the vertical component of the lift (which directly opposes the weight) is less than the weight.

Not only the vertical component of lift opposing the weight , even the lift proper (if I´m allowed to use this term ) perpendicular to the wing is less than weigth .

I do not have resolved the weight force in this modified diagram. You have a weight acting downwards to earth. You want to have equilibrum so draw a force vector opposing it with same value (green dashed ). You can resolve it into drag acting in the flight path and lift acting perpendicular to it. You see lift will always be less than weight as long as drag exists. Drag takes a part in opposing weight.
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Will you be more happy if I put it more precicely as : “g” as used in this discussion, as load factor in aviation. g= L / W , a ratio, a dimensionless value.

I do not speak of the value of the acceleration of gravity, which is
about 9.81 (m/s2), or 32.174 ft/s2 . But it seems to me that even this definition of “g” cannot descibe effects, being just a value , too.

If you describe free fall, than you use the quantitiy accelaration (a) , g beeing just the value of this acceleration.

EDIT : Was meant as reply to Beermat who wrote above:

I was somewhat disappointed by:

Originally Posted by fanavion View Post
G is a measured quantity and no means to explain physical processes

But it was already edited it out, when I posted my reply.

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.” …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.

Yes, you are right ! In a dive in practice to keep it cleanly vertical there may be lift from the wings, the stabilizers and controls. But they are in equilibrum so there is no net lift (the sum of forces in the a/c vertical axis is zero).

But still g=0.

EDIT: maybe not even this is the case. The definition of g may not apply here. I have to think about it. For the time being I pull back the dive as an example for zero g.

But I stick to : the sum of forces in the a/c vertical axis is zero.

Edit Edit : A question: How does the stress on the airframe (wing) from forces acting in the a/c vertical axes in such a dive compare with that on straight and level flight ?

Beermat and me speak of zero g. And yes at zero g an aircraft indeed would not fly by the air streaming around the wing. There are forces of inertia (kinetic energy) which keeps the aircraft aloft against weight – for a while:) . And in a clean vertical dive there is no lift , the a/c does not fly by the airstream around the wing..

Lift is a function of speed over the airfoil and angle of attack.

No speed no lift at any angle. No angle no lift at any speed.

g=n= lift / weight

1g: lift = weight

2 g : lift is 2x weight , in order to oppose centrifugal forces in a curved flight path to keep a plane aloft and on track.

0 g: lift is = 0

0,5 g : Lift is 1/2 weight aircraft sinks but inertia may keep the a/c aloft and on track for a while

No, pagen01 is right

http://www.fiddlersgreen.net/models/aircraft/Northrop-XP79.html

If it has an angle of attack relative to the airstream it produces lift, that is the principle.

are there aircraft that have symetric aerofoils?

Lockheed L-1649A Starliner, N.A. F-86 Sabre, Extra 300, to name a few.

I introduced “inverted straight and level flight” in my post above to have a counterpart to the inverted curved flight path. I stated that not every aircraft will be able to do it . I know that the angle of attack may be larger if we have a unsymmetric airfoil and ordinary instruments will go wild. It was a theoretical consideration. But if steady flight is accomplished there is no difference in forces.

But if we take an aerobatic aircraft with symmetric airfoil, engine and systems adapted for high end aerobatics were do you think are differences in flight dynamics from upright flight ?

I repeat my question: Is there another definition of “g” than lift/weight ?