"Chris Wells" wrote in message
...
The point I was making is that this is not true. You can rotate the
diagram any which way, but the lift vectors won't be the same. I think
confusion is caused because you're looking at the diagram head-on, but
the plane doesn't fly through the air that way.

It doesn't? I normally make every effort to fly my airplane through the air
"head-on". Granted, it's possible to fly through the air in a wide range of
attitudes, but "head-on" is the most efficient and is what most pilots use
for normal, straight-and-level flight.

With dihedral, the AOA
on each wing is only equal when they're level.

Only because of the resulting slip. Which is what several people have been
trying to point out already, including Jose (in his latest post).

Ignoring gravity (as Jose suggested), if you take an airplane flying
straight and level and bank it, all that changes is the net lift vector, and
all that changing that will do is change the direction of flight. It will
do nothing to return the airplane's attitude back to straight and level.

It's only when you reintroduce gravity into the equation that rolling the
airplane will *also* result in a change in the resulting vertical component
of the lift, resulting in a descent, resulting in a slip (ta da!) that
changes the actual lift on each wing.

Which is what the people pointing out the flaw in the usual presentation of
dihedral diagrams have been saying all along (including Jose, now).

Pete