Can inexperienced 'MythBusters' really fly commercial aircraft?

Originally posted by Mayan2012
If this is true then i guess all them Carriers out in the Gulf and whatnot wont have to use slingshots anymore for their planes to take off without much runway. We can just put em on a big conveyor belt and let them take off.

The connection you make here is a logical fallacy. What you are suggesting will not work. The problem you are having in your mind is visualising that an airplane trying to take off on a conveyor belt that is matching the airplanes speed in the opposite direction, will still, regardless, move forward through air as normal! In fact, it will move forward along the conveyor belt as normal. The conveyor belt has no effect, other than on the wheels, which will spin faster to match both the speed of the conveyor belt and the forward motion of the airplane. This, in reality, can cause enough friction to melt or otherwise damage the wheels; however, if you discount this problem, the airplane will take off as normal. Understand?

yeah i understand very well, in fact im reading alot of material about aerodynamics for college.


but we will just have to see on dec 12th wont we. i set a reminder on my cable box for the mythbusters show to come on. i cant wait to see what happens.

reply to post by Mayan2012


The reason why this will not work on a carrier is that even on a conveyor belt you have to have enough distance to generate the speed and build the lift required to overcome the weight of the aircraft. The catapult shortens the take-off distance by increasing the forward velocity, while the conveyor belt will cause a longer rollout due to friction. In a perfect world with zero friction from the tries and belt, the plane would have the exact same rollout as is would on a normal piece of cement. On the conveyor belt, it’s going to be a longer rollout due to friction, but it will still take off.

i c, so how long are we talking about? and whats the point of doing this test if it is so inconvenient.

like why would we ever use a conveyor belt to get an aircraft in the air when it takes a much longer rollout than taking off regularly.

Originally posted by Mayan2012
like why would we ever use a conveyor belt to get an aircraft in the air when it takes a much longer rollout than taking off regularly.

We wouldn’t. Nobody would. It's stupid.

Mythbusters are doing it to “bust” a common misconception.

ah, well, seems to be an awful waste of time then lol. geez.

Originally posted by Mayan2012
ah, well, seems to be an awful waste of time then lol. geez.

Aren't most of them?

I mean really; is there much value in setting the record straight regarding things like; "Is it humanly possible for a ninja to catch an arrow in mid air?"

It's all for fun, entertainment, and trying to set the record straight regarding myths & urban legends.

This conveyor belt issue is really begining to remind me of an old riddle...

A father and son are heading home after a weekend fishing trip. Rounding a tight corner, a deer jumps out into the middle of the road. The father swerves to avoid hitting the deer, but in the process he looses control of his vehicle. The car spins, hits a tree, and the father doesn't survive the crash. A passing motorist sees the wreckage, stops, and calls 911. An ambulance arrives to find that it's too late for the father; however, with emergency care, the boy may survive. The ambulance races the boy to the hospital, and rolls him in for emergency surgery. The surgeon enters the room, takes one look at the boy, and states; "I cannot operate on this child; he's my son."

How can this be?

The answer... the boys mother was the surgeon.

Admittedly, that riddle doesn't baffle as many people as it did twenty years ago, but for a long time people were far to familiar with the preconceived notion of a surgeon being male. Similarly, people are far too used to the idea that forward thrust is reliant on surface friction.

When you crawl, walk, or run your body's friction acts against the 'ground'; so a conveyor can counteract this, and 'hold you in place'. Bicycles, motorcycles, cars, buses, etc. all have torque at the wheels. Their tires' friction, with the 'ground', creates their forward thrust; so a conveyor can 'negate' that as well. Many people are so ingrained in this concept that it's hard for them to visualize what happens when a thrust comes from an entirely independent source. Most wheeled vehicles need their tires to generate/increase friction (translating to forward thrust), while a plane's tires are actually there to reduce the friction (they're free spinning) that would otherwise be 'the belly of the plane scraping against the ground'. When the thrust is not generated by an object's interaction with the 'ground', a conveyor cannot 'nullify' it.

And yes Bhadhidar. For as long as the wheels & bearings held out, a Helicron would still advance forward on a conveyor belt moving in the opposite direction. Also, I'm a bit surprised that, with almost 2 years to ponder over this, you still haven't gained a grasp of the issue.

That said, the old "plane on a conveyor belt" riddle doesn't have much to do with 9/11. If anyone wants to discuss it further, we might want to take it to the origional thread.

[edit on 12/10/07 by redmage]

Let's think about this for a sec.

The conveyor is on the ground. The aircraft is on the conveyor.

If the aircraft flies ---> way, and the conveyor moves

Originally posted by mirageofdeceit
If the aircraft flies ---> way, and the conveyor moves 0. The conveyor belt merely causes the wheels to spin faster than usual while it's happening.

[edit on 12/10/07 by redmage]

If the conveyor belt could "counteract" the forward motion of the plane while thrust was being applied, then the plane would move in reverse when thrust was not being applied. This does not happen however, because the wheels negate friction, and therefore negate any effect of the conveyor belt leaving the plane at zero velocity.

If the plane doesn't move backward with the thrusters off, it can move forward when thrust is applied.

Originally posted by Now_Then
If they are on about landing a 747 they must be on about a simulator right? I can't imagine any insurance company would give the go ahead for the real thing.

should be good tho - any idea when that episode will make it this side of the pond?

Sure, however a B747 Level D full motion-sim behaves very much like "the real thing" .
So, if a non pilot can land the sim he can most likely land a B747 real life.

Couple of years back after a line-check we had a microsoft-flightsim dude with no actual experience on any aircraft
flying a complete leg with a experienced first officer in a full motion B737-NG sim.
To our surprise he programmed the FMC, asked for the right checklists at the right time, and pretty much followed company procedure during the entire flight.
On approach he disconnected the autopilot and did a manual landing, landed a tad to fast and floated, not a perfect landing but all onboard would have walked, and the aircraft could have been used again.

So yes it is possible.

Let's see if good ol' Aim can resolve this airplane on the tredmill issue.

Here is the thing. When the tredmill first starts, the plane will begin to move backwards - like anything else. However, once the aircraft's propulsion kicks in, things begin to change.

There will be several forces in motion, now. First, we have the thrust of the engines, which will be counteracting the inertia of its reversed-motion. Second, we will have the wheels, which will be offering friction to any velocity difference between the aircraft and the surface of the tredmill.

Now - the tredmill has no effect on the air (aside from right at the very surface... but we won't get into tiny little details like that). The air is not moving forward, or backwards..... the plane is moving backwards through the air (at the very start).

Once the thrust of the aircraft overcomes the inertia of reverse motion and the equalizes the friction of the wheels, it will be moving at 'zero' airspeed. Note - it's only having to overcome the friction produced by the wheels at that speed - any force applied beyond that will accelerate it to a positive airspeed.

Eventually, the aircraft would be capable of becoming airborne - although at a relatively higher speed than what would normally be required to achieve a 1:1 lift/weight ratio.

It's not as simple as "the aircraft has to negate the speed" - nor is it as simple as "the aircraft will take off normally."

However... we can look at it from other scenarios.

Some aircraft, due to the structure of their design (namely, the YF-23), the mere operation of the engines produces lift because of the way the airflow is ducted. Although none possess the ability to obtain a 1:1 lift:weight ratio, it is still a factor beyond simple airspeed.

Thrust:Weight ratio is also irrelevant to a standard horizontal takeoff (aside from acceleration). This only comes into play through maneuvers, and whether or not the aircraft can continue to climb (accelerate) through a completely vertical position.

Does that help clear some things up?

I guess they can after all.

Both, Adam and Jamie, failed miserably on their first attempt without any help. They both landed successfully on their second try with assistance from the simulator operator.

Did anyone else catch the episode?

What happened to the airplane on a treadmill segment?

Originally posted by Boone 870
What happened to the airplane on a treadmill segment?

Discovery bumped it, and pissed off a large portion of their viewing audience in the process.

A moderator over at the Mythbusters forum posted an e-mail from the exec. producer that states:

Dear all,

As wbarnhill called out, I thought I should step in to what is rapidly becoming a hornet's nest. I will try to calm things down but I don't hold out much hope!

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.

Cont...

Originally posted by jackinthebox
If the conveyor belt could "counteract" the forward motion of the plane while thrust was being applied, then the plane would move in reverse when thrust was not being applied. This does not happen however, because the wheels negate friction, and therefore negate any effect of the conveyor belt leaving the plane at zero velocity.

If the plane doesn't move backward with the thrusters off, it can move forward when thrust is applied.

That's what I said above, pretty much.

If you can fly MSFS with any semblance of accuracy, then you can fly the real thing. If you learn, say, the Level-D 767 for MSFS inside-out, or the PMDG 747-400, then you've got a very good chance of doing the same in the real thing.

About the only thing to remember about FS is that its flight model isn't completely accurate, and there are situations in RL that would bite you if you weren't careful (the biggest is the effect of flying below minimum maneuvering speed - you don't want to roll more than 15°!), and the symptoms of approaching low and high speed stalls, with both power on and power off.

If you want some real fun - take a real Piper Meridian in the landing config, and throw open the power. I do not suggest you try this unless you have LOTS of altitude, and know what you're doing before you do it. It will be the quickest lesson in torque reaction and control effectiveness you'll ever have.

EDIT: Level-D 767 in MSFS on hand-flown approach onto RW27R, Heathrow (ICAO: EGLL).

EDIT2: Could a mod please fix the image? Thanks.



[edit on 13-12-2007 by mirageofdeceit]

At the risk of opening a sore old thread, I'd like to pose this variation for consideration to all those who contend that "the plane will fly":



If the contention is that the wheels of the plane do not contribute in any significant way to the plane's ability to achieve take-off, they merely serve to support the mass of the plane at rest and lessen the friction against the ground imposed by the mass of the palne as it taxis, cancelling the effect of the wheels as they roll along a surface by use of a treadmill-like system, should not duly encumber the plane from taking off, albeit requiring a somewhat higher take-off speed.

That being the case, let's try this: If the wheels don't really contribute, let's "stick them in the air like they just don't care",

that is to say.

Let's stand the plane on its tail, and without modifying the propeller in any way, let's see if the plane will fly.

I contend that it won't be able to.


Those of you who believe it will lift off, answer this question:

Why then are the blades on a helicopter so much larger (speaking in terms of diameter) than the propeller of a similarly sized airplane?

Why haven't they built a helicopter the size of a 747?

reply to post by Bhadhidar
If you're suggesting a vertical take-off it certainly won't get off the ground because that would require a total thrust exceeding the plane's mass and that's not a normal feature of domestic aircraft which rely on the wings to provide lift.



[edit on 15/1/2008 by Pilgrum]

I should add that some military planes would have a chance at this. They've proven that even a brick can fly if a large enough engine is attached to it

reply to post by Zeta115



Amazing how many overlook your post, Probably as it completely destroys their ignorant theories, I've also got many many hours on My PC Simulater, its not the real deal but its close enough to know how to read instruments and navigate along with many other things...

good post star for you.

reply to post by mirageofdeceit



You get a star also.


[edit on 15-1-2008 by C0le]

I really hope that it eventually "clicks" for you Bhadhidar. You're developing a frightening knack for drawing irrelevant & dissimilar comparisons in an attempt to prop up your mistaken belief. The blades on a helicopter are so much larger (speaking in terms of diameter) than the propeller of a similarly sized airplane because a plane generates thrust at the prop and lift by its wings, while a helicopter's rotating blades generate its thrust and its lift. The rotating blades of a helicopter are its "wings".

Oh boy, this pilot is in for quite a surprise!

[edit on 1/15/08 by redmage]