There are far many more aircraft with anhedral that don't have gear on the wingtips. A-6 Intruder, A-7, F-8 Crusader, F-11, - F-104, F-105, and to a lesser degree the F-14, F-15, F-16 - all of these Mid or Top Wing Aircraft. Mid or top wing position increased the Dihedral "effect", thus to keep it in parameter, the Anhederal is added

Anhedral has the opposite effect as Dihedral - one of the more popular texts is 'Aircraft Performance, Stability and Control' (by Perkins / Hage), covers Diheral effect and it's control.

Roll coupling is complicated by Dihedral effect and Wing sweep, (researched after Melburn Apt was killed in the X-2) is also controlled by several other features, such as Dorsal Fins, etc. Roll coupling is a concern is high speed manuevers.

In a large Transport (C-17) you already have roll control problems due to the long wingspan, so exceccive dihederal effect is not wanted. Check these links also

[link]http://www.aerospaceweb.org/question/dynamics/q0055.shtml[/link]

and the NASA link: [link]http://www.grc.nasa.gov/WWW/K-12/airplane/geom.html[/link]

Anhederal on the stabilizer gives directional stability - as on the F-4 anhederal was added to the tail, and dihederal to the wing tips after the test aircraft experienced directional stability problems.

When they get all of the wind tunnel stuff done, then they bring in Mechanical Engineers to design the gear, and they will get gear to the ground, no matter where the wing is.

Dennis