I debated where to put this, but it's definitely got a whiff of the "woo" about it.Popular Mechanics article about circular runways for commercial airports
The traditional runway—a long concrete stripe across the landscape—has some problems. A big one is crosswinds. If the wind blows hard and perpendicular to the direction of the runway, planes face harrowing takeoffs and landings. If the winds are bad enough, airports must close certain runways and reroute air traffic, sending a chain reaction of delays through the system.
But if a runway were circular, then a plane theoretically could take off in whatever direction was most favorable. And multiple planes could use the Endless Runway simultaneously.
1. I can see the advantage of always being able to takeoff / land into a headwind. But since the headwind is tangent to the circle at one point, I don’t see how multiple planes can use it simultaneously. (The source website says something about using more of the track in low wind conditions).
2. The track is 6.2 miles (32,700 ft) long. According to Google (the ultimate source of all knowledge) the minimum takeoff distance for a Boeing 737 is about 5300 ft, so from start to takeoff, the plane would be covering about 60 degrees. Bigger aircraft like a 777 would be closer to 90 degrees.
3. More fun with a 737:
Takeoff speed = 150 mph (220 ft/s)
Radius of the circle the plane would be traveling on = 5200 ft
Centripetal acceleration at the point of takeoff (v^2/r) = 9.3 ft/s^2
What provides the centripetal force to keep the plane moving in a circle? Supposedly the track is sloped, but my (increasingly dubious) calculations show it’d have to have a 15 degree slope to do that.
Some of the turning acceleration has to be provided by the plane, either the landing gear (I doubt it’d designed for that) or varying the engine thrust. Same thing with landing -- differential thrust reversers?
Yeah, more than a whiff of woo.