Aerodynamic front bumper license plate frame?

There are Reynolds Number effects that make the two vehicles difficult to compare, but in general you're right that "things would commonly look that way if it was better". I agree this this is a "solution to a problem that doesn't exist".

Nonetheless, it would be interesting to try to measure the effect of these things. My gut feeling is that the extra drag added by the surface area of the duck bill would offset any purported airflow shaping gain. If the Pirus were an airfoil shape (which it isn't, but let's think of it that way for now), the front license plate would be at or near the "stagnation point" of the shape in profile. The air doesn't move very much at this point, and thus it doesn't really matter what the surface looks like.

 

Patsparks, patparks, patparks!!!!!

Why can't you be positive. You are surrounded by water. If we cut down on Carbon, it will benefit you the most (or your grandchildren) than anybody lives in Nepal.

Please be positive and get on with the class, OK?

Say Hi to the Koala Bears and Kangroos for us

Peace

 

off topic here, but you can check with your city DMV to find if you even need a front plate. In las vegas anyway, you only need one or the other. My car had no pre-cut holes or plate installed when bought. And DMV said it was fine, as long as I had a plate on the rear. You could do the dashboard thing, but it's kinda of "ghetto"

 

I almost thought I had a rock dent on the front of my prius .. until I realized it was where you'd install the front license plate holder .. only clued in because of the identical dent on the opposite side.

We don't have front license plates.

 

Because I live on a hill (really) and would like to live at the beach.

Because it would be better for the environment if you spent your money on shares in a bluegum plantation than this.

 

Re: Aerodynamic In Seattle!

Hello Sea Wolf,

Your prayers have been answered! Believe it or not, I'm the one that makes a truly Aerodynamic License Plate cover. Go to Craigslist Seattle & search "aerodynamic license plate cover" it'll blow you away.

2 years ago I contacted Priuschat.com & sent them samples of my aerodynamic license plate covers to test, but they opted not to carry them.

Funny thing is, the aerodynamic Front License Plate issue is one of the most talked about subjects in the Prius Chat forum, & other hybrid forums? So Sea Wolf, it seems you have some friends on Prius Chat, if you can stir things up with forum members to try and convince PriusChat.com to reconsider carrying aero lic covers, I'll send you a ZIPPCO USA cover for Free.

And yes, a flat front lic plate on the front of a Prius or Insight is a crime, just read what I say about it on Craigslist, it'll blow you away.

TKS
Dan

 

Just a comment, you can find airplanes with unaerodynamic front ends, but none with unaerodynamic back ends. You may be fixing the wrong problem.

 

Yes, those tinted cover shields look good, too. I had to take mine off my previous car and cannot use on my Pri, because as last July, Tennessee lawmakers made it illegal to use any cover shield color tone that might inhibit visibility of the license plate. Basically, they could legally say that even the clear cover shields affected visibility, saying that the sun reflected too much or some other visibility problems.
You understand? mo money - mo money
Yes, you're right, I got a citation.

hwell:

 

Improved aerodynamics don't always require major redesigns, or even rounded shapes. Wonder if any of these ideas might work?

First, take the license plate and lose the "surround" of a dealer plate, which does create a concave surface. The OP is right, in this respect.

Second, the plate is flat...but its primary problem seems to be rooted in the fact that it is mounted perfectly vertical, creating the greatest drag possible. Maybe shifting it to tilt either upwards or downwards would improve aerodynamics, sufficiently, without unduly affecting its appearance. This wouldn't require a complete redesign, or some weird plastic bubble...but only a simple spacer mounted behind the upper or lower screws.

Similarly, a *slight* cylindrical rounding might create a similar benefit, without violating the law.

Oftentimes it doesn't take much change to effect a significant difference.

Chuck

 

Re: Aerodynamic In Seattle!

I ran with no front plate for a while mostly because it just looks better, nice and clean. Then my wife got pulled over and warned so I had to put it back on. So I'd been looking at it lately and trying to think of another solution when I saw this thread pop up today.
I have to say I don't like the look of any of the bubble covers. I think I'll look into the rules and then maybe find a way to mount it lower, in the lower grill area if it won't get us in trouble again. It'd just be a little bit of grill blocking, which ain't a bad thing.

- D

 

Re: Aerodynamic In Seattle!

Hmmm, has anybody actually measured an MPG improvement with any of these covers? Personally I'm a bit skeptical that they would make a noticable difference.

 

Nobody is considering the added weight gain of these covers. vs. the aerodynamic drag reduction. A wind tunnel will not tell the end result of any savings in fuel.

Just seems like a waste of time and money to get unmeasurable results.

 

That's a joke, right? Plate covers should weigh ounces, maybe a pound. That amount of weight will have a truly unmeasurable impact on a vehicle this heavy. Add 50 or 100 pounds and you should be able to measure some impact.

I disagree on both counts. A wind tunnel could indeed determine the relative contribution of the plate (but should be done for the whole car.) I wouldn't run with a front license plate if it was not required. It makes little to no difference on my Tundra because the plate actually blends in with the bumper, making a slight rearward sweep at the bottom, and partially covering the a drag producing opening.

The Prius plate on the other hand disturbs the form of the front of the bumper that protrudes. This unnecessarily creates a very non-aerodynamic slab. Fortunately the disturbed area is only about 3-4% of the total frontal area of the car.

So back of an envelope, let's say this small area is doubling the effective Cd contribution of that portion of the area and only for the front of the car. It wouldn't surprise me if this amounted to a 1% or greater overall hit to aerodynamics.

It would be tough for an individual to coax statistical significance from this except on a test track with many runs, but like running with/without lights that doesn't mean the effect isn't real or isn't measurable/quantifiable.

It's been a long time since I did wind tunnel testing in college, but I did enjoy optimizing the aero of my son's Pinewood Derby car last year. We had some fun doing something I've not seen done on any others...and it appears to have been successful. There are some substantial drag and lift components that none of the Pinewood Derby guides seem to have noted.

 

How accurate is the "Matchbox "Prius?

I used to have a mini wind tunnel at home...and could run matchbox cars (remarkably accurate, especially for my 97 Ranger) through any number of tests.

If the Prius model is equally accurate, then small scale testing would be simple.

Of course, we could also use CFD, with today's powerful processors...but I don't have that software.

Chuck

 

I just think it looks awful on that chunky black frame, if any modification is to be done it must also include a cosmetic improvement for my troubles.

- D

 

Check out the aerodynamic front license plate cover on Craigslist Seattle, it actually saves 1.2mpg!

 

If duckbills didn't work, wouldn't ducks have lips?

 

Sorry . . . I just HAD to resurrect USB's front bumper license plate frame thread when I found THIS:

These must drive the fix it ticket cops up the wall