The body was a dull copper color, except for the front end and the sides back to midships, which were plastic glass. The door was just abaft his enormous view-port on the starboard side. Diana swung it open and they stepped inside. The interior was very roomy, there being nearly five feet of clear floor space thwartships and almost that much abaft the twin pilots' chairs. A lazy bench ran around the outer wall except for the space forward of the chairs, where it was replaced by a belt of instruments with clear glass above and below. Perry saw that the level inner floor plate and the corresponding curved outer hull were largely of glass.
Diana seated herself in the right hand pilot's chair. "Come sit beside me, Perry." He did so and examined the dual controls in front of him. Diana touched a lever control and the car rolled out on the platform. She grasped the joystick and pulled it toward her, thumb pressing a button on the end. Perry heard a soft hum and a slight haze appeared over the car. The rotor had unfolded. The hum grew to a high-pitched whine, then died away. The car trembled and he noticed a slight feeling of heaviness. He glanced down between his feet and watched the mountain with its crags and pine trees drop away. A few minutes later Diana moved the stick forward to the vertical. Perry felt as if he were riding in an express elevator which had just stopped at the top floor. The car hovered about two thousand feet over 'Diana's mountain'. She turned to him. "Now where shall we go?"
"I don't want to go any place until I learn to fly this thing."
"I'm not exactly a flying instructor, but I'll try. You saw me take off. First I started the main motor with this switch turned to 'helicopter.' I pull back the stick to rise straight up. With the stick vertical the car hovers. The stick won't move unless you press the button on the end. Push the stick forward—so—and the car lowers. Then return it to vertical when you are at the altitude you wish. In landing you settle it down slowly with a slight pressure forward."
"Suppose the main motor stops while you're in the helicopter?"
"It settles down on the rotor. The wheels snap out into place. They are held retracted magnetically by a field off the main motor. You settle down pretty hard—It's about like falling ten meters at sea level, a little harder in this thin air. But the carriage takes most of the shock and this pneumatic upholstery soaks up the rest. It is pretty much of a jolt however. Anyone standing in the cabin should lie down quickly on the couch."
"Suppose it fell over water."
"The car will float. If you can start the rotor again, you can even take off again. I've done it with this one from Lake Tahoe. If you can't take off, you can just sit there and wait to be rescued."
"Now tell me how to maneuver this baby."
"Turn the main control switch from 'helix' to 'plane'. The wings come out,"—Sure enough, Perry saw them spread on each side—"and the screw starts. As it gathers speed, it drags more and more current, and the rotor slows down and stops and folds up. If you stop the screw by throwing the switch back, or if something happens to it, the rotor starts. The wings don't retract until the rotor is maintaining lift. See, there goes the rotor." The great vanes passed by, turning more slowly each revolution, finally stopped, folded back on each other like a Japanese fan, and disappeared. "We are flying now. If I pull back on the stick now the speed increases. When the air speed meter shows the speed I want I return the stick to vertical. If I pushed the stick forward the speed slows. If I slow to stalling speed before I reach it the rotor will start."
"How do you change direction?"
"If you push the stick sideways, the car turns in the same direction. When you are on your new course you return the stick to vertical."
"Does that both bank and handle the rudder? Say, I didn't see a rudder nor any other control surfaces. Why should it turn?"
"There aren't any control surfaces. The car is gyro stabilized. We rotate the car around the rigid reference frame of the gyros and let the screw push away in our new direction."
Perry nodded slowly. "That seems all right, except that she must side slip like the very devil on a turn."
"That's right, Perry, but ordinarily it doesn't matter. If you need to prevent it, you can turn past your new course and hold it there until the side slip is killed."
Perry's face cleared. "Yes, I suppose so, but I would hate to try to fly a tight military formation in her."
"You couldn't. This is a family model, for quiet people like me. It isn't very fast and it's as nearly foolproof and automatic as they can make it. They claim that if you can use a knife and fork you can fly a 'Cloud House'."
"What speed does she make?"
"I cruise her at about five hundred kilometers. I could make five hundred and fifty but there's a nasty vibration at that speed. I may need a new propellor."
Perry whistled. "If that is a moderate speed for a family car, what's the record these days?"
"About three thousand. That is with rockets of course. But I don't like a rocket ship. They make me nervous and they are devilish to handle. Give me my old-fashioned electric runabout. I'm in no hurry."
"Which reminds me. I gather this baby must be electric drive, but how?"
"The rotor and the prop are driven by induction motors. The power comes from storage batteries. The gyros each have their own induction windings. They run all the time."
"Storage batteries—I should think they would be too heavy."
"These aren't heavy for the power they store. They call 'em chlorophyll batteries because the principle involved is supposed to be similar to the photosynthesis of plants. But don't ask me why. I'm a dancer, not a physicist. However there are some new models on the market that make their own electricity from coal."
"Directly?"
"I don't know. It doesn't burn if that's what you mean."
Perry slapped his thigh. "Edison was working on that when he died."
"Too bad he didn't perfect it. We've had it only about ten years. See here, Perry, want to try the controls?"
"Yes indeed. Wait a minute though. How do I change altitude when I'm in 'plane' combination. "
"You can get as much as ten degrees dive or climb by changing this setting. It rotates the car about the horizontal gyro axis. You can use that when hovering with the rotor to keep from drifting in the wind, provided the wind isn't more than seventy-five kilometers."
"In that case you could maneuver by rotor if you wanted to, couldn't you."
"Yes, but it's slow of course. Do you know what all your instruments mean?"
"You keep an eye on the instruments. I'll fly by ear for a while." Perry took the car up a couple of thousand feet and cautiously put her through her paces. Presently when he had the feel of the controls he undertook to see what it would do. He soared and dropped, flew straight away and slewed her into sudden turns. He discovered that he could jamb her about one hundred and eighty degrees and stop her dead with the propeller. After this stunt Diana touched his arm:
"Perry, if you knock off the propeller, we'll have to go home on the rotor." He looked crestfallen.
"Oh, I'm sorry. I thought anything she could do, she could handle."
"That is very nearly true. But my prop may be out of balance, you know. In any case the screw itself is a gyro and you were processing it on a rigid frame."
He set the controls at neutral and turned to her. "Diana, if you are a dancer and no physicist, how do you know so much about mechanics?"
She looked surprised. "Any schoolgirl knows that much."
"I can see education has improved." He returned to the controls and tried new stunts; stalling, changing combinations, maneuvering on the rotor. The flight brought them back near the canyon—'Diana's canyon' as Perry regarded it—and the waterfall caught Perry's eye. He lowered away cautiously and eased the craft slowly over toward the veil of water until they hovered halfway down and a hundred feet from the falls. They both sat in silent contemplation for several minutes until a shift in the wind forced Perry to return to the controls. He rose out of the canyon and settled down in level flight. Then he spoke. His voice was low and fervent. "Boy, but that fall is something!" He turned to Diana. "It's nearly as beautiful as you are, Dian'." She looked up and met his eyes for a moment, then dropped her lids, without replying. They were flying west. Presently Diana spoke.