Free Perigee by Patrick Chiles

entirely, bypassing the hurricane of air around the compressors to feed fresh liquid oxygen straight into the combustion chambers. This was the essence of the combined-cycle engine, which allowed them to function as jets or rockets depending on the need.
    They quickly went supersonic, hurtling past Mach one within minutes. Although the plane was shaped to minimize their sonic footprint, the noise couldn’t be completely eliminated. A rapid boom-boom echoed dully onto the moonlit plains miles below.
    …
     
    Denver
     
    Penny hovered behind the dispatcher consoles, habitually twisting a strand of hair as she watched them gaining speed and altitude. The rest of the fleet was well under their control, which gave her the luxury of shepherding this one flight.
    “You’re acting like a mother hen back there.”
    She ignored Charlie’s barb. “You slackers need all the help you can get,” she wisecracked, but it sounded testier than she’d intended. “Sorry.”
    He waved it off, signaling her it was okay. “You haven’t been in here long enough, that’s all. I’ve heard worse. Said worse, too.”
    “I can believe that,” she said, finally taking an empty seat beside him.
    “What’s eating you? We wouldn’t have released the flight if it wasn’t safe, and you know Tom wouldn’t have accepted it. This was his idea, remember?”
    She brushed her hair back in place with a sigh. “Call me a wuss, but I just don’t like going this far out on the edge of the envelope. Not with pax aboard.”
    “I might call you a lot of names, but that isn’t one of them,” he said. “And it’s a mighty big envelope once they get out of the atmosphere. You know that better than I.” Any airplane was limited by its own maximum speed and altitude, which were entirely dependent on its stability in the air. Once a Clipper was in space, those rules no longer applied. The only limit was how fast it could be going when it came back into the atmosphere.
    “What’s their status now?”
    He highlighted their route and a page full of information appeared. “Looks like they’re sticking to the climb schedule…altitude sixty thousand, Mach two-point-five.” They had leveled off to build speed while drawing in outside air to liquefy for its oxygen. “O2 just topped eighty percent.” By the time their tanks were full the plane would be traveling close to four times the speed of sound.

13
     
    Austral Clipper
     
    “Ladies and gentlemen, this is your captain. We’ve just been cleared to start our boost climb. Please make sure you’re strapped in tight and have no loose items.”
    Tom placed the handset back in its cradle and looked to Ryan for confirmation that nothing had changed since their final checks. He gave a thumbs-up sign and ceremoniously moved his hands away from the controls, signaling that the plane was his. “Ready to zorch, skipper. Center just cleared us into the boost corridor.”
    “Good man—almost forgot that! Guess I’m a little excited.”
    “You are easily amused.”
    “Just easily bored. You all set back there, Mr. Kelly?”
    “Wade, please,” he said again, adding with mock bravado, “and I was born ready.” He would never admit his own trepidations to either pilot.
    “Put the spurs to her,” Ryan drawled as he cinched down his four-point harness.
    Tom slid the throttles forward, simultaneously unlocking a safety lever beneath his thumb to light the afterburners. This injected more fuel into an already furiously burning mixture in the tailpipes to dramatically boost their thrust. The steady rumble of the engines suddenly became a howling vibrato as the plane bolted ahead.
    “Whoa,” Wade gasped against the sudden acceleration.
    “Warned you.”
    Their speed and climb angle had to be pitch-perfect, or they would not make Singapore in a single hop much less set any records. The flight computers were programmed to precisely hit those targets, but Tom was so closely following the yoke and throttle