Mirror designs, if we can't use cameras yet.

[Joggernot]

I heard a rumor that we couldn't mount anything on the car that stood proud because it might cause more damage to a person in the case of an accident. Today's mirrors fold back. Does the retro mirror fold back?

[cowmeat]

Turtle's stock mirrors are in big fat rigid housings and stick out pretty much the same distance as these, but are bulkier and less aerodynamic.
Not sure if that would be an issue or not, anybody know for sure?

[freebeard]

http://www.gerrelt.nl/section-aerodynamics/aerodynamics-vitaloni-mirror.html

I won't do this for gas mileage because I only drive about 2K miles/year; but I would if I was going to show the car.

The Vitaloni mirror is/was only about $15 and the mod is essentially free, it's smaller and more aerodynamic. I could add a right hand mirror so I can see the right rear bumper and tire when I'm backing up with little or no penalty. But it would fold up or down instead of back.

It would be quieter. Note also the raingutter filler.

[benphyr]

Originally Posted by aerohead

...by moving a structure away from the body sides,it encounters slower air,reducing its drag due to the velocity-cubed relationship to aerodynamic power,and also interference drag associated with it.
...
*This can also reduce aero-acoustic effects,minimizing wind noise.

So on my Odyssey which has large flat mirrors (almost like a pickup truck's) and which fold inwards rotating on a vertical pin it would actually be better aerodynamically to fold them horizontally? The folded frontal area would be exactly the same but the proportion that is right near the body of the van would be less and the proportion further away would be greater. (All other things being equal, etc.) And does it matter if they are directly on the A-pillar?

??

[benphyr]

Originally Posted by aerohead

Again,the very fast A-pillar flow is the culprit.You don't want anything near it.

So vent-visors in my Odyssey picture above are worse drag culprits per their frontal area than say roof racks or something else of the same area located elsewhere on the vehicle because they are right at the A-pillar.

Thanks for helping those-who-knows-less.

[Madact]

Originally Posted by benphyr

So on my Odyssey which has large flat mirrors (almost like a pickup truck's) and which fold inwards rotating on a vertical pin it would actually be better aerodynamically to fold them horizontally? The folded frontal area would be exactly the same but the proportion that is right near the body of the van would be less and the proportion further away would be greater. (All other things being equal, etc.) And does it matter if they are directly on the A-pillar?

??

Generally if you must have a small flat object sticking into the flow, having it perpendicular to the body (or more specifically, equal angles on each side) is the best case. In the vicinity of the A-pillar though, not only is the flow very fast (and thus a high potential for drag), it may not be going in the direction you think it is, so a horizontal mirror might actually be at an angle to the airflow... this 'local' angle of attack will produce drag in itself, and acting like a little winglet, may have larger effects on downstream flow than even a mirror in normal position (for better or worse is hard to say, but 'better' would take a bit of luck).

Where they are might be OK folding to horizontal, it's a fair way back from the A-pillar by the looks of it. But there is the safety / damage avoidance aspect (which is the original reason for folding, not aero) - I suppose it depends on what the local regulations are.

[Xist]

Is there any way to just use lenses and mirrors, like with cameras and LCDs, but without electronics?

Like a U-shaped periscope, projecting onto a larger screen?

I imagine that image quality would degrade, though.

If somehow you could do that, you could have a mirror in the normal location, and a series of other mirrors reflecting into the car.

[Joggernot]

I seem to remember at least one car that had a periscope looking back over the roof with the view in the normal windshield location for a rearview mirror. Maybe someone can find it...

[freebeard]

Bucky Fuller's Dymaxion, plus various 'safety cars' over the years.

[aerohead]

Originally Posted by benphyr

So on my Odyssey which has large flat mirrors (almost like a pickup truck's) and which fold inwards rotating on a vertical pin it would actually be better aerodynamically to fold them horizontally? The folded frontal area would be exactly the same but the proportion that is right near the body of the van would be less and the proportion further away would be greater. (All other things being equal, etc.) And does it matter if they are directly on the A-pillar?

??

I don't think all the research has been done yet to say for sure.
*For a horizontal mounting,some successful lower drag cars used mirrors which were relatively wide for the height and moved away from the body.
Here is Volvo's Environmental Concept Car mirrors.They would be a benchmark for a horizontal mount mirror
http://image.motortrend.com/f/wot/vo...ee-quarter.jpg
*On you Honda,if you fold them vertically,your reducing frontal area but moving the mirror into faster air which seems to be a no-no.
*If you fold them horizontally,you maintain the same velocity profile around them,but the strut which attaches them is still in fast air causing high interference.
*For 'vertically' mounted mirrors,they're also moving the mirror away from the body into slower air,like Stingray.And the mounting strut may be more like a streamlined strut.
For lowest drag,the mounting strut would want a profile like the center strut in the following table,and you'd want to blend it into the 'wall' with a fillet to kill hook-vortice formation there.