NASA’s Iconic Red Vortex Photo: ‘The Rest of the Story’
theatlantic:
The physics of producing lift with a wing creates an aircraft wake which has a large vortex (tornado) generated at each wingtip. The strength of this vortex increases as aircraft weight increases. The flow from a wingtip of a crop duster picks up the seeds or chemicals and sends them far from the area directly below the aircraft. The strong spinning flow in the vortex can also cause a problem for other aircraft under some conditions. NASA and the FAA had done extensive research beginning in the 1970s and continuing today to understand and predict flow behind transport aircraft to determine safe separation distances (spacing of aircraft). We believed that this research could help the “Aerial Applications Research” program, perhaps, if the physics of the flow behind crop dusters could be understood, predicted, and tamed.
Because we see computer images on TV of airplanes the size of counties flying over a map of the U.S., we come to think of the airspace as crowded. In reality, the airspace is not crowded. Instead, the runways and the arrival queue of airplanes lined up to land are crowded. The airplanes are spaced in the queue that keeps each safely following an airplane away from the spinning wake vortex of the previous airplane.
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