What you say makes sense to me in the main, but I didn't like the idea of the roll damping 'catching' the roll. Unless I'm mistaken, damping is just a resistance to movement (in this case the roll), an inertia if you like. It will not actively restore the wings level, rather make the aircraft less susceptible to the 'fine detail' level of the wings stalling *exactly* at the same time? I'd still suggest they need to stall substantially together.
Yes, I think we more or less agree, when I am saying the wings do not need to stall at the same time I mean not
exactly at the same time. A small asymmetry, such as one wing being
slightly more stalled than the other, will be damped out by the roll damping. Without roll damping
every stall would have a wing drop since there is always some tiny asymmetry present. But I agree with you that if there is any significant asymmetry, such as when stalling out of a slip, the roll damping will not be enough to prevent the roll.
There is a subtle difference between roll damping and roll wise inertia: The latter is resistance to rolling motion starting when a rolling torque is applied, but once a roll has started the roll wise inertia actually keeps the roll going. Roll damping on the other hand is resistance to the roll
motion and will tend to stop the roll if it has started.
I'm also interested in the definition of slip and particularly yaw. Does an aircraft in a stable, straight line sideslip have yaw? It definitely has slip, and I know the fuselage is not pointing in the direction of travel, but I'm inclined to suggest it doesn't have yaw, and if it does, it doesn't have a rate of yaw - all parts of the wing move at the same speed, and in terms of direction and space, it is not moving around the yaw axis. In a sense it's no different to an oblique wing
NASA AD-1 - Wikipedia, the free encyclopedia flying in a perfectly straight line.
Agreed there as well! When we use rudder to create a slip that will be turned into a bank by the slip roll coupling, we need to yaw... Once the slip is established, there is no yaw. In a dynamic situation where we try to keep the wings level with the rudder there will be altering amounts of slip needed and commanded, thus there will be yaw as well. Overcontrolling and dropping the wing in that situation is likely to carry both yaw and slip into the stall, and that is where the fun starts!
Seriously, great fun at 4000 ft when practicing or just goofing around, knowing we are going to stall and that it might be spectacular. Not fun at 400 ft on a slow final for a short field landing in gusty condition, when all we wanted was to keep the wings level in as safe and effective a way as possible. That is why I suggest and will only use rudder-only to keep wings level as a fun exercise at altitude when in that mood, not as a method for slow flight.
Of course, the rest of you do as you see fit!