Anyone who has ever attended an air show has witnessed the deadly acrobatics performed by the pilots. But one maneuver stands out as a crowd favorite: the barrel roll, in which the plane spins 360 degrees in midair.
It should come as no surprise that performing this exercise is no easy task – even in a small stunt plane or fighter jet – and requires an experienced pilot to perform. But is it possible to do a barrel roll in something bigger like a commercial aircraft?
Richard P. Anderson — a pilot, aeronautical engineering professor and director of the Eagle Flight Research Center at Embry-Riddle Aeronautical University in Florida — said they do, and even knows people who have proof that they do.
“I know people on their own with video tapes [doing barrel rolls]Anderson told Live Science.
Perhaps the most famous pilot to ever achieve one in a commercial airliner was Alvin Melvin “Tex” Johnston, a Boeing test pilot. In the summer of 1955, Johnston took the four-engine Boeing 367-80 (also known as the Dash 80) for a spin—literally.
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To impress Boeing executives watching from a yacht on Lake Washington near Seattle, the “solo pilot” performed two barrel rolls along with a chandelle, a stunt in which a pilot combines a 180-degree turn with a climb, according to Los Angeles Times. That Monday, Johnston’s boss called him into his office and asked him what he was doing. Johnston allegedly replied, “I sell airplanes,” according to Airplane & Pilot Magazine.
So how did he successfully perform a barrel roll in such a large aircraft? Anderson said the size of the plane doesn’t matter as much as the pilot’s ability to mitigate the amount of g-forces acting on the plane during a roll.
“The physics are the same regardless of the size of the aircraft,” Anderson said. “In the barrel, the pilot is trying to keep the G load on the plane close to 1g. In other words, pretty close to what we feel here on Earth.”
To complete the maneuver, the pilot must perform a roll while tilting the nose of the aircraft up and then letting the nose drop down – all while flying the aircraft at a cruising speed of roughly 885 to 965 km/h. , as if it flew through the barrel, according to Flying magazine.
“The only real limiting thing in barrel roll is how fast the aircraft rolls,” Anderson said. “In a barrel roll, what you do is pull the nose up, and as you do the roll, you let the nose drop, which allows you to maintain this low-stress environment. When the nose drops, when you’re rolling, what you’re supposed to do is be able to get the airplane into of bank before the nose would point too far down, if the plane has a reasonable rate of bank, physics says any size plane can do that.”
David Haglund, a veteran U.S. Air Force pilot and associate professor at The Museum of Flight near Seattle, added that the amount of airspace available to complete the role is also important, especially with a large plane versus a small Cessna.
“Before performing this maneuver, the pilot would have considered the available airspace,” Haglund told Live Science in an email. “In an airliner, barrel rolling would require a block at 2,000 feet [600 meters] above and below level flight altitude (4,000 feet total) [12,000 m] be on the safe side.”
But although it is physically possible, some manufacturers have built restrictions into large, modern aircraft, perhaps to discourage future Tex Johnstons from performing similar aerobatic stunts, especially with passengers on board.
“Airbus doesn’t give the pilot the ability to bank beyond 60 degrees without disabling the part of the automatic flight system that controls the operating envelope of the aircraft,” said Haglund, who has experience flying the A330 and A350.