What perpetuates the aerofoil myth?

Question

Has nobody thought to compare the lift of an aerofoil with that of an equally massive simple inclined sheet in a wind tunnel?

Kev R: try http://www.physicsmyths.org.uk/bernoulli.htm for why Bernouilli effect DOES NOT APPLY!!!

just 'JR': NO! Since you know so much go to your precious wind tunnel and do the experiment and then wonder why you doubted me!

Answer 1

Inclined sheet of what? The same material that the aerofoil is made of? That would be a floppy sheet then, and absolutely hopeless at supporting even itself, let alone anything in flight.

For a lift generating plane to be of any use, it needs to have some stiffness so that it:

a) holds its shape to maintain the level of lift generated (an inclined sheet in a windtunnel would just flop back on itself or even break, and not produce any lift beyond that initial point)

b) provides a platform on which an aircraft (or whatever) that lift can act on

An aerofoil works because it is the best compromise between the plane (as in the sheet that you've mentioned), and structural integrity through its stiffness (given by its depth).

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A neutral aerofoil (one that has the same curvature on the top and bottom surfaces) works well on aerobatic aircrafts by relying on angle of attack. True, the shape of the aerofoil helps in generating lift, but it doesn't need to be that as can be seen in the neutral aerofoil

Answer 2

An aerofoil works by creating uneven pressures above and below the wing, due to the shape and how it directs air flow.

I'm certain that early users of wind tunnels would have used massive inclined sheets.. look at the wing on the rear or early racing cars and dragsters.

The problem is that this simply creates a large amount of drag as well as downforce. The airflow has to managed in an efficient manner to reduce drag and maximise lift or downforce.

A large inclined sheet is an overly simple approach.

Answer 3

You have not understood the Bernouilli principle at all, and your comment giving the site is also wrong!
The site is showing a symetrical wing (front and rear), with a flat bottom. It also shows the movement "normal" to the profile.
In this particular case, it is correct that there is NO lift produced (as the increase of pressure in front is compensated by the decrease at the back.
A symectrical aerofoil (same curvature on top than on bottom), IF travelling in its longitudinal axis WILL NOT GIVE LIFT.
However, if you incline the profile a few degrees, (that is: changing the angle of attack), AND you apply Bernouilli principles (if yours maths are good enough, of course), you WILL see that a lift is produced.
Persist in your silly affirmation, and you will be still a moron in a 100 years!

Answer 4

Taking Formula 1 racing cars as an example one only has to see how a better solution to racing car downforce was arrived at. From the wedge shape of the 70`s, your inclined sheet, to the sophisticated curves of today.
The motor racing fraternity and aviation industry spend millions of pounds on wind tunnels and advanced computer technology to produce subtle changes in aerofoil technique.
I am quite sure that a flat piece of mild steel tilted at an angle would have been used if it were the right shape, but, alas it is not capable of creating the correct pressure differences for stable and controlled use.

Answer 5

The next time I go flying and look at the wing supporting my aircraft, I shall sincerely hope that the aerofoil myth continues to be perpetuated!

Seriously, after nearly 100 years of wing design/research I think you'll find that the aerofoil as we know it, is somewhat superior in performance to a 'massive simple inclined sheet' .

Answer 6

Try to work out what the eddies would be like over the top of an inclined sheet, and how you would prevent them. You will end up with a curved surface over the top of your inclined sheet - like an aerofoil.

Answer 7

Yes an inclined sheet will give you lift. But an aerofoil is engineered to give better lift, which happens due to its shape.

There is no myth about aerofoils.

Answer 8

I think you need to research Bernoullis principle. This very simply states that the faster air travels over a surface then the less pressure it exerts on that surface. An aerofoil has one flat and one curved surface - the same amount of air has to travel further over the curved surface therfore it must travel faster than the air passing the flat surface to reach the same point. Lower air pressure on the curved surface induces lift - sort of sucks the wing into the air. This is always better than a purely flat surface deflecting air like a kite does.

Answer 9

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Answer 10

I don't think you understand how an aerofoil works then. It's not just the angle that gives lift, it is the shape.