Tuesday, September 21, 2010
We Fly The Space Shuttle (Simulator, That Is)
What’s it like to reenter the atmosphere from Earth’s orbit?
As you descend through 2,000 feet at roughly 300 knots glide speed, a pair of triangles begins to rise from the bottom, one on each side of the HUD, and Gibson suggested I’d better not let them get ahead of me. “That’s your flare indicator,” he explained. “If you don’t catch the rising triangles and begin your flare before they reach the middle of the HUD, you’re going to be low, and of course, you don’t have any power to recover.”
I learned that lesson on my fifth approach. I flew my first three approaches to the Kennedy Space Center and managed to plant the airplane on the runway all three times, though not necessarily with style or grace. One of the parameters NASA uses to evaluate a pilot’s ability to land the shuttle is gear G-load at touchdown. I received a print-out of my landing results at the conclusion of two hours in the sim and noted that the max allowable sink rate was 9.0 fps, or 540 fpm. My worst effort was about 8.1 fps, barely within tolerance. My best effort of the five successful touchdowns was 3.5 fps—not bad, but no cigar.
On my second approach to Edwards, however, I blew it completely. I missed the rise of the flare indicators and wound up too low with no way to recover. I landed short, and the simulator simply locked up. Gibson, always the ultimate diplomat, laughed and reminded me that landing short at Edwards is no major sin, as the runway is fronted by several miles of flat lake bed.
You typically come across the fence at 220-230 knots, but again, the speed is masked slightly if you’re flying the HUD. Just as with an airliner, the nonflying pilot calls out radar altitude as the commander eases the Shuttle down to the runway. The goal is to touch down 2,500 feet down the runway. At touchdown, the nose is still high above the runway. During initial flight tests in the late ’70s, pilot John Young experimented with holding the nose off as long as possible to maximize aerodynamic braking. Eventually, it was decided to lower the nose earlier to minimize the load on the nose gear. The runway at Kennedy is three miles long, and the one at Edwards five miles in length, not counting the lake bed, so there’s a little fudge factor if you’re long. Just don’t be short.
After all three wheels are on the asphalt, the pilot deploys the drag chute and applies the brakes to “maintain the center line, so the media will have a photogenic subject,” said Gibson. Just as with the real aircraft, there’s a certain let down when you’re stopped on the runway at Kennedy or Edwards. But at least, in the sim, you have the satisfaction of knowing you just landed a near-exact replica of the world’s fastest and highest-flying spacecraft.
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