Mythbusters "tests" efficiency of dimples vs. smooth, and clean vs. muddy car

[pgfpro]

OK I guess I'm one of the ones that you are referring to for complaining without watching. Your right I shouldn't of said anything.

But now after seeing the episode I will have to say they are not even close to being accurate and there are way to many variables that they didn't address. This whole episode was a major fail other then the test with the golf balls themselves.

But the show is entertainment not true science.

[pgfpro]

Originally Posted by PaleMelanesian

Your math is a bit off here.
1/26 * 6 lb = .231 lb of gas
1/29 * 6 = .206 lb
difference .025 lb, or 11 grams of fuel.

Still small, but more significant. Remember too that they averaged 5 runs each.

Yes I know I address this in post #64

[PaleMelanesian]

I missed those. My post is irrelevant. I deleted it.

[robertwb70]

Originally Posted by Christ

I'm not sure how you could tell someone hadn't watched it anyway

When they say stuff like this "I wonder how long it took them to spray that clay on" it's obvious they didn't watch it...

And there are other examples in posts here but you get the idea, sometimes you CAN tell.

[MadisonMPG]

Originally Posted by pgfpro

OK I guess I'm one of the ones that you are referring to for complaining without watching. Your right I shouldn't of said anything.

But now after seeing the episode I will have to say they are not even close to being accurate and there are way to many variables that they didn't address. This whole episode was a major fail other then the test with the golf balls themselves.

But the show is entertainment not true science.

I think I have said this before.

[wagonman76]

The simplest assumptions often seem the most clever ones. They are also usually wrong.

Yes I thought the same thing. Scale is the same. Small difference on a golf ball scales to small difference on car. Ratio of improved air flow to total air flow would likely be the same.

Tire pressure didn't change, hence more rolling resistance. The car is definitely sitting lower with 800 pounds on it, hence less aero drag. But then again it's got a slightly larger frontal area. It's kind of surprising all of that evens out, but anyway.

And those cars are so lightly sprung too, at least the ones I've seen and ridden in. I bet it sat quite a bit lower with all that clay. Wonder about the tire pressure too. May have been more resistance at the start, but then again more sidewall flex means more heat which raises pressure and maybe compensated somewhat.

I think there's a reason land speed record cars do not look like this.

That's for sure, they've got the freedom to make it however it will perform best, regardless of if anyone will buy it.

They like A-B only testing do they. Even the beer-liquor test was done that way.

My first comment when watching the test was that they started with a cold engine for the mud test. Hard to say with the dimple test, but I bet it took a long time to apply all that clay (cold engine) and it didn't take that long to cut the dimples and test again (warm engine).

And Kari makes the show worth watching regardless of how bad they do testing. Baby or no baby she is fine

[shovel]

One thing I gotta say is, no matter how many "flaws" there may have been in their testing, they have definitely done better golf-ball-dimples-on-a-car testing than any of us have done.

I know I haven't personally done any better golf ball dimple testing than Mythbusters did.

Have you? If so, share it with us! If not, be glad someone did something.

[RobertSmalls]

I dunno, shovel, we do far better testing than they do. The kind of coastdown testing you read about here is generally valid, unlike Mythbusters' attempt to measure aerodynamic drag by measuring fuel consumption during a one mile run.

The reaction of the presenters upon revealing the mileage of the dimpled car was the same as mine. They realize an 11% improvement is impossible, but they go with it anyway, because it's a TV show.

My golf ball car testing (none at all) is better than theirs, because theirs will lead people to try out devices that, in theory, don't work on most cars, and whose effects are beyond the ability of most people to measure.

Cars should have creased rear edges. See the Prius spoiler, the Insight's sudden transition from sloped to vertical, the angular aft of a Volt, and similar details on Accords, Malibus, and Volvos. If your car has a round trailing edge, like the Taurus, it just might benefit from dimples, trip wires, vortex generators, etc. Still not enough to make up for the several inch thick layer of clay on the sides and top.

[alohaspirit]

so whos gonna email them?

[Cd]

If dimples really don't work, why did Audi, VW, and Lexus put them on the underside of their cars body panels ?
( Not being 'smart' with this question guys. I'm really sincere. I want to know why that they would go through all the trouble of adding them. )

Thanks