For The Last Time: The Plane Takes Off!

So, after months and months of online dis­cus­sion, Myth­busters Jamie and Adam put the physics where the rub­ber meets the road.


Almost two years ago, I (and most of the inter­net, it seems) saw a thought ques­tion at regard­ing an air­plane on a giant con­vey­or belt. If the belt moved the exact same speed as the air­plane’s wheels – only in the oppo­site direc­tion – would the plane take off? Well, the answer was imme­di­ate­ly clear to me, but that’s for the sole rea­son of I took sev­er­al semes­ters of sta­t­ics, dynam­ics, and physics in col­lege. I knew imme­di­ate­ly that the plane would take off, with­out any ques­tion. I did my best to clear­ly explain why this was the case in the ensu­ing dis­cus­sion on Jason Kot­tke’s web­site1.

Mythbusters graphic

Well, last night, I (and Kot­tke, along with a lot of oth­ers) were vin­di­cat­ed as we watched a lit­tle yel­low, sin­gle seat ultra­light take off from a 2,000 foot long con­vey­or belt on a new episode of Myth­busters.

Now, as just a brief – and par­en­thet­i­cal – after­thought: it always feels good to be proven right. How­ev­er, one of the most awe­some expe­ri­ences in sci­ence is when all com­mon sense tells you one thing, but the num­bers and sci­en­tif­ic log­ic tell you the oppo­site. In that case, when a empir­i­cal result sup­ports the unlike­ly or seem­ing­ly impos­si­ble, it is a mar­velous and won­der­ful sur­prise. Think about all the real­ly cool exper­i­ments you ever saw in sci­ence class or on Mr. Wiz­ard, and I’ll bet they fit into that lat­ter case. What you thought could­n’t hap­pen does indeed hap­pen right before your eyes. That very thing has made many a per­son fall in love with sci­ence for the rest of their lives and I sin­cere­ly hope that this exper­i­ment did the same for a lot of peo­ple last night.

Plane taking off.

In the mean­time: I told you so!

  1. Kot­tke has real­ly tak­en some own­er­ship of this ques­tion, too. He even live-blogged last night’s episode. I, unfor­tu­nate­ly, had to TiVo it and watch it this morn­ing. Hence, the some­what late post of mine. []

By Jason Coleman

Structural engineer and technical content manager Bentley Systems by day. Geeky father and husband all the rest of time.


  1. Uh, yeah. So I know there are prob­a­bly a dozen more impor­tant things I should have been blog­ging about for the past month. There’s just been too much going on. The short & skin­ny? We’ve moved to TN, we’re all doing fine, work is good for both of us, you’ll all get updates very soon.

    In the mean­time, you get stuff like this to enter­tain you…

  2. Ok. I nev­er had any cours­es in sta­t­ics, dynam­ics or even physics in col­lege, but I still can’t believe peo­ple would even ques­tion this. I’ve been hear­ing about this all day today. How did this make it to Myth­busters? This is just com­mon sense. The plane is push­ing against the air. What’s under­neath has noth­ing to do with it. Seems to me, the only thing the con­vey­or belt is doing is cre­at­ing a tiny bit more resis­tance due to the fric­tion in the wheel bearings.

    In the words of GOB Bluth, COME ON!!

  3. It would have at least been slight­ly more inter­est­ing to have a fan blow­ing toward the front of the plane at the same speed as the pro­peller (I mean wind force, not RPM). 

    Of course, the plane would still take off; it just would­n’t move foreward.

  4. Well, I was try­ing to be polite, but yeah — it kind of shocks me, too, that peo­ple are being so insis­tent on the wrong answer. Basi­cal­ly, the wheels spin twice as fast as they would dur­ing a nor­mal take-off (if they are remote­ly decent wheels, they offer neg­li­gi­ble increased resis­tance). How­ev­er, you — per­haps more than the aver­age indi­vid­ual — have a fair­ly innate sense of mechanics.

    Peo­ple keep try­ing to (either inten­tion­al­ly or not) mis-rep­re­sent the ini­tial prob­lem state­ment as being some­thing else. Now, as for the fan, that would cer­tain­ly change the sit­u­a­tion as it would intro­duce out­side forces onto the plane.

  5. Oh come on Jason, it’s the freak­ing Myth­busters, not NASA. They’ve screwed up tons of exper­i­ments. Go back and watch it again, that air­craft was not sta­tion­ary. That air­craft was mov­ing for­ward on the track the entire time. All you have to do is pay atten­tion to it’s motion in rela­tion to the cones placed along the track. Until some egghead from the JPL steps up and does this for real (with a real con­vey­or belt as the myth stip­u­lat­ed and not a track dragged my a vehi­cle that did not main­tain a con­stant speed), the jury is still out.

  6. You dolts. The prop was pulling the plane for­ward through space, and push­ing air over the wings, cre­at­ing LIFT.

    The plane will always take off at a par­tic­u­lar speed through the air. Air speed is not to be con­fused with speed over the ground, which is total­ly irrelevant.

    The prop gave the plane the nec­es­sary for­ward air­speed to become air­borne, and the expect­ed result was seen: liftoff.

    If you think com­mon sense con­flict­ed with sci­ence, then you’re not real­ly famil­iar with either. The result was com­plete­ly predictable.

    The wheels have NOTHING what­so­ev­er to do with either propul­sion or lift.

  7. Will — I ful­ly admit that the Myth­busters are hard­ly the equiv­a­lent of a peer-review jour­nal. How­ev­er, they rou­tine­ly re-vis­it prob­lems with exper­i­ments and do a pret­ty good job of test­ing and I hon­est­ly don’t see that the results would be any dif­fer­ent on a more con­trolled con­vey­or belt.

    Sue — I appre­ci­ate your enthu­si­asm, but this isn’t the World Wild Web and call­ing peo­ple names isn’t wel­come here (espe­cial­ly when we all know one anoth­er but not you). This argu­ment has been going around for two years now and leav­ing a less-than-pleas­ant com­ment here isn’t going to end any­thing. Be nice or move on.

  8. I missed part of that episode and was just won­der­ing what the make and mod­el of the yel­low ultra­light was?

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