my coanda thrusters mod :)

[gabi]

i did this a couple of days ago,
realy fast and easy, i used an empty botle of mouthwash split in half attached with tape to the back wheels' cover

the idea is that the wheel is spraying a jet of air upwords that will hit the coanda device and provide thrust (forward)

now i'm not expecting much at all, any significant amount of thrust will rip the tape of for sure, but up to 5 lb of thrust maybe possible....who knows

i havent got to highway speeds yet, just 55 mph top speed so far .
cant really tell somthing's there to it....will see

[Joenavy85]

somebody needs to read up on Bernoulli's Principle, i smell unicorn poop.

[Christ]

The coanda effect is real. It can be displayed by placing a spoon into a vertical stream of water flowing downward, with the convex surface of the spoon facing down, as well. The spoon crates an example of coanda effect, displayed as adhesion. The water will briefly follow the curve of the spoon before continuing down. A spray with enough energy can actually temporarily reverse direction and travel up the curve of the spoon, against gravity.

How this would effect thrust on the car, I have no clue.

[Joenavy85]

the problem is that thrust doesn't just appear out of nowhere, if you make a veturi the air will travel out the nozzle faster than it enters, but it's due to the pressure difference, and the thrust created out the back is nowhere near the drag created in the front.

i understand that fluid dynamics is very broad, but the spoon demonstration is hydrodynamics not aerodynamics, the flow of water is completely separate from surrounding air, that is more of a demonstration of surface tension.

[gabi]

Originally Posted by Joenavy85

the problem is that thrust doesn't just appear out of nowhere, if you make a veturi the air will travel out the nozzle faster than it enters, but it's due to the pressure difference, and the thrust created out the back is nowhere near the drag created in the front.

i understand that fluid dynamics is very broad, but the spoon demonstration is hydrodynamics not aerodynamics, the flow of water is completely separate from surrounding air, that is more of a demonstration of surface tension.

http://www.youtube.com/watch?v=S-SAQtODAQw

[Joenavy85]

so you want to take the air hitting the inside of the fender (creating drag, as the fender works as a king of parachute) and divert it out of the wheel well (effectively increasing the wake of the car) i'll jest restate beroulli's principle here, the greater the difference in pressure the greater the velocity.

i'm not questioning that the effect can exist in this situation, i'm simply stating that you won't see any benefits from any kind of thrust due to the drag from the high pressure area offsetting any thrust created

[gabi]

Originally Posted by Joenavy85

so you want to take the air hitting the inside of the fender (creating drag, as the fender works as a king of parachute) and divert it out of the wheel well (effectively increasing the wake of the car) i'll jest restate beroulli's principle here, the greater the difference in pressure the greater the velocity.

i'm not questioning that the effect can exist in this situation, i'm simply stating that you won't see any benefits from any kind of thrust due to the drag from the high pressure area offsetting any thrust created

who said anything about diversion?
in fact with this set -up the air will have the tendency to stick more to the curved surface(of the coanda thing) ,thus creating less diversion to the ouside of the fender....double gain

[Joenavy85]

so it's sticking to the coanda thingy and going where? under the car? into the car? the side of the car?

[orange4boy]

There are all kinds of thrust vectors on various parts of a object moving through the air. The sum of them is usually expressed in drag, lift and yaw (and sometimes downforce) So what you are doing here is focusing on a small area to try to create a favourable vector out of an unfavourable one.

Drag reduction is usually expressed in the reduction of the rearward drag vector. Thinking about it in the other terms is an interesting idea. Does it apply to your mod? If there is actually a favourable thust vector and it outweighs the other changes in the airflow and the changes in other vectors then, yes.

Interesting way of looking at the problem. Almost impossible to verify without some sort of testing.

[Christ]

The idea appears to essentially have rounded the hard edge at the bottom of the inner fender, which will help keep flow attached and going under the bumper, rather than out the sides. Since the flow haas better attachment, the issue in front of the square edge is lowered, making for what would appear to be thrust. In reality, its just less negative forces, and probably by a negligible amount. Wheel skirts would probably compliment the mod.