[This is in regard to the Airplane-on-a-conveyor belt myth]
It has occurred to me that the wacky explanation of the Mythbusters producers can mean only one thing. They KNOW how badly they have loused up this myth and so they are going deep into stonewall country and insisting the myth was something entirely different.
But they are steadily losing valuable credibility with their sophisticated core audience. They need to come clean and admit that they were way, way off on this. The idea that the myth is provable by a skateboard on an exercise treadmill leads to the obvious question: WHAT WAS THE AIRPLANE FOR THEN? Why go through all those gyrations if that was what the myth was about? Why not put a little fan motor on a skateboard and do the myth on a treadmill? Come on, guys; we are not swallowing this hooey! The reason there’s an airplane in the myth is because the myth is centered on the concept of LIFT, which is something that skateboards and cars and even shallow draft everglades fanboats DON’T trade in!
We are not swallowing your lame explanation that you hit this myth out of the park and we don’t understand the concept. The more time that ticks away without a mea culpa from the show, the more your credibility erodes with your incredibly loyal audience! How about it, Mythbusters? –Fog
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Below is the important snippet of my earlier post re this:
Click here to read the full post
Click here to read the producers’ lame explanation in a new window
The producers drone on and on about how us dopey guys out there in TV land don’t understand how the engine moves the airplane forward. To me, the myth was never about that. The myth is about LIFT. Lift is how an airplane takes off. If the wheels never leave the ground, an airplane is just a car with a propeller.
The very instant the wheels leave the earth even a millimeter, the myth is over and proved, so long as the plane was prevented from moving forward WHILE ITS WHEELS TOUCHED THE GROUND. That’s the whole point of the dopey conveyor belt, which has just got everyone so snafu’d here. If your experiment allows the plane to move forward AT ALL, then you aren’t doing the concept that I am talking about. You’re doing another myth entirely and frankly, one that doesn’t make much sense because if you allow forward motion, you’ll increase the likely hood of a takeoff, greatly.
What would have been a far clearer and more definitive experiment, would have been to rig a plane up so that it could only rise on the vertical, but not travel an inch forward. A big cable? Or a “pin” of some sort at the tail would have done nicely. That way, the only lift forces generated would have been generated by the isolated engine, moving air over the control and lift surfaces.
I don’t think the producer’s explanation mentions the word “LIFT” even ONCE! If you don’t mention that word, then you (a) were doing a totally different myth, or (b) didn’t understand the thing at all (what they accused US of!).
Add to all of this, the fact that this myth (my interperatation) is not a good myth for the show at all because there is a different answer to this myth for EVERY AIRPLANE EVER BUILT! I would be willing to bet that an old, under-powered WWI Sopwith Camel would not be able to lift itself absent of any forward motion through the air. For a propeller plane, I would rather test one like the uber-powerful Grumman Bearcat of late in WWII. A plane that could do well over 400 MPH in level flight. Perhaps the Bearcat had a powerful enough powerplant (engine) to lift itself while cabled.
When you get into jets, the myth changes again, because on a plane like the early MIG’s, where the air intake is at the front of the craft and the exhaust is at the back, you have the situation where the engine is not moving ANY air over the lifting surfaces, but rather is providing only THRUST, the very thing the myth removes from the equation with the silly conveyor belt. So, with the MIG situation, you are into rocketry, where it’s raw thrust on one side of the seesaw and the weight of the craft on the other.
In fact, now that I think of it (hey, someone had to because the producers and Jamie and Adam sure weren’t), a rocket, like the Saturn V, is a pure example of this experiment. It gets absolutely NO LIFT AT ALL from air movement over it’s surfaces; it gets all of it’s ability to leave the ground through thrust. Anyway, forget about the details; just remember that there is a different result for this experiment for each and every plane ever built: not one result for all airplanes. That’s another item the producers and Jamie and Adam neglected to ponder and comment on.
As a parting thought, understand that I love this show. I think it is fantastic in so many ways and I will not stop watching it or thinking (because it makes you think!) and I do believe that for a show of this nature, their overall batting average is very, very high and I am, and remain, impressed with the science on the show. If I met Jamie or Adam, I’d put it up there with meeting Willy Mays. Keep it up, guys.
Another addendum: If you read the Executive Producer’s explanation and then read the cold read done by Adam in the show, you’ll notice on thing has changed. The open read by Adam says clearly: “a huge conveyor belt that is matching the planes forward speed in reverse“.
And the producer changes it to: “…a plane on a treadmill where both the plane and treadmill are going the plane’s take-off speed”
Ah-HA! To cover their fannies, the producer has added the limitation that the belt only go at the plane’s takeoff speed, and no faster. Well, that’s the problem right there. Any airworthy plane will be able to exceed by a reasonable margin, it’s average takeoff speed, or it wouldn’t be a very safe or effective craft. So, in effect, the producer wants us to swallow, that the myth centers around whether or not planes can exceed their own takeoff velocity, never mind that takeoff velocity is really a curve and depends on many variables such as wind on the runway and fuel load and cargo and passenger load. There isn’t one definitive takeoff velocity for a plane. Are we to assume that a plane can only do its own theoretical takeoff speed and no more? No margin for payloads or wind? Nothing extra? Are you telling me THAT was what this myth was about? Then you are insulting my intelligence and that of many, many of your loyal viewers. C’mon, Mythbusters! Don’t blow smoke! Come clean here!
– an increasingly annoyed fan
