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I was going through social media and I came across this GIF image that showed a plane doing some sort of roll.

enter image description here

It was labeled "Barrel Roll" but in the comments to the post, someone said that it was an "Aileron Roll". What is the difference between a barrel roll and an aileron roll?

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anyone who hasn't seen Bob Hoover pouring tea while doing a roll needs to watch this: youtube.com/watch?v=yO8GyU8asEI – rbp Apr 2 at 16:09
up vote 33 down vote accepted

The difference between an aileron roll and a barrel roll is that an aileron roll's centre of rotation is very close to or on the aircraft. A barrel roll has its centre of rotation around a point further away from the aircraft itself.

The difference can be appreciated in this image:

Image showing path of plane for barrel and aileron rolls

Image Source You can find out about the difference in feeling that these two manoeuvres have.

Having stated these things, the manoeuvre shown in the GIF is certainly an aileron roll.

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I noticed in that GIF that at certain points the roll seemed to slow. Is this inherent to an Aileron roll or was that just some quirks of the pilot? – David Grinberg Mar 15 at 14:05
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@DavidGrinberg I see slowing down only at the very end of the video (perhaps also the end of the maneuver). Of course the apparent motion of the wingtips is faster when they are going up or down from the camera's point of view than when they are going directly toward or away from the camera, but that's only apparent motion, not the actual speed of the rotation. – David K Mar 15 at 14:56
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@DavidGrinberg: In an aileron roll, the rate of roll is fully controllable by the pilot. With the right aircraft the pilot can literally stop the roll at any point and maintain the aircraft's orientation. There is a precision variant of the aileron roll called the "four point roll" where the pilot rolls 90 degrees then pause then another 90 degrees then pause etc. – slebetman Mar 16 at 1:51

In a barrel roll, the aircraft rotates both in its longitudinal and lateral axes, while in case of aileron roll, the rotation is only about the longitudinal axis.

Barrel roll

A barrel roll, image from flightsimbooks.com

If properly executed, there is no change in alttitude in case of an aileron roll, while during barrel roll, the aircraft follows a helical path.

aileron roll

An aileron roll, image from globalsecurity.org

In short, think like this- in a barrel roll, the aircraft goes along the surface of the barrel, while in an aileron roll, the aircraft corkscrews around inside a barrel, with the wingtips grazing the barrel surface.

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So Peppy got it wrong? – corsiKa Mar 15 at 5:33
    
@corsiKa - Knew I would find a comment like that here =). Those of you who don't know, Peppy was a character in the video game Starfox who's famouse quote was "Do a barrel roll!". – Joseph Mar 15 at 12:01
    
I heard that the definition of a barrel roll was that the aircraft was always under positive Gs. Is this accurate? – Steve Mar 15 at 12:39
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@Steve Yeah, the definition I've always heard is that a barrel roll (when executed properly) is a constant +1 g downwards manuver (meaning even large planes not capable of high g forces could accomplish one), whereas the aileron roll has an additional acceleration. – DC177E Mar 15 at 14:46
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@DC177E You must have more than +1G in the pullup between point 3 and 4 in aeroalias diagram. – Wirewrap Mar 15 at 19:15

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