SHOCKWAVE,
Sorry, no offence intended. Your profile just states plot and your pprune registration date of 1999 suggests a more recent arrival. This (incorrect)first impresion was then reinforced by the question "what is spiral stability".
The majority of the people who have taken their JAR ATPL POF exam over the past couple of years would probably ask that question, quite simply because the emphasis tends to be on longitudinal , lateral and directional, with only a brief mention of spiral. About 95% of those people would immediately tilt upon hearing terms like partial derivative.
BOOKWORM,
That sounds close enough to me. (and this string is getting a bit too long anyway)
JOHN,
Although your statement regarding dihedral is entirely true,it isn't actually an answer to Shockwave;s second question. This was "In an overspeed/overbank condition positive static spiral stability is used to level the wings. In an alpha or high angle of attack, low speed, overbank condition, the same positive stability is used to reduce bank to 33 degrees(which is the normal max allowable bank).
But again this string is getting very long!!!