"No one knows exaclty how they stay in the air..."

runswithascript

I heard it said recently that there are three competing theories on the physics of aviation and that no one actually knows which, if any, is correct.

Is there any truth to this?

What do you mean I 'can't say bomb on an aeroplane'?

oscarBravo

I had only heard about two - the Newtonian model, and the Bernoulli model. Neither perfectly explains aerodynamic behaviour (although Bernoulli comes closer), but a combination of the two provides quite a comprehensive explanation.

The physics of flight are well-understood. They're just hard to explain simply, is all. Have a look at "See How It Flies" for a very good explanation.

RoundyMooney

Someone once compared the fine balance of helicopter flying to "riding a unicycle on a tightrope while juggling a couple of chainsaws".

And that's flying the thing, not to mind the physics of it all...

junkyard

RoundyMooney wrote:

Someone once compared the fine balance of helicopter flying to "riding a unicycle on a tightrope while juggling a couple of chainsaws".

And that's flying the thing, not to mind the physics of it all...

Its not quite that hard.....really.:)

peasant

The thing that always baffled me ...

We all know how a wing works ...fast airflow on top, slower airflow on bottom, updraft, lift, etc ...

So how come airplanes can fly upside down ?

RoundyMooney

/goes to tear my hair out and realise I don't have any.

Too early on a Patrick's day morning to be worrying about things like this! I only logged on for a few minutes...

/goes to Google and searches like a man possessed.

oscarBravo

peasant wrote:

We all know how a wing works ...fast airflow on top, slower airflow on bottom, updraft, lift, etc ...

So how come airplanes can fly upside down ?

Because even upside down, you get fast airflow on top, slower on the bottom. Read the link I posted.

hibby

oscarBravo wrote:

The physics of flight are well-understood. They're just hard to explain simply, is all. Have a look at "See How It Flies" for a very good explanation.

oscarBravo, that is a truly excellent site you linked to. It's going straight in my Favourites, thanks!

The problem with the classic (flight school) explanation of how lift is generated is at the point where they claim that the air flowing over the upper surface of the wing has to move faster, so as to meet the air flowing under the wing, so that they can both arrive at the trailing edge at the same time. Questions beginning with the word "why" are most unwelcome at this point in the class!

There is no rule that says that particles of air that are adjacent before separation at the leading edge must meet again at the trailing edge. In fact, at positive angles of attack the air-flow over the upper surface arrives at the trailing edge before the air that flows underneath, resulting in a downdraft off the trailing edge that contributes to lift.

electric69

Lift = cl 1/2 P V^2 S

Chiron

I always thought the formula for flight was:

Lift=€xlots+10

Oilrig

Make it ugly and the earth will repel it

cp251

Lift=€xlots+10

It's absolutely is. Put a big enough engine on it and anything will fly!

derry

Hitch hikers guide to the galaxy defines it...
"The art or rather the knack to flying is to throw yourself at the ground and miss"

derry

Kevster

I see it as a rather simple thing to understand, actually. The air underneath the wing is partially obstructed and is then at a higher pressure than the air that moves over the wing (which is at a lower pressure). We then all know that air moves from a region of high to low pressure. Thus, the air below the wing rises upward against the underside of the wing creating lift.

cp251

No Kevster that is in fact incorrect. I actually believed that at one stage. Counter intuitively, it's airflow over the top of the wing that produces lift. In effect the lower pressure on the top side of the wing 'draws' the wing upwards not the pressure from below pushing. That of course is the Bernoulli version. In the Newtonian version it's the downwash behind the trailing edge which produces an equal and opposite force generating lift. But both explanations are correct just arrived at differently.

Lift is a complicated, much misunderstood subject.