• Please make sure you are familiar with the forum rules. You can find them here: https://forums.tripwireinteractive.com/index.php?threads/forum-rules.2334636/
  • Weve updated the Tripwire Privacy Notice under our Policies to be clearer about our use of customer information to come in line with the EU General Data Protection Regulation (GDPR) rules that come into force today (25th May 2018). The following are highlights of our changes:


    We've incorporated the relevant concepts from the GDPR including joining the EU and Swiss Privacy Shield framework. We've added explanations for why and how Tripwire processes customer data and the types of data that we process, as well as information about your data protection rights.



    For more information about our privacy practices, please review the new Privacy Policy found here: https://tripwireinteractive.com/#/privacy-notice

Plane Problem

Status
Not open for further replies.

melipone

FNG / Fresh Meat
Mar 22, 2006
1,672
259
0
Can we point and laugh :D joking. It was a good question..had us all thinking :) We should start a puzzle thread just for things like this
 

Nestor Makhno

FNG / Fresh Meat
Feb 25, 2006
5,758
1,118
0
55
Penryn, Cornwall
Oh yeah, more of these :rolleyes:

But I suppose people did get thinking and I seriously doubt that any other podium thread has gone from 0 to 302 posts in under 32 hours.

One side question here - do you think such a thread would exist in a 'women only' forum?
 

Deeival

FNG / Fresh Meat
Sep 4, 2006
674
1
0
The "Should I wear pink or white today" thread would grow at a similar rate in that forum
 

User Name

FNG / Fresh Meat
Jan 12, 2006
1,125
19
0
How can the wheels move at the same speed as the tread. While the plane is moving faster? The plane can't leave it's wheels behind. If the tread mill is matching the speed of the wheels. They can't move forward because if they started to. The tread mill compensates and moves faster too.

This results in zero net forward movement. For the wheels to move forward. They have to be moving faster than the tread mill, but they can't because it speeds up and continues to travel at the same rate as them.

Without net forward movement. The plane will remain stationary on the platform. It's forward motion. Is always countered by the tread's rearward motion. Which means the wheels while spinning, AND the plane they are connected to remain stationary on the platform.

The plane can move as fast as it wants on the treadmill. As long as the treadmill moves and accelerates in the opposite direction at the same speed. It will never be able to move forward in relation to the air around it.

The thrust of the jet's engines alone is not enough to lift the plane off the ground. Zero air speed equals zero lift.

In other words the plane will be going no where fast.
 

spraduke

FNG / Fresh Meat
Nov 21, 2005
1,522
4
0
34
wiltshire
www.spraduke.co.uk
How can the wheels move at the same speed as the tread. While the plane is moving faster? The plane can't leave it's wheels behind. If the tread mill is matching the speed of the wheels. They can't move forward because if they started to. The tread mill compensates and moves faster too.

This results in zero net forward movement. For the wheels to move forward. They have to be moving faster than the tread mill, but they can't because it speeds up and continues to travel at the same rate as them.

Without net forward movement. The plane will remain stationary on the platform. It's forward motion. Is always countered by the tread's rearward motion. Which means the wheels while spinning, AND the plane they are connected to remain stationary on the platform.

The plane can move as fast as it wants on the treadmill. As long as the treadmill moves and accelerates in the opposite direction at the same speed. It will never be able to move forward in relation to the air around it.

The thrust of the jet's engines alone is not enough to lift the plane off the ground. Zero air speed equals zero lift.

In other words the plane will be going no where fast.
Ladys and gentlemen we have a winner!
 

Xendance

FNG / Fresh Meat
Nov 21, 2005
4,484
572
0
30
Elitist Prick Club RS Branch
How can the wheels move at the same speed as the tread. While the plane is moving faster? The plane can't leave it's wheels behind. If the tread mill is matching the speed of the wheels. They can't move forward because if they started to. The tread mill compensates and moves faster too.

This results in zero net forward movement. For the wheels to move forward. They have to be moving faster than the tread mill, but they can't because it speeds up and continues to travel at the same rate as them.

Without net forward movement. The plane will remain stationary on the platform. It's forward motion. Is always countered by the tread's rearward motion. Which means the wheels while spinning, AND the plane they are connected to remain stationary on the platform.

The plane can move as fast as it wants on the treadmill. As long as the treadmill moves and accelerates in the opposite direction at the same speed. It will never be able to move forward in relation to the air around it.

The thrust of the jet's engines alone is not enough to lift the plane off the ground. Zero air speed equals zero lift.

In other words the plane will be going no where fast.
Sigh.... even Nestor said that Moz was right.
 

melipone

FNG / Fresh Meat
Mar 22, 2006
1,672
259
0
As long as the plane is moving along the treadmill then it is moving through the air - move fast enough and it lifts. As long as its possible for the plane to gain some net velovity then we can assume it is possible for it to take off. Edit: I mean as long as its moving forward and not in equalibrium
 

BuddyLee

FNG / Fresh Meat
Apr 12, 2006
2,088
20
0
NCC 1701-D Neutral Zone
How can the wheels move at the same speed as the tread. While the plane is moving faster? The plane can't leave it's wheels behind. If the tread mill is matching the speed of the wheels. They can't move forward because if they started to. The tread mill compensates and moves faster too.

This results in zero net forward movement. For the wheels to move forward. They have to be moving faster than the tread mill, but they can't because it speeds up and continues to travel at the same rate as them.

Without net forward movement. The plane will remain stationary on the platform. It's forward motion. Is always countered by the treads rearward motion. Which means the wheels while spinning, AND the plane they are connected to remain stationary on the platform.

The plane can move as fast as it wants on the treadmill. As long as the treadmill moves and accelerates in the opposite direction at the same speed. It will never be able to move forward in relation to the air around it.

The thrust of the jet's engines alone is not enough to lift the plane off the ground. Zero air speed equals zero lift.

In other words the plane will be going no where fast.
The forward speed of the surface of the tires is equal in speed to the surface of the treadmill/ground, because the wheel spins freely and is in contact with the treadmill until liftoff. They are coupled together so they travel at the same speed in relation to one another.

The speed of the airplane in relation to the Earth, is different than the speed of the wheels in relation to the treadmill surface. (which is stationary on the ground with a moving conveyor ).
 
Last edited:

User Name

FNG / Fresh Meat
Jan 12, 2006
1,125
19
0
The forward speed of the surface of the tires is equal to speed the surface of the treadmill/ground, because the wheel spins freely and is in contact with the treadmill until liftoff. They are coupled together so they travel at the same speed in relation to one another.

The speed of the airplane in relation to the Earth, is different than the speed of the wheels in relation to the treadmill surface. (which is stationary on the ground ).

The plane can't outrun it's own wheels! It can only move as fast as they do. If they can't be pushed forward by the thrust of the jet, because they are being countered by the rearward movement of the runway. They can't move forward, and niether can the plane.

It's just like I said. For the plane to move forward the wheels HAVE to be spinning faster than the tread is moving. They can't though because their forward motion is always countered by the tread's rearward motion. Which is always the same as the speed of the wheels.
 

Nestor Makhno

FNG / Fresh Meat
Feb 25, 2006
5,758
1,118
0
55
Penryn, Cornwall
Even Nestor? wtf does that mean? :p

No, the thing that misled me was the assumption that the jet uses it wheels to 'kick off' on the ground - it doesn't - one way of looking at it is that its engine is like a corkscrew, drilling thru the air - it moves relative to the air. If you like it pushes off against the column of air going thru/behind it.

Therefore the motion of the wheels/treadmill is of minor importance.
 

User Name

FNG / Fresh Meat
Jan 12, 2006
1,125
19
0
As long as the plane is moving along the treadmill then it is moving through the air - move fast enough and it lifts. As long as its possible for the plane to gain some net velovity then we can assume it is possible for it to take off. Edit: I mean as long as its moving forward and not in equalibrium
Yes, if the plane can get net forward movement. It can eventually speed up and take off. However, The tread mill is designed to match the speed and acceleration of the jet. So whenever it starts to accelerate. The treadmill counters, and speeds up too. Resulting in zero net forward movement.
 

BuddyLee

FNG / Fresh Meat
Apr 12, 2006
2,088
20
0
NCC 1701-D Neutral Zone
The plane can't outrun it's own wheels! It can only move as fast as they do. If they can't be pushed forward by the thrust of the jet, because they are being countered by the rearward movement of the runway. They can't move forward, and niether can the plane.

It's just like I said. For the plane to move forward the wheels HAVE to be spinning faster than the tread is moving. They can't though because their forward motion is always countered by the tread's rearward motion. Which is always the same as the speed of the wheels.
A wheel is always traveling at the same rate as the gound passing underneath it. Unless you break traction.

Think of it this way,
are you moving forward 10mph toward your destination,
or is your destination moving towards you at 10mph,
or are you and your destination converging towards each other at 5mph each?
 

Xendance

FNG / Fresh Meat
Nov 21, 2005
4,484
572
0
30
Elitist Prick Club RS Branch
Even Nestor? wtf does that mean? :p

No, the thing that misled me was the assumption that the jet uses it wheels to 'kick off' on the ground - it doesn't - one way of looking at it is that its engine is like a corkscrew, drilling thru the air - it moves relative to the air. If you like it pushes off against the column of air going thru/behind it.

Therefore the motion of the wheels/treadmill is of minor importance.
That's what at least I tried to explain. I guess I sux at explaining D:

Btw, I planted the seed of devil here http://forums.guru3d.com/showthread.php?t=206144
 

User Name

FNG / Fresh Meat
Jan 12, 2006
1,125
19
0
A wheel is always traveling at the same rate as the gound passing underneath it. Unless you break traction.

Think of it this way,
are you moving forward 10mph toward your destination,
or is your destination moving towards you at 10mph,
or are you and your destination converging towards each other at 5mph each?
Yep, your right. Except for the fact that this ground is moving. If your wheel moves at 10 MPH and the tread is moving at 10 MPH hour in the opposite direction. You are moving zero MPH in relation to the platform the tread is on. Resulting in zero net movement.

If you speed up to 10.1 MPH. You would be moving .1 MPH in relation to everything else. This treadmill is designed to detect that though. So when you speed up to 10.1, so does it. So now you are both going 10.1 MPH. Which results in zero net movement for your car, plane, or whatever else.
 

Bobdog

FNG / Fresh Meat
Nov 22, 2005
1,916
218
0
Texas
Ok, people, I'm going to have to use my amazing Photoshop skills to explain this to you people.

For this demonstration we shall need:


The point of reference is an object NOT on the conveyer belt; it is connected to the ground and therefore stands still. Everything else is pretty self explanatory.

If you've been living under a rock and don't know what a hotwheels car is, go here

The important thing to note about the car is that it has wheels that spin freely.

Ok, here goes.

Imagine if you were to take a hotwheels car and hold it on the surface of a treadmill with your hand. You do not push the car forward; you simply apply the force necessary to keep the car in place.

In the first case, neither your hand nor the treadmill is moving.



The treadmill is moving 0 miles per hour backwards relative to the car, and the car is moving 0 miles per hour relative to the treadmill AND relative to the point of reference.

In the second case, we turn the treadmill on to a speed of 5 miles per hour.



The treadmill is moving 5 miles per hour backwards relative to the car, and the car is moving 5 miles per hour forward relative to the treadmill. However, the car is moving 0 miles per hour relative to the point of reference.

Now, we turn the treadmill up to 100 miles per hour.



The treadmill is moving 100 miles per hour backwards relative to the car, and the car is moving 100 miles per hour forward relative to the treadmill. However, the car is STILL moving 0 miles per hour relative to the point of reference.

NOTICE that your hand is applying almost no forward force, it is simply sitting there holding the car, regardless of the speed at which the conveyer moves.

Now, for the scientific magic :p

With the treadmill screaming at 100 miles per hour, you move your hand forward RELATIVE to the point of reference at 5 miles per hour!!!!



The treadmill is moving 105 miles per hour backwards relative to the car, and the car is moving 105 miles per hour forward relative to the treadmill. BUT the car is still moving forwards at 5 miles per hour relative to the point of refrence.

Why does this happen? Simple.

As you saw in the first 3 examples, no matter how fast the treadmill moved, the car stood in place without being pushed forward. This is because the car's wheels spin freely and as long as your hand is there holding it (applying a minimal amount of force) it will stay in place. Any extra force over that minimal amount will move the car forward relative to the reference point while causing the wheels to spin even faster. Now replace the car with a plane and your hand with multiple jet engines capable of putting out thousands of pounds of thrust. The engines only need to exert a small amount of thrust of counteract the rolling resistance of the plane's wheels. Once it overcomes this rolling resistance, it will easily start moving forward, giant treadmill or not.
 
Last edited:

BuddyLee

FNG / Fresh Meat
Apr 12, 2006
2,088
20
0
NCC 1701-D Neutral Zone
Yep, your right. Except for the fact that this ground is moving. If your wheel moves at 10 MPH and the tread is moving at 10 MPH hour in the opposite direction. You are moving zero MPH in relation to the platform the tread is on. Resulting in zero net movement.

If you speed up to 10.1 MPH. You would be moving .1 MPH in relation to everything else. This treadmill is designed to detect that though. So when you speed up to 10.1, so does it. So now you are both going 10.1 MPH. Which results in zero net movement for your car, plane, or whatever else.
The ground is not moving, the surface of the treadmill is. As well as the surface of the tires. The ground only moves in relation to the body of the plane after the engines thrust it forward, or the plane puts on its brakes.
 

fiftyone

FNG / Fresh Meat
May 6, 2006
5,453
284
0
Its all about thrust, if yer thrust is = to x2 inert weight then you should get lift...
I spent a day at a play park this summer, had ago on a treadmill, believe you me I went flying !!!!:p

Good thread !
 
Status
Not open for further replies.