Side mirror drag & effect on fuel economy - quantified

[gascort]

I researched the Missouri law and there's nothing but the statement that the driver must be able to turn their head to have a clear view of the rear, or have a mirror. I have both! (and no exterior mirrors)

[Prizmism]

Hey, sorry to bring up an old(er) topic but I have been doing some extensive research regarding side mirrors and the legalities behind them. I've noticed a wide range of laws and regulations for various states within the U.S. which made me wonder what federal regulations were regarding those aero-killers (well, perhaps aero-infirmers ) since obviously federal standards trump state and local regulations unless the state/local ones are more stringent. Here is what I have come up with:

571.111

The "basics":

1) All cars must have an inside rearview mirror that is not convex, provides a 20 degree horizontal viewing angle, and a view of a flat road surface (not greater than 61 meters past the rear of the vehicle) vertically to the horizon.

2) All cars must have an outside driver side mirror that is not convex, and "shall provide the driver a view of a level road surface extending to the horizon from a line, perpendicular to a longitudinal plane tangent to the driver's side of the vehicle at the widest point, extending 2.4 m out from the tangent plane 10.7 m behind the driver's eyes..." EDIT: That creates an angle of view of approximately 12.5 degrees. See the attachment for a quick visual I drew up.

3) An outside passenger mirror is only required if the inside rearview mirror is insufficient in providing an adequate field of view outlined in item #1. That means most if not all trucks with campers, vans, or other such vehicles legally require a passenger mirror.

Read the full regulation for more info; there's a lot of interesting stuff in there. I hope this helps anyone who wants to or already has modified their mirrors and wishes to stay within the law.

How's that for a first post

[Prizmism]

It seems Canada has a near carbon copy regulation in the books (even to the point of having the same regulation number - 111)

Standard 111

[tasdrouille]

Although I had read stnd 111, I'm the visual type and hadn't seen the picture, so thanks for posting it.

On top of that my province's law adds a minimum allowable surface to the mirror, and states that it must be adjustable from the inside of the vehicle.

[i_am_socket]

Jersey law is nearly identical, but adds that it must provide visibility to at least 200 feet?/yards? behind the vehicle.

[eco_generator]

Since most mirrors are nicely rounded or contoured on the forward side, has anyone tried the kammback approach and create a shroud that would help keep the flow attached past the largest cross section part of the mirror.

The shroud could be clear or constructed in a way to keep most of the mirror surface visible.

[Eddles]

Originally Posted by WaxyChicken

Rather than completely remove the mirror on the driver side and replace it with an uncomfortable in-side side mounted mirror, why not aero mod it? give it a boat nose and add wind spreaders to the top side.

This looks very similar to what the Opel/Vauxhall Vectra has. Have a look here (warning, 456k picture)

[Otto]

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

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

[winkosmosis]

Originally Posted by eco_generator

Since most mirrors are nicely rounded or contoured on the forward side, has anyone tried the kammback approach and create a shroud that would help keep the flow attached past the largest cross section part of the mirror.

The shroud could be clear or constructed in a way to keep most of the mirror surface visible.

I've been meaning to try that using pieces of plastic cut from the top dome area of 2L soda bottles.

[ojman873]

This is my first post here and I wanted to express my appreciation for all the valuable and useful tips and hints posted throughout the site from all of you.

I had a few questions regarding the mirror topic. I have folding mirrors on both sides of my 4-door 2007 Hyundai Accent GLS. I was considering folding in the passenger side one after having read about the FE/aero benefits. But are there any negative effects resulting from lopsided airflow when only one mirror is extended? For instance, might the car pull to one side or something? Also, is folding in just the passenger mirror better for FE/aero than not doing anything at all? What I mean is could the uneven airflow somehow have a negative FE effect? I appreciate any input. Thanks.

OJ