[alancalverd]

Drivel.

There are plenty of elementary texts on aerofoils, well worth studying before trying to explain it to others. I think it was part of the National Curriculum for 10-year-olds a few years ago.

Bored Chemist knows a lot more about aerodynamics than NASA, who keep designing asymmetric aerofoils in the mistaken belief that the upper surface has some influence on lift. You would think that they would have learned their lesson after 105 years and billions of dollars getting it wrong.

If you visit a science museum, beware! They will try to kid you that aeroplanes can fly and the world is not flat.

[Just thinking (OP)]

There are plenty of elementary texts on aerofoils, well worth studying before trying to explain it to others. I think it was part of the National Curriculum for 10-year-olds a few years ago.

Bored Chemist knows a lot more about aerodynamics than NASA, who keep designing asymmetric aerofoils in the mistaken belief that the upper surface has some influence on lift. You would think that they would have learned their lesson after 105 years and billions of dollars getting it wrong.

If you visit a science museum, beware! They will try to kid you that aeroplanes can fly and the world is not flat.

I'm not quite sure where you are going but I never questioned any of the many airfoils and wing designs that exist only that of the very simple Cessna 172 as an example of my question how can a plane fly inverted. And I think the question has been quite reasonably explained we all know that it starts with an increased angle of attack. ps Did you know that the boing 707 and your sweet concord have bean flown fully inverted at least in the process of a barrel roll.

[alancalverd]

No, the angle of attack of a symmetric airfoil is the same whichever way up the plane is flying. The 707 and Concorde airfoils are almost symmetric. The C172 wing is highly cambered and asymmetric for max lift and low cruise speed. Combined with differential ailerons, Fowler flaps, and a faired strut, it really doesn't work well upside down. It's actually a much more complicated shape than the Boeing in cruise mode. Interestingly the 707 is quite a good glider: the airfoil has a very flat lift/drag curve over a wide range of speeds  and a max of about 15:1 at 200kt, whereas the 172 maxes at around 8:1 at 65 kt and mimics a piano if you get it a few knots wrong.

[Petrochemicals]

Drivel.

There are plenty of elementary texts on aerofoils, well worth studying before trying to explain it to others. I think it was part of the National Curriculum for 10-year-olds a few years ago.

Bored Chemist knows a lot more about aerodynamics than NASA, who keep designing asymmetric aerofoils in the mistaken belief that the upper surface has some influence on lift. You would think that they would have learned their lesson after 105 years and billions of dollars getting it wrong.

If you visit a science museum, beware! They will try to kid you that aeroplanes can fly and the world is not flat.

Yes but that is up for debate whether a plane utilises the low pressure high pressure principle of boomerangs or the magnus effect, or whether a aeroplane simply planes the air, creating the pressure beneath the wing. Me personally believe the 2nd.

As to how a plane can fly upside down, think why a plane cannot fly upside down.

[Just thinking (OP)]

No, the angle of attack of a symmetric airfoil is the same whichever way up the plane is flying. The 707 and Concorde airfoils are almost symmetric. The C172 wing is highly cambered and asymmetric for max lift and low cruise speed. Combined with differential ailerons, Fowler flaps, and a faired strut, it really doesn't work well upside down. It's actually a much more complicated shape than the Boeing in cruise mode. Interestingly the 707 is quite a good glider: the airfoil has a very flat lift/drag curve over a wide range of speeds  and a max of about 15:1 at 200kt, whereas the 172 maxes at around 8:1 at 65 kt and mimics a piano if you get it a few knots wrong.

They are very interesting facts If you look closely at the footage of the 707 rolling you will notice that it plummets very quickly when inverted maybe just a case of little or no down elevator it was more of a corkscrew than a level barrel roll. Possibly the pilot did not want to over stress the airframe by torquing it.

[Just thinking (OP)]

Yes but that is up for debate whether a plane utilises the low pressure high pressure principle of boomerangs or the magnus effect, or whether a aeroplane simply planes the air, creating the pressure beneath the wing. Me personally believe the 2nd.

As to how a plane can fly upside down, think why a plane cannot fly upside down.

I feel that there is more going on with the underside of the wing than credit is given. Think of it as a flat stone skipping on the water the faster a plane flys the more the air is like water ore another example waterskiing the wing of the plane is air skiing..

[alancalverd]

Yes but that is up for debate whether a plane utilises the low pressure high pressure principle of boomerangs or the magnus effect, or whether a aeroplane simply planes the air, creating the pressure beneath the wing. Me personally believe the 2nd.

As you increase the angle of attack, the pressure below the wing obviously increases until α = 90°. But as shown in the video clip, when α > 15° or thereabouts, the flow over the upper surface becomes turbulent and, er, the lift decreases sharply, producing a stall condition.

Only an idiot, an aerodynamicist or a qualified flying instructor would conclude that this implies  that the airflow over the upper surface contributes significantly to lift. A born genius like yourself knows that airplanes are held up by faith, magic, and the underside of the wing.

Thousands of fools all over the world are busy right now removing dew, frost or insects from the upper surfaces, and designing ever more "efficient" curves that clearly contribute nothing to controlled flight.  O we of little faith!

[alancalverd]

As to how a plane can fly upside down, think why a plane cannot fly upside down.

Eppur si muove (Galileo)

"Now raise the nose and roll 180" (Charlie Kovac DFC, who taught me how to do it)

[alancalverd]

Possibly the pilot did not want to over stress the airframe by torquing it.

It's a serious consideration for transport aircraft. Most are rated for + 2.5 -1g, so don't like sustained inverted flight where the wing root stress is effectively -1g because there is no margin for error or gusts. I've seen a military KC135 tanker fly an aerobatic sequence (with empty tanks!) because the design and demonstrated limits are a bit wider (and the USAF is populated by lunatics) but it's not something you'd do with an airliner even if the seats were empty.

Most gliders are rated at +5 -3g and fighters go a lot further, so fly inverted quite happily. I think the Pitts Special biplane is stressed to ± 10g, by which time most pilots have lost interest in the proceedings.

[Petrochemicals]

Yes but that is up for debate whether a plane utilises the low pressure high pressure principle of boomerangs or the magnus effect, or whether a aeroplane simply planes the air, creating the pressure beneath the wing. Me personally believe the 2nd.

As you increase the angle of attack, the pressure below the wing obviously increases until α = 90°. But as shown in the video clip, when α > 15° or thereabouts, the flow over the upper surface becomes turbulent and, er, the lift decreases sharply, producing a stall condition.

Only an idiot, an aerodynamicist or a qualified flying instructor would conclude that this implies  that the airflow over the upper surface contributes significantly to lift. A born genius like yourself knows that airplanes are held up by faith, magic, and the underside of the wing.

Thousands of fools all over the world are busy right now removing dew, frost or insects from the upper surfaces, and designing ever more "efficient" curves that clearly contribute nothing to controlled flight.  O we of little faith!

An airplane is held up by the wing having an angle onto the oncoming air, thus planing it. If wings needed to be aerofoil, flat shape wings would now work but yet they do.

The stall demonstrated is the leaking of air from beneath the wing to the top of the wing which creates  destructive turbulence, due to the angle and trim that is required upside down and the lack of thrust capability that is required to summount this turbulence that most planes exhibit, this is why the planes have a bit of trouble flying upside down.

They also remove rivets from wings, as well as barn doors and gremlins as the  efficiency tends to drop.

[alancalverd]

The stall demonstrated is the leaking of air from beneath the wing to the top of the wing which creates  destructive turbulence, due to the angle and trim that is required upside down and the lack of thrust capability that is required to summount this turbulence that most planes exhibit, this is why the planes have a bit of trouble flying upside down.

Air leaking through solid aluminum. Never thought of that before.

Perhaps it's the high pressure air creeping round to fill the low pressure area above the wing, but you have stated that there is no pressure reduction above the wing.  And the air above the wing is still moving backwards at 50 - 70 kt in the video.

Those fools who run wind tunnels and design airplanes, cars and golf balls talk about boundary layer separation, but what do they know about fluid dynamics?

We do control leakage with spoilers, but these are fitted at the maximum camber and open both above and below the wing. Mostly on gliders and other very high performance aerofoils. They reduce lift and increase drag, but don't induce a stall.

[Bored chemist]

They also remove rivets from wings, as well as barn doors and gremlins as the  efficiency tends to drop

Thanks for sharing.

[Just thinking (OP)]

Quote from: Petrochemicals on Yesterday at 20:21:13

    They also remove rivets from wings, as well as barn doors and gremlins as the  efficiency tends to drop

Thanks for sharing.

If you live close to an airport it drops the price of real estate but that's better than some places where planes only drop bombs.

[Petrochemicals]

The stall demonstrated is the leaking of air from beneath the wing to the top of the wing which creates  destructive turbulence, due to the angle and trim that is required upside down and the lack of thrust capability that is required to summount this turbulence that most planes exhibit, this is why the planes have a bit of trouble flying upside down.

Air leaking through solid aluminum. Never thought of that before.

speed holes alan

Perhaps it's the high pressure air creeping round to fill the low pressure area above the wing,

sounds like capitulation

but you have stated that there is no pressure reduction above the wing.  And the air above the wing is still moving backwards at 50 - 70 kt in the video.

No I didn't, if a falling object creates a bow wave of pressure, it has to create negative pressure to the stern, or rear., the area it has just passed through., something to do with vacuum creation.

[alancalverd]

If you live close to an airport it drops the price of real estate but that's better than some places where planes only drop bombs.

We had to defend the noise of a gliding club when a new neighbor complained to the local magistrates. He had just bought a house 100 yards from the end of the main runway. Magistrate read the deposition then said "The reason you can buy any house you like is because, among other things, this has been an active airfield since 1939. Case dismissed."

[Bored chemist]

Magistrates are good at getting things right for the wrong reasons (on a good day).

[alancalverd]

something to do with vacuum creation.

But that would create lift from the upper surface, which you and BC do not believe in.
Fortunately, modern cars don't use carburettors, which rely on the same (Bernouilli) principle as the upper surface of a wing. Just as well because you tell me that the laws of physics have changed and Bernouilli no longer applies. I must get rid of the carb on  the old Cessna - it's hard enough to fly with only half the wing generating lift, and if the carb doesn't suck petrol, we are doomed.

[Bored chemist]

and BC do not believe in.

That's not what I said...

[Just thinking (OP)]

Quote from: Petrochemicals on Today at 05:22:11

    something to do with vacuum creation.

But that would create lift from the upper surface, which you and BC do not believe in.
Fortunately, modern cars don't use carburettors, which rely on the same (Bernouilli) principle as the upper surface of a wing. Just as well because you tell me that the laws of physics have changed and Bernouilli no longer applies. I must get rid of the carb on  the old Cessna - it's hard enough to fly with only half the wing generating lift, and if the carb doesn't suck petrol, we are doomed.

In a normally aspirated engine is the air sucked in or pushed into the carburetor.

[Bored chemist]

In a normally aspirated engine is the air sucked in or pushed into the carburetor.

Anywhere except a physics classroom, the fuel an air are sucked through the carburettor.
In a physics classroom, the external air pressure pushes fuel and air into the carburettor.