or: How we learned to stop worrying and love the gyroscope
July 10, 2010 4:31 PM   Subscribe

The Turn by William Langewiesche tells the story of pilots' fight against their innate sense of balance, which due to Newtonian physics, may insist a graveyard spiral is level, or vice versa. wikipedia has more, but essentially SLAtlantic.
posted by d. z. wang (27 comments total) 18 users marked this as a favorite
 
This is fascinating. "If Man was meant to fly, he'd have wings." Technology allows Man to fly, but our biology catches up with us. We discuss evolutionary biology, but is there a similar discussion about evolutionary technology? Pilots and astronauts are at the edge of what Man can do, given his origins. Perhaps we expect too much from them.
posted by SPrintF at 4:37 PM on July 10, 2010 [1 favorite]


Oldie but a goodie.
posted by chinston at 4:54 PM on July 10, 2010


The sense of spatial disorientation in the cockpit is truly frightening. It only takes a minute or two of flying blind to get "lost", confused as to your orientation, and the only correct thing to do is to narrow down your vision to the attitude indicator, a little 3" ball. You have to trust it to tell you what's up, not your intuition or senses. The new glass cockpit displays have a much bigger attitude indicator, a 7" or so wide LCD screen. Apparently having twice the display size leads to a distinct improvement in the pilot's ability to fly the plane level.
posted by Nelson at 5:23 PM on July 10, 2010 [3 favorites]




The peripheral vision horizon display (PVHD, aka Malcolm Horizon) is a fascinating instrument used to augment (or simply replace, given it seems to be often faulty) a pilot's sense of the plane's attitude. A line of light, kept level with the horizon, is projected across the entire cockpit instrument panel, and it is adjusted to be just dim enough that the pilot can't see it when looking directly at it. It won't obscure or distract the pilot's attention from the instruments, but it's just enough, apparently, for the pilot's peripheral vision to catch movement when the plane's attitude changes.

[digs around] Yes! I knew I had learned about this on Metafilter: the inventor, Richard Malcolm, commented about it here.

Anyway, I'll add this knowledge to the piloting skills I've been developing ever since first flying an SR-71 in Chuck Yeager's Advanced Flight Trainer. I think I'm pretty much set for my next trans-atlantic flight if the pilot and copilot both have the fish for dinner.
posted by whatnotever at 5:50 PM on July 10, 2010 [7 favorites]


You may recall that the plane crash that killed John F. Kennedy Jr., his wife, and her sister occurred because Kennedy, who was an inexperienced pilot, became disoriented flying in foggy conditions and put his plane into a spiral. This essay by a pilot named Eric Nolte talks about the Kennedy crash and this very problem.
posted by briank at 5:57 PM on July 10, 2010 [1 favorite]


When John F. Kennedy Jr. crashed, my fighter-pilot brother-in-law very accurately predicted, "They'll find them still strapped into their seats, wings shorn off, and the data will show they were in a death spiral."

"How do you know?"

"Because that's what happens to inexperienced pilots. They die thinking they're driving a car."
posted by Cool Papa Bell at 6:03 PM on July 10, 2010


Pinch poke, owe me a Coke, Cool Papa Bell.
posted by briank at 6:09 PM on July 10, 2010


Jinx!
posted by Cool Papa Bell at 6:32 PM on July 10, 2010


When I was in pilot training, one of the basic exercises was in unusual attitude recovery- the instructor would have you close you eyes and bow your head deeply. The bowing your head part was to move your vestibular canals 90 degrees out of normal phase.

At this point, he'd starts a random series of climbing or diving turns, sideslips, usually keeping near cruising speed so that increased or decreased wind noise wouldn't give the game away. When he thought I might be flummoxed enough, he'd take his hands off the controls and say "You have the airplane." I would then recover.

Of course, the game was to teach me not to trust my instincts, I usually had quite a different idea in my mind of what the airplane was doing versus the reality outside the window when I looked up.

Really advanced shamanic levels of this game came during instrument training, when I'd do the same exercise without outside visibility.
posted by pjern at 6:56 PM on July 10, 2010


On the other hand, Eric Nolte seems much less concerned with turning right than left. I'm feeling vaguely disoriented.
posted by sneebler at 6:58 PM on July 10, 2010 [1 favorite]


Oh I hate the Atlantic but I love reading about airplanes. WHAT TO DO

(I'll read it, of course. Thanks!)
posted by mwhybark at 7:30 PM on July 10, 2010


whatnotever: "peripheral vision horizon display"

cannot favorite enough. What an awesome doohickey. UI, flight, cogsci, perceptual stuphs: it's like a big bag of candy with my name on it!
posted by mwhybark at 7:33 PM on July 10, 2010


This was great, but is anyone else surprised that birds have tiny magnetite crystals in their brains? Is that common knowledge? I think that fact alone could have been enough to make me take science in school.
posted by doublehappy at 7:37 PM on July 10, 2010


doublehappy: I was under the impression that the knowledge that many birds can see magnetic fields was fairly recent, but that article was written in 1993, so maybe not.
posted by Malor at 7:48 PM on July 10, 2010


If you liked this (or are interested in flight at all), read Stick and Rudder by Wolfgang Langewiesche (the father of this article's author). The most practical description of why a plane flies, and how to keep it doing so that I have ever read.
posted by bitmage at 8:10 PM on July 10, 2010 [1 favorite]


read Stick and Rudder by Wolfgang Langewiesche

Can't repeat this enough. When I was an aviation-crazy young teen, living barefoot in the trailer park, one of the ways I kept myself sane was reading a copy of this, and practicing over and over the movements described with a toilet plunger as a stick and a kitchen chair as a pilot seat, and a rudder bar made of the back brace of another chair. I got to a zenlike state where I could imagine feeling the G-forces just from reading them.
posted by pjern at 8:58 PM on July 10, 2010 [2 favorites]


I think magnetite crystals were suspected but not known? (IIRC they are/were in specific muscles, not in their brains.) There's also a wacky quantum chemical mechanism that might be the basis of a magnetic sense in animals.
posted by hattifattener at 11:20 PM on July 10, 2010


A question I have always wondered is do birds actually fly inside clouds and if they do then how do they avoid spatial disorientation. I'm not sure I buy the built-in compass idea (it might be fine for navigation, but not orientation), I know for sure I couldn't fly a plane in the clouds using only the heading indicator or compass.
posted by Long Way To Go at 11:42 PM on July 10, 2010


What's hardly known is that the coordinated turn was the Wright brothers' actual invention. They didn't invent "flight", nor the banked turn (Otto Lilienthal probably has the best claim to that), nor, as it is often claimed, wing warping: a little-known Frenchman by the name of Mouillard came up with that first, and the Wrights were aware of him.
Mouillard, however, proposed to warp the wings not in order to bank the aircraft by differential lift like the Wright brothers did, but for yaw control by differential drag, as it is still done in spoiler-equipped aircraft and by paragliders.
Starting from Lilienthal's and Mouillard's work, the Wright brothers first had the idea that, with ever-heavier powered aircraft, moving the center of lift would be more efficient and safer than moving the center of weight, like Lilienthal, for lateral control, and that Mouillard's wing warping could actually be useful for that. Then, when they started experimenting, they encountered adverse yaw (which is actually the vindication of Mouillard's ideas), and were stuck for a while before deciding to use a rudder to counter this effect, and keep the nose of the aircraft pointing in the correct direction.
I am quite convinced that the Wrights' background as bicycle makers really helped them understand both the principle of the banked turn and that of yaw control...
That said, the Wrights' were so obsessed by the idea of "automatic control" that they actually physically linked the rudder and wing warp control cables. Even worse for them, they also linked them in their patent claims. As other early airmen quickly recognised that there wasn't such a need for a physical link between the two controls, and that the pilot could actually get much more control over the aircraft by playing separately with roll and yaw, the Wrights' had to try to get an interpretation of their patent that went beyond the literal meaning of the claims. They ultimately succeeded, but not before Wilbur died from typhoid and exhaustion from the legal battle...
posted by Skeptic at 5:07 AM on July 11, 2010 [3 favorites]


Sorry, but I have to ask something... if you had a sufficiently powerful magnet, would it attract birds/bugs (either in one big mish mash of birds/bugs stuck to your giant magnet, or they might just think you were north). Actually, come to think of it, how much iron is inside a human?
posted by doublehappy at 7:02 AM on July 11, 2010




What my cousin told me after JFK Jr's small plane crash is that it might have been prevented if he'd taped a ping-pong ball to the end of a length of string and had that hanging from the ceiling in his cockpit.
posted by TWinbrook8 at 9:43 AM on July 11, 2010


TWinbrook8: What that whole article is telling you is that that wouldn't work. The ping pong ball would stay hanging resolutely downward even as the plane spiraled out of control. It would only work if he started swinging it like a pendulum in a known flight state, and then observed the change in the swing.

If I understand the physics involved correctly, as long as you're not stalling, your wings are always going to be generating lift, pulling the plane away from its bottom. Therefore, the bottom of the plane is always going to feel 'down', even if it's inverted.

When the plane is in normal, level flight, it'll be exerting 1g of upward force, exactly counteracting the 1g (or less, at high altitude) of gravitational force. If it's inverted, it'll still be generating 1g of lift, which will ADD TO the Earth's pull, instead of counteracting it. You'll be falling at 2g toward the ground, but you would feel the 1g of normal flight. You'd be blissfully unaware of your impending doom, unless you looked out the window.
posted by Malor at 10:14 AM on July 11, 2010


When the plane is in normal, level flight, it'll be exerting 1g of upward force, exactly counteracting the 1g (or less, at high altitude) of gravitational force.

Not quite, then you'd be weightless.
posted by atrazine at 2:48 PM on July 11, 2010


No, because the Earth is still exerting its usual 1g force on you, pulling you down. (It's also pulling on the plane.) The plane's wings generate lift, exactly counterbalancing that force. You're "pushing" against the plane's body at 1g, but it's pushing back via lift force. So you stay level, and feel that you have weight.

When you turn upside down, it feels the same, even as you plunge toward the earth at 2g. The plane still generates the same 1g force relative to you, even though both you and the plane have an additional 1g force pulling you 'up'. You're being pulled toward the Earth at 1g, just like the seats, and then the wings are adding an additional 1g force. So, to you, the plane still feels 'down', even as both of you fall at twice normal acceleration toward the Earth below.
posted by Malor at 8:05 PM on July 11, 2010


And to elaborate, you can do a number of aerobatic maneuvers without spilling your drink or deviating much from 1g. Barrel rolls, for example. A passenger not looking out the window might not even notice that was going on, as Langewiesche notes.
posted by hattifattener at 12:13 AM on July 12, 2010


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