The lift formula explains lots of the other things you listed as well.

You're confusing an equation with an explanation, and a knowledge of algebra with an understanding of the physics. Equations never explained anything to anyone.

For a good lift example, go to about 3:20.

http://www.youtube.com/watch?v=WpmILPAcRQo

photofly wrote:Equations never explained anything to anyone.

No? Not F=ma? Not (Gm1m2)/r^2? If you understand the formulas, you understand what happens

There is a reason why we use the lift formula and more specifically why we use a coefficient of lift rather than some other value. It is because the only way we know what is going on is by taking and shape, sticking it into a wind tunnel, and analyzing the effects. Multi-billion dollar modern airliners designed on computer still give surprises to the test pilots in terms of flutter, shock separation, or performance shortfalls because all we have are simple theories as to why air behaves the way it does.

But your 'explanations' do just as good as somebody who is explained something wrong. In fact, your explanation of the aircraft shedding its first vortex on rotation is wrong, because Circulation is equal to Cl and the chord portion of the Wing Area in the Lift Formula, and we have both of those as soon as the aircraft starts moving with any sort of angle of attack.

But I don't think that you fly a plane any worse or better because of it.

I simply explain that air is accelerated over the wing creating a low pressure area above it. 100% factual and very simple.

The truth is you could take someone who can not read or write and them to fly an airplane....it is just another machine that is manipulated by controls.

No? Not F=ma?

No.

Not (Gm1m2)/r^2?

No, definitely not.

If you understand the formulas, you understand what happens

If you know the formula you know *what* happens - but won't have a clue why.

You picked two great examples, perhaps without meaning to. The fact that the force on a body is proportional to its acceleration (with the constant of proportionality being called the inertial mass) is one of the greatest mysteries of the universe. I don't think anyone actually understands the "why". And the formula for gravitational attraction just tells you the "what" of what happens, it doesn't tell you why two massive bodies feel an attractive force. Do you need a knowledge the General Theory of Relativity to put a satellite into orbit? No. Does it make you a better physicist? Undoubtedly, yes.

I simply explain that air is accelerated over the wing creating a low pressure area above it. 100% factual and very simple.

But that's no more useful (or indeed untrue) than saying "airplanes fly because they have wings."

Regarding where vortices are shed: whenever lift is generated. In that most of the lift is generated when the aircraft rotates (otherwise it would fly off the runway earlier) that is where most of the starting vortex is shed.

photofly wrote:I don't think anyone actually understands the "why".

I hope I don't take this out of context but this is what I am getting at and really it applies to lift just like it does to relativity or gravitation or simple forces.

Ultimately when we come to it, we have no idea why the air likes to flow of the trailing edge of a wing instead of curving up to the low pressure area. And to fly an aircraft, we don't need to know. And for somebody who just wants to fly an aircraft they can figure it out several steps before that. 'H' doesn't even believe there is suction above the wing, but I would struggle to turn even a single Aresti diagram into something judgeable.

Back to formulas, if more students knew the implication of 1/2mv^2 on their overly padded approach speeds (which you can correct with the lift formula, of which a version of the kinetic energy formula is a part) maybe we wouldn't see the float fest on typical student and even professional pilot's landings.

I would teach that before circulation, because circulation takes care of itself in the aircraft with the right combination of airspeed, attitude, and power.

Every airplane performs differently, learn the behavior of the airplane you are flying and how to safely fly it.

Formulas mean sweet @#$! all once you lose control.

. . wrote:Every airplane performs differently, learn the behavior of the airplane you are flying and how to safely fly it.

Formulas mean sweet @#$! all once you lose control.

As an engineer who caused himself much grief during my PPL training by constantly overthinking things, I think I'll frame this and put it on my wall.

I hope I don't take this out of context but this is what I am getting at and really it applies to lift just like it does to relativity or gravitation or simple forces.

Ultimately when we come to it, we have no idea why the air likes to flow of the trailing edge of a wing instead of curving up to the low pressure area.

You're right, in that for every explanation you can dig deeper and ask another "why". It really depends on how many layers of "why" you want to delve into.

Personally I've found it helpful and interesting to know what the airflow off the trailing edge is like as well as why, and to see how this leads to circulation around the wing. I'm not invested in whether anyone else does.

Obviously . doesn't give a stuff, it sounds like he's too busy trying to keep control of his aircraft to care

On the subject of formulas, I like John Denker's "9 feet per knot per hundred knots" formulation. It's both correct and easy enough to apply in a cockpit. In fact I like a lot of what Denker says, but perhaps that's because I have a degree in theoretical physics and he's a physics prof.