[gif] too much front brake and leaves cycle before impact

['73 H1 Triple]

I don't think this ended well for the motorcyclist :tremble:

http://i.imgur.com/rbwUIqv.gif

I hope the bike somehow missed him.

I have no info on this, I found it on another forum.

[Particle Man]

Is that a "Student Driver" sign on the roof?? :td:

[Turbo Ghost]

I don't know what but, something doesn't look right about that. I need a way to slow it down. The physics don't seem correct. I may be wrong but, it wouldn't be the first time!

[Trip]

Thats just a crazy gif. The car wouldn't of been even able to make that turn if the bike didn't hit them. Impressive flipping of the bike.

[Porkchop]

I don't know what but, something doesn't look right about that. I need a way to slow it down. The physics don't seem correct. I may be wrong but, it wouldn't be the first time!

This. I'm not sure how the bike did a complete flip...

[Homeslice]

BS clip. I don't see how the bike would launch off the ground, 2 feet high. Flip, sure, but not launch. What forum was this?

['73 H1 Triple]

BS clip. I don't see how the bike would launch off the ground, 2 feet high. Flip, sure, but not launch. What forum was this?

http://www.thevettebarn.com/forums/off-topic/51964-ouch.html

No explanation, just the gif.


As far as the cycle, could his weight moving forward and then down, alter the center of gravity enough to get that (very bad) result? You do have the front end compressing too.

[fasternyou929]

Oh boy, here we go.

But would it launch if it were on a treadmill?

[Kaneman]

Oh boy, here we go.

But would it launch if it were on a treadmill?

hahahahaha! That's legit.

['73 H1 Triple]

Oh boy, here we go.

But would it launch if it were on a treadmill?

http://img.photobucket.com/albums/v78/JRD77VET/gif/plane-on-belt-animated-1.gif

[Turbo Ghost]

I will say that the impact against the car and the movement of the bike after a verrrry realistic! It's the launch that's the big issue. Physics don't seem to be obeying the laws!

[njchopper87]

I dunno.. it looks like he still had quite a bit of momentum before coming to a stop.. or it could just be the crappy camera.

[dReWpY]

That's ninja skills right there

[Particle Man]

Oh boy, here we go.

But would it launch if it were on a treadmill?

:lol: I remember that conversation

[Homeslice]

:lol: I remember that conversation

If the question is would a plane take off without its engine running, if the treadmill had brought it up to a sufficient speed? The answer is yes, since airspeed is the only thing required to generate lift. However, as soon as the plane starts to lift off the treadmill, it would glide back down, and actually fall back a bit, because the treadmill was the only thing giving it its forward momentum.

[goof2]

If the question is would a plane take off without its engine running, if the treadmill had brought it up to a sufficient speed? The answer is yes, since airspeed is the only thing required to generate lift. However, as soon as the plane starts to lift off the treadmill, it would glide back down, and actually fall back a bit, because the treadmill was the only thing giving it its forward momentum.

Unfortunately that isn't the question. The question comes from the following scenario. A plane is on a "treadmill" trying to take off. This theoretical treadmill accelerates to match the speed of the airplane with the result being the groundspeed of the airplane is 0mph. Will the airplane take off? It is a bullshit question.

[fasternyou929]

Unfortunately that isn't the question. The question comes from the following scenario. A plane is on a "treadmill" trying to take off. This theoretical treadmill accelerates to match the speed of the airplane with the result being the groundspeed of the airplane is 0mph. Will the airplane take off? It is a bullshit question.

Yep - no different than saying "if a plane's brakes were adequate to hold it still and the pilot applied full throttle, would it take off?" Completely implausible, however, change "brakes" to "treadmill" and suddenly it's a raging internet debate with physics experts pouring in from all directions. :lol

[Homeslice]

Unfortunately that isn't the question. The question comes from the following scenario. A plane is on a "treadmill" trying to take off. This theoretical treadmill accelerates to match the speed of the airplane with the result being the groundspeed of the airplane is 0mph. Will the airplane take off? It is a bullshit question.

I don't see why it wouldn't. Doesn't matter WTF the treadmill is doing. As long as the plane has its own motive power (engines) and it reaches sufficient airspeed, it will take off.

[Turbo Ghost]

I don't see why it wouldn't. Doesn't matter WTF the treadmill is doing. As long as the plane has its own motive power (engines) and it reaches sufficient airspeed, it will take off.

That's just it! The plane isn't moving! There IS no airspeed! The only things moving are the treadmill and the wheels which are only rotating. I don't quite think you understand why planes fly. The motor and propeller and wheels have nothing to do with it!

['73 H1 Triple]

That's just it! The plane isn't moving! There IS no airspeed! The only things moving are the treadmill and the wheels which are only rotating. I don't quite think you understand why planes fly. The motor and propeller and wheels have nothing to do with it!

The only difference would be the wheel bearing speed since they are freely rotating and the propeller or jet engine thrust is what actually makes the plane fly.

[goof2]

The thrust of a jet or propeller doesn't make a plane fly, the forward motion that thrust imparts pushes the wings through the air creating lift which leads to flight. Assuming it is possible for a treadmill to move fast enough to create enough friction in the tires, wheel bearings, etc. that the thrust couldn't overcome to create forward movement then the airplane would not take off. It would have to be extremely fast since that would take a hell of a lot of speed to generate that much friction, there couldn't be enough wind to create lift without forward motion, and of course it couldn't be a VTOL aircraft.

['73 H1 Triple]

The thrust of a jet or propeller doesn't make a plane fly, the forward motion that thrust imparts pushes the wings through the air creating lift which leads to flight. Assuming it is possible for a treadmill to move fast enough to create enough friction in the tires, wheel bearings, etc. that the thrust couldn't overcome to create forward movement then the airplane would not take off. It would have to be extremely fast since that would take a hell of a lot of speed to generate that much friction, there couldn't be enough wind to create lift without forward motion, and of course it couldn't be a VTOL aircraft.

I think if the treadmill was moving that fast, just the speed of the tread itself would generate enough wind currents for the plane to lift off of the tread itself.


:lol

~~~~~~~~~~~~~~~~~


So did the biker do a head plant into the car or not? :boobs:

[Turbo Ghost]

Alright, let's try to get this cleared-up.
If I put a treadmill in front of a wall and told you to run on it, would you say "NO! I'll hit the wall!"?? Of course not! Your body would be STATIONARY while running on the treadmill! THIS is the whole basis of the treadmill/plane concept. The propeller DOES NOT make the plane fly! Airflow over the wings is what creates lift. The propeller only moves the plane forward so that air moves over the wings which provides the lift to get the plane airborne. If the plane isn't moving (which it is not because it is on a treadmill!) it has no lift!
If you had a glider which is simply an airplane without a motor and you put a giant fan in front of it that could provide enough airflow for lift, it would lift off the ground BUT, it wouldn't move forward! It has no prop therefore it has no forward motion.
So, here's the bottom-line! If a plane is on a treadmill, it is stationary. A stationary plane does not fly! UNLESS, you perform this test during a tornado or hurricane in which the windspeed surrounding the plane is sufficient to provide lift.

['73 H1 Triple]

Alright, let's try to get this cleared-up.
.

but, but, I had so much fun with this subject before :lol

['73 H1 Triple]

Alright, let's try to get this cleared-up.
If I put a treadmill in front of a wall and told you to run on it, would you say "NO! I'll hit the wall!"?? Of course not! Your body would be STATIONARY while running on the treadmill! THIS is the whole basis of the treadmill/plane concept. The propeller DOES NOT make the plane fly! Airflow over the wings is what creates lift. The propeller only moves the plane forward so that air moves over the wings which provides the lift to get the plane airborne. If the plane isn't moving (which it is not because it is on a treadmill!) it has no lift!
If you had a glider which is simply an airplane without a motor and you put a giant fan in front of it that could provide enough airflow for lift, it would lift off the ground BUT, it wouldn't move forward! It has no prop therefore it has no forward motion.
So, here's the bottom-line! If a plane is on a treadmill, it is stationary. A stationary plane does not fly! UNLESS, you perform this test during a tornado or hurricane in which the windspeed surrounding the plane is sufficient to provide lift.

1) The spinning prop generates forward motion and the wings provide the lift as the air moves over them.
Do you agree?

2) Lets pick a forward speed of 50 mph that generates enough lift for the plane to "have the opportunity to become airborne".
Agree with statement 2?

3) The big treadmill has a belt speed of 60 mph. If they plane had it's brakes applied, it would be moving backwards at 60 mph.

3A) Since the brakes are not applied, the wheel are moving "backwards" at 60 mph. ( let's pretend somebody is at each wingtip holding the plane in place, only to prevent backwards movement ) The pilot applied throttle and the plane moves forward. Once he gets to 50 mph , the wheels are moving the equivilent 110 mph and the plane becomes airborne.

:rockwoot:

edit, added the bold wording for clarity

[Turbo Ghost]

1) The spinning prop generates forward motion and the wings provide the lift as the air moves over them.
Do you agree?

2) Lets pick a forward speed of 50 mph that generates enough lift for the plane to "have the opportunity to become airborne".
Agree with statement 2?

3) The big treadmill has a belt speed of 60 mph. If they plane had it's brakes applied, it would be moving backwards at 60 mph.

3A) Since the brakes are not applied, the wheel are moving "backwards" at 60 mph. ( let's pretend somebody is at each wingtip holding the plane in place) The pilot applied throttle and the plane moves forward. Once he gets to 50 mph , the wheels are moving the equivilent 110 mph and the plane becomes airborne.

:rockwoot:

A spinning prop generates forward motion. HOWEVER, the entire purpose of a treadmill is allow work without forward motion.
In 3A, you contradict yourself. If the wings are being held, the plane is not moving and therefore will not lift. The speed of the wheels is irrelevant.
The whole problem with this entire scenario is the fact the wheels are not driven. Since the prop acts upon air and not the treadmill itself, there is no way to make it work.
As I said before, the purpose of a treadmill is to allow you to remain motionless relative to your surroundings. A motionless plane will not lift.

[Turbo Ghost]

but, but, I had so much fun with this subject before :lol

Physics theories always create great opportunities for Devil's Advocates! You can entertain yourself for days with this stuff!

[Homeslice]

That's just it! The plane isn't moving! There IS no airspeed! The only things moving are the treadmill and the wheels which are only rotating. I don't quite think you understand why planes fly. The motor and propeller and wheels have nothing to do with it!

Actually I have full understanding of what causes lift. Airspeed over a wing surface. That's all. What a treadmill is or isn't doing doesn't mean jack shit, as long as the airspeed is sufficient.

However, once a plane takes off, it WILL need engines to STAY aloft. That's all I was saying.

[Homeslice]

If you had a glider which is simply an airplane without a motor and you put a giant fan in front of it that could provide enough airflow for lift, it would lift off the ground BUT, it wouldn't move forward! It has no prop therefore it has no forward motion.

Not only that, but it would get pushed backwards as soon as it lifts off. And then sink back down to earth.

['73 H1 Triple]

A spinning prop generates forward motion. HOWEVER, the entire purpose of a treadmill is allow work without forward motion.
In 3A, you contradict yourself. If the wings are being held, the plane is not moving and therefore will not lift. The speed of the wheels is irrelevant.
The whole problem with this entire scenario is the fact the wheels are not driven. Since the prop acts upon air and not the treadmill itself, there is no way to make it work.
As I said before, the purpose of a treadmill is to allow you to remain motionless relative to your surroundings. A motionless plane will not lift.

I didn't word it perfectly ( my error/mistake ) but what I inferred was the wings were being held only to prevent backwards movement. ( correction/edit added )

Therefore, the the spinning prop would generate the forward momentum needed to achieve takeoff after the required lift was generated.

All the treadmill would do is spin the wheels. The only "extra" would be addition bearing RPM from the wheels being on the treadmill.

~~~~~~~~~~~~~~~~~~

Maybe your looking at this from a different prespective than I am. See the "Myth Busters" episode on this? That's what I "see". A normal plane and a movable "runway" under the wheels. The prop generates enough forward speed to achieve takeoff regardless of the wheel speed.

Physics theories always create great opportunities for Devil's Advocates! You can entertain yourself for days with this stuff!

:iagree: :cheers:

[goof2]

3A) Since the brakes are not applied, the wheel are moving "backwards" at 60 mph. ( let's pretend somebody is at each wingtip holding the plane in place, only to prevent backwards movement ) The pilot applied throttle and the plane moves forward. Once he gets to 50 mph , the wheels are moving the equivilent 110 mph and the plane becomes airborne.

Actually I have full understanding of what causes lift. Airspeed over a wing surface. That's all. What a treadmill is or isn't doing doesn't mean jack shit.


All the treadmill would do is spin the wheels. The only "extra" would be addition bearing RPM from the wheels being on the treadmill.

~~~~~~~~~~~~~~~~~~

Maybe your looking at this from a different prespective than I am. See the "Myth Busters" episode on this? That's what I "see". A normal plane and a movable "runway" under the wheels. The prop generates enough forward speed to achieve takeoff regardless of the wheel speed.

You are both ignoring one of the central premises of the question, that the treadmill is able to prevent the forward motion you both know is required for flight. No the treadmill does not directly act on the source of the airplane's source of motive power, the propeller or jet. That doesn't mean the treadmill isn't creating friction/drag on the airplane. Maintain that part of the question and assume the treadmill can attain a sufficient speed so the friction/drag it imparts on the airplane through the tires, wheel bearings, etc. is enough to counteract the effect of the propeller or jet and keep the aircraft from moving. If that is the case, and the air remains still, then the airplane will not take off.

The speed of the wheels is irrelevant.
The whole problem with this entire scenario is the fact the wheels are not driven. Since the prop acts upon air and not the treadmill itself, there is no way to make it work.
As I said before, the purpose of a treadmill is to allow you to remain motionless relative to your surroundings. A motionless plane will not lift.

Making it work is why it is a bullshit question. The treadmill would need to be rotating at hundreds, if not thousands, of mph in order to generate enough friction to counteract the effect of the propeller or jet to prevent motion. Even if that could be done the tires would explode or the wheel bearings would melt in very short order likely resulting in a spectacular crash.

Physically possible? Probably not. If we ignore that and accept the premise of the question though, the airplane will not take off.

[Papa_Complex]

The plane isn't moving forward by driving its wheels, so the conveyor belt/treadmill is meaningless. It would have to move so quickly that the drag caused by friction in the wheels' bearings would be enough to match the energy put into forward movement.

http://www.youtube.com/watch?v=01Q83yxdDaI

[Homeslice]

You are both ignoring one of the central premises of the question, that the treadmill is able to prevent the forward motion you both know is required for flight. No the treadmill does not directly act on the source of the airplane's source of motive power, the propeller or jet. That doesn't mean the treadmill isn't creating friction/drag on the airplane. Maintain that part of the question and assume the treadmill can attain a sufficient speed so the friction/drag it imparts on the airplane through the tires, wheel bearings, etc. is enough to counteract the effect of the propeller or jet and keep the aircraft from moving. If that is the case, and the air remains still, then the airplane will not take off.



If the treadmill was actually powerful enough to prevent the plane from achieving takeoff velocity, then it would not take off, and the wheel bearings would melt as you suggest. However, an example was made earlier of a giant fan blowing at it, in which case the wing surfaces could see sufficient airspeed to take off, regardless of what the treadmill, bearings etc. are doing.

[fasternyou929]

http://blog.xkcd.com/2008/09/09/the-goddamn-airplane-on-the-goddamn-treadmill/
:lol

[fatbuckRTO]

http://blog.xkcd.com/2008/09/09/the-goddamn-airplane-on-the-goddamn-treadmill/
:lol

Lol. Goof2 and I are clearly "JetBlue scenario" types. That kind of thinking made you unpopular at CF:

http://www.cycleforums.com/forums/showthread.php?t=287810

But dammit, that's what the wording of this so-called "thought problem" implies. My favorite was when I was told my answer to a question about a plane on a giant treadmill was unrealistic...



Rofl at "pterosaurs for stability"... :lol

[goof2]

If the treadmill was actually powerful enough to prevent the plane from achieving takeoff velocity, then it would not take off, and the wheel bearings would melt as you suggest. However, an example was made earlier of a giant fan blowing at it, in which case the wing surfaces could see sufficient airspeed to take off, regardless of what the treadmill, bearings etc. are doing.

Sure, with the treadmill scenario on its own the plane cannot accelerate relative to the ground. Assuming still air it will not take off. If you move the air with enough speed toward the plane (and in the right direction) it will take off regardless of ground speed.

[goof2]

Lol. Goof2 and I are clearly "JetBlue scenario" types. That kind of thinking made you unpopular at CF:

http://www.cycleforums.com/forums/showthread.php?t=287810

But dammit, that's what the wording of this so-called "thought problem" implies. My favorite was when I was told my answer to a question about a plane on a giant treadmill was unrealistic...



Rofl at "pterosaurs for stability"... :lol

Yep, JetBlue for sure!

I had forgotten about the frictionless wheels part. That kind of changes things for me and I suspect explains why I never got deep in to the thread on CF. The treadmill always matching the speed and the frictionless wheels/tires are mutually exclusive. You can have one or the other, but both to me isn't worth thinking about.