The conveyor belt myth - poll

Will the airplane on the conveyor belt take off?

  • Yes

    Votes: 56 80.0%

  • No

    Votes: 14 20.0%
  • Total voters
    70
gkainz

gkainz

Final Approach
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Greg Kainz
Ok, no fights, no arguments, no postulating, speculating, pontificating, or breast beating ... simply vote Yes or No.

Will the airplane on the conveyor belt take off?
 
gkainz said:
Ok, no fights, no arguments, no postulating, speculating, pontificating, or breast beating ... simply vote Yes or No.

Will the airplane on the conveyor belt take off?
Click to expand...

That is not the point. The point is why will it take off.

Back when it was on the red board there were guys that believed it would take off then explained it wrong.

Dan
 
Is the conveyor belt the hangar flying equivalent of playing "Stairway to Heaven" at a guitar store? Do we need to have a bouncer that will beat anyone who brings up the topic?
 
gkainz said:
Ok, no fights, no arguments, no postulating, speculating, pontificating, or breast beating ... simply vote Yes or No.

Will the airplane on the conveyor belt take off?
Click to expand...

Post the full question. Not that I don't know the arguments, I think the reason for the division is semantics and not a misunderstanding of aerodynamic principles.
 
jwriteclub said:
I loved the video, and yes, we need a bouncer.
Click to expand...

I worked as a bouncer for part of a summer. Funny thing is, the guys are more scared when you're not 6-8 350, because you know they are thinking "Holy &%*$! What does this guy know that HE'S working as a bouncer?"
 
Voted yes, but it depends on which assumptions you make.

Assuming frictionless bearings in the wheels, then yes.

Assuming perfect treadmill, but real world wheels, then no.
 
Pi1otguy said:
Voted yes, but it depends on which assumptions you make.

Assuming frictionless bearings in the wheels, then yes.

Assuming perfect treadmill, but real world wheels, then no.
Click to expand...

*sigh*

The the total coefficient of fricton of wheels is probably somewhere around 0.01. What does this mean in the real world? If the plane were to sit on the conveyor belt with the engine off, and the conveyor belt were turned on, the wheels would spin at 100mph, but the plane would only move in whichever the direction the conveyor is moving at about 1mph.

Think about that for a second.
 
This THREAD is on a conveyor belt. And mark my words, it will take off.

*groan*
*sigh*
*yawn*
*oh brother*:rolleyes:
 
The video was awesome.

Everyone should be required to take a physics course in kinematics and one in EM in college. Period. So many otherwise well educated people are really quite ignorant in these topics.

~ Christopher
 
stingray said:
That is not the point. The point is why will it take off.

Dan
Click to expand...

Airplanes take off because the lift on the wings exceed the force of gravity on the airplane. Ground School 101.

Lift is created by air passing over the wing. Which is effected by the shape of the wing (think about flaps), angle of attack (Think rotate to climb pitch attitude) and speed of the wing through the air (Think Vr, Vx, Vy).

The only other effect at low altitude is Ground effect which is based on Wing generating lift and proximity to the ground.

The conveyor belt is nothing more than a a land based version of a float plane on river and how the current effects it's take off.

1) Can I setup the conditions so that an airplane on a conveyor will take off? Yes

2) So the answer to the question in the post is Yes? No, I can also setup the conditions so an airplane on a conveyor belt cannot take off.

3) So the answer to the question in the post is No? No, see question 1.

Replace the word conveyor with runway there is still no answer. Think Density altitude.

This is making my head hurt:dunno:
 
EdFred said:
I worked as a bouncer for part of a summer. Funny thing is, the guys are more scared when you're not 6-8 350, because you know they are thinking "Holy &%*$! What does this guy know that HE'S working as a bouncer?"
Click to expand...

Ron White: "I don't know how many of them it would have taken to kick my a*, but I know how many they were gonna use."
 
RMCN172RG said:
Airplanes take off because the lift on the wings exceed the force of gravity on the airplane. Ground School 101.

Lift is created by air passing over the wing. Which is effected by the shape of the wing (think about flaps), angle of attack (Think rotate to climb pitch attitude) and speed of the wing through the air (Think Vr, Vx, Vy).

The only other effect at low altitude is Ground effect which is based on Wing generating lift and proximity to the ground.

The conveyor belt is nothing more than a a land based version of a float plane on river and how the current effects it's take off.

1) Can I setup the conditions so that an airplane on a conveyor will take off? Yes

2) So the answer to the question in the post is Yes? No, I can also setup the conditions so an airplane on a conveyor belt cannot take off.

3) So the answer to the question in the post is No? No, see question 1.

Replace the word conveyor with runway there is still no answer. Think Density altitude.

This is making my head hurt:dunno:
Click to expand...

And any conditions you set up will never have anything to do with the conveyor belt. You proved that with ground school 101. The conveyor belt has no bearing on whether the plane will take off. If you want to compare a float plane then it has to be designed with a special float that has very little friction (Hydrofoil) or is already up on step, (then it does not matter anyway, the faster the current the faster and higher you will be on step). Airplanes take off because the lift on the wings exceed the force of gravity on the airplane. Ground School 101. The only way that the belt can counter act this is if you bolt the plane to the belt. (ie forget to untie it from the tie down). Even then I have heard of planes taking off with the tie down tires still attached.

Dan
 
EdFred said:
*sigh*

The the total coefficient of fricton of wheels is probably somewhere around 0.01. What does this mean in the real world?
Click to expand...

Its not about whether the plane moves, but that the wheels will overheat and explode sending FOD through the wings and greatly increasing the friction by forcing the airplane to slide on the wheel-less gear.

But I believe the plane will move.
 
Pi1otguy said:
Its not about whether the plane moves, but that the wheels will overheat and explode sending FOD through the wings and greatly increasing the friction by forcing the airplane to slide on the wheel-less gear.

But I believe the plane will move.
Click to expand...

If the wheels are rated to 120kts on a PA28 or C172, it will take off without the expldoing wheels. I can get either plane off the ground <60kts.
 
gprellwitz said:
Alright, Kate, HOW did you find that! It was perfect!:rofl::yes: Of course, how they managed to keep from breaking their legs doing that, I don't know! (Or just breaking into flight! :rofl::rofl::rofl:)
Click to expand...

I'm not sure where I first heard of the video, but I remember it being in a story on TV about the year's most popular YouTube videos.

Still makes me laugh when I associate it with this thread.
 
There is no choice for me. I say it won't take of nor will it stay on the conveyor belt. I say the pilot's reaction will be too slow to keep up with the conveyor speed fluctuations and that the plane will be thrown backwards and become a crumpled heap just off of the arrival end of the runway. ;)
 
gkainz said:
Ok, no fights, no arguments, no postulating, speculating, pontificating, or breast beating ... simply vote Yes or No.

Will the airplane on the conveyor belt take off?
Click to expand...


Points deducted for explanations, qualifications or any other "showing your work" ... ok, I should have added
  • Don't Know
  • Don't Care
to the poll choices ... except the poll doesn't allow an "and/or" qualifier
 
gkainz said:
Points deducted for explanations, qualifications or any other "showing your work" ... ok, I should have added
  • Don't Know
  • Don't Care
to the poll choices ... except the poll doesn't allow an "and/or" qualifier
Click to expand...

I would vote here, I really don't think I am going to be taking off from or landing on a conveyor belt anytime soon.:D Its kind of like the question, Which came first, the chicken or the egg? you cares, they're both good to eat!
 
Pi1otguy said:
Its not about whether the plane moves, but that the wheels will overheat and explode sending FOD through the wings and greatly increasing the friction by forcing the airplane to slide on the wheel-less gear.

But I believe the plane will move.
Click to expand...

How are the wheels going to overheat? A ragwing stork is off the ground in 30' that's 2 maybe 3 sec. You need a better argument or more proof that you can ignite a tire in less than 10 sec even for a standard airplane.

Dan
 
I wonder if the FAA saw this poll and the answers then decided to put it on the PPL test and have it count towards 50% of the total score. I bet everyone would get it right then, or everyone that should be a pilot anyway.:)

Dan
 
Well, it appears we have moved from the conveyor debacle to not understanding what tire limit speed is and the effect it has on takeoff planning.
 
AWACSEng said:
Well, it appears we have moved from the conveyor debacle to not understanding what tire limit speed is and the effect it has on takeoff planning.
Click to expand...

Which would be different on each plane would it not. If someone could design a conveyor belt to go fast enough to match a tire speed in reverse instantly then someone could also design a tire that could hold together under the same conditions.

Dan
 
Dan, you are correct. TLS is different for every model of tire. To me it appears that folks are not seeing that the speed in which the tire rotates is double that it normally is on takeoff. This fact could put a damper on the whole using a conveyor for takeoff thing. Before anyone loses thier mind, I understand the original question was merely would the airplane take off, not anything else. I'm just saying that if the numbers don't check, TLS could be exceeded just in the experiment, causing a catostrophic failure. I have no idea what TLS is for a light single, so it may not even be a factor. I'm looking at this from a heavy point of veiw and if one doubles the tire speed normally seen at rotate speed, the tires would no doubt fail. Hope that all makes sense.
 
AWACSEng said:
Dan, you are correct. TLS is different for every model of tire. To me it appears that folks are not seeing that the speed in which the tire rotates is double that it normally is on takeoff. This fact could put a damper on the whole using a conveyor for takeoff thing. Before anyone loses thier mind, I understand the original question was merely would the airplane take off, not anything else. I'm just saying that if the numbers don't check, TLS could be exceeded just in the experiment, causing a catostrophic failure. I have no idea what TLS is for a light single, so it may not even be a factor. I'm looking at this from a heavy point of veiw and if one doubles the tire speed normally seen at rotate speed, the tires would no doubt fail. Hope that all makes sense.
Click to expand...

This would all be true but if they are going to start redoing the question and giving the belt some kind of steroids no reason I cannot give my tires some extra help. I'm going with steel wheels with space age Teflon type bearings special made for this experiment. Actually I will just leave the tires off and use Teflon skid plates that inject water under them. What's fair is fair. Soft field takeoff vs no flaps coming in a little hot. (tires doing twice the speed). No big deal

Dan

Dan
 
AWACSEng said:
Well, it appears we have moved from the conveyor debacle to not understanding what tire limit speed is and the effect it has on takeoff planning.
Click to expand...


I understand quite well what tire limit speed is, I just don't know if the particular tire on the particular plane will be able to hold up. Big difference between a light bush plane with 8 plys that unsicks at 25 and a high performance plane with 4 plys that unsticks at 80. Thats why automotive tires have speed ratings lik P,V & Z.
 
I would be more worried about the bearings. Those babies are going to be getting hot very quickly with the tire speeds we are talking about. The bearing grease will run out and in no time at all the bearing surfaces will be unlubricated long before the tires hit their speed limits.
 
smigaldi said:
I would be more worried about the bearings. Those babies are going to be getting hot very quickly with the tire speeds we are talking about. The bearing grease will run out and in no time at all the bearing surfaces will be unlubricated long before the tires hit their speed limits.
Click to expand...

No they won't.
 
Not in a couple of seconds. Plus, you are slowly spinning the wheels up, not sticking a landing.

Even in a heavy jet, I doubt that the tires will actually rupture before you get airborne, and certainly not in a light single.

Besides, as Dan pointed out, the question is, will the plane fly, not will the tires pop before the plane flys.

~ Christopher
 
smigaldi said:
I would be more worried about the bearings. Those babies are going to be getting hot very quickly with the tire speeds we are talking about. The bearing grease will run out and in no time at all the bearing surfaces will be unlubricated long before the tires hit their speed limits.
Click to expand...


Nope, that's not a worry, we use the same bearings on much higher speed industrial applications. The bearings are a very small diameter and travel at relatively low speeds.
 
Dean said:
I would vote here, I really don't think I am going to be taking off from or landing on a conveyor belt anytime soon.:D Its kind of like the question, Which came first, the chicken or the egg? you cares, they're both good to eat!
Click to expand...

Yeah, but which one do you eat first? :rofl:
 
jwriteclub said:
Not in a couple of seconds. Plus, you are slowly spinning the wheels up, not sticking a landing.

Even in a heavy jet, I doubt that the tires will actually rupture before you get airborne, and certainly not in a light single.

Besides, as Dan pointed out, the question is, will the plane fly, not will the tires pop before the plane flys.

~ Christopher
Click to expand...

No, the question as it originated long ago was "Can the plane take off from a conveyor belt?" tire explosion could very well effect that. As far as aerodynamics & power transfer, of course it can. Now, what happens when you put the plane and conveyorbelt in a downwing wind tunnel....
 
What does wheel speed have to do with flying?

I say you need relative wind to fly.

With a plane on a belt with a belt doing 5000 MPH, and the planes wheels are doing 5000 MPH to stay in the same spot, there is no relative wind except for prop wash.

A maule might almost take off, a C-172 will not.

To see if the test type plane will take off, try the same plane with no wheels attatched just sitting on the bare gear.

Sit the bare gear on cement, add full power & the test is about the same.

An F-16 might take off, Sean Tuckers plane might take off, a 172 will not.
 
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