"EVERYBODY ALL SET?" Young Ross Jenkins glanced nervously at his two chums. "How about your camera, Art? You sure you got the lens cover off this time?"

The three boys were huddled against a thick concrete wall, higher than their heads and about ten feet long. It separated them from a steel stand, anchored to the ground, to which was bolted a black metal shape, a pointed projectile, venomous in appearance and an ugly rocket. There were fittings on each side to which stub wings might be attached, but the fittings were empty; the creature was chained down for scientific examination.

"How about it, Art?" Ross repeated. The boy addressed straightened up to his full five feet three and faced him.

"Look," Art Mueller answered, "of course I took the cover off, it's on my check-off list. You worry about your rocket, last time it didn't fire at all and I wasted twenty feet of film."

"But you forgot it once, okay, how about your lights?"

For answer Art switched on his spot lights; the beams shot straight up, bounced against highly polished stainless-steel mirrors and brilliantly illuminated the model rocket and the framework which would keep it from taking off during the test.

A third boy, Maurice Abrams, peered at the scene through a periscope which allowed them to look over the reinforced concrete wall which shielded them from the rocket test stand.

"Pretty as a picture," he announced, excitement in his voice. "Ross, do you really think this fuel mix is what we're looking for?"

Ross shrugged, "I don't know. The lab tests looked good, we'll soon know. All right, places everybody! Check-off lists, Art?"

"Complete."

"Morrie?"

"Complete."

"And mine's complete. Stand by! I'm going to start the clock. Here goes!" He started checking off the seconds until the rocket was fired. "Minus ten ...inus nine... minus eight... minus seven... minus six... minus five... minus four... ."

Art wet his lips and started his camera.

"Minus three! Minus two! Minus one! Contact!"

"Let it roar!" Morrie yelled, his voice already drowned by the ear-splitting noise of the escaping rocket gas.

A great plume of black smoke surged out the orifice of the thundering rocket when it was first fired, billowed against an earth ramp set twenty feet behind the rocket test stand and filled the little clearing with choking fumes. Ross shook his head in dissatisfaction at this and made an adjustment in the controls under his hand. The smoke cleared away; through the periscope in front of him he could see the rocket exhaust on the other side of the concrete barricade. The flame had cleared of the wasteful smoke and was almost transparent, save for occasional sparks. He could actually see trees and ground through the jet of flame. The images shimmered and shook but the exhaust gases were smoke-free.

"What does the dynamometer read?" he shouted to Morrie without taking his eyes away from the periscope. Morrie studied the instrument, rigged to the test stand itself, by means of a pair of opera glasses and his own periscope. "I can't read it!" he shouted. "Yes, I can—wait a minute. Fifty-two—no, make it a hundred and fifty-two; it's second time around. Hunder' fifty-two, fif'-three, four. Ross, you've done it! You've done it! That's more than twice as much thrust as the best we've ever had."

Art looked up from where he was nursing his motion-picture camera. It was a commercial 8-millimeter job, modified by him to permit the use of more film so that every second of a test could be recorded. The modification worked, but was cantankerous and had to be nursed along. "How much more time?," he demanded.

"Seventeen seconds," Ross yelled at him. "Stand by, I'm going to give her the works." He twisted his throttle-monitor valve to the right, wide open. The rocket responded by raising its voice from a deep-throated roar to a higher pitch with an angry overtone almost out of the audible range. It spoke with snarling menace.

Ross looked up to see Morrie back away from his periscope and climb on a box, opera glasses in hand.

"Morrie-get your head down!" The boy did not hear him against the scream of the jet, intent as he was on getting a better view of the rocket. Ross jumped away from the controls and dived at him, tackling him around the waist and dragging him down behind the safety of the barricade. They hit the ground together rather heavily and struggled there. It was not a real fight; Ross was angry, though not fighting mad, while Morrie was merely surprised.

"What's the idea?," he protested, when he caught his breath.

"You crazy idiot!" Ross grunted in his ear. "What were you trying to do? Get your head blown off?"

"But I wasn't-" But Ross was already clambering to his feet and returning to his place at the controls; Morrie's explanation, if any, was lost in the roar of the rocket.

"What goes on?" Art yelled. He had not left his place by his beloved camera, not only from a sense of duty but at least partly from indecision as to which side of the battle he should join. Ross heard his shout and turned to speak. "This goon," he yelled bitterly, jerking a thumb at Morrie, "tried to-"

Ross's version of the incident was lost; the snarling voice of the rocket suddenly changed pitch, then lost itself in a boneshaking explosion. At the same time there was a dazzling flash which would have blinded the boys had they not been protected by the barricade, but which nevertheless picked out every detail of the clearing in the trees with brilliance that numbed the eyes.

They were still blinking at the memory of the ghastly light when billowing clouds of smoke welled up from beyond the barricade, surrounded them, and made them cough.

"Well," Ross said bitterly and looked directly at Morrie, "that's the last of the Starstrack V."

"Look, Ross," Morrie protested, his voice sounding shrill in the strange new stillness, "I didn't do it. I was only trying to- "

"I didn't say you did," Ross cut him short. "I know you didn't do it. I had already made my last adjustment. She was on her own and she couldn't take it. Forget it. But keep your head down after this-you darn near lost it. That's what the barricade is for."

"But I wasn't going to stick my head up. I was just going to try-"

"Both of you forget it," Art butted in. "So we blew up another one. So what? We'll build another one. Whatever happened, I got it right here in the can." He patted his camera. "Let's take a look at the wreck." He started to head around the end of the barricade.

"Wait a minute," Ross commanded. He took a careful look through his periscope, then announced: "Seems okay. Both fuel chambers are split. There can't be any real danger now. Don't burn yourselves. Come on."

They followed him around to the test stand.

The rocket itself was a complete wreck but the test stand was undamaged; it was built to take such punishment. Art turned his attention to the dynamometer which measured the thrust generated by the rocket. "I'll have to recalibrate this," he announced. "The loop isn't hurt, but the dial and the rackand-pinion are shot."

The other two boys did not answer him; they were busy with the rocket itself. The combustion chamber was split wide open and it was evident that pieces were missing.

"How about it, Ross?" Morrie inquired. "Do you figure it was the metering pump going haywire, or was the soup just too hot for it?"

"Hard to tell," Ross mused absently. "I don't think it was the pump. The pump might jam and refuse to deliver fuel at all, but I don't see how it could deliver too much fuel unless it reared back and passed a miracle."