Airplane on a treadmill Concept #1

[HX3D014]

This is a rewording of the question to remove any (paradoxical phenomenon) confusion from the original question.

Concept #1
The treadmill will move backwards (matching As best as we can with todays science) at the same speed and time the PLANE moves forward.

So if the plane can Run down the runway at a constant acceleration rate of say 5m/s^2 then the belt will accelerate at that same rate.

New addition to these Concept reworded questions.

The plane in use is a CH701
The runway is as long as the shortest take off distance of this plane on a normal ISA day. (Plus a few feet, so if the planes shortest distance for take off is 50 feet, then lets make the treadmill runway 53ft)

At the end of the runway there is a drop of 2ft onto rough rocky ground where any plane would no doubt rip its landing gear off and crash should it try to roll over it. (This is just to prevent the use of more than the runway for the take off run)

The plane speed is relative to the stationary belt platform.
The belt speed is relative to the stationary belt platform.
There is no wind, and the atmospheric conditions are ISA.

Will the plane Take off ?

(OK this is the easy one. It is no doubt a yes all around)

[vintage1]

Yawn. We did this one to death last year.

[HX3D014]

Yawn. We did this one to death last year.That would explain why I got so many answers and Comments on my Suggestions to Re word the question!

Can you help me. Where is that one ?

[JetPlaneFlyer]

The plane Speed is relative to the stationary belt platform.



Then there is no paradox. The paradox only occurs if you try to match belt speed with wheel speed relative to the moving belt itself

The plane takes off virtually as normal, just the wheels spin twice as fast. As long as the bearings, wheels and tyres can take it then no problem. Take off run will be very slightly longer due to need to accelerate the wheels twice as much but as the wheels are a tiny proportion of the overall plane weight this is a very minor effect.

Can we stop talking about stupid conveyor belt scenarios now?

Steve

[HX3D014]

Then there is no paradox. The paradox only occurs if you try to match belt speed with wheel speed relative to the moving belt itself

The plane takes off virtually as normal, just the wheels spin twice as fast. As long as the bearings, wheels and tyres can take it then no problem. Take off run will be very slightly longer due to need to accelerate the wheels twice as much but as the wheels are a tiny proportion of the overall plane weight this is a very minor effect.

Can we stop talking about stupid conveyor belt scenarios now?

Steve
Very Good. Go to the Front of the Class an Demonstrate you Intellectual Ability by Drawing a Force Diagram for us (Please ;))

"The Paradox is over". Both Concepts #1 and #2 are an attempt to clarify the question enough that Those wishing to Talk about the "interactions" rather than the Specific wording of the question can have a place to talk. No Fairy land talk, No Confusion. Just the Points......

Been thinking of Energy in turns recently? ;)

(Glad I had Spell check on. I nearly Misspelt "Intelectual")

[teookie]

Even though we all know the answer by now I still love this question. Next time your with non airplane buddies bring it up and let the hilarity ensue. :D

[HX3D014]

Even though we all know the answer by now I still love this question. Next time your with non airplane buddies bring it up and let the hilarity ensue. :D
Don’t bring this one up (Concept #1). There will be near none disagreeing with each other ;)

Bring up concept #2 and any who say it will take off will be in for a surprise ;)

Bryce.

[NoFlyZone]

I've read the first post a dozen times, and if it's meant to clarify, or simplify Haney's joke about the plane on a conveyor belt.. then it's my opinion only that this question is at least 50 times more difficult to grasp.

Then again, I'm not exactly the sharpest tool in the shed... :)

[HX3D014]

I've read the first post a dozen times, and if it's meant to clarify, or simplify Haney's joke about the plane on a conveyor belt.. then it's my opinion only that this question is at least 50 times more difficult to grasp.

Then again, I'm not exactly the sharpest tool in the shed... :)
Thats OK.

Hay, If you feel you can help me by explaining what part is causing your Confusion. I would be more than happy to Soften it up for those of us Not so sharp tools ;)

Bryce.

Oh... Its supposed to be answerable. IE not a Paradox. you think wording one for concept #1 is hard. have a look at my attempt at Concept #2.

Its not so much to clarify the other one. but make two different questions out of the one question. one each for the Different groups Yes and No.

So this one needs to be Scrutinised mainly by those who say no to Wills WIF II? poll.
on wills one.

I first said yes. Thinking of first impressions of the question
then I changed to no just 4 moths ago

[Texas Buzzard]

Contrary to a few posters - I like this question. Yes I saw the original last year.

Yes the plane WILL takeoff because the bearings in the wheels make the plane independant of the surface. The wings do not know there is a moving belt.

This question is very similar to the aircraft question:

An aircraft carrier is moving South at 40 mph relative to the water. There is a wind from the North moving at 40 mph relative to the water.
The plane in question is at the North end of the carrier and usually lifts off at an airspeed of 40 mph. If the maximum thrust of this plane can produce a maximum airspeed of 50 mph will this plane be able to take off? List any extra required info needed to give an answer.

JETPLANEFLIER Gave a Perfect answer Nothing else is needed!!

JPF said,"Then there is no paradox. The paradox only occurs if you try to match belt speed with wheel speed relative to the moving belt itself

The plane takes off virtually as normal, just the wheels spin twice as fast. As long as the bearings, wheels and tyres can take it then no problem. Take off run will be very slightly longer due to need to accelerate the wheels twice as much but as the wheels are a tiny proportion of the overall plane weight this is a very minor effect.

Can we stop talking about stupid conveyor belt scenarios now?"

Just skip this if you don't like these questions.....

[HX3D014]

Contrary to a few posters - I like this question. Yes I saw the original last year.

Yes the plane WILL takeoff because the bearings in the wheels make the plane independant of the surface. The wings do not know there is a moving belt.

This question is very similar to the aircraft question:

An aircraft carrier is moving South at 40 mph relative to the water. There is a wind from the North moving at 40 mph relative to the water.
The plane in question is at the North end of the carrier and usually lifts off at an airspeed of 40 mph. If the maximum thrust of this plane can produce a maximum airspeed of 50 mph will this plane be able to take off? List any extra required info needed to give an answer.

Just skip this if you don't like these questions.....
Yes.
But I would Suggest making sure there is nothing behind it when you let go of it. because its going to start to move backwards (Relative to the aircraft carrier)the moment you do let go of it;).
Relative to the water the plane is already doing 40 while held to the deck.
Relative to the air the plane is doing 80, the plane is already going through the air faster than the max thrust can produce. so, as soon as you let go of it, it will slow down relative to the air the moment it is airborne. Seeing as the ship continues doing 80 relative to the air. the ship will be faster than the plane. the real trick would be trying to land one on the deck from the front to the back . Relative to the Ship the plane would come in from the front of the ship but facing the same direction of the ship. it would move back as the ship passed it. the idea is to fly down to the same altitude as the deck and apply breaks so the plane will speed up through the air. thus Slow down relative to the deck . and then hope the guys and gals on deck can catch your wheels and lock you down ;) Get that on video and play it backwards! it would look like a strange looking normal landing ;)

Bryce.

Doh. I thought it was the wind is traveling North.

OK. boat and Air moving same direction and same speed. So there is no wind on deck. so the plane will need to accelerate off the deck with out any wind. No head wind no tail wind. just still conditions (of sorts ). So the question is , can this plane accelerate to the take off airspeed in the distance allowed. ??
IE If this plane can not take off of this deck when the ship is doing 0mph relative to the water and the Wind is also doing 0mph relative to the water, then the plane will not be able to take off with the ship and air moving at the same speed in the same direction.

[HerkS]

Contrary to a few posters - I like this question. Yes I saw the original last year.

Yes the plane WILL takeoff because the bearings in the wheels make the plane independant of the surface. The wings do not know there is a moving belt.

..

Sorry Al, The aircraft is affected by the belt. Because there is acceleration involved there is a drag force between the tires and the belt. The old F=MA equation is functional. The force is needed to accelerate the rotational speed of the wheels and tires. This becomes a drag force on the plane. And if the belt wheel system is in a runaway feedback mode as the belt tries to catch up with the wheel speed it's magnifying, the speed would become very great and besides holding back the plane it would destroy the wheels and tires.

Answered more fully on thread two.

[Majortomski]

Herk, sorry, you've bought into the "other' threads bad physics.

In all cases the resistance force is only the rolling resistance.

http://en.wikipedia.org/wiki/Rolling_resistance

It is constant and extremely small. It is NOT increasing with speed.
It is so small, that takeoff computations for full scale aircaft don't even include it in the equation.

No matter how you word the problem the aircraft takes off at its normal take off speed and distance.

The belt is moving at the same speed in the opposite direction

The wheels are turning at twice their nomal speed, and since up to the point of lift off they are not slipping or skidding they too are matching the speed of the belt. This is the self evident point that all the no flyers miss.

Sorry but under the physics of this planet, the plane will fly.

[NoFlyZone]

And if the belt wheel system is in a runaway feedback mode as the belt tries to catch up with the wheel speed it's magnifying, the speed would become very great and besides holding back the plane it would destroy the wheels and tires.



Maybe you can explain to me how the belt would be accelerating at these GREAT speeds, capable of destroying wheels, when the fastest the belt can ever move is only as fast as the planes wheels can go????

[David A Ramsey]

Get rid of the dang wheels and bearings. Lets have some real friction and put on snow skies.

[HX3D014]

Maybe you can explain to me how the belt would be accelerating at these GREAT speeds, capable of destroying wheels, when the fastest the belt can ever move is only as fast as the planes wheels can go????
Herk was partly discussing concept #2 when he mentioned "if the belt wheel system is in a runaway feedback mode"

This one. Concept #1 is a yes. The plane will take off.

Under the Physics of this planet? the plane will take off.

But have a look at Concept #2. (http://www.rcgroups.com/forums/showthread.php?t=1033524) for a real Plane v Belt Competition.

Majortomski;
"the "other' threads bad physics"
?
which thread?

[Majortomski]

Herk was partly discussing concept #2 when he mentioned "if the belt wheel system is in a runaway feedback mode"

This one. Concept #1 is a yes. The plane will take off.

Under the Physics of this planet? the plane will take off.

But have a look at Concept #2. (http://www.rcgroups.com/forums/showthread.php?t=1033524) for a real Plane v Belt Competition.

Majortomski;
"the "other' threads bad physics"
?
which thread?


The thread to end all threads and to end all civil relationships amongs RCG memebers

http://www.rcgroups.com/forums/showthread.php?t=550903

[NoFlyZone]

The thread to end all threads and to end all civil relationships amongs RCG memebers



That thread of Will's is a work of art. Do you want to know my honest opinion? Will knows beyond a shadow of a doubt that plane will take off his conveyor belt. For being able to pull that thread off, and revive it every once in a while and put forth his 'proofs' with such a straight face, I give Will an "A+".

If you stand 'outside the box' and look in, as an outside observer, on what Will is pulling off over there, you will laugh your butt off.

I love it the way Will thanks people for having the intelligence to know the plane can't take off; even as those same people screw up basic physics that even a 3rd grader would scoff at.

Einstein and Newton themselves could participate in that thread and Will would have them frothing at the mouth within a dozen posts.... :)

Chuck

[HX3D014]

The thread to end all threads and to end all civil relationships amongs RCG memebers

http://www.rcgroups.com/forums/showthread.php?t=550903
LOL
So true. But also the opposite can happen. That is, You may find civil calm with those who seem to agree with your answer there, or more importantly , their description or conclusion as to what is at Play seems to agree with ones own. Provided they are at an agreement as to what the question at hand is asking. and an image of the same aircraft on said Working belt.

that is why these two threads exist. Its an attempt to have a yes and a no answer where everyone can agree.

Concept #1 is Yes and Concept #2 is a No.


Here is what got my attention.
"In all cases the resistance force is only the rolling resistance."
assuming it is just for This Thread, (almost contradicting the "In all cases" part of that statement)

Rolling resistance is not the ONLY force.

This Thread Concept #1 is worded so that the rolling resistance and the Rotational Inertia of the Wheel are Negligible.

But Concept #2 is (supposed to be) worded so that the Rotational Inertia is of a Magnitude sufficient to prevent the Plane reaching any speed >stall speed before it reaches the end of the treadmill runway.

[Montag DP]

That thread of Will's is a work of art. Do you want to know my honest opinion? Will knows beyond a shadow of a doubt that plane will take off his conveyor belt. For being able to pull that thread off, and revive it every once in a while and put forth his 'proofs' with such a straight face, I give Will an "A+".

If you stand 'outside the box' and look in, as an outside observer, on what Will is pulling off over there, you will laugh your butt off.

I love it the way Will thanks people for having the intelligence to know the plane can't take off; even as those same people screw up basic physics that even a 3rd grader would scoff at.

Einstein and Newton themselves could participate in that thread and Will would have them frothing at the mouth within a dozen posts.... :)

ChuckReally? Seems to me like he just keeps repeating the same 2 lines over and over and over and over again without ever qualifying them.

I asked him to back up his statements with physics and he couldn't do it; nay, he didn't even see the reason to do it, so I ended up doing it for him.

[NoFlyZone]

Really? Seems to me like he just keeps repeating the same 2 lines over and over and over and over again without ever qualifying them.

I asked him to back up his statements with physics and he couldn't do it; nay, he didn't even see the reason to do it, so I ended up doing it for him.

Actually, that's exactly my point! Don't you see? The people who realize it will take off can not stop themselves from trying to convince Will that both his logic and science are wrong.

They know beyond a shadow of a doubt that Will will come right back with one or the other of those two lines... and yet they are driven to make him stop the silly repetitions. And the more they try to make him stop, the more he keeps at it. And the more he keeps at it, the more frustrated people become.

It's like the little kid whom says "Why?" to everything you tell him; leading you further and further back in your reasoning to put an end to his incessant "Why" to everything you say. And you actually try to find the ultimate reason, and you KNOW he is just going to once again say "Why?".... yet you keep up the battle until you get mad and yell at the kid.

Will is the winner, and he's playing mind games with everyone.... and yet they still keep trying to make him stop.

Chuck

[lucasavaitor]

This was on mythbusters, and was busted. Obviously, it will take off as the wheels do not move the airplane, the propeller does.

[loadnabox]

This was on mythbusters, and was busted. Obviously, it will take off as the wheels do not move the airplane, the propeller does.


http://www.youtube.com/watch?v=0KsdMuhYJPw


Proves the wheels do not create power/thrust the prop does which is why the wheels only add minimal rotational mass in the take-off roll-out.