- Wed Oct 29, 2003 1:39 am
It's true that in the real world you don't always get a direct headwind. Large airports, if they have a choice (not all have that choice), have several runways at different headings to give the pilots more options. And aircraft can, and do, land in crosswinds. But what if the wind is going in the same direction as the aircraft, so that they have to land downwind (ADD windspeed to aircraft's landing speed) in order to use the incline? Uphill/Downhill is a bigger deal than windspeed but most pilots would prefer to land into the wind, or at least a quartering headwind. Adding 25 mph to your landing speed is a really big deal, esp. if you are a heavy, fast airliner. No pilot likes to land downwind if he can help it. Plus, it would cost an awful lot of bucks to engineer dirt for an 8,000 foot runway. I'm not saying it's impossible, but debatable about it's cost efficiency.
I doubt that they would have parallel runways with opposite slopes. Runways are just too expensive, and at typicial major airports there is an aircraft landing every minute or so, often 24/7. Besides the cost of building, I'm sure airports wouldn't want a runway idled because the wind was running up the slope of the runway. A flat runway is more versatile because you can choose to land from direction or its opposite.
There are some airports that are built on slopes of varying degrees, esp. in mountainous areas, and you nearly always take off downhill and land uphill, regardless of wind. But it's a choice forced on them by the geography, and is regarded as far less than ideal. They'd rather have a flat runway so they have more choice when the wind comes from the opposite direction.
Built-up runways strong enough to support an airliner? What about strong enough to LAND an airliner? They don't always just settle dwn gently, esp. when it's turbulent. I've seen some pretty skanky landings.
I'm NOT suggesting a catapult, but some sort of magnetic induction system. You know how a generator/electric motor works: If YOU turn the motor, you generate current. If current is applied to the motor, IT turns. Why couldn't we do the same thing with an aircraft's landing gear, with electromagnets buried in the runway interacting with magnets fixed to the aircraft? Current would be generated by slowing down the aircraft, then the polarity reversed and used to accelerate outgoing aircraft. Besides, I'm just thinking of a helper for the orginal acceleration to reduce (not eliminate) energy requirements. You still need full power on the engines because the second you're off the ground, the "catapult" is of no further consequence.
That being said, I don't know what effect the magnetic stuff would have on the aircraft's instrumentation, or even if such a helper would be practical enough to make a difference. But as a pilot I don't see ramps as a practical option.