PDA

View Full Version : Plane Takeoff on a Conveyor Belt Thread - UPDATE



BrewsterPilot
12-05-2007, 05:11 AM
Next week, (12/12) mythbusters will test if anyone can land a commercial airliner (with no training) and if a plane can takeoff from a conveyor belt speeding in the opposite direction... http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Finally this legendary issue will be set to rest. http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

rnzoli
12-05-2007, 05:23 AM
I doubt about this (i.e., putting the issue at rest). http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif
There were some really stone-headed guys in our last 659-pager discussion http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif whatever they will see on TV, will be just "a strange coincidence of photonic radiance looking like the plane taking/not taking off, but in reality it would never/always take off" http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Breeze147
12-05-2007, 06:00 AM
I'm a big fan of photonic radiance. It's how I choose my women.

willyvic
12-05-2007, 06:13 AM
Ah, memories. What a great friggin thread that was.


WV

Bearcat99
12-05-2007, 06:25 AM
Yeah and I bet that plane goes no where... http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

MEGILE
12-05-2007, 06:29 AM
Originally posted by Bearcat99:
Yeah and I bet that plane goes no where... http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

Amusingly this notion is still propagated to this day, on forums everywhere.

http://img.villagephotos.com/p/2005-8/1070810/inconceivable_1.jpg

willyvic
12-05-2007, 06:29 AM
lmfao BC. I bet ya a dollar and a donut it do.


http://forums.ubi.com/images/smilies/88.gif http://forums.ubi.com/images/smilies/88.gif http://forums.ubi.com/images/smilies/88.gif


WV

HuninMunin
12-05-2007, 06:43 AM
NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

OO

OOO
OOOO

OOOOO
OOOOOOOO
OO
O
!

Viper2005_
12-05-2007, 06:47 AM
Surely the correct answer is "it depends".

In the simplest scenario, the velocity of the conveyor belt is transmitted to the aeroplane by the rolling friction associated with its landing gear.

From a standing start, it's quite easy to see how you might arrange for the conveyor belt to accelerate such that the rolling resistance of the landing gear cancelled the thrust of the aircraft's engines. Of course, since the rolling resistance is pretty small, the conveyor belt would have to move very fast; but since this is a totally bizarre scenario to begin with it's not as though you can throw that out of court for being unreasonable...

However, there are other more complicated scenarios:

Most aeroplanes have tyres. Tyres have limiting speeds. Depending upon the performance capability of the aeroplane, tyre limiting speed may become the limiting factor.

If the sum of the speed of the conveyor belt and the aircraft's unstick TAS exceed the tyre limiting speed then the aeroplane couldn't takeoff safely. Tyre limiting speeds are to be treated with considerable respect; there's a lot of energy involved, and explosive tyre failure can destroy aircraft and kill people. Normally you can stay within the limits by careful reference to TAS. This isn't easily possible in this scenario, so you'd need to perform some calculations beforehand.

Then you've got the vexed question of whether you start the conveyor belt before or after the aeroplane. Since most aeroplanes are directionally stable, if you move them backwards at high EAS they will attempt to swap ends. It's easy to see how the aeroplane might be damaged in this scenario.

OTOH, if the conveyor belt moves sufficiently slowly that factors such as those I have mentioned above do not become limiting then you should be able to go flying; why you'd want to take on the extra risks associated with this particular runway arrangement is another question...

ploughman
12-05-2007, 06:59 AM
The n00b in a passenger jet seems to me to be a daring departure from established good taste, not to mention the size of the risk assesment they'd've had to fill out to satisfy the Health and Safety wallahs; it must have been epic.

I look forward to viewing the crash/fire ball.

If it's just some schmo in an industrial flight simulator I shall be disapointed.

Now, if all the animals around the equator were to indulge in flattery...

Whirlin_merlin
12-05-2007, 07:18 AM
If it's true to the 'original' the belts speed backwards is the same as the planes speed forward. So the wheels just spin twice as fast as they would otherwise. As long as the tires, bearings etc can take that then all will be well.

This one is almost as good an idiot detector as the three doors, goat, game show one or inteligent design.

HotelBushranger
12-05-2007, 07:29 AM
I vote for bans for Viper and merlin for bringing science into this thread http://forums.ubi.com/images/smilies/51.gif

willyvic
12-05-2007, 07:29 AM
For those that want a trip down memory lane;

http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/8551099804/p/1

It took our minds off the normal Blue vs Red cr*p for a bit.


WV

Whirlin_merlin
12-05-2007, 08:18 AM
Originally posted by Bearcat99:
Yeah and I bet that plane goes no where... http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

Got bored rereading the thread by page 7 but please tell my that's irony and you did actually get it in the end. http://forums.ubi.com/images/smilies/16x16_smiley-tongue.gif

MEGILE
12-05-2007, 08:21 AM
LMAO I didn't notice this name the first time I read it.

KrashanTopolova http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Breeze147
12-05-2007, 08:40 AM
This is true: I almost lost my member when my pants got caught in the gears of a conveyor belt that did not have a safety cover.

FliegerAas
12-05-2007, 08:54 AM
Originally posted by Bearcat99:
Yeah and I bet that plane goes no where... http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

+1

http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Waldo.Pepper
12-05-2007, 11:04 AM
It took our minds off the normal Blue vs Red cr*p for a bit.

Blue! NO! I mean RE ----

jadger
12-05-2007, 11:48 AM
wow, I havent thought of this scenario since elementary school http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

and to think, someone will shatter my lifelong dream without my help http://forums.ubi.com/groupee_common/emoticons/icon_confused.gif I'm devestated. but at the same time I want to watch this.

are they going to land it on the conveyor belt as well? that was the second part of my plans in Grade 4. If you have the wheels spinning before you touch down on the conveyor belt that is already in motion, you should easily be able to set her down on a conveyor belt.

xTHRUDx
12-05-2007, 10:45 PM
i'm shocked to think that there are grown ups here that think the plane will not move. i guess they are correct when saying that "helicopters don't fly, there just so ugly the earth repels them"

next thing you know they'll say a car can't go over 60 in a 60 mph head wind.

Viper2005_
12-06-2007, 02:52 AM
Well that all depends upon the car doesn't it?

http://img389.imageshack.us/img389/2182/71nu.jpg

SOLO_Bones
12-06-2007, 03:48 AM
Just so you all know. The plane WILL move forward, but won't take-off. There, that settles it.

Addendum: It won't take off unless the conveyor belt is 1000 ft long or so

Klemm.co
12-06-2007, 04:22 AM
No, I will settle it: The conveyor belt doesn't move at all by itself. When the plane starts rolling (which it does through pushing off the air around it rather than the ground wich takes the belt out of the equation almost immediately and completely), the conveyor belt moves in the opposite direction of the plane FROM THE PLANE'S POV.
You don't even need a conveyor belt for that. Every runway does it. The airplane moves through space, or you could say that space moves in the opposite direction of the plane.

Snodrvr
12-06-2007, 04:42 PM
This could be settled easily and far more simply than a conveyor belt. Tie a rope around the tail of an RC plane then tie the other end to a sturdy stake of some sort.

Run the engine up to full throttle and try the elevator contols. I'm willing to bet the plane lifts into the air and will stand indefinitely with the rope pulled taut.

The same should apply for the conveyor belt, except once it's in the air it should be able to move freely.

erco415
12-06-2007, 09:03 PM
I cannot believe I'm getting into this...

It's simple. Tape a piece of yarn to the wing, out beyond the prop wash. Do whatever you want, the frikken plane won't take off until that yarn is being blown back over the wing. Airflow over the wing gives us lift, no flow over the wing, no lift. The end.

BfHeFwMe
12-06-2007, 09:42 PM
http://www.richard-seaman.com/Aircraft/AirShows/Yuma2005/Flying/HarrierNearGround.jpg

Mind if I leave some melted convey behind? http://forums.ubi.com/images/smilies/59.gif

erco415
12-06-2007, 09:45 PM
Well, see, that doesn't count - no conveyor! http://forums.ubi.com/images/smilies/11.gif

Nice picture, btw.

I should've known it would come to this, carry on with the discussion.

badatit
12-06-2007, 10:03 PM
It will fly.
http://www.youtube.com/watch?v=-EopVDgSPAk&NR=1

na85
12-07-2007, 01:17 AM
Except in the limiting case where the bearings in the wheels explode or otherwise fail, causing the wheels to seize and sending the plane propeller first into the ground, the plane can obviously take off.

It's basic physics.

rnzoli
12-07-2007, 02:14 AM
Remove the chocks before flight, that is also important! http://forums.ubi.com/images/smilies/59.gif

SOLO_Bones
12-07-2007, 03:59 AM
Originally posted by badatit:
It will fly.
http://www.youtube.com/watch?v=-EopVDgSPAk&NR=1

It will move foreward. It won't fly. Unless the conveyor(runway) is long enough to get air flow over the wings. Propeller wash ain't enough.

Whirlin_merlin
12-07-2007, 08:24 AM
I know I shouldn't but here goes.

Firstly most seem to get that an airplane flies because the wings generate lift, to do this the wing needs to be moving forward relative to the air.

The exceptions are situations were the 'engine' provides more thrust than the weight of the aircraft, of course this thrust has to be pointing down for this to happen eg a hovering harrier, helicopter of an F22 stood on it's tail!

So back to the con' belt problem. The real question is will the plane move forward (relative to the air around it)?
If it were a car on the con' belt then we could match it's speed to the car's and the car would remain stationary relative to the air, Earth etc. This is because the car moves forward by 'pushing' against the road beneth it. If the 'road' moves back as it pushes, and at the same 'speed' the car stays in one place. (It's abit like trying to run across a rug an a highly polished floor.)
If planes worked like cars then, no the plane would not take off, as the wing is stationary.
However a plane does not work like a car. A planes forward motion is not provided by the wheels. Using the example of a prop' plane, the plane is 'pulled' through the air by the prop'.

The 'riddle' says the speed of the con' belt backwards matches that of the plane forwards. Some have interpreted this to mean the plane is not moving relative to it's surroundings.
To them I ask how does the belt stop the plane moving forward?

In the case of the car the belt stops the car moving forward by moving back as the wheel 'push' themselves forward on it. For the plane how can the belt act apon the prop'?

Now if the plane had it's breaks on the belt could drag the plane backward and so 'resist' the power of the prop'. However if the breaks are off the only force the belt can 'use' to do this is the friction in the bearings,axel etc.

I would take the fact that when a plane lands it doesn't start to decelerate rapidly until the brakes are applied. As proof that the friction in the bearings etc is insignificant over all.

If the belt cannot resist the 'power' of the prop the plane will start to move forward, the only difference being that the wheels have to spin faster to compensate for the belts movement (so aslong as twice normal speed isn't enough to make them blow up, no problem). There will be some influence of course equal to the friction in the wheel bearings etc but not enough to overcome the panes forward motion.

I think that's as simple as I cna make it, if you still think the plane wont 'move forward' I ask again, How does the belt stop the plane moving forward?

Typed in a hurry sorry for spelling, grammer, typos etc.

Messaschnitzel
12-07-2007, 10:28 AM
Originally posted by Breeze147:
I'm a big fan of photonic radiance. It's how I choose my women.

I think that I have heard of this "photonic radiance phenomenonum" before. Does it have anything to do with looking through the bottom of a sudsy beer glass? http://forums.ubi.com/images/smilies/winky.gif

This bears further investigation. Kind of like why do the wheels go backwards on stagecoaches when you see them in the movies. This always amazed me when I was a little kid.

It's Googletime! http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

Cajun76
12-07-2007, 05:38 PM
Originally posted by Messaschnitzel:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Breeze147:
I'm a big fan of photonic radiance. It's how I choose my women.

I think that I have heard of this "photonic radiance phenomenonum" before. Does it have anything to do with looking through the bottom of a sudsy beer glass? http://forums.ubi.com/images/smilies/winky.gif

This bears further investigation. Kind of like why do the wheels go backwards on stagecoaches when you see them in the movies. This always amazed me when I was a little kid.

It's Googletime! http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif </div></BLOCKQUOTE>

Wagon wheels are one thing, this will blow your mind! http://forums.ubi.com/images/smilies/35.gif

http://www.youtube.com/watch?v=E8ftEKI0cLg&feature=related

Messaschnitzel
12-07-2007, 06:36 PM
Originally posted by Cajun76:

Wagon wheels are one thing, this will blow your mind! http://forums.ubi.com/images/smilies/35.gif

http://www.youtube.com/watch?v=E8ftEKI0cLg&feature=related

Those sneaky Russians. They'll do anything for a laugh. They merely photoshopped the hand holding the 1/48 scale model out of the video! http://forums.ubi.com/images/smilies/59.gif

xTHRUDx
12-07-2007, 09:48 PM
umm.. no. it was the cameras shutter speed matching the RPMs of the rotor.

han freak solo
12-07-2007, 10:20 PM
A great food processor this is.

http://www.ecse.com/images/tunnel_motors.jpg

BSS_CUDA
12-08-2007, 07:02 AM
Originally posted by xTHRUDx:
i'm shocked to think that there are grown ups here that think the plane will not move. i guess they are correct when saying that "helicopters don't fly, there just so ugly the earth repels them"
well we do know for a fact that when Chuck Norris does push-ups he not lifting his body he's actually pushing the earth down.
so it does seem to reason that a helicopter does not fly, it is in reality being repelled from the earth because of its ugly http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Cajun76
12-08-2007, 07:34 AM
Originally posted by BSS_CUDA:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by xTHRUDx:
i'm shocked to think that there are grown ups here that think the plane will not move. i guess they are correct when saying that "helicopters don't fly, there just so ugly the earth repels them"
well we do know for a fact that when Chuck Norris does push-ups he not lifting his body he's actually pushing the earth down.
so it does seem to reason that a helicopter does not fly, it is in reality being repelled from the earth because of its ugly http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif </div></BLOCKQUOTE>

Total BS, because if true, I would zoom around like Superman.

Messaschnitzel
12-08-2007, 01:27 PM
Originally posted by Cajun76:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by BSS_CUDA:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by xTHRUDx:
i'm shocked to think that there are grown ups here that think the plane will not move. i guess they are correct when saying that "helicopters don't fly, there just so ugly the earth repels them"
well we do know for a fact that when Chuck Norris does push-ups he not lifting his body he's actually pushing the earth down.
so it does seem to reason that a helicopter does not fly, it is in reality being repelled from the earth because of its ugly http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif </div></BLOCKQUOTE>

Total BS, because if true, I would zoom around like Superman. </div></BLOCKQUOTE>

If this is true, then all of the so called "beautiful people" will be driven 500 feet into the earth. http://forums.ubi.com/images/smilies/59.gif

Bearcat99
12-08-2007, 01:47 PM
Originally posted by xTHRUDx:
i'm shocked to think that there are grown ups here that think the plane will not move. i guess they are correct when saying that "helicopters don't fly, there just so ugly the earth repels them"

next thing you know they'll say a car can't go over 60 in a 60 mph head wind.

Why be shocked? At first glance it seems like a logical conclusion... won't be the first time I got something all wrong for sure...

FoolTrottel
12-08-2007, 02:07 PM
a car can't go over 60 in a 60 mph head wind.
I know of one:
http://img.photobucket.com/albums/v668/fooltrottel/BeetleSmall.jpg

Loco-S
12-08-2007, 02:12 PM
if a C-130 can land on an aircraft carrier, a single engine can take off from a conveyor belt:

http://www.youtube.com/watch?v=CfwJJD5jGXk&feature=related