Except for the whistling of wind, there is complete silence in a soaring glider. Max Mainz began to call back to his superior, was taken back by the volume, and dropped his voice. He said, "Look, captain. What keeps it up?"
Joe grinned. He liked the buoyance of glider flying, the nearest approach of man to the bird, and thus far everything was going well. He told Max, "An airplane plows through the air currents, a glider rides on top of them."
"Yeah, but suppose the current is going down?"
"Then we avoid it. This sailplane only has a gliding angle ratio of one to twenty-five, but it's a workhorse with a payload of some four hundred pounds. A really high performance glider can have a ratio of as much as one to forty."
Joe had found a strong updraft where a wind ran up the side of a mountain. He banked, went into a circling turn. The gauge indicated they were climbing at the rate of eight meters per second, nearly fifteen hundred feet a minute.
Max hadn't got the rundown on the theory of the glider. That was obvious in his expression.
Joe Mauser, even while searching the ground below keenly, went into it further. "A wind up against a mountain will give an updraft, storm clouds will, even a newly plowed field in a bright sun. So you go from one of these to the next."
"Yeah, great, but when you're between," Max protested.
"Then, when you have a one to twenty-five ratio, you go twenty-five feet forward for each one you drop. If you started a mile high, you could go twenty-five miles before you touched ground." He cut himself off quickly. "Look, what's that, down there? Get your glasses on it."
Max caught his excitement. His binoculars were tight to his eyes. "Sojers. Cavalry. They sure ain't ours. They must be Hovercraft lads. And look, field artillery."