so must weight at least 25kg with the whole lot of it

 

[McGherkin]

There are sound engineering principles as to why the spoiler could both increase or decrease drag. However the interaction between every minute feature on the vehicle body is so complex that it's really not worth guessing either way without wind tunnel or CFD evidence. E.g. the rear of a car could be shaped brilliantly, only for the turbulent airflow off of a wing mirror to just-so-happen to land in a really bad place and mess everything up. You might think you've noticed that a cup spoiler makes the rear window more dirty & therefore reason that it creates turbulence at that spot. That may well be true, but you have no idea of the overall effect on the vehicle. E.g. canards (dive planes) on a front bumper deliberately cause turbulence (you would normally assume this is bad) in a very strategic place which ends up significantly increasing the performance of a rear diffuser (which far outweighs a little bit of turbulence on the edge of the front bumper)...

P.S. On the weight front no-one can notice 0.01% more weight lol (assuming a 1kg difference to a 1000kg car) even on the roofline.

Literally the only noticeable thing it does is look better.

This pretty much.

But it's a b*****d for getting that bloody back window dirty!

 

[atgregory]

I had a 172 cup new when they came out then a 182 and never considered the back spoilers until I had my R27, what a difference without one, car felt unstable in the back end slowing down from speed, I never purchased a back spoiler for it but I always thought it was down to it not having a spoiler

 

[Cub.]

Wrong section.

Number 8.