a friend and I were waiting for the sunset at the far west observing area when I watched a stingray shaped craft cruise in from the south and hover at the edge of a cloud formation, after sitting in the clouds for about 15 seconds 2 more craft flew in at a high rate of speed from the west at this time the first craft made a u-turn an zoomed away then the other 2 craft turned and flew away. the craft only appeared to be shadows of the craft. as the last craft turned to fly away a spiral cloud of exhaust (the only truly completly visible evidece) began to fall through the air until it disapated into the clouds.the first craft to appear came from the south heading toward the grand canyon it was alone. it came to a halt at the edge of a cloud formation and just sat there as if it could not be seen. it was a black color that was shaped like a stingray, it even appeared to have some sort of tail. as the clouds moved over the craft i began to search the sky for anything else moving. at this time 2 more craft (one a few sec. ahead of the other) appeared from the west. they were both identical in shape and size and color to the first craft, they all appeared to just be shadows as if they thought they were camoflouged at this time the first craft did a slow u-turn and picked up speed and flew back to the south. the second craft from a hovering position then turned back to the west and flew away at a very high rate of speed the third craft then did a slow u-turn at this time the only clear visual evidence appeared, it was a spirial shaped cloud of exhaust it started as a small cloud of smoke and gradually turned into a spirial cloud that began to extend itself in size and shape until it stretched across the skyline at about a 45 degree angle then the 3rd craft from a hovering position flew off at a great rate of speed. it was out of sight in a matter of 1 to 2 seconds. the backgroud was an open sky with the sun just clearing the horizon, but you could still see the top crest of the not yet covered by the horizon.