strongest wing tip vortices when slow, clean and heavy. BUT WHY?

[Brian Abraham]

With plain flaps and split flaps, changing flap setting changes none of these things - no change in weight, load factor, indicated airspeed or wing planform area. Consequently changing flap setting doesn't change instantaneous lift coefficient. In the minute or two after changing flap setting there is usually a significant change in airspeed that brings about an equally significant change in lift coefficient, but it is the change in airspeed doing that, not the change in flap setting

G'day D. Call me a dullard but I'm having trouble getting my head around this little bit. On flap retraction the immediate aircraft reaction is to reduce its rate of climb - read a loss of lift, on flap extension the immediate reaction of the aircraft is to balloon - read increase in lift (as I see it). In the lift formula the only thing that is changing to bring about these effects (once again as I see it) is a change in CL.

As I understood it CL = lift coefficient and cl (both lower case) the section coefficient. Should the section l be a capital as per your last?

While we have you D as an expert to hand, can you give a definitive explanation as to the reasons why a swept wing (eg Boeing 707 or like) stalls at much higher angles of attack than a straight wing.

Thanks D, and standing by to be educated.