Side mirror drag & effect on fuel economy - quantified

[cfg83]

aerohead -

Originally Posted by aerohead

I won't be able to put my hands on it anytime soon,but in the past it has been reported that the EPA ignores mirrors and their frontal area in certification of new cars.
If the Cd reflected the drag of the mirrors,it would skew the CdA of the car,as the CdA would be figured on the smaller frontal area of the car sans mirrors.
It's kind of a book-keeping foible.I'll try and dredge that up.

I think it was a safety issue in the sense that they didn't want to penalize manufacturers for having big side-view mirrors. If there was a penalty there would be the temptation to make the "minimum size" mirror.

CarloSW2

[spacer]

While I don't imagine it'd be as big percentage-wise, the dumbo ears hanging off my '86 Silverado could be replaced with something a bit more aero. Ok, a LOT more aero.
I don't guess it'd make for a very noticeable difference in MPGs, but every drop in the bucket...

[Cd]

Originally Posted by Frank Lee

That is a good point. It would have been helpful if they'd given more detail.

I think it would be a great idea to invite the guy over to this site to discuss some of the aero that he knows.

( If we didn't scare him off with a million and one questions .)

Perhaps Darin could send do a short interview with him.

[Joenavy85]

Originally Posted by Otto

What is the lowest drag shape yet found for an outside mirror?

How about noise measurements from outside mirrors--which are quietest?

with these it could all be in the distance from the vehicle, too close and the boundary layers (from car and mirror, depending on design obviously) will interfere with each other, also the shape of the mount makes a big difference, my Jeep mirrors mounts are kinda like vertical cylinders since they fold in. If the brackets are made of oval shaped tubing, there would be less turbulence on the back side and subsequently there would be less noise. i'm in the process of designing some wedges for the leading edge of the mirror mounts to make them more streamlined with the mirrors folded back. i'll post some pics of the mounts tomorrow.

[fjasper]

I finally understand why the "blind spot" exists. It's in the regulation. Never thought of that. They could widen out the required field of view, and every company selling cars in the affected jurisdiction would have to come up with a solution. Some of them would probably be very clever and effective.

I think they should include the mirrors in the drag calculus, because the object of the game is awareness of objects behind and alongside the vehicle, not square inches of glass or number of pixels, or whatever someone might come up with.

Rearview cameras are already cheaper than side mirrors, probably easier to defrost, safer, more aerodynamic, compatible with thermal imaging (which is where night vision augmentation will go), lighter, and just generally more high-tech.

"More High Tech" is always good for a marketing campaign. Personally I prefer low tech unless high tech provides some actual benefit to the user other than the illusion of progress.

Sorry about the rants (there have been others), I'm a shut-in today because I'm sick, and it's driving me nuts. Fingers crossed, they'll let me out of here tomorrow.

[Joenavy85]

here are a couple pictures i found showing what the side mirrors look like on my Jeep, big bricks on the side of the giant brick.

[aerohead]

Originally Posted by Otto

What is the lowest drag shape yet found for an outside mirror?

How about noise measurements from outside mirrors--which are quietest?

Somewhere along the line,I believe one of the Ford guys claimed net zero for the mirrors on one of the Probe cars.Perhaps I can re-discover that one.
As to noise,I have no idea.You will notice turbulators on some of them to move their resonant frequency out of human range.

[jtbo]

Many of you probably remembers 70's, some Japanese cars did have mirrors shaped as a bullet back then, you can find plenty of pics if you search from Google for bullet mirror.

But is that giving benefits? Would it still require some boat tail to be even better or does that edge often seen in them release air so well that no further improvements are required?

[AeroModder]

I should make some videos testing this. I pulled the passenger side mirror off the Aspire, but didn't notice a difference right away. Then again, the weather is always different.

[MetroMPG]

You wouldn't notice the MPG impact of a single mirror removal outside of controlled-as-possible testing.