data. He'd never talked to an airplane before, and the thought gave him some disquiet.
Two minutes.
"What do I do first?"
"You probably should start by attaching that nozzle there on the legs of your G-suit to the pressure hose on the console. When the G-forces go above eight, tubules in the legs automatically inflate using bleed air from the engines. It's going to squeeze hell out of your lower extremities. If you begin to gray-out, try to grunt as hard as you can. The M-l maneuver, I think you Americans call it. If your vision begins to go entirely, just try and talk Petra through."
"What else?"
"Once you start pushing through the hypersonic barrier, keep an eye on screens B-5 and B-6, which report engine strut temperature and stress loads. Those are the most important data for the scramjet mode. But first check the C-2 screen. Core rpm has to be zeroed out before the scramjet geometry modification, since the compressors need to be completely shut down. If it's not, then instruct Petra to abort the sequence. It could cause a flameout."
"And that's when I switch over to liquid hydrogen?"
"Exactly. Petra will set the new engine geometry, then sample compression and temperature and tell you the pre¬cise moment. But the actual switch-over is manual. I in¬sisted on it." He pointed. "It's those blue toggles right behind the throttle quadrant. Just flip them forward."
"Got it."
"After you toggle her over, just ease the throttle for¬ward, and pray." He settled himself into the right-hand seat, tugging at the tourniquet. "When we enter the hy¬personic regime, I don't know what will happen. Above Mach 6 or Mach 7 we may begin to critically overheat. Or the airframe stresses could just tear this damned samolyot apart. Whatever happens, though, you've got to keep pushing her right on out, to stabilize the shock wave in the scramjets and bring them to full power."
Vance glanced up at the screen—thirty seconds—and fingered the sidestick and the throttles, trying to get their feel. As he began lowering the massive flight helmet, he noted that with the engines on military power they had exactly eighteen minutes of JP-7 left. When he kicked in the afterburners to push them into the hypersonic regime, the fuel readings would start dropping like a stone. But this was their ball of string, their way out of the maze. Would it work?
"Remember," Androv said with finality,