Riddle Me This......... - Page 7

flappist · 30-11-2005, 07:48 PM

The conveyor's only contact with the aircraft is via the wheels.
The thrust is developed relative to the air not the ground.
What the ground is doing is irrelevent as all that happens is the wheels spin faster.
As the air is stationary and the aircraft develops accelleration relative to it because although the conveyor is going flat out in the opposite direction it just turns the wheels faster it does not slow the aircraft because although it is trying to push the aircraft in the other direction it is acting on the bottom of the wheels NOT the axles.
The aircraft's engines are creating thrust on the whole whole aircraft and the opposing force is only on a moving surface that is rotating around a fixed point on the aircraft.

ALL of the force from the conveyor does is spin the wheels

What is so difficult about understanding this ?

JAJH · 30-11-2005, 07:54 PM

All you guys have really talked about is the conveyor and is relation to the plane. Not one of you have convinced me or the other doubting Thomases how you overcome the 'non-existence' of lift. Please explain this because my head hurts.

30-11-2005, 07:57 PM

Ok, long time member, but this is my first post on this forum (what a way to start!)

Firstly, the person on a treadmill analogy is useless, as propulsion is provided by means of friction between the soles of the feet and the treadmill, whereas a plane generates it's propulsion by the movement of air particles which creates it's forward thrust. If you must use the person on a treadmill analogy, think of it this way: You are standing on a treadmill in a pair of roller skates (in the same way the plane is sitting on the conveyor on it's own set of roller skates (wheels)). The treadmill moves backwards at the same speed as you move forwards. Now the treadmill has built up some speed and you are standing motionless in the same spot, with the wheels of your roller skates spinning at the same speed as the treadmill. A helpful person now comes along and pushes you forward on the treadmill. Are you going to move forward relative to the ground? Of course! As even if the speed of the treadmill increases, the only difference to you will be the speed that the wheels on your skates are spinning. You are being propelled by a source that does not require friction with the treadmill to move you, and therefore no matter what speed the treadmill (and therefore your skates) are spinning, you can still be moved by an outside force. Now rather than somebody pushing you, say that you have a huge fan in your hands, which you turn on, are you still going to move forwards on the treadmill? Again, of course you are, so what is the difference between somebody standing on a treadmill in rollerskates holding a fan, and a plane on a conveyor belt?

But back to the plane of the conveyor. Think of it this way - If the plane was sitting on the conveyor and held in place by a strap to a pole on each side of the conveyor, and the conveyor started turning, would the plane not remain motionless with it's wheels solely spinning at the speed of the conveyor? Now that is using an outside means to maintain it's position, what makes you think it cannot use another outside means (it's engines) to propel itself along the conveyor, with the only difference to a normal take-off being that the wheels are spinning at twice the speed.

The ONLY difference to a normal take off is the fact the the wheels are spinning twice as fast as they normally would be. Considering the fact that these wheels have no driving components attatched to them, they ONLY spin freely, the plane simply has to overcome twice the bearing friction that it would on a normal takeoff. Now considering the force available from it's engines, and the relativley tiny amount of friction from the bearings in a plane wheel, bearing friction becomes negligible, and there is no difference to that of a normal takeoff.

Cheers
Tom.

30-11-2005, 08:04 PM

Quote:

Originally Posted by JAJH

All you guys have really talked about is the conveyor and is relation to the plane. Not one of you have convinced me or the other doubting Thomases how you overcome the 'non-existence' of lift. Please explain this because my head hurts.

Lift is generated when the wings of the plane pass through the air at speed, agreed? I'm not sure if this is the way you are still thinking, but if you are still trying to picture it as the plane taking off relatively motionless to it's surroundings, you have the wrong idea.

It is still going to be moving forward relative to the ground and the rest of its surroundings (conveyor included) and therefore it will reach the speed required to generate lift.

Once again, the ONLY difference to a normal take-off is that the wheels of the plane will be spinning at twice the forwards velocity of the plane, the instant it lifts off the conveyor. It's not trying to take off motionless. If you were standing beside the conveyor watching it take off, it would still be moving as quick as usual, with the ONLY difference being the wheels spinning twice the speed they usually would!

FordFan86 · 30-11-2005, 08:07 PM

Ok. Let's all pool together. Buy ourselves a nice shiny tea-pot airburshed 747 and a huuuge treadmill. End this once and for all.

xdclevo · 30-11-2005, 08:08 PM

What sort of plane??
The engines are used only to get the plane to enough actual speed for the airspeed to lift the plane. Like every other SMART person said, the plane would NOT lift up, or there would be no need for runways or damn WINGS on the plane. You guys crack me up, but why on earth i read any of this stuff is beyond me. Especially all the real pilots that said it would lift. Yous crack me up the most.
(if you say YES, you are saying is a plane doesn't need wings to fly)

the_scotsman · 30-11-2005, 08:08 PM

JEEEEEEEEEEEEEEEEEEEEEEZ!!

I read the first 2 pages them came to the last page to reply....

What is so difficult to understand....IT WILL FLY!!!

CASPER summed it up perfectly with the skateboard analogy!

The wheels have NOTHING to do with it, they dont drive the plane forward...when the plane is first started...sure it wont move, but as thrust develops, the plane will be pulled forward THROUGH THE AIR...and will then of course speed up until enough lift is generated the same as any other take off and fly!

DAMN what a frustrating thread!

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xdclevo · 30-11-2005, 08:11 PM

Quote:

Originally Posted by the_scotsman

...sure it wont move, but as thrust develops, the plane will be pulled forward THROUGH THE AIR...and will then of course speed up until enough lift is generated the same as any other take off and fly!

DAMN what a frustrating thread!

:

What air will the plane be pulled through. The plane is STILL and the air is STILL. There is no air/plane moving anywhere.

Perana · 30-11-2005, 08:12 PM

Damn....

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the_scotsman · 30-11-2005, 08:13 PM

WHY????

What Air???

The air will be still for an instant, but as the thrust pulls the PLANE FORWARD, AIR WILL FLOW OVER THE WINGS.....I honestly can't see whats so difficult to understand.....

30-11-2005, 08:14 PM

Quote:

Originally Posted by xdclevo

What air will the plane be pulled through. The plane is STILL and the air is STILL. There is no air/plane moving anywhere.

Care to explain how the plane could possibly be still?

Casper · 30-11-2005, 08:17 PM

Ok, I’ll try to explain this one more time as simple as I can using some examples.

Lets take the original scenario to start with but at a simple element of another plane on a normal runway connected via a tow rope to the first plane. For the sake of argument the first plane will have its engine off.
The Conveyor is still under the original plane and is still operational The tow plane is on a normal runway.
Now, the towplane starts its engine and moves forward.. the slack on the rope goes.. what’s going to happen to the plane on the conveyor? Of course.. it starts to move. The conveyor senses this and goes the same speed in reverse. Is this going to stop the plane from being towed forward? No. Why? Because it is being pulled by a force external to the conveyor and, as the conveyors reverse direction is only effecting the (free spinning) wheels, the plane is towed forward regardless of the conveyor and takes off behind the tow plane.
Does this make sense to everyone?

Ok. Now. Lets look at the towplane itself. What caused it to move forward and take off (with the conveyor plane behind it). Was it because it put power through its wheels? No. Its wheels were just there to hold it off the ground. It created “thrust” via its propeller. This thrust didn’t actually cause lift, it caused forward motion.. the motion caused lift. This is how planes work. The ground itself had NOTHING to do with the plane moving forward. It was just there. The thrust moved it forward fast enough to create lift in the wings.

So, we have a tow plane making thrust.. which makes forward motion.. which makes it move and eventually take off. At the same time, because it was tied to the tow plane, the original plane also moved forward.. regardless of the conveyor matching its forward speed with a reverse direction.. and it also took off.
Everyone agree still?

Right. Ok.

Now, lets put the same engine “thrust” into the original plane that made the tow plane take off.. and cut the rope. Same thrust, same atmosphere around it… same conveyer. Guess what.. the plane will move forward under the same thrust, regardless of what the ground is doing under it free spinning its wheels.

the_scotsman · 30-11-2005, 08:21 PM

CASPER has made it as simple as it can get!

The ground (or conveyor belt) is IRRELEVANT......it could be going a million miles an hour, the plane would still take off...think about it ffs!

Your thinking about a car, where it would NOT (fly) or move forward...

flappist · 30-11-2005, 08:29 PM

Quote:

Originally Posted by xdclevo

What sort of plane??
The engines are used only to get the plane to enough actual speed for the airspeed to lift the plane. Like every other SMART person said, the plane would NOT lift up, or there would be no need for runways or damn WINGS on the plane. You guys crack me up, but why on earth i read any of this stuff is beyond me. Especially all the real pilots that said it would lift. Yous crack me up the most.
(if you say YES, you are saying is a plane doesn't need wings to fly)

Planes that fly without wings....

ME 163, Bell X15, ALL helicopters, Bell VTOL, Osprey, Moller Skycar....... need I go on.

If you are such a SMART person you would know that you will make a fool of yourself if you ask a SMART question that you do not know the answer to......

But then maybe you are just not SMART enough to actually comprehend the issue.

Mark351 · 30-11-2005, 08:45 PM

This is a question for those who do believe it will take off as I do, yet somehow belive the plane's wheels spin twice the speed of the conveyor belt.

Please tell me how this is humanly possible?

If the plane's wheels are purely a mechanism to allow the plane to move under it's engines thrust, how does a conveyor belt travelling at 200kph make it's wheels travel 400kph when the plane's wheels have no bearing on it's own air speed?

Casper · 30-11-2005, 08:54 PM

Quote:

Originally Posted by DeathXR

This is a question for those who do believe it will take off as I do, yet somehow belive the plane's wheels spin twice the speed of the conveyor belt.

Please tell me how this is humanly possible?

If the plane's wheels are purely a mechanism to allow the plane to move under it's engines thrust, how does a conveyor belt travelling at 200kph make it's wheels travel 400kph when the plane's wheels have no bearing on it's own air speed?

convayor moving 200mph in reverse, plane moving 200mph forward. Even though the plane is only travelling 200mph forward the combined speed of the plane going forward and the convayor going backwards is 400mph.

Think like 2 cars travelling at each other at 100mph each. Even though the car is only doing 100mph the impact when they both hit each other head on is 200mph because you have to add the speed of both cars.

zetec · 30-11-2005, 08:55 PM

Quote:

Originally Posted by DeathXR

This is a question for those who do believe it will take off as I do, yet somehow belive the plane's wheels spin twice the speed of the conveyor belt.

Please tell me how this is humanly possible?

If the plane's wheels are purely a mechanism to allow the plane to move under it's engines thrust, how does a conveyor belt travelling at 200kph make it's wheels travel 400kph when the plane's wheels have no bearing on it's own air speed?

Because if the plane is moving at 200km/h the wheels on a solid runway would be turning at 200km/h. The conveyoer is stated as moving at the same speed in reverse, so 200km/h backwards - thus the wheels are effectively moving 400km/h.

flappist · 30-11-2005, 08:56 PM

Quote:

Originally Posted by DeathXR

This is a question for those who do believe it will take off as I do, yet somehow belive the plane's wheels spin twice the speed of the conveyor belt.

Please tell me how this is humanly possible?

If the plane's wheels are purely a mechanism to allow the plane to move under it's engines thrust, how does a conveyor belt travelling at 200kph make it's wheels travel 400kph when the plane's wheels have no bearing on it's own air speed?

Because the plane is travelling at 200km/h relative to the air, ground around the conveyer, people watching, a teapot in a tree next to the conveyor and 400km/h relative to the conveyor top surface.

As the only bit of the plane that touches the conveyer is the outside edge of the wheels they are doing 400km/h, the axels are doing 200km/h.

The wheels are there to reduce friction, the same as a skateboad......

The plane is moving, not stationary.....

Remember, when you are driving along at 100km/h the bottom of your tyres are always stationary (except during burnouts) and the top are doing 200km/h

Casper · 30-11-2005, 08:59 PM

I'll make this riddle REALLY simple.

Take 1 sidewinder missle. Strap it to a skateboard. Place on the conveyor. Light fuse.

Do you REALLY think when that baby goes off it will sit in one spot and not disappear into the horizon... regardless of how fast the conveyor is going in reverse?
Dont think so. Its Goooooooooooooone.

Why? Cause its creating thrust to push it forward and it doesnt give a hoot what speed the conveyor is going because the skateboard is only there to hold it off the ground.

Same principle as the plane only MUCH more powerful. (Something I'd love to see too!)

Want to use the same principle? Strap said sidewinder to the light plane on the conveyor and light fuse. GOOOOOOOOOONE

JAJH · 30-11-2005, 09:05 PM

Look, you believers are still in LA LA land. There is no relation to the conveyor whatsoever...agreed? Put it another way, if a plane was stationary on a normal concrete runway with the engine off - no thrust, no conveyor and a gale force wind came along, do you think it possible the plane (assuming it is a small focker) could be flipped over. Why, because the force of air over the wings (albeit turbulent) has created lift. Thrust and every other variable you lot are throwing around is not relevant.

Perana · 30-11-2005, 09:07 PM

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Casper · 30-11-2005, 09:12 PM

Quote:

Originally Posted by JAJH

Look, you believers are still in LA LA land. There is no relation to the conveyor whatsoever...agreed? Put it another way, if a plane was stationary on a normal concrete runway with the engine off - no thrust, no conveyor and a gale force wind came along, do you think it possible the plane (assuming it is a small focker) could be flipped over. Why, because the force of air over the wings (albeit turbulent) has created lift. Thrust and every other variable you lot are throwing around is not relevant.

Thrust is critical.. thats what moves a plane forward. Without thrust you dont go forward.. even on a normal runway. The whole point of a planes engine (be it prop driven, jet or rocket) is to produce thrust. The point is that this thrust is generated by forcing air backwards into the atmosphere.. forcing the plane forward. Newtons law. Every action has an equal and opposite reaction. In the riddles case the action of a planes engine creating thrust is to move it forward. The action of the conveyor going (any speed in reverse) only has a reaction of spinning the planes wheels. Since no plane takes off by powering its wheels.. this conveyors actions are simply lost on the overall situation. The thrust from the engine is still going to move it forward and its going to take off.

DOC · 30-11-2005, 09:15 PM

Quote:

Originally Posted by Casper

The thrust from the engine is still going to move it forward and its going to take off.

If the thrust on a plane was to say move it forward at 10KPH, then you placed it onto a treadmill running at 10KPH in the opposite direction ( relative speed as in the Q ) would the plane move ?

Casper · 30-11-2005, 09:18 PM

Quote:

Originally Posted by DOC

If the thrust on a plane was to say move it forward at 10KPH, then you placed it onto a treadmill running at 10KPH in the opposite direction ( relative speed as in the Q ) would the plane move ?

yes. It would move at 10kph. What the conveyor would do is simply make the wheels (which have no drive and are only to keep the plane off the ground and able to roll) spin at 20kph. 10kph for the planes movement forward.. 10kph for the conveyors movement in reverse.. 20kph.

jabba · 30-11-2005, 09:20 PM

Quote:

Originally Posted by DOC

If the thrust on a plane was to say move it forward at 10KPH, then you placed it onto a treadmill running at 10KPH in the opposite direction ( relative speed as in the Q ) would the plane move ?

That would depend on how much force it would take to get the wheels rolling. So I would say yes the plane will move foward, but a a lesser speed then 10KPH

FordFan86 · 30-11-2005, 09:20 PM

I think I actually see the light now!

Casper · 30-11-2005, 09:27 PM

Ok, just to really prove something here, lets use some logic Darkhorse said to me in MSN

What would happen if a plane was coming into land on this conveyor. Plane is traveling at 200mph, conveyer is traveling at 200mph in reverse. What would happen when it touched down?

Based on the logic that the plane won’t take off .. it would be like it hitting a brick wall.

Sorry guys, it would touch down, the wheels (being non powered) would simply accept a combined speed (plane 200mph, conveyor 200mph) of 400mph and the plane would land safely.

Hell, if the conveyor was going forward 200mph and the plane was doing 200mph the wheels would touch, not rotate at all, and the plane would land safely.

Why? Cause the planes wheels have nothing to do with the planes ability to take off or land apart from allowing it to roll.

clontarf_x · 30-11-2005, 09:29 PM

why the hell would you post something like that on here :(
it made my brain tingle

xdclevo · 30-11-2005, 09:43 PM

I have changed my mind after reading the question properly. Like many others, i assumed the plane was standing still, while the conveyer and wheels were doing the moving. Ofcoarse, when the plane gets up enough speed, the air/wings do there usual thing and create flight, irrellavant or what the (trick question) conveyer is doing.

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the_scotsman · 30-11-2005, 09:44 PM

This is the most annoying and frustrating thread ever....

I SIMPLY CANNOT BELIEVE YOU GUYS ARE FOR REAL!!!!!

Casper has spoon fed you guys....the rocket on the skateboard....its there in black and white!!!!!!!