Originally Posted by onehundred80
Franc you flatter me, I could not have spelled aeronautics engineer if you hadn't shown me.
The pressure under the car is greater than the air over the car but it is the same as the ambient air pressure. It's the difference in pressure that gives lift.
I do not understand your first question..... less pressure on the underside?
We get all that dirt on the rear bumper because the air coming from under the car carries the spray from the road and this air rushes up to balance out the lower air pressure coming over the car. Nature abhors an imbalance of pressure.
Deploying the spoiler on the na I think would tend to keep the dirt off the bumper. I'll have to try that experiment.
Oops, I forgot this.
Sorry the air over the car is faster than the air under it, my mistake. Faster equals less pressure. I should proof read my posts better.
I wondered at first why you had high lighted that statement, a senior moment I'm afraid.
Your not an Aeronaughty engineer?
I guess I'm remembering a booze amplified conversation we had at the Dragon.
Hmmmmmm.
OK so my question was valid in relation to your misspeak.
I feel better now.
I still believe you know more about air flow than most. Including me.
Now,, our feeble experiment with ram air gave me some clues and one of them was the high pressure area just forward of the wheels. The area behind the front air dam is lower pressure creating a downforce relative to ambient air in that area.
Therefore it is logical to assume that extention of a front air dam past the front wheels will cause the following;
A reduction in turbulence under the chassis
A reduction in air pressure under the chassis
A resulting increase in adhesion to the road and at the very least, better fuel economy.
As to Tech9's request, I believe it will also improve his co-efficient of drag ratio.
Lowering the chassis will only improve the beneficial forces.
Separately, I agree about the personality of the air flow at the back of the vehicle. I actually suggested putting a diverting baffle at the diffusers under the car's rear bumper. This would aim the air from under the car (a high pressure bubble) into the low pressure bubble just aft of the Crossie's big butt.
It would also, however, keep the bumper covered in slop from the road.
Sorry Dave for putting such a strain on an old Canadian's brain. Just getting even.
No I can't remember for what. But, I'm sure there is a smart quip back there somewhere in our history for which I owe you a quick barb.
I'm just not quick.
roadster with a stick