"Before we are finished, the world will know of his achievement. I intend to make sure of it."
“Three minutes,” Petra announced. “Reducing alpha by three degrees.”
The screen above reported that they'd reached Mach 22.4. Their altitude was now ninety-three thousand feet.
She's leveling out, Vance thought. Are we going to make it, or just fade in the stretch?
The scramjets were punching through the isolation of near-space now, the underfuselage scooping in the last fringes of atmosphere. He doubted if there'd be enough oxygen above a hundred thousand feet to enable the engines to continue functioning, but if they could capture the vehicle's design speed, seventeen thousand miles per hour, they still could coast into the perigee curve of a huge orbital elipse.
He looked at the screens again. They were now at Mach 23.7, with two and a half minutes left. The complex calculus being projected on Petra's main display now showed their rate of acceleration was diminishing rapidly as the atmosphere continued to thin. Maybe, he thought, there's a good reason why no one has ever inserted an air-breathing vehicle into orbit before. Maybe all the aerodynamic and propulsion tricks in the world can't compensate for the fact that turbines need to breathe.
Petra seemed to sense they were in trouble. “Constricting venturi by seven point three,” she said. “Reducing alpha by four degrees.”
She was choking down the scramjets and leveling them out even more. Their thrust to weight ratio—which at thirty thousand feet had been greater than one, meaning they could actually fly straight up—was dropping like a stone. It was now down to 0.2. Daedalus was slowly smothering.
But now their velocity had reached Mach 24.6. Almost, almost . . .
“Thirty seconds,” Petra said, as though trying to sound confident. She was busy sampling the combustion ratio in the scramjets and making micro adjustments to the hydrogen feed.