Another din like the wailing of a baby volcano with a toothache. It began, and moved, and went through the series of changes that ended in a climbing, droning hum. Another. Another. The launching of pushpots for their morning flight was evidently getting well under way.
Joe hesitated in the nearly empty mess hall. Then he recognized the two seated figures. They were the pilot and co–pilot, respectively, of the fateful plane that had brought him to Bootstrap.
He went over to their table. The pilot nodded matter–of–factly. The co–pilot grinned. Both still wore bandages on their hands, which would account for their remaining here.
"Fancy seeing you!" said the co–pilot cheerfully. "Welcome to the Hotel de Gink! But don't tell me you're going to fly a pushpot!"
"I hadn't figured on it," admitted Joe. "Are you?"
"Perish forbid," said the co–pilot amiably. "I tried it once, for the devil of it. Those things fly with the grace of a lady elephant on ice skates! Did you, by any chance, notice that they haven't got any wings? And did you notice where their control surfaces were?"
Joe shook his head. He saw the remnants of ham and eggs and coffee. He was hungry.
There was the uproar to be expected of a basso–profundo banshee in pain. Another pushpot was taking off.
"How do I get breakfast?" he asked.
The co–pilot pointed to a chair. He rapped sharply on a drinking glass. A door opened, he pointed at Joe, and the door closed.
"Breakfast coming up," said the co–pilot. "Look! I know you're Joe Kenmore. I'm Brick Talley and this is Captain—no less than Captain!—Thomas J. Walton. Impressed?"
"Very much," said Joe. He sat down. "What about the control surfaces on pushpots?"
"They're in the jet blast!" said the co–pilot, now identified as Brick Talley. "Like the V Two rockets when the Germans made 'em. Vanes in the exhaust blast, no kidding! Landing, and skidding in on their tails like they do, they haven't speed enough to give wing flaps a grip on the air, even if they had wings to put wing flaps on. Those dinkuses are things to have bad dreams about!"
Again, a door opened and a man in uniform with an apron in front came marching in with a tray. There was tomato juice and ham and eggs and coffee. He served Joe briskly and marched out again.
"That's Hotel de Gink service," said Talley. "No wasted motion, no sloppy civilities. He was about to eat that himself, he gave it to you, and now he'll cook himself a double portion of everything. What are you doing here, anyhow?"
Joe shrugged. It occurred to him that it would neither be wise nor creditable to say that he'd been sent here to split up a target at which saboteurs might shoot.
"I guess I'm attached for rations," he observed. "There'll be orders along about me presently, I suppose. Then I'll know what it's all about."
He fell to on his breakfast. The thunderous noises of the pushpots taking off made the mess hall quiver. Joe said between mouthfuls: "Funny way for anything to take off, riding on—it looked like a truck."
"It is a truck," said Talley. "A high–speed truck. Fifty of them specially made to serve as undercarriages so pushpot pilots can practice. The pushpots are really only expected to work once, you know."
Joe nodded.
"They aren't to take off," Talley explained. "Not in theory. They hang on to the Platform and heave. They go up with it, pushing. When they get it as high as they can, they'll shoot their jatos, let go, and come bumbling back home. So they have to practice getting back home and landing. For practicing it doesn't matter how they get aloft. When they get down, a big straddle truck on caterpillar treads picks them up—they land in the doggonedest places, sometimes!—and brings 'em back. Then a crane heaves them up on a high–speed truck and they do it all over again."
Joe considered while he ate. It made sense. The function of the pushpots was to serve as the first booster stage of a multiple–stage rocket. Together, they would lift the Platform off the ground and get it as high as their jet motors would take it traveling east at the topmost speed they could manage. Then they'd fire their jatos simultaneously, and in doing that they'd be acting as the second booster stage of a multiple–stage rocket. Then their work would be done, and their only remaining purpose would be to get their pilots back to the ground alive, while the Platform on its own third stage shot out to space.
"So," said Talley, "since their pilots need to practice landings, the trucks get them off the ground. They go up to fifty thousand feet, just to give their oxygen tanks a chance to conk out on them; then they barge around up there a while. The advanced trainees shoot off a jato at top speed. It's gauged to build them up to the speed they'll give the Platform. And then if they come out of that and get back down to ground safely, they uncross their fingers. A merry life those guys lead! When a man's made ten complete flights he retires. One flight a week thereafter to keep in practice only, until the big day for the Platform's take–off. Those guys sweat!"
"Is it that bad?"
The pilot grunted. The co–pilot—Talley—spread out his hands.
"It is that bad! Every so often one of them comes down untidily. There's something the matter with the motors. They've got a little too much power, maybe. Sometimes—occasionally—they explode."
"Jet motors?" asked Joe. "Explode? That's news!"
"A strictly special feature," said Talley drily. "Exclusive with pushpots for the Platform. They run 'em and run 'em and run 'em, on test. Nothing happens. But occasionally one blows up in flight. Once it happened warming up. That was a mess! The field's been losing two pilots a week. Lately more."
"It doesn't sound exactly reasonable," said Joe slowly. He put a last forkful in his mouth.
"It's also inconvenient," said Talley, "for the pilots."
The pilot—Walton—opened his mouth.
"It'd be sabotage," he said curtly, "if there was any way to do it. Four pilots killed this week."
He lapsed into silence again.
Joe considered. He frowned.
A pushpot, outside the building, hysterically bellowed its way across the runway and its noise changed and it was aloft. It went spiraling up and up. Joe stirred his coffee.
There were thin shoutings outside. A screaming, whistling noise! A crash! Something metallic shrieked and died. Then silence.
Talley, the co–pilot, looked sick. Then he said: "Correction. It's been five pushpots exploded and five pilots killed this week. It's getting a little bit serious." He looked sharply at Joe. "Better drink your coffee before you go look. You won't want to, afterward."
He was right.
Joe saw the crashed pushpot half an hour later. He found that his ostensible assignment to the airfield for the investigation of sabotage was quaintly taken at face value there. A young lieutenant solemnly escorted him to the spot where the pushpot had landed, only ten feet from a hangar wall. The impact had carried parts of the pushpot five feet into the soil, and the splash effect had caved in the hangar wall–footing. There'd been a fire, which had been put out.
The ungainly flying thing was twisted and torn. Entrails of steel tubing were revealed. The plastic cockpit cover was shattered. There were only grisly stains where the pilot had been.
The motor had exploded. The jet motor. And jet motors do not explode. But this one had. It had burst from within, and the turbine vanes of the compressor section were revealed, twisted intolerably where the barrel of the motor was ripped away. The jagged edges of the tear testified to the violence of the internal explosion.
Joe looked wise and felt ill. The young lieutenant very politely looked away as Joe's face showed how he felt. But of course there were the orders that said he was a sabotage expert. And Joe felt angrily that he was sailing under false colors. He didn't know anything about sabotage. He believed that he was probably the least qualified of anybody that security had ever empowered to look into methods of destruction.