Brothers,

what's the name of this beautiful aerodynamic piece installed on the roof of this Countryman WRC?:



I promise you not to install it on my r56 (I think ).

 

roof scoop? I think generally they are used for fresh air for the drivers, PS I couldn't see the pic, but I am aware of the looks of the WRC CM

 

You are correct sir. Roof scoop for fresh air. Made famous by the green Eclipse in The Fast and the Furious. Does nothing for a road car. I.e. Rice

 

Well unless it's the Subaru STI S204 in Japan that came with it from the factory

 

Yea... the Renault Megane Trophy cars run the roof inlet as well.

Motor on!

 

The special RA-R came out of the factory with one, but that was a purpose built race car and its intentions were the same as discussed above. For use on a road car, its still rice. However, on a well-known rally car with factory interior parts for a vent -its passable. Throwing a hood scoop on the roof and calling it a day is not.

-Tecnica
Former STi Owner - That is where the name Tecnica comes from: STi Subaru Tecnica International

 

Roof intake = more drag = slower car (all bets off with a TRUE race car, no interior, etc)...unless you are from the school of thinking that most Pontiac designers came from... The one that says, the more plastic you bolt on to add weight, makes a car look faster, and that is all the counts....

 

Obviously for urban use, it's a 100% cosmetic accessory.
If the accessory has an air in hole and an air out hole, there is not drag. It would have the same effect as the rear spoiler (more grip at high speed). Even the "dummy" Cooper S hood scoop generates more drag than this accessory (if not modified to make it functional).
As for the weight, I assume it's fiberglass or ABS so it is not a problem!

I'm still thinking in to give it a chance in my R56 ...

 

I believe I can give it a chance on my roof ...

 

Yes, there is drag. In fact, there may be more drag than if there was no opening at the back! And a design like the one shown will produce no measurable downforce at any speed on its own. (There's some chance it might help the rear wing to work a little more effectively, though?)

BTW, the earliest cars that I know of with this type of air intake were the MacLaren F1 cars. The intake fed directly into the engine, which was in the middle of the car. Several other mid-engine race cars (and the super high-end cars they were based on) used similar intakes later on.

 

No, there is only noticeable drag if NO opening the back.
In example: a parachute hehe

If there is a way where the air can flow freely, there is no drag, because ... there is no drag. Surely there is downforce, and that is not bad at high speeds.
It's possible we are using different "drag" concepts?





NO DRAG EXAMPLES:







DRAG EXAMPLES:

 

Your understanding of aerodynamic leads me to say....er....WOW!? Self taught I'm assuming?!
Drag is not just caused by air getting "stuck" buy also the byproduct of making lift or dowforce, aka upsidedown lift....so if the part is in the airflow of the car, disturbing the airflow, it is 100% making drag....
The internet is full of bad and poor information..... Just cause it is published online does not make it true....

 

We are all talking about a MINI right? It's a box on wheels. Who really cares about adding a little drag at this point?

 

There is the problem! ... and you are correct: my "drag" concept is air getting "stuck", so, for that, we have different points of views for the same situation.
That's great because these differences are (often) the origin for new ideas.

I need to clarify that my intention is not to discuss who is right (I'm a simple system engineer and I have nothing related to aerodynamics experience).
I like to share my opinion to know and learn from others and, if possible, help others with my Mini troubles experience.

 

Additionaly, who really cares about trying it on my "box"?

 

There are many things that we add to our cars that have no (or very little) purpose on a road car. For example, how many of us have splitters? Do you think we really need them, hell no, some of us just think they look cool.

If you like it and think it looks good then put it on.

 

Yes, I understand you perfectly and I agree totally... BUT if I like wheel with square shape and I ask in the forum what is your "opinion", you could tell me don't do it! (because it's not convenient).

Since the roof scoop is not something shocking to the vehicle (cosmetic only, as you said so) it is good to know other experiences/suggestions for the pros and cons.

That's all folks!

 

My main concern is how to secure it well enough, but still be reversible....
On a race car, they just cut and bolt, no worries about rain, rust, etc...car will not last that long...
Then sounds and by buffeting...ever each up through an open sunroof at highway speeds?

 

I have the same concern too, ZippyNH. Since it will be a cosmetic scoop I've been thinking on a decorative roof scoop (3M double tape). Really, I don't know if it can sustain with the wind generated at high speed.
And surely, as you say, it will generate some kind of sound. I had not considered that important detail ...

 

First, there is always drag--pretty much any object moving through a fluid generates drag. The question is how much does it generate?

A faired-over blister makes very very little. A faired-over blister with an opening at the front generates not much more. Air can get "stuck" in the opening, but once there it starts spinning around, which acts kind of like a ball bearing and smooths out the air flowing over the rest of the blister. (This spinning air is called a "recirculation bubble".)

Shapes at sharp angles to each other, or parallel to each other in close proximity, will create interference drag. The wakes coming off of each one will hit one another, and will create lots of turbulent flow which is very draggy. (This is why it is best to have fairings around the wing roots of airplanes rather than have the wings abruptly jut out the sides.)

The "no drag examples" you give are not "no drag". While it is possible that the top element of the multi-element wing on that open-wheel racer does reduce drag, it is very tightly engineered to work in that one circumstance--on top of another wing on the back of a race car going well over 100 MPH. It may reduce the drag compared to that car without the upper wing, but one reason is that race cars with large wings like that typically have terrible Cd (coefficients of drag), on the order of 0.5-1.0, rather than the ~0.35 of most street cars today.

The second wing is most likely just for looks. Marketing drives automotive design more than aerodynamics.

Aero is one of the least-intuitive sciences out there, so trusting your common sense can actually lead you quite astray there.

 

Just install the roof air scoop and have it formed around a jet engine, good to go.

 

Totally agree. I think we're talking about the subject superficially and the mistake (my mistake) is the definitions "no drag" as "little drag" and "much drag" as "100% drag".
Only applicable to moon cars




OK, I understand you. Let me clarify that it is not my intention to invent a perfect roof scoop, I'm just researching the impact for a commercial roof scoop and aerodynamically pre designed (or at least I assume).

Thank you so much for your time and your clear explanation!

 

Duell is doing what looks like a roof scoop on Their Instagram page. Fully gutted interior on an f56 and there's wente opening to the passenger and driver. Looks as if it's designed to cool the drivers but I could be and probably am way far off.

 

I'm gonna need just a little more space for more seats and more fuel!

 

There's actually a YouTube video out there of someone doing this experiment (I think it was a feather and a rock, not a feather and a hammer?) in a large vacuum chamber. And the results matched exactly what you see in the image, once the air was gone.