Starting in about 40 minutes, I'll be liveblogging the Mythbusters episode where they take on the infamous airplane on a conveyor belt problem. Updates will be reverse chronological (newest at the top) so don't scroll down if you're DVRing the episode for later viewing or otherwise don't want anything spoiled.
Fair warning? Ok here we go.
10:32p I've turned comments on. Why not!!
10:04p
The plane took off so easily. The laws of physics are proven correct once again. But I'm not sure this is going to settle anything. I'm getting email as we speak that the test was unfair. Plane was too light. Tarp was pulled too slowly. Etc. But the thing is, it doesn't matter how large the plane is...given enough runway and a strong enough conveyor belt, it will still take off. Ditto for the speed of the treadmill...it doesn't matter how fast the treadmill is moving. It could be going 300 mph in the opposite direction and as long as the bearings in the plane's wheels don't melt, it's gonna take off. (For an explanation, try this one by my friend Mouser, who has a MIT Ph.D in Physics Sc.D. in Nuclear Science and Engineering.)
9:58p
Update: Due to popular demand, the above graphic is available on a t-shirt at CafePress. Prices start at $18 and they're available in men's and women's sizes.
9:58p
Heeeeeeeere we go.
9:56p
The pilot flying the ultralight is predicting that he won't be able to take off.
9:55p
Orville Wright died 60 years ago today.
9:50p
Cockroach mini-myth: cockroaches would survive a nuclear blast longer than humans but there were other kinds of bugs that fared better. Another commercial.
9:47p
Back to the shaving cream in the car prank. Now they're going to use A-B foam...they're trying to fill all the space in the car and perhaps explode it. Totally worked.
9:44p
Expedia commercial. Nice synergistic placement. Good work, Discovery Channel's ad sales team.
9:43p
Ok, to do the large-scale plane test, they're using a 2000 foot tarp and a 400 pound ultralight. Tarp is pulled in one direction and the plane tries to take off in the other direction. The wind is picking up and blowing the tarp runway all over the place. They're also having problems with punching holes in the tarp. They're going to try again after we hear some more about radioactive cockroaches. Aaaand, another commercial.
9:36p
Second mini-myth: if you freeze a can of shaving cream, cut it open, and then put the foam in a car, it will heat and expand to fill the car. One can did almost nothing. 50 cans didn't do too much either.
9:32p
Off to commercial again. Macbook Air ad. I don't understand all the whining about how expensive and underpowered it is. You can't get by with an 80 GB hard drive? Come on.
9:30p
Now a bit of explanation from the boys. (Things are moving faster now, which is welcome.) The thrust from the airplane acts upon the air so it doesn't matter too much what the runway is doing to the plane's wheels. And then back to the roach thing. They irradiated them (and some other bugs) and most of the roaches died. Still pending...
9:25p
Ok, they're dragging paper behind a Segway and trying to take off with the model airplane in the opposite direction. IT JUST TOOK OFF.
9:19p
Back to the roach thing. More recapping and a little bit more setup. I don't see how people can watch this show...it's sooooo slooooow. And now another commercial break. Hello picture-in-picture.
9:18p
As expected, the model airplane "flew" off the end of the exercise treadmill. It didn't have enough room to take off, but if it stayed straight, it probably would have.
9:14p
First recap...they took a solid minute to explain what they've already done. Ugh.
9:13p
Going into the first commercial, we've caught a glimpse of how they're going to test the main myth. They're going to drag a huge plastic sheet long the ground and have the plane sit on the plastic and being going the other way attempting to take off. A reasonable substitute for the treadmill.
9:08p
They're starting off small with a model airplane on an exercise treadmill. They're showing the two hosts learning how to fly the tiny airplane. One of them is riding around on a Segway. Oh, and they're also doing two other mini-myths during the episode. They just switched gears to the first mini-myth: can a cockroach survive a nuclear blast?
9:04p
And we're off. They're calling it "the moment we've all been waiting for". My guess: the plane will take off.
8:58p
I've only watched one other episode of Mythbusters before today. I found the show to be a little slow and very repetitive; 8 minutes of material stretched into 45 minutes of show. Unfortunately, this practice seems to be common among science programs on television.
8:40p
Watching Family Guy as a warmup. The one with the nudist family. Good stuff.
8:22p
Preemptive answer for the inevitable "Do you realize how boring/stupid/goofy it is to liveblog this?" Most definitely.
For real this time: Mythbusters will air their challenge of the airplane on a conveyor belt puzzle this Wednesday at 9pm ET. (thx, darin)
According to their web site and TV Guide, last night's episode of Mythbusters was supposed to address the airplane on a treadmill question. They didn't and nerds everywhere are upset. According to an email from the executive producer of the show, the segment got rescheduled:
First up, for those concerned that this story has been cancelled, don't worry, planes on a conveyer belt has been filmed, is spectacular, and will be part of what us Mythbusters refer to as 'episode 97'. Currently that is due to air on January 30th.
Secondly, for those very aggrieved fans feeling "duped" into watching tonight's show, I can only apologise. I'm not sure why the listings / internet advertised that tonight's show contained POCB. I will endeavour to find out an answer but for those conspiracy theorists amongst you, I can assure you that it will have just been an honest mistake.
Not sure that's going to quench the nerdfury, but I'm glad the piece will air in January.
The closure, it draws near. Remember the epic thread about the plane and the conveyor belt from last year...the one that pitted pilot against physicist against random internet commenter? In an upcoming episode of Mythbusters, they're going to air the results of a test they conducted with an ultralight and a quarter-mile-long conveyor belt:
If a plane is traveling at takeoff speed on a conveyor belt, and that conveyor belt is matching the speed in reverse, can the plane take off? "We put the plane on a quarter-mile conveyor belt and tested it out," says Savage about the experiment using a pilot and his Ultralight plane. "I won't tell you what the outcome was, but the pilot and his entire flight club got it wrong."
Awesome. If the laws of physics hold, that plane should take off. (thx, matt)
Q. Is it possible to use a wireless Internet connection on a plane?
A. Yes, if you happen to be flying on an airline that offers the service. International carriers like Korean Air, Lufthansa and Singapore Airlines already have wireless broadband service on many routes; fees for using it vary. Check with your airline to see if it offers in-flight Internet.
So says the NY Times. While it may not be possible to use wireless Internet connections on the plane, it is possible to use wireless connections. Apple laptops can create networks which other computers with wireless capability can join. Bluetooth capable devices like laptops and cellphones can communicate with each other over smaller distances.
Since 9/11, I've often thought that this would be an effective way for a group of people to coordinate some nefarious action on a plane without attracting any attention. Five or six people scattered about the plane on laptops, iChatting plans to one another, wouldn't be unusual at all. Of course, a properly trained group wouldn't need to communicate with each other at all after boarding the plane. Nor, says Bruce Schneier, should we ban things like cellphones and Internet access on airplanes for security reasons.
Now that I've closed the comments on the question of the airplane and the conveyor belt, I'm still getting emails calling me an idiot for thinking that the plane will take off. Having believed that after first hearing the question and formulating several reasons reinforcing my belief, I can sympathize with that POV, but that doesn't change the fact that I was initially wrong and that if you believe the plane won't take off, you're wrong too[1].
The only thing is, I'm not sure how to prove it to you if you don't understand the problem and the physics involved. I guess I could urge you to read the question and answer again carefully. I could tell you that not only does the conveyor belt not keep the plane stationary with respect to the ground but it *can't* keep that plane stationary with respect to the ground[2] and once you know that, of course it'll take off. My pal Mouser has a Ph.d in Physics from MIT and he says the plane will take off:
The airplane would take off normally, with the wheels spinning twice as fast as normal and a *slight* reduction in acceleration due to added friction.
Is that enough to convince you?
[1] This situation reminds me of Richard Dawkins' and Jerry Coyne's assertion that "one side can be wrong".
[2] The motion of the conveyor belt does nothing[3] to affect the movement of the plane when the plane is in motion...it doesn't matter if it's moving forward, backward, at 2 MPH, or at 400 MPH. If the plane were on castors that could spin freely from side to side as well as front to back, that treadmill could be spinning 100 MPH to the left and the plane would take off.
[3] Well, almost nothing. The friction of the turning wheels will slow things down a bit, but not enough to not make the plane take off. After all, the main function of the wheels of a plane is to provide a near-frictionless interface with the ground (or whatever the plane happens to be taking off from).
This question posed to Cecil at The Straight Dope has occupied most of my day today:
Here's the original problem essentially as it was posed to us: "A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?"
I'll give you a few moments to think about that before discussing the answer...
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Cecil says that the obvious answer -- that the plane does not take off because it remains stationary relative to the ground and the air -- is wrong. The plane, he says, can take off:
But of course cars and planes don't work the same way. A car's wheels are its means of propulsion--they push the road backwards (relatively speaking), and the car moves forward. In contrast, a plane's wheels aren't motorized; their purpose is to reduce friction during takeoff (and add it, by braking, when landing). What gets a plane moving are its propellers or jet turbines, which shove the air backward and thereby impel the plane forward. What the wheels, conveyor belt, etc, are up to is largely irrelevant. Let me repeat: Once the pilot fires up the engines, the plane moves forward at pretty much the usual speed relative to the ground--and more importantly the air--regardless of how fast the conveyor belt is moving backward. This generates lift on the wings, and the plane takes off. All the conveyor belt does is, as you correctly conclude, make the plane's wheels spin madly.
After reading the question this morning and discussing it with Meg for, oh, about 3 hours on and off, I was convinced that Cecil was wrong. There's no way that plane could take off. The conveyor belt keeps pace with the speed of the plane, which means the plane remains stationary from the POV of an observer on the ground, and therefore cannot lift off.
Then I read Cecil's answer again this evening and I've changed my mind; I'm fairly certain he's right. For a sufficiently long conveyor belt, that plane is taking off. It doesn't matter what the conveyor belt is doing because the airplane's energy is acting on the air, not the belt. I had better luck simplifying the problem like so: imagine instead of a plane, you've got a rocket with wheels sitting on that belt. When that rocket fires, it's eventually going to rocket off the end of that belt...which means that it doesn't remain stationary to the ground and if it had wings, it would fly.
What do you think? Can that plane take off?
See also Feynman's submerged sprinkler problem (answer) and an old argument of Newton and Huygens: can you swim faster through water or syrup?
Update: Well, that got out of control in a hurry...almost 300 comments in about 16 hours. I had to delete a bunch of trolling comments and it's not productive to keep going, so I closed it. Thanks for the, er, discussion and remember, the plane takes off. :)
Photos of some difficult runways on which to land a plane. (via tmn)
Update: Oops, looks like that link has some NSFW ads on it. Sorry about that and thanks to everyone who wrote in. I totally didn't see the ads when I looked at the photos before...my ad blindness is now complete if I'm missing pr0n.
A Boeing 777 lifted off from Hong Kong last night enroute to London with an eye toward breaking the world record for greatest distance flown by a commercial airliner (13,423 miles in 22 hours, 22 minutes).
AirTroductions is a social networking/dating site for frequent flyers.
Papalotzin is a project to follow the migration of the monarch butterfly from Canada to Mexico in an ultralight airplane (they call it their big butterfly). They've made it as far as NYC so far and are blogging and taking pictures as they go. (via gurgly)
