Aerodynamic front bumper license plate frame?

[chuckknight]

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

[don_chuwish]

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

[uart]

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.

[Bob.H]

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.

[Shawn Clark]

Originally Posted by Bob.H

Nobody is considering the added weight gain of these covers. vs. the aerodynamic drag reduction.

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.

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.

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.

[chuckknight]

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

[don_chuwish]

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