Re: OT: Fuel mileage and wings
 

I will take 3 dozen of those golf balls! lol

Re: OT: Fuel mileage and wings
 

LOL.....well, I think the PGA officially outlawed them years ago. However, I believe you can make them yourself if you really wanted to. I'm sure you can find directions somewhere on the internet. :)

Re: OT: Fuel mileage and wings
 

There was a problem back in the 50's with a certain chrysler model with curved tail fins. At high speeds the rear end would lift.

Many cars have spoilers, Some are for show but the low slung ones are purely to break up the air sucking the car backward (Drag) Therefore improving Milage

Re: OT: Fuel mileage and wings
 

Originally Posted by are39:
Actually, it depends on where the dimples are at. They need to be placed prior to the boundary layer seperation point. A golfball has them all over since a golf ball spins, and you don't know which part will be the point of attack when. The dimples cause the boundary layer to stay attached longer, thus reducing drag. Did you ever see the 'slice proof' golf ball? They filled in a certain portion of the dimples on the ball, the remaining dimples would cause the ball to right itself during flight, and go straight. Anyway, anything out away from the car body will help cause boundary seperation and induce drag which of course is bad for fuel mileage.

not true.. Myth busters did a show on this.. they used clay on the whole car, and dimpled the whole car.. both before the clay and after the clay and then after the dimples on the car.. The car with the clay and dimples actually got better gas mileage than the regular car minus all the weight from clay.. so if it is dimpled all over, you will get better gas mileage plain and simple.. so bring the hail, now im not sure how deep the dimples have to be before you start gaining anything.. it was a good amount they gained if memory serves right..

Re: OT: Fuel mileage and wings
 

Originally Posted by 9racing:
not true.. Myth busters did a show on this.. they used clay on the whole car, and dimpled the whole car.. both before the clay and after the clay and then after the dimples on the car.. The car with the clay and dimples actually got better gas mileage than the regular car minus all the weight from clay.. so if it is dimpled all over, you will get better gas mileage plain and simple.. so bring the hail, now im not sure how deep the dimples have to be before you start gaining anything.. it was a good amount they gained if memory serves right..

I guess I should clarify. What I was trying to say is that you really don't need them over the entire car. Yes, MB did show an improvement with dimples over the entire car, but dimpling at certain spots on the car probably would have gotten the same result. Here's an excellent Air Force paper on some dimple research: http://stinet.dtic.mil/cgi-bin/GetTR...c=GetTRDoc.pdf

Part of the background research for this particular paper cited previous dimple testing:
"James Lake [6] examined dimple location along with comparing dimples to v-grooves and trip wires in his investigation on reducing sparation on a Pak-B turbine blades. He found that dimple location had an effect on dimple effectiveness. Dimples were most effective when placed slightly upstream of the unmodifed blade separation point. As the dimple was moved further upstream of the separation point, its effectiveness decreased. His research shows that for maximum effect, dimples should be placed as closely as possible to the point of separation."

That's what I was trying to say originally. Although hail-damage could aid in fuel mileage, properly placed dimples would be most advantageous. Now, the paper I posted goes further, looking at the diameter/depth ratio of the dimples, and how that affects the flow characteristics.

Re: OT: Fuel mileage and wings
 

Interesting topic. I love "talking airflow". We "dimpled" a couple of different Brigg's cylinder head's in the combustion area in different "pattern's/area's when we were racing kart's and we def. saw improvement's in "burn" and had to actually richin up the engine. It must have improved "swirl" as the engine sure "came off the corner" better / had better throttle response.