Hey Airbus, let's see your A380 do this.
June 21, 2006 8:31 AM   Subscribe

Do a Barrel Roll! [emvedded WMV, or view it on YouTube here] Test pilot Tex Johnston shows off the capabilities of Boeing's new 367-80 "Dash 80" prototype -- which would later become the Boeing 707 -- at a 1955 air show. The barrel roll (or aileron roll to others), done twice, was a no-hazard 1G maneuver for the Dash 80, but thoroughly impressed the crowd. Following the roll, it's said that William Allen turned to an elderly attender to ask for heart attack pills. You can still view the Dash-80 today at its final resting place, the Smithsonian National Air and Space Museum's Udvar-Hazy Center.
posted by brownpau (36 comments total)
That Smithsonion building is just a few minutes from my house, but I've never made the trip. Maybe I'll check it out this weekend.
posted by empath at 8:41 AM on June 21, 2006

Post title etymology (?)
posted by grobstein at 8:42 AM on June 21, 2006

Oh grobstein... I nearly said something, then thought nah, that's way too geeky even for mefi. Live and learn, eh?
posted by RokkitNite at 8:51 AM on June 21, 2006

Officials of the Aircraft Industries Association (AIA) and International Air Transport Association were meeting in Seattle, Washington during August 1955. Seattle's Seafair and Gold Cup hydroplane races were being held at the same time and Bill Allen, then President of Boeing, invited dignitaries of these associations to watch the boat races from three chartered yachts Boeing had reserved for the event. As a special treat for the guests, Allen told Tex Johnston to stage a fly by in the Dash-80 on the day of the hydroplane races.

Tex Johnston, a test pilot for Boeing, would simply make a routine flyover, at a prescribed time, to introduce the airplane of the future. Everything was going according to the plan and the local news media turned out to not only cover the races, but to view Boeing’s new airplane. However...

According to the book "Legend and Legacy", by Robert J. Serling, the account of this eventful fly by is recorded and here quoted:Tex never did anything halfway. PR Director Carl Cleveland had told him to come over Lake Washington, where the boat races were being held, at a prearranged time. When that moment arrived, the Dash-80 was in the middle of a routine test flight over the Olympic Peninsula and Johnston said to his copilot Jim Gannett. "I'm gonna roll this bird over the gold Cup course."

"They're liable to fire you," Gannett warned.

"Maybe, but I don't think so."

The Dash-80 was doing 450 mph when Tex brought it over Lake Washington at only 300 feet, put the jet into a 35-degree climb and proceeded to to do a complete 360-degree barrel roll. Then he reversed course, came back over the lake and repeated the maneuver - again in full view of 300,000 awed spectators, some vastly impressed industry officials, and a very unhappy William McPherson Allen.

After the second roll, Allen turned to Larry Bell of Bell Aircraft, one of his guests. "Larry, give me about ten of those heart pills you've been taking. I need them worse than you do."

Bell laughed. "Bill, I think he just sold your airplane."
posted by rotifer at 8:51 AM on June 21, 2006

I think I posted the first link wrong, but the YouTube video still works.
posted by brownpau at 8:58 AM on June 21, 2006

Dear Mr. Question Man,

Does the 707 eat its young?
posted by Captaintripps at 9:12 AM on June 21, 2006

I visited the Udvar-Hazy Center last Thanksgiving and could have spent another couple days just wandering around, it was fantastic.
posted by beowulf573 at 9:27 AM on June 21, 2006

The video you describe is easy to spot, near the bottom of the page.

It's next to this one, which I can't stop watching for some reason. It cracks me up.

"Jet blast is powerful." (rip...... bash... squeeee... smash bash crunch roll smash tumble smash flip SPLASH)
posted by Tubes at 9:31 AM on June 21, 2006 [1 favorite]

I bet John Travolta does this in his 707 all the time.
posted by squalor at 9:38 AM on June 21, 2006

"Upon landing, a European wild rabbit (Oryctolagus cuniculus) was on the runway as the aircraft (367-80) decelerated after its flight. The bunny managed to make it to safety."
posted by Sprocket at 9:55 AM on June 21, 2006

"Ladies and Gentlemen, please fasten your seatbelts."
posted by caddis at 10:45 AM on June 21, 2006

That interview made me giggle.
posted by notsnot at 10:52 AM on June 21, 2006

Is there any reason to think the A380 couldn't do this?
posted by delmoi at 11:03 AM on June 21, 2006

I like "shrinking the world" as a metaphor for building a faster airplane. Neat way to look at it.
posted by GeekAnimator at 11:11 AM on June 21, 2006

Previously linked to with tangential discussion here.
posted by Busy Old Fool at 11:16 AM on June 21, 2006

"Ladies and Gentlemen, please fasten your seatbelts."

Actually, it was a 1g maneuver, so htere should have been no real disruption.
posted by subaruwrx at 11:24 AM on June 21, 2006

Actually, it was a 1g maneuver, so htere should have been no real disruption.

You sure about that? It would seem a body in the seat would still need a way for that 1G force to hold it up. When right-side up, the seat cushion takes that role. When upside down, you'd need to rely on the belt.

Or maybe I'm completely out of it. It's been a while since I took physics.
posted by Opposite George at 12:24 PM on June 21, 2006

delmoi: Most any plane *should* be able to do this. But.... the a380 is a fly by wire system, so I'm not sure the computer would let a pilot do this.
posted by drleary at 12:24 PM on June 21, 2006

Opposite George: at the top of the roll, centrifugal force would keep you in your seat.
posted by exogenous at 12:27 PM on June 21, 2006

I would imagine that if you can pour tea you wouldn't need a seatbelt.
posted by puke & cry at 12:36 PM on June 21, 2006 [1 favorite]

Finally a subject on metafilter I know something about!

The author of the article very much mangled the description of different types of roll maneuvers. They were probably poorly described to him by pilots who really haven't much more than second or third hand experience in the various maneuvers that fall under the "roll" heading.

An aileron roll and a barrel roll are two quite different things and a snap roll is even further different.

A barrel roll is where the aircraft flies a path that describes a spiral along the perimeter of a cylinder--a blend between a loop and a roll--and it is a coordinated maneuver that is flown with a consistent positive G load. The center of rotation is considerably displaced from the longitudinal, or roll, axis of the aircraft, and falls in the center of the cylindrical path the aircraft flies as the maneuver is performed.

An aileron roll, or slow roll, is a roll where, in it's most perfect implementation, the aircraft rotates nearly perfectly about its longitudinal axis with no change in pitch attitude. For all but the most agile of aerobatic aircraft a perfect slow roll is unachievable as wing dihedral and other stability enhancements cause the pilot to have to make exaggerated control inputs across all three axes to keep the nose of the craft at the center of rotation. A slow roll is far from a coordinated maneuver and is often surprisingly uncomfortable for those experiencing it for the first time as there are fairly dramatic shifts from positive to negative G and back during the course of the roll. It is a difficult pattern to fly well and most first attempts in non-aerobatic aircraft result in a very lumpy maneuver with a lot of altitude loss.

A snap, or flick, roll is yet again different in that the maneuver is performed with the wings stalled altogether. The airplane isn't flying at all rather it is flung as an autorotational horizontal spin and one that can be entered as either a positive or negative G accelerated stall. As there are almost no aerodynamic forces at work in a stall, the rolling moment--rotational force--comes from energy carried into the snap roll before the stall, autorotational forces (spin) and a blend of engine torque and gyroscopic precession from the spinning propellor. Snap rolls are seldom performed by pure-jet aircraft as engine flame outs can occur due the loss of relative wind velocity and disruption of laminar airflow. The snap roll is often considered a violent maneuver but when well flown is quite graceful.

I doubt Tex flew anything but a barrel roll and, judging from the footage I've seen of the event, a shallow barrel roll with a lot of altitude loss.
posted by bz at 12:45 PM on June 21, 2006

Aha -- altitude loss explains it -- what's holding the passenger in his seat is the fact that the plane is dropping when upside down!

I was picturing the plane's altitude being constant (the aileron roll,) which of course, makes no sense in the context of a positive 1G maneuver.

Thanks, bz!
posted by Opposite George at 12:49 PM on June 21, 2006

altitude loss explains it -- what's holding the passenger in his seat is the fact that the plane is dropping when upside down

No, it's centrifugal force; it's the fact that the plane is moving through a large arc as it is upside down that causes the centrifugal force which holds you in your seat.
posted by caddis at 1:14 PM on June 21, 2006

Uh, caddis -- where do you think the "centrifugal force" comes from?

Perhaps it's better to say "the plane is accelerating downward when its upside-down" (my definition of "dropping" is a downward acceleration) if you want to be pedantic, but in a full, real-life roll this means the plane's altitude needs to decrease between the upside-down and right-side up phases if that force is going to be maintained.
posted by Opposite George at 1:28 PM on June 21, 2006

And yes, I was thinking "downward acceleration" instead of "downward translation" when I said "dropping," but again, in this situation that's pretty much splitting hairs (not always the case, obviously.)
posted by Opposite George at 1:30 PM on June 21, 2006

puke & cry's link to the Bob Hoover footage is a great example of someone applying physics to aviation. It's worth noting that Hoover did this routine well into his 70's, until insurers for airshows (and the FAA), citing 'medical concerns', grounded him, evem though he could still pass a flight physical.
posted by pjern at 1:43 PM on June 21, 2006

I just made my first visit to DC this weekend. Went to the Air & Space Museum (the one downtown), and was definitely awed -- A lot of old stuff, but a lot of neat stuff.

Then we went to the Udvar-Hazy center on Sunday. I will say it was, hands-down, the coolest museum I've ever seen in my entire fucking life. We went with 3 hours before closing, thinking we'd head out after awhile and snag a late lunch afterwards. They ended up having to shoo us out 5 minutes after closing, none of us wanted to leave.

Seriously, if you're anywhere near DC, go see this place. Twelve bucks for parking seemed like a ripoff when we pulled in, but I ended up dumping my wallet's monetary contents into the donation box as we were leaving. The parking price is a steal given how staggeringly awesome this place is.
posted by wolftrouble at 2:17 PM on June 21, 2006

Okay, this was way cool.
posted by pmurray63 at 2:43 PM on June 21, 2006

Is there any reason to think the A380 couldn't do this?

the a380 is a fly by wire system, so I'm not sure the computer would let a pilot do this.

Didn't the Airbus have a slew of crashes because the pilot would attempt a go-around but the computer would shit it's silicone pants and fight back because it felt they were too low to bank that sharply?
posted by CynicalKnight at 2:51 PM on June 21, 2006

OG, you have a strange vocabulary for acceleration.
posted by caddis at 3:05 PM on June 21, 2006

Odd that this story got posted today, because I saw this story on the internal news site this morning.
posted by printdevil at 4:22 PM on June 21, 2006

CynicalKnight: Yeah, I've heard something about that, but I don't have any links to back me up. I think that was in the original a320 series though, I'm sure the a380 has been improved over that.
posted by drleary at 8:54 PM on June 21, 2006

That Bob Hoover link is worth seeing, folks. What a character, and what a pilot. Wow. Once he gets up high he cuts the engines and does a mess of crazy maneuvers and then lands like a glider. Terrifying, and he makes it seem like figure skating. puke and cry, thanks.
posted by fourcheesemac at 9:26 PM on June 21, 2006

Opposite George, it appears you are in dire need of a whiteboard and the company of someone who understands centripetal forces.

Please explain how "downward acceleration" keeps the passengers in their seats during the traversal from "right-side up" to "upside-down," specifically the instant just before their asses have higher altitude than their heads.
posted by quite unimportant at 4:52 AM on June 22, 2006

OG is correct. Centrifugal/centripetal forces arise from conservation of momentum and the changes in direction of an orbiting object. In this case the plane is orbiting about a central axis of the barrel. If you use an on-the-ground frame of reference and just think about the upward and downward components of velocity and acceleration, at the lateral edges of the orbit, say -1, 0 and 1, 0 in cartesian coordinates, the vertical speed is maximum, up at -1, 0 and down at 1, 0. As the plane approaches the top of the orbit, 0,1, vertical speed is zero. However, it was decelerating from -1,0 to this point and is about to pick-up downward speed toward 1,0. That change in velocity is an overall downward acceleration. Just as acceleration in your car can pin you to the seat this downward acceleration pins you to your seat at 0,1. It is centrifugal force but just looking at the vertical component.
posted by caddis at 6:00 AM on June 22, 2006

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