Chevron trailing edge applications

[Xist]

So, if we make super-long mirrors, our cars will be more aerodynamic?

[kach22i]

Originally Posted by Xist

So, if we make super-long mirrors, our cars will be more aerodynamic?

A super long mirror would weigh more, obscure vision more and has diminishing returns based on speed. If you were going near supersonic speeds perhaps it would make sense to go much longer.

I like the idea of looking to what Porsche does as a leading indicator for what optimum length is might be a good one in my opinion.

I think we need to keep in mind that cars turn at speed in tighter circles than aircraft and boats. Some of our design consideration should for off angles or "cross wind" conditions. This means excessively long bodies and lengths may be a liability under some conditions.

Just my opinion.

[aerohead]

Originally Posted by Xist

So, if we make super-long mirrors, our cars will be more aerodynamic?

I think Kach22i has made a good list of 'practical' considerations for design.
Hucho would 'optimize' for a shape.As soon as a feature got drag to 'saturate,' he'd quit and move on to another feature.
*The mirror,1st of all,needs to provide the optical pathway we need for safe motoring.
*So the design needs to respect that.
*Manufacturers would target something like the 99th percentile for human factors in their design.
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*I have notice that,say for Toyota,many of their side-view mirrors are identical in 'design',but scaled for each vehicle 'size' as if respecting that a pair of ears on a mouse should be proportioned like a pair of ears on a deer.
*The Echo mirror looks just like a Corolla,Camry,Avalon,Tacoma,T-100,and Tundra,but a smaller size,as if the human eye behaved differently from vehicle to vehicle.
* I might install Echo mirrors on the T-100 and have basically the same optical performance,but with a smaller frontal area (CdA).
*A random thought is about the CLA 180 M-B Blue-efficiency car.It's Cd 0.22 side mirrors are lower drag than the other CLA cars.Whatever they've done would be a tip off to us as far as low drag mirror tech.
*Also check out the new VOLT/Enclave/FIT/Cadillac CTS/BMW/Lexus............

[WD40]

super-long could look good..
http://img168.imageshack.us/img168/8461/garage2fb6.jpg

[calfianu]

WD40 ... you know, each time when I was drawing a car, I felt this is the only way the mirrors should be designed. Integrated. We've seen this idea applied on many vehicles, but the latest with high aerodynamic performance gave up this idea. From aesthetic point of view, this approach is my only choice. And, if the future will bring cameras in the place of mirrors, I would integrate them in the same way.

[serialk11r]

I think we need more pictures.


As you can see, if you took the windshield's curvature and extended it a few inches to the side of the car, that's about where Porsche's mirrors start, the shape is like a "bullet" that goes back and is cut off at the place where the driver expects to see a mirror out the window.

Compare to the new Corolla:

A blunt, flat angled rectangle shape. A few inches shorter overall.

I wonder, how might one add length to the front of that Porsche mirror without increasing interference drag? Maybe extend the "bullet nose" forward and curve it in a little?

The Lexus LFA has really wild looking mirrors and they claimed it helps aerodynamics, but they're about as long as the Porsche mirrors:

I think the Nissan GTR also supposedly had aerodynamically tuned mirrors:

Also short and stubby!

Finally, the McLaren P1, a car that supposedly had every body detail carefully designed:


Looks a lot like the Porsche mirror!

[calfianu]

with an ordinary shape this W124 Mercedes has a Cx=0.28.

Same for Opel Vectra B2:

While the 0.26 Opel Calibra has half "integrated" mirror (the mount side), leaving half "separated".

[calfianu]

Reading aerohead's observation about "base pressure" another idea (hopefully the last one)regarding the reduction of the drag of these mirrors. I am not sure I got the right understanding about "base pressure", but these movies will explain the idea better than words. In few words is about a mirror that becomes "porous" or "permeable" to avoid a low pressure area formed on the reflexive element.

https://www.youtube.com/watch?v=uSwQ...ature=youtu.be

https://www.youtube.com/watch?v=mEdA...ature=youtu.be

https://www.youtube.com/watch?v=tpDa...ature=youtu.be

[freebeard]

What's the premise? One seems to be a flat plate in a cup, and the others—segmented mirror elements with air gaps? I don't see how the air is introduced.

And how do you generate the [hexidecimal?] number to name the videos?

[serialk11r]

Originally Posted by freebeard

What's the premise? One seems to be a flat plate in a cup, and the others—segmented mirror elements with air gaps? I don't see how the air is introduced.

And how do you generate the [hexidecimal?] number to name the videos?

I think the air is introduced through a hole at the front.

In rain, I would imagine the spray of water coming out the mirror gaps to make them impossible to see?