HELI-90/120/140 refers to a helicopter, with the servos orientated at 90 degrees (2 servos, generally beginner helicopters with forward, back, right, and left movement on the cyclic stick), 120 degrees (3 servos- generally for more advanced helicopters that have collective pitch controls on the rotor blades (yes, this means inverted flight too)), ...
canyon. n. 1. (Physical Geography) a gorge or ravine, esp in North America, usually formed by the down-cutting of a river in a dry area where there is insufficient rainfall to erode the sides of the valley.
Valleys are one of the most common landforms on the surface of the planet. They are carved by flowing water or flowing ice through the process of erosion, which is the gradual wearing away of Earth surfaces through the action of wind and water. valley is a relatively large hollow or depression bounded by hills or mountains on Earth's surface that is developed by stream erosion or glacial activity and that is drained externally. A basin is another hollow or depression on Earth's surface, but it has no outlet to drain the water.