DC-3 on floats:

http://www.youtube.com/watch?v=pJ6zTZuq5zw&feature=feedwll

Here you go, and this is more than any pilot needs to know:

Fineness ratio is a term used in aerospace engineering to describe the overall shape of a streamlined body. Specifically, it is the ratio of the length of a body to its maximum width; shapes that are “short and fat” have a low fineness ratio, those that are “long and skinny” have high fineness ratios.

Now you can forget it.

Good post. He mentions another technique but I’ve never heard of anyone preferring a zero G version and that certainly wouldn’t be preferable in the Dakota. I also suspect that during the zero G version that the wings are still producing lift. 😀

From the Jeppesen Instrument/Commercial Pilot Manual:

“The four fundamental flight maneuvers–straight-and-level flight, turns, climbs, and descents–are controlled by changing the balance between the four aerodynamic forces: lift, thrust, drag, and weight. As you know, opposing aerodynamic forces are balanced in straight-and-level flight. Lift balanances weight, and thrust balances drag. The airplane is in a state of dynamic equilibrium, and there is no acceleration in any direction. A change in any one of the forces will result in an acceleration until equilibrium is reestablished.

The same principles apply in climbs and descents.”

The above chart clearly shows lift and weight equal in the descent.

Perhaps I confused it by then asking whether critical angle also changes with G too. This is a can of worms, and my instinct still says ‘no”.

Your instincts are correct.

The critical angle of attack a measurement to that particular airfoil. At that point is maximum lift generation. Above that point is a stall.

It is the angle between a reference line on an airfoil (chord line) and the vector representing the oncoming wind known as the relative wind.

I think I’m right in saying, that a common mistake is for people to confuse “Lift” as being the opposite of gravity.
Lift is the force which is perpendicular to the airflow over the wing. If the wing is upside down, lift is still acting on the wing so long as A-o-A and speed is correct.
If a wing loses lift, due to the A-o-A being wrong, we have a stall.

For the non pilot math geeks here, this is student pilot stuff about the four forces that act on an airplane. It’s pretty easy to understand as it is at a 16 year old level (the age in which you can solo a powered airplane).

http://www.nasa.gov/audience/foreducators/k-4/features/F_Four_Forces_of_Flight.html

Now for the frequent fliers here.

If you are in the back of my Airbus on a runway and I push the power levers (throttles) forward, the airplane will begin to roll and at about 115 knots I will rotate the aircraft, initiate a climb and accelerate to our climb airspeed of 250 knots below 10,000 feet. There is excess thrust over drag and the result will be a climb of 3-4 thousand feet per minute (initially). The airplane will be at one G in the climb. Again, when thrust is greater than drag you will climb.

When we level off in cruise at 35,000 feet (FL350) in my Airbus, I will pull the power levers (throttles) back to cruise thrust and trim the aircraft for level flight. I will then turn off the seat belt sign. At this point all four forces acting on the airplane are in equilibrium. Lift equals weight and thrust equals drag. The aircraft is at one G.

At 70 miles from our destination I will pull the power levers back to idle and we become a glider. We are now descending at about 300 knots. The wings are still producing lift to hold 145,000 pounds in the air during the descent. If they were not we would soon be tumbling out of control and a fire ball on impact. During the descent the four forces altered in that drag is now greater than thrust. Additionally, in the descent at constant 300 knot airspeed the aircraft is still at one G.

When I level off at 10,000 feet to slow to 250 knots I will add the appropriate thrust to level off at 10,000 feet and hold 250 knots and the four forces will once again be balanced. Lift equals weight and thrust equals drag.

Then I will start a descent again and begin to slow down for the approach. I am still at one G. I will extend flaps to position one, drop the landing gear, set flaps to position two add thrust to compensate for the additional drag then select the flaps to position three. I will then fly the rest of the approach with what sounds like a high power setting. The flaps allow me to fly at a lower airspeed and also create a fair amount of drag. If it is not turbulent the approach will still be at one G. At thirty feet I will slowly arrest the rate of descent and at 15 feet I will retard the power levers and initiate the landing flare.

It’s not rocket science. just established fact.

Could there be confusion with the non effect of aerofoils in space here where there is little density to the air?

Not when he says this: “And in a clean vertical dive there is no lift , the a/c does not fly by the airstream around the wing.” He is talking in the atmosphere and is wrong on both accounts. An aircraft in a dive is producing lift on both the wings and the horizontal stabilizer. It also produces lift on all the movable control surfaces, hence it is controllable. That is how control surfaces work.

Zero g condition means that there is no lift ( I suppose it is that what you mean with “no load”).

That I don’t agree with. Lift is a function of airflow over the airfoil. and it does not cease with negative Gs. The airplane would not fly.