Goldfish Mirror - Side Mirrors

[kach22i]

Would there be any merit to increasing the body size of a side mirror so that it is elongated?

If this mirror were large enough, you could even sneak in some downforce for racing.

My better judgement tells me the smaller the mirror, the better. However if you look at some motorcycle mirrors they can get pretty long, even though the glass/mirror area is the same.

I drew such a mirror up, with Gurney flap like spoilers it looks just like a Goldfish. However, it might work better, if it works at all, without these vortex creators.

In fact you might want to view this as a mirror image Kammback mirror, if there ever was such a thing.

I get crazy ideas all the time. You won't hurt my feeling if you think this one fails to swim up river.



Motorcycle example:...........fashion statement or science?
http://www.moto-works.jp/products/ca...o_mirrors.html

[Otto]

You can get most if not all the same aero streamlining benefit, at ~1/10 the cost, via eBay motorcycle mirrors.

[kach22i]

Originally Posted by Otto

You can get most if not all the same aero streamlining benefit, at ~1/10 the cost, via eBay motorcycle mirrors.

I guess I wanted to talk theory, not cost.

Smaller mirrors as found on motorcycles are going to be more aerodynamic than truck mirrors for towing, those are perhaps two extreme examples.

I guess if the side mirror housing were too long, it would impair the scope of vision around it. And maybe even hit the side of the car when you open the door. Those issues aside, I'm still wondering why we don't see mirrors like I've drawn everyday.

[graydonengineering]

My current mirrors are large, square, and flat on the front. I have been considing the idea of designing a dome on the front and producing it on a 3d printer to add a bulett shape to the front. Since I have a canopy with no windows on the sides, I really do need my mirrors WITH cheaters to check my blind spots so reducing the size of the mirror is not really an option for me.

I like the fish fin idea to produce a raised low presure zone, however, I fear the flow disturbance my futher inturupt atached flow down the side of the car past the mirror. Hard to say without some testing. Maybe someone could provide some detailed data on mirror shapes and CD??

[Patrick]

Originally Posted by kach22i

Those issues aside, I'm still wondering why we don't see mirrors like I've drawn everyday.

I know you said those issues aside, but IMHO it boils down to: cost and styling. Manufacturers provide the mirror that allows the driver to see well to the rear at the lowest possible manufacturing cost that complies with regulations. But it has to look good enough for consumers to buy it. So they put a slab of glass out there and wrap it in something that they think looks halfway decent. They're not going to spend 2, 5, or 10 times the money to get a .1 mpg increase with an aero mirror that the majority of consumers won't like the looks of.

[kach22i]

Originally Posted by Patrick

They're not going to spend 2, 5, or 10 times the money to get a .1 mpg increase with an aero mirror that the majority of consumers won't like the looks of.

Good point, and I bet we have at least a couple of people in this forum willing to experiment.

graydonengineering, I think after looking at several different types of Google images some observations can be made.

The length of the dome is typically no more than double the height. The motorcycle might be closer to 3-times.

The Goldfish, would be +4X's, which could get parade float like in a hurry.

[Patrick]

My guess is the goldfish would be better off without the gurney flap.

http://ntrs.nasa.gov/archive/nasa/ca...1989004024.pdf

[cfg83]

kach22i -

We have speculated that adding a clear "boat tail" would be the best way to make a mirror more aero. The problem is that the clear material often distorts the reflection off the mirror, and/or adding more reflactions, rendering the mirror useless.

I did a version of this by making an "Easter Egg" rear view mirror :




I only tried it on the passenger side. In addition to the distortion it was pretty small. It may have worked better on the driver's side.

Imagine the bubble canopy of a P-51 Mustang. You could probably get one meant for an R/C plane. I think *that* would be the ideal shape.

CarloSW2

[jime57]

I've been experimenting a bit with mirrors on my Insight 1. I taped off all but 2x4.4" on the drivers side to simulate the small size available in racecar mirrors. It was pretty frightening to drive. I think that the reason that small mirrors work well in some applications, like bikes and race cars, is that the mirror can be close to the driver. As the mirror gets a ways away, the reverse image doesn't provide much coverage. I think that the inside "warp" mirror or the "wink" multipane, both used inside race cars, might be a better bet for good visibility. Of course, "good" will always be in the eye of the driver.

Re your idea of the Kamm back mirror, there was a similar picture offered up on this site around a year ago. Forget the manufacturer, but you can probably turn it up with a search. I think the idea has merit, assuming the mirror face isn't too small.

Hucho rates the delta Cd of mirrors at about .01 for the total of both sides. For "extreme" modders, it is probably worth the effort.

[botsapper]

[QUOTE=cfg83;256313]kach22i -

We have speculated that adding a clear "boat tail" would be the best way to make a mirror more aero. The problem is that the clear material often distorts the reflection off the mirror, and/or adding more reflactions, rendering the mirror useless.


We have speculated about the optical distortion and light glare on different 'boattail' shapes.



...and try to optimize it by having a flat plane parallel to the side glass.