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Rear view mirror drag

Posted: 02 May 2010, 19:17
by Shrey
How much drag does the rear view mirror contribute (in %) to the overall drag. Its about 5% for a road car from what I managed to find on google. I can't seem to find any numbers for formula 1 cars.

Also how badly would the inboard mirrors affect the the rear wing ?

Re: Rear view mirror drag

Posted: 03 May 2010, 00:10
by newbie
moving them inboard would probably cost less than a point of drag, so you're looking at 0.5% increase in drag for a loss of 0.2% downforce although you could probably recover all of the lost downforce with some tweaking.

Re: Rear view mirror drag

Posted: 03 May 2010, 04:14
by Shrey
Thanks :)

What if there were no rear view mirrors at all, how much drag would that save ?

Re: Rear view mirror drag

Posted: 03 May 2010, 06:58
by tomislavp4
newbie wrote:moving them inboard would probably cost less than a point of drag, so you're looking at 0.5% increase in drag for a loss of 0.2% downforce although you could probably recover all of the lost downforce with some tweaking.
Is this actually a fact or just a wild guess?

Re: Rear view mirror drag

Posted: 03 May 2010, 20:34
by nacho
If it was that much I would assume all of them would have outboard mirrors?

Re: Rear view mirror drag

Posted: 05 May 2010, 16:20
by speedsense
newbie wrote:moving them inboard would probably cost less than a point of drag, so you're looking at 0.5% increase in drag for a loss of 0.2% downforce although you could probably recover all of the lost downforce with some tweaking.
Source?
Having the mirrors outboard puts the mirrors in the trailing wake of the front tires, thus greatly reducing drag (from the mirrors)...
IMHO..

Re: Rear view mirror drag

Posted: 05 May 2010, 19:14
by Shrey
Source?
Having the mirrors outboard puts the mirrors in the trailing wake of the front tires, thus greatly reducing drag (from the mirrors)...
IMHO..
Yep, I guess the rear view mirror is among the few (or only) bluff bodies in an F1 car (leaving the tyres out). What I want to know is how much of an approximate difference would it make if you took them out of the picture. Does moving them inboard mess up the flow to the rear wing in any way ?

Re: Rear view mirror drag

Posted: 05 May 2010, 19:44
by Shrek
I think it does Shrey because if you look at it head on the mirrors will at least affect flow to the rear wing and might even mess up that flow.

Re: Rear view mirror drag

Posted: 06 May 2010, 00:37
by ringo
The rear wing is at a far distance, so it's possible the disturbance wont be so bad, but in terms of the side pods, yeah it will have a bigger effect on the flow over them. What's more it's very critical to prevent eddies from forming over the steep side pods we are now witnessing.

Renault have some interesting aerodynamic mirrors very long and sleek. If only a smoothly curved transparent cover could be put over the flat face of the mirrors to keep the flow over the mirror attached as it passes over and under.

Re: Rear view mirror drag

Posted: 06 May 2010, 01:24
by newbie
source is personal experience : )

Re: Rear view mirror drag

Posted: 06 May 2010, 06:46
by Shrey
If only a smoothly curved transparent cover could be put over the flat face of the mirrors to keep the flow over the mirror attached as it passes over and under.
Exactly my thoughts and one of the reasons I started the thread in the first place :). But the regulations don't make it all that easy. The Rear view mirrors shouldn't be more than 12000mm2 when projected to a horizontal plane. They should be atleast 150mm wide so that means it can be only 80mm long. But even then a streamlined cylinder type profile would delay separation (and reduce the size of the wake ?). So a profile with a maximum thickness of 50mm and length of 80mm would fit into the rules. What I can't get around is why the teams haven't tried it yet.

I've been learning FLUENT and thought it would be interesting to see the difference.free stream velocity is 83m/s. Below are the velocity contours. (it's a very rough simulation, the grid isn't fine, but I guess it gives a decent idea of the difference)

Image

The only problem I see is with any glare that might occur as a result of a transparent surface in front of the mirror.

Re: Rear view mirror drag

Posted: 08 May 2010, 06:11
by Shrey
http://scarbsf1.wordpress.com/2010/04/0 ... d-mirrors/

read comments

It might be legal but the visibility would suffer, so I guess that rules it out.

Re: Rear view mirror drag

Posted: 08 May 2010, 15:30
by newbie
there is a maximum plan-view area rule that governs mirror design, and all of the allowed area is used in the current mirrors. as i see it, there is little scope for adding a transparent fairing without seriously compromising the size of the actual reflective mirror (in which case the more efficient design would probably be banned on safety grounds anyways)

Re: Rear view mirror drag

Posted: 09 May 2010, 10:10
by speedsense
newbie wrote:source is personal experience : )
mine too...just wondered about the numbers...

Re: Rear view mirror drag

Posted: 09 May 2010, 11:04
by casper
Use of transparent fairing is not good, for the reasons that
angled glass = diffraction, and sunlight reflection (glare).
during car collisions = fragments may pose additional potential risk