Thanks for the replys guys,
Could another reason why the kreuger flaps and the variable camber leading edge flaps (midspan) retract when reverse thrust is selected, is to reduce lift over the inboard section of the wing, hence put more weight on the wheels and therefore allow more effective breaking?? Just a thought.
I don't fly the B744 however my understanding of the difference between the two are:
Physical difference:
Kreuger Flaps have no slot (they increase the camber of the wing and are designed to smooth out the section between the inboard engines and the fuselage, therefore reduce drag, increase lift)
V.C.L.E Flaps have a slot (designed to accelerate airflow over the wing and therefore delay the separation point at high AoA's). Also known as a boundary layer control device. They also increase the camber of the wing.
I haven't been able to find a convincing answer to what kreuger flaps actually do
Anyway, these pictures may assist in understanding the 744 leading edge:
http://en.wikipedia.org/wiki/Image:U...e.b747.arp.jpg
http://www.airliners.net/open.file/0228836/L/
B&N