A barrel roll is a maneuver in which an object (usually an airplane or roller coaster) makes a complete rotation on its longitudinal axis while following a helical path, approximately maintaining its original direction. The G-force is kept positive (but not constant) on the object throughout the maneuver, commonly not more than 2-3 G, and no less than 0.5 G.

A barrel roll element on Gerstlauer's Speed roller coaster

Etymology

The barrel roll is so-named because an aircraft executing this maneuver looks as though it were flying with its wheels running along the inside edge of a barrel. A more common modern visualization is to imagine an airplane trying to fly in a horizontal corkscrew around the line of the direction of travel.

Aviation

In aviation, the maneuver includes a constant variation of altitude in all three axes, and at the midpoint (top) of the roll, the aircraft is flying inverted, with the nose pointing at a 90-degree angle ("sideways") to the general path of flight. The term "barrel roll" is frequently used, incorrectly, to refer to any roll by an airplane (see aileron roll), or to a helical roll in which the nose remains pointed generally along the flight path. In fact, the barrel roll is a specific and difficult maneuver; a combination of a roll and a loop. One advantage of the barrel roll over the aileron roll is that it is possible to maintain positive "g" force throughout the maneuver. (If the interior is not immaculately clean any loose material will be thrown about under negative g force and also the aircraft fuel flow may be momentarily interrupted.)

Barrel rolling is not used exclusively in aerobatic competition. Both the Boeing 707 and Concorde prototypes were barrel rolled during testing. The 707 was rolled just once by Tex Johnston while Concorde was rolled multiple times by her test pilots, including Jean Franchi and Brian Walpole.

One of the best and most accurate depictions of a barrel roll in any aviation movie occurred in the 1966 film The Blue Max, when one of the two German pilots flying a pair of Fokker Dr.I triplanes executes one, as seen from directly behind the pair of aircraft in the film.

Military attack

A barrel roll attack is a military maneuver that improves the attacker's offensive position and prevents the attacker from overshooting. In this maneuver the defender breaks one direction and so the attacker rolls the opposite direction from the defender's break then climbs to reduce closing speed. Finally the attacker completes the roll so he is level again and turns in behind the defender. The P-47 Thunderbolt USAAF World War II fighter could be barrel rolled in a dogfight, when chased by Luftwaffe fighters, particularly the Focke-Wulf Fw 190, to place itself on an enemy's tail.

Skiing

The barrel roll is a challenging maneuver to execute on skis. It is more commonly referred to as a "Lincoln loop" The Trick was named after 1970's hot dogging pioneer Eddie Lincoln. The Lincoln Loop is essentially a cartwheel or sideways roll in the air.

See also

• Inline twist
• Star Fox 64
• Roller coaster
• Skiing

External links

• 707 "DASH 80" completes a barrel roll during early airline flight testing to show the aircraft's abilities (note that this was not an "aileron roll" as the vehicle maintained positive g forces at all times)
• Lincoln Loop (skiing trick)
• Aerobatic maneuver website
• Avro Vulcan Roll

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