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What's a barrel roll?

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I figured it's an aircraft maneuver where one keeps flight path parallel to the ground while making a 360.
Like being a bullet travelling through a rifled barrel - pointed to horizon.

This guy's barrel is pointed to the ground, so no barrel roll:
https://www.youtube.com/watch?v=FHimh9YVuME
(I think it's called spiralling/spinning)

This IS a barrell roll:
https://www.youtube.com/watch?v=gxCLmNOEb7A

Now, what is this?
https://vimeo.com/122025704
What goes around, comes later.

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I didn't check the videos, but the skydiving definition differs from that in the rest of aviation. Our "barrel roll" is just a "roll" for aircraft. Well, with the exception that we're also dropping 120mph at the same time, so it is a "horizontal roll" only in the sense of a horizontal axis of orientation, and not a horizontal flight path.

The flight path difference is just because we don't stay level very well, and the "barrel" part must just have been some casual terminology early in skydiving that stuck.

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***A typical definition would be, a horizontal corkscrew around the line of the direction of travel.


I agree, so comment on these 3 examples, please


A 'barrel roll' in aviation maintains a positive G load all the way through the roll. Planes can do it because they generate lift.

Skydivers typically do an 'alieron roll' while in freefall as Paul pointed out - rotating around the horizontal axis only.

Even under canopy like the videos you posted, we're not doing a aviation-type barrel roll. For it to be a barrel roll the axis of rotation must be above the wing. We just can't generate that type of lift.

The rolls we see under canopy are seen much more frequently in speedflying wings (and usually performed badly - getting away with luck more than skill) due to their difference in controllability.

There is some really good info here: http://www.schnellcraft.com/index.php/knowhow/114-barrel-roll-secrets as well as some good videos of well executed and not-so-well executed ones.


Regardless - personally even under my speed wings the risk level outweighs the cool-factor. I've done a couple and that's more than enough... They scared the living shit out of me each time.
For me, that risk is increased when you try to do it with anything but the most aggressive skydiving canopy. If you get it wrong you unload the lines halfway through and can fall into the bottom skin of your canopy, covered in lines. A that point you're properly fucked.

I wouldn't make it an aspiration. ;)

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Now, what is this?
https://vimeo.com/122025704



In Paragliding we'd call what's in the third video wingovers, you use the power and pendulum swing generated from one to drive into the next, he does that a bit too but the timing is off and he's only using rears, because everyone in skydiving knows trusting your rears proves you have mad skillz.

https://www.youtube.com/watch?v=Ms67kJoC7mE

Be careful if you try this, under a skydiving canopy you can induce line twists if you get the timing wrong and whip a toggle while your canopy is lightly loaded etc.

Tangentially I saw someone accidentally do what paraglider pilots call a helicopter under a skydiving canopy recently. I was watching them toggle whipping "wingovers" and getting the timing so bad that I was sure they'd go into line twists, but to my amazement they put their canopy into a helicopter. When they recovered they surged directly at me, fun times.

https://www.youtube.com/watch?v=1gVPLAjkcmA

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A 'barrel roll' in aviation maintains a positive G load all the way through the roll. Planes can do it because they generate lift.



Parachutes don't generate lift? Then what are they there for?

I think that barrel roll might be the correct term considering that the skydiver, lines, and canopy are all experiencing a positive G-loading during the roll, imagine what it would look like if they weren't.

Quote

Even under canopy like the videos you posted, we're not doing a aviation-type barrel roll. For it to be a barrel roll the axis of rotation must be above the wing. We just can't generate that type of lift.



I think a more accurate definition is that the axis of rotation has to above the center-of-gravity which in the videos is the case. Again, why don't you think that a parachute generates lift? A normal barrel roll in an airplane is done at little more than 1G, it's one of the least stressful aerobatic maneuvers that an airplane can do.

Another term for a barrel-roll is 'displacement roll' in that the aircraft is displaced from it's flight path during the roll. Clearly, the flight path of the center-of-gravity of the parachute system (the parachutist) is clearly displaced around the flight path at a positive G loading.

I submit that the maneuvers in the videos are in fact barrel rolls.

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Oh c'mon. Do you really want a semantic discussion?

There is a varying scale of the amount of lift a wing produces and you know it.


yes. Parachutes produce lift. Fair enough. You win. So do skydivers in a track. And paper airplanes.

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yoink

Oh c'mon. Do you really want a semantic discussion?

There is a varying scale of the amount of lift a wing produces and you know it.


yes. Parachutes produce lift. Fair enough. You win. So do skydivers in a track. And paper airplanes.



I think perhaps he read too much literal into your remark but I don't think he was being unreasonable or pedantic. When he discusses lift in the context of a parachute and a barrel roll it's absolutely appropriate. He's spot on with his observation that a parachute in these scenarios is still generating enough lift to sustain positive G forces on the jumper. His suggestion of a center of rotation above the CG as a definition is insightful but probably either an emergent property or requirement of any barrel roll.

A possible distinction I think is the importance of the pendulum effect or rather the sustained angular momentum of the skydiver under the parachute and resulting centripetal "force" loading the wing in opposition to the lift, but they're pretty equivalent maneuvers IMHO, because this centripetal force also exists in a fixed wing barrel roll when I think about it.

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skycatcher68


I submit that the maneuvers in the videos are in fact barrel rolls.

I throw my vote in with you on video #2. You're above the canopy, pulling positive G's and rotating around your direction of flight, which is basically horizontal?

Barrel roll. :)
BTW, I've never done, and probably never will do, one of those under canopy. I have been barrel rolled in a Twin Beech jump plane. I was kneeling by the open door and stayed firmly on the floor the entire way around. B|

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IMO, a barrel roll in skydiving is a 360 degrees rotation around the longitudinal axis (ie. axis going from feet to head) of the body when on belly at the start. This longitudinal axis is horizontal. The barrel roll can be done, seen from the rear, clockwise or counter clockwise.

A 360 degrees rotation around the lateral axis (which is horizontal and perpendicular to the longitudinal axis) of the body (ie. axis going across the chest) is a back loop or a front loop, while

a 360 degrees rotation around the vertical axis passing by the center of gravity of the body being on belly is a flat turn (right or left)

When an airplane does a barrel roll (similar to this skydiving definition) it drops by few hundred feet depending on the speed. To see that drop, look at the airplane (low enough) and the ground for reference. The drop is then obvious.
Learn from others mistakes, you will never live long enough to make them all.

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Do you think this at (https://youtu.be/LJr70PKbgOE?t=38s) at 0:40 is a barrel roll? Is the pilot doing much more than pulling down hard on the left rear riser and balancing on the harness?

I try this maneuver up high on a much more forgiving canopy and it feels awesome, I thought I was doing barrel rolls :), but now you got me a little worried.

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Watched 3rd video w/the Valkyrie.
Barrel rolls?? Nope. Mostly a bunch of 90 to 120 degree turns under canopy, alternatingly jerking the rear risers right, then left etc., finishing off with a couple of 360's under canopy. A 360 under canopy is not a barrel roll. Not even close.

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