lafrance@xxxxxxxxxxx wrote: > Starry, a self-educated engineer Uh oh. > Ever since, he's been trotting the globe trying to sell his=20 > alternative design, an airport with runways that gently slope at a 2 > percent grade to the roof of a 12-story terminal. He calls it the=20 > StarPort. > The airport's environmental manager Kristi McKenney, was curious, but > skeptical. For one thing, Starry envisions two end-to-end 6,000-foot > runways ending above the terminal, rather than the current=20 > 10,000-foot landing strips. Well, his numbers don't work. Normal rule of thumb is 10 feet per story in a building. For a 2 degree slope over a 6000 foot runway, you'll need a 21 story building (6000 * sin 2=B0 =3D 209.4 feet). Or if you wan= t to stick with a 12 story building, you won't have much over a 1=B0 slope (arcsin [120/6000] =3D 1.1=B0). Or you can keep your 12 story building a= nd 2=B0 slope, but you'll only have a 3438.4 foot runway. Or each floor can= =20 be 17 feet high. Most airline terminals today are 1 to 3 stories. In order for this to work, you'd have to park on the roof. Otherwise, you'll need extra engine thrust to push the airplane up a taxiway parallel to the runway at a 2=B0 slope. Thus, the terminal building will have to pretty much cover the entire airport. Then you need lots of energy to power the elevators that would replace the jetways. Do you really want to park lots of heavy 747s and A380s on top of a mostly-hollow structure? > With the terminal underneath the runway, airplanes would have very=20 > short distances to taxi. You'll lose terminal space because you still can't park a plane on the runway. Also where the runway is the roof will slowly get lower. Unless you use a conical design for the whole building (which means you lose a lot of rooftop ramp space) you also limit the wingspan of the aircraft that can use it. Had this design been done during the DC-8/707 era, the 777 would not have been possible. > He has another idea, one borrowed from BART. It's called regenerative > breaking. On BART trains, the motors on each car are turned into > generators, and as the train slows down electrical power is stored. > On a plane, Starry says, kinetic energy can be saved by sending the > wheels on the landing gear into forward motion when it touches down. > By gradually decelerating the wheels, less energy would be needed for > reverse engines. Regenerative braking is mostly good for recharging batteries. It works=20 for BART since the trains run on electric power anyway (thus needing to=20 draw less power from the electric grid), and for the Toyota and Honda=20 hybrid cars, since regenerative braking is used to power the batteries=20 that run the electric motor. Or is he just talking about using the wheel-slowing properties of=20 regenerative braking. In other words, breaks. Which airplanes already=20 have. --=20 David Mueller / MRY dmueller7@xxxxxxxxx http://www.quanterium.com