Busting an aerodynamic myth -- Planes don't fly due to Bernoulli Effect

[Arragonis]

Bernoulli sucks.

Literally.

[robchalmers]

Originally Posted by winkosmosis

An analog would be a car... Remember the Audi TT lift fiasco? Even at zero chord angle, a car can have dangerous lift, necessitating spoilers. It's not because air flows faster over the top of the car, but because of the angle of the sloping windshield and trunk. If it was Bernoulli, the little spoiler that they added to the trunk wouldn't have solved the issue.




Heck... if Bernoulli was that powerful, cars with air dams preventing much airflow underneath would lift off.

oh dear.

first the audi solution generates seperation to kill lift a the rear most point, the phase 1 TT still generats lift, just not as much.

as for airdams they limit the flow under the car which is accelerated as it leave the underside and resumes normal flow therefore the flow is faster than the upper surface .

I thinking you really need to seperate Benoullis law from the longer line theory.
lift is resultant from benoulli lift and downwash lift
nealy every single car on the road produces lift.

if you don't fancy the paper trick mentioned earlier try hanging a spoon between you forefinger and thumb with the head hanging down loose enough to wobble. now run your fosset and put the curve back into the flow. ok, now repeat with the dished inner side - 9times out of 10 depening on the spoon the back will get more movement than the dish.

Benoulli works - long line is Boll***s

[Arragonis]

Fossett - forcet, i.e. tap - I think.

[winkosmosis]

Originally Posted by Philscar

Stand on your bathroom scale.
Hold hair dryer in your hand and point it at your forehead.
Run blow dryer on cool setting(don't fry your brain).
Check weight before and after.
If you get lighter with wind blowing over your head,you are developing lift!

Sailboat sails develop lift .
Airplane wings develop lift.
Cars develop lift if they are shaped like a wing.

Tape a sheet of paper to a table edge with most of it hanging down.
Blow some air over the table in the direction of the paper.
Shazam! The paper lifts up!
Lift caused by the airflow faster over the top than the bottom.

I rest my case........

Phil

Those amounts of lift are tiny. The reason the paper experiment convinces people that planes fly through the Bernoulli effect and not airflow turning is because the paper is so light for its surface area.

If the Bernoulli effect really was that strong, you could tilt a flat plate downward into airflow, and it would generate lift at any angle up to the point that flow turning balances it out.

What about those Bonneville Salt Flats spoilers? Fast airflow on top, virtually no airflow below. So do they create lift?

[robchalmers]

Originally Posted by winkosmosis

What about those Bonneville Salt Flats spoilers? Fast airflow on top, virtually no airflow below. So do they create lift?

I refer you to my earlier comment

[aerohead]

Originally Posted by winkosmosis

Those amounts of lift are tiny. The reason the paper experiment convinces people that planes fly through the Bernoulli effect and not airflow turning is because the paper is so light for its surface area.

If the Bernoulli effect really was that strong, you could tilt a flat plate downward into airflow, and it would generate lift at any angle up to the point that flow turning balances it out.

What about those Bonneville Salt Flats spoilers? Fast airflow on top, virtually no airflow below. So do they create lift?

They create negative lift.They 'spoil' the lift.

[euromodder]

Originally Posted by winkosmosis

Those amounts of lift are tiny. The reason the paper experiment convinces people that planes fly through the Bernoulli effect and not airflow turning is because the paper is so light for its surface area.

Errr ... the Coanda effect works.

[winkosmosis]

Originally Posted by aerohead

They create negative lift.They 'spoil' the lift.

And why is that?

To clarify: Why does a flat plate, with air flowing quickly over the top of it, and no airflow below it except sneaky eddies spilling around, spoil the lift created by the sloping rear window of the vehicle?

[robchalmers]

Overall - it counld be used to extend the chord lenth of the body flowin through the air and therefore reduces the relative camber of the top surface but bonneville 'spoilers' don't create downforce or negative lift - they reduce aid the laminar seperation of flow from the rear of the vehicle. You've choose a bad example there mate. sorry

[winkosmosis]

Originally Posted by robchalmers

Overall - it counld be used to extend the chord lenth of the body flowin through the air and therefore reduces the relative camber of the top surface but bonneville 'spoilers' don't create downforce or negative lift - they reduce aid the laminar seperation of flow from the rear of the vehicle. You've choose a bad example there mate. sorry

I didn't choose a bad example. I said they don't create lift, even though flow is fast over the top and nonexistent (or almost) below. If the Bernoulli effect is as powerful as some believers in the myth think, a spoiler like that would increase lift.