To an airplane moseying behind, a vortex may seem like no more than a little speed bump, but the whorl could also act like an unseen hand, suddenly flipping an airplane upside down. Aviation authorities manage the problem by imposing buffer zones between aircraft, especially on takeoff and landing, when vortices are most dangerous. A light aircraft, like a Cessna 172, must stay at least six miles behind a 747.
Through wind tunnel tests and computer modeling, Airbus adjusted the A380’s wing design to keep vortices in the same range as those of a 747, but the International Civil Aviation Organization said early simulations and preliminary flight test data found much more powerful vortices, and ordered aircraft to stay at least 10 miles behind the Airbus. Congested airports like Heathrow would have to space flights out so widely they’d lose the advantage of packing more people onto the bigger airplane. An anxious Airbus has now committed to measuring vortices as the A380 continues its early flights at various locations around the world. It’s doubtful the 10-mile buffer will stick; a similar buffer imposed on the 747 when it first entered service turned out to be stricter than necessary.
Kroo’s imaginary 1,500-seater would no doubt trail monster vortices. Long wings dampen the whirlwinds, but no little Cessna would want to get within many miles. Perhaps airports and regulating authorities would find a way to channel traffic to lessen the impact of a superduperjumbo.
Richard Marchi of Airports Council International says that airports are adjusting to airplanes with larger, more efficient wingspans. “If aerodynamics are going to drive you to a bigger wing, then the airports are going to accommodate it eventually,” he says.
Boeing’s humped 747 entered service in 1970 as the biggest airliner in history amid fears that it too would be more trouble than it was worth. But in an era of booming air travel, it proved so popular with airlines that it turned out to be one of the most successful airplanes in history—1,117 are still in service today.
No doubt there is some size at which an airplane would be too big to get off the ground, Ilan Kroo says. But he hasn’t found it yet.