The DragBean

[DragBean]

So i had to drive to LA today and while on the 5 North a semi sent a huge chunk of concrete into the air. It clipped the car in front of me one lane over on the passenger side and exploded into a bunch of chunks of debri. Luckily i hit the brakes in a split second and didn't end up with a caved in windshield. But a huge chuck went through the passenger side of my front body kit and popped my tire :\ Thankfully no one got hurt but a total of 5 cars got popped tires. What's crazy is after i pulled over i ran back down the freeway waving my hands in a stopping motion so i could get the cinder block size of concrete that hit me in the middle of the freeway. I did this for 5 minutes and people hardly slowed down so i gave up and later 3 more cars to make 5 were on the side of the freeway with popped tires.

[DragBean]

Here's the chunk after it got hit 5 times and crushed down

[BabyDiesel]

Hate that for your ride, DragBean. I know you are looking for replacements already, let us know if we can help.

Also, I love the way your pizza pans look. Except the front passenger side one, "looked"

[Cd]

So........um.....what about the back of the car where the drag is ?

[freebeard]

I'd call that a successful stress test. Did the concrete fall off the truck or was is dislodged from the roadside?

You said you need better fasteners on the wheel covers. But these seem to have done their job. Are they threaded into the rim itself or the wheel studs? And the fiberglass appears to have survived. Was it only the curved paneling that was shredded?

[DragBean]

@freebeard

I replaced the #8 screws with 1/8"x3/4" self-tapping screws with 3/8 hex heads and rubber washers.

The pizza tray saved the rim for getted scouged up, although the rim got a little bit where the concrete impacted it.

And yes the concrete was from the road, it got dislodged and sent up by the semi. The curved redwood cut a chunk tore out right on the edge where the wood curves the most. I'll probably have to figure out how to separate the fiberglass from the existing wood and re-do it. Or I might be able to backplate it and fiberglass it.

@CD How do you recommend I deal with the back? I'm going to put side squirts on, but I'm at a loss as to figure out the back. Maybe a little Nascar thing on the trunk?

[freebeard]

Make a patch that looks like a riveted gusset plate and add another on the driver side.

I think the wheelwells and floor-pan offer as much potential as the tail, and Cd will have suggestions; but there are

• fixes—like spoilers, vortex generators and Gurney flaps
• mods—Kamm-backs, skirts, spats and difussers
• boat tails—extend the overall length by the wheelbase and wonderful things happen to the Cd. If you can live with the aggravation.

The really exotic stuff includes Coanda nozzles and Plasma actuators.

[Cd]

I don't mean to disrespect what you are doing. I just see a lot of folks here recently concentrating on the front of the car.
If you are trying to decrease drag, the best place for that is at the back of the car.
There is plenty of information here on E.M. from user " Aerohead " on the subject.

Your car had attached airflow on the front of the car from day one. You have rounded the front end and possibly sent the airflow around the sides of the car. This may, or may not decrease drag. Yor modification has also plugged the grille and added a section that is lower - much the same as a spoiler, so this will certainly decrease drag and you will see MPG gains....but as you can see from the attached image, there is no need to extend the nose of the car. A simple grille block, and a front spoiler will do the same thing.

You asked about what to do at the back of the car. This guy did a wonderful job of taking a '3-box' design, such as yours, and streamlining it :


The only thing he might improve on is to round out the sharp edges on the rear extension.

Disclaimer : I am just an 'armchair' aero enthusiast. I just repeat things I have read. I am constantly surprised at new things that I learn about aerodynamics. I know nothing. Carry on .

[freebeard]

Cd's disclaimer applies to me as well.

That's a good example for the build quality.

christofoo posted this picture (in 2013) at http://ecomodder.com/forum/showthrea...tml#post394186 I had suggested a 4-bar linkage at Permalink #171, but he improved on the idea by eliminating two. The bars are bolted to the holes for the license plate.

[DragBean]

@CD

So why would rounding the front NOT decrease the overall drag? Pretty much in any sub-sonic application a rounded approach will allow air to slip around the object far better than a flat face.

Maybe it could create unwanted flow separation on the sides but that would definitely already be there.

Aerospaceweb.org | Ask Us - Drag of Cylinders & Cones

And I did the front fiberglass part (originally there was an air gap between the rounded word part and the hood- that was hardly a 1 mpg improvement) and pizza rims on my tires both at the same time and my mpg went from 31-36 to now I have at 38.7 tank and a 41 mpg tank. Pizza Rims were probably only about 25% of the gains because other people would see 10% gains with terribly unaerodynamic rims.

But this is good news. It looks like if I do the back I'll get some huge improvements.

I also have a panoramic mirror that relies on the back not being obstructed... That means I would have to make the rear panel out of bended plexiglass to still have the benefit of essentially no mirrors. A little bit of a curve might be a tad better than a flat panel.