Compressed air for drag reduction ( Coanda slots )

[MadisonMPG]

Drive "fast" when you do the test, it will help show the benefits, if any, better.

[aspera]

What do you guys think will happen ?
B. The drag will actually be worse.

Your interior will now be part of the wake bubble. Air will enter through the tailgate area and get sucked out your front windows at the low pressure area by the A posts. It will also be loud. You'll also enjoy road spray on the inside of your windshield if the road is wet.

[The Atomic Ass]

Originally Posted by Cd

Probably 99.7% of the world thinks that cars look 'ugly' or 'odd' with a boat tail. People don't want a big thing sticking out the back side of their SUV. I see this invention as a way of catering to the rest of the world.

It sucks to be part of the 0.3% of the world that thinks an SUV is an ugly contraption.

[Piwoslaw]

Originally Posted by The Atomic Ass

It sucks to be part of the 0.3% of the world that thinks an SUV is an ugly contraption.

Why does it suck? Remember: you're in the top 0.3% !! You should be proud

[Cd]

Originally Posted by aspera

What do you guys think will happen ?
B. The drag will actually be worse.

Your interior will now be part of the wake bubble. Air will enter through the tailgate area and get sucked out your front windows at the low pressure area by the A posts. It will also be loud. You'll also enjoy road spray on the inside of your windshield if the road is wet.

Would the air entering the tailgate have more force than the air trying to escape through it ?

Also, I assumed that the wake was already pretty messy back there, and that the messy air coming out the back would be pretty much the same .

Thanks for your advice.

[Cd]

If I know from the start that that the results of the testing will be more drag, I won't even waste my time with it.
Will the drag still be worse if I create a smooth channel for the air to run out the back ?
I plan to create a channel running from the passenger side window out to the back of the car. ( I'd remove the passenger seat and fold down the back seats flush.
Since this would be asymmetrical, would this lead to any problems with the test ?

In the real world, this would never be practical on a car like mine, but as I look at cars such as a VW Jetta, it seems that you could create a channel for the air that would be weather tight and would not cause extra wind noise. You could exhaust the air out slots on the back of the trunk.

[Cd]

Here is a really sloppy example :

[lunarhighway]

It sucks to be part of the 0.3% of the world that thinks an SUV is an ugly contraption.

most people don't think about these things... if all cars look a certain way they think it looks good especially if comertials cofirm that.

if all carmakers would suddenly bring out boattails or if the next james bond movie would have a production car with a boattail than people would want it (of course a true solid boattail is just very unpractical for most people wich is why cars don't have them)

[Nerys]

Smoke testing JUST might be doable. I hear (and saw for myself) that seafoam through the throttle body creates an ass ton of smoke. I am thinking seafoam (or other similar) injection maybe directly into the exhaust? in the lead car the subject car follows close in and a chase car alongside off to the side with a video camera.

get the smoke going video tape the results. not perfect but MIGHT garner usable results.

I am thinking kamback and air injection under the kamback to virtually "extend" the kamback.

as for costing more energy than saved this is an oxymoron. entrophy says this is 100% what will happen 100% of the time. Period so even saying it kind of sounds silly.

what matters is NOT energy in versus energy out (which is ALWAYS negative) but DOLLARS in versus dollars out.

even if it takes 3 times the energy you save is the alternative CHEAPER.

ie compressing the air at home uses your household current and as we know this is virtually FREE compared to the cost of gasoline. so unless your using hundreds of kilowatts each drive your never going to spend as many dollars on E as you do on GAS. This is why EV's are so damned desirable.

you run into another problem though. your going to expend you compressed air VERY VERY quickly. as a short TEST with say a scan gauge this might garner results but you only going to be able to carry at best a few minutes of air power with you without going to very very expensive tanks and pumps. ie you need a giant tank at THOUSANDS of PSI not the measily 120-150psi your can do with conventional affordable tech and the 20-40 gallons of air you can carry at that pressure.

you need more along the lines of 50-80 gallons of air at 4000-5000psi to get anything usable. the COMPRESSOR to do that costs more than most of our cars cost and it was not designed for such a duty cycle ie even more expensive.

real time generation is likely going to be whats needed. I am not sure how to do this. it does make the thought juices flow though :-)

[aerohead]

I found the reference for earlier work:
"Trapped Vortex Flow Control For Automobiles," by J.J.Cornish,III,Chief Engineer,Lockheed Aircraft Corp.,Marrieta,Georgia division.
Presented,Los Angeles,California meeting,Aerospace Industries Association of America( 100 Wilson Blvd.,Suite 1700,Arlington,VA 22209 USA Aerospace Industries Association ).