So...about that plane on the treadmill...

"Peter Duniho" wrote in message
...
"Darkwing" theducksmail"AT"yahoo.com wrote in message
...
So lets say I know my little RC plane takes off at exactly 25mph. So I
crank up the treadmill to step up to 25mph so I can keep the RC plane up
on the treadmill, the plane is completely stationary in regards to anyone
standing next to the plane but when the treadmill hits 25mph and my
little RC plane is staying even with the treadmill you are telling me I
can pull back on the elevator stick and the plane will take off? I don't
think so.

The scenario you suggest is impossible. The RC plane will accelerate
regardless of how fast the treadmill is running. Your "little RC plane"
will NOT be "staying even with the treadmill". It will take off, just as
it would from a normal runway surface.

And it doesn't take a video of such an attempt to prove it. All it takes
is a person who has a minimal education in physics and (key point here) is
willing to listen until they understand, and someone else willing to
explain it. You clearly fail to meet either the first or second criteria,
or possibly both, since we do have the third criteria met here in the
newsgroup.

You are disrespectful of the various posters here who have made an honest
effort to explain the situation to you and others.

Man you are a dick. This has NOT been adequately explained or there would be
no question about it. If the plane is not moving on the treadmill but rather
keeping up with the speed that the treadmill is moving (yes planes DO have
throttle controls) the thing is going to takeoff with no air moving over the
wings? NO WAY.

This is because you refuse to bother to read the wealth of information on
the topic that already exists. Until you have done so, it would be a waste
of time for anyone to bother responding to any more of your assertions or
questions. I know that I won't.

Pete


Thank God for that, because you are a prick. Oh yeah, *PLONK*!

-------------------------------------------
DW

"Darkwing" theducksmail"AT"yahoo.com wrote in message
...


Man you are a dick. This has NOT been adequately explained or there would
be no question about it. If the plane is not moving on the treadmill but
rather keeping up with the speed that the treadmill is moving (yes planes
DO have throttle controls) the thing is going to takeoff with no air
moving over the wings? NO WAY.

Maybe, in your infinite wisdom, you can explain to me why the
treadmill is moving. Eh?

"Darkwing" theducksmail"AT"yahoo.com wrote in message


This has NOT been adequately explained or there
would be no question about it. If the plane is not moving on the
treadmill but rather keeping up with the speed that the treadmill is
moving (yes planes DO have throttle controls) the thing is going to
takeoff with no air moving over the wings? NO WAY.

Assuming you're a pilot, I don't understand why you think no air would be
moving over the wings, but I'll give this one good "college try"...

First, the question posed in the link by the OP of this thread is an
incorrect variation of the original. The original problem asks: "A plane is
standing on a giant treadmill. The plane moves in one direction, while the
treadmill moves in the opposite direction and at the same speed as the
plane. Can the plane take off?"

As has been explained, placing a car on the question's treadmill would
result in a stationary vehicle relative to the observer standing beside the
treadmill. The reason is the car derives its propulsion through the wheels
sitting on the treadmill and the speed of the car is measured by how fast
the wheels are turning. The faster the wheels turn, the "faster" the car
moves. However, this is only relative to the treadmill belt. To the observer
standing beside the treadmill, the car is motionless. If the driver placed
his hand out the window, he would feel no wind even though his "speed" as
indicated by the speedometer may be 100 miles per hour.

This is very similar to your example of running on the treadmill. You did
not feel a relative wind in your face because you were stationary relative
to the observer standing beside the treadmill. The reason you were
stationary is you generate your propulsion by moving your feet against the
ground (or belt, in this case) and the belt is moving in the opposite
direction and same speed of your "travel". Like the car, your speed is
measured by how fast your feet move from front to rear and they match the
speed of the belt to cancel out each other.

Now, replace the car and runner with an airplane. The airplane derives its
propulsion from its engine pushing air from front to back. None of this
energy is sent to the wheels to propel the airplane. The speed of the
airplane is measured by the flow of air past the airplane, not the turning
of its wheels. As the airplane's engine spools up to takeoff power, air is
forced from front to rear and the plane moves forward regardless how fast
its wheels are turning. The observer standing beside the treadmill would
notice the treadmill speed up, the airplane's wheels turn twice as fast as
normal, and the airplane move forward (not stationary).

Speed is relative and the key here is the means of propulsion. The
airplane's speed is measured by how fast the air is moving past it, not by
how fast its wheels are turning or how fast the ground is flashing by. None
of the airplane engine's energy is transmitted to the wheels to generate
speed. All of the airplane's propulsion is derived from moving air
(otherwise it would never stay in the air after takeoff). Since the
treadmill has very little effect on the air (and what little effect it does
have actually helps the airplane generate more lift), the airplane will
indeed takeoff in the same distance it normally would use without the
treadmill. However, the airplane wheels would be turning at twice their
normal speed at the time of takeoff.


Try this experiment:

Take a toy car and attach it to a string. Tie the other end of the string to
a small spring scale. Place the car on the treadmill belt and hold the scale
in front of the car while you turn on the treadmill. Observe nearly zero
(essentially 1G) force being exerted on the string/scale. Speed up the
treadmill (for simplicity, let's say you set it to a constant 10mph) and
you'll observe no significant difference in force exerted on the string (the
only additional force is the friction of the car's axles). Now gently pull
the string/scale forward. As long as you maintain a 1G force on the string,
the car will continue to accelerate.

Now, to the observer standing beside the treadmill, was the car stationary
or moving forward? It's speed was certainly not zero as the car most
definitely moved from rear to front of the belt. What was the speed of the
car relative to the "driver" sitting inside the toy? The wheels would be
turning faster than 10mph. If the "driver" were to put his hand out the
window, how fast would the air be moving? Much slower than his wheels would
say he's moving, but faster than the driver I mentioned at the beginning of
this post.

Replace the toy with the mythical airplane above, replace your arm with the
airplane's engine (and propeller, if appropriate), then replace the string
with the airplane engine mounts. You should now be able to visualize why the
airplane sitting on that giant treadmill would most definitely takeoff.

If not, I wish you good luck and safe flight. You'll need it.

--
John T
http://sage1solutions.com/blogs/TknoFlyer
Reduce spam. Use Sender Policy Framework: http://openspf.org
____________________

"John T" wrote in message
...
"Darkwing" theducksmail"AT"yahoo.com wrote in message


This has NOT been adequately explained or there
would be no question about it. If the plane is not moving on the
treadmill but rather keeping up with the speed that the treadmill is
moving (yes planes DO have throttle controls) the thing is going to
takeoff with no air moving over the wings? NO WAY.

Assuming you're a pilot, I don't understand why you think no air would be
moving over the wings, but I'll give this one good "college try"...


Yes I am a pilot.


First, the question posed in the link by the OP of this thread is an
incorrect variation of the original. The original problem asks: "A plane
is standing on a giant treadmill. The plane moves in one direction, while
the treadmill moves in the opposite direction and at the same speed as the
plane. Can the plane take off?"

As has been explained, placing a car on the question's treadmill would
result in a stationary vehicle relative to the observer standing beside
the treadmill. The reason is the car derives its propulsion through the
wheels sitting on the treadmill and the speed of the car is measured by
how fast the wheels are turning. The faster the wheels turn, the "faster"
the car moves. However, this is only relative to the treadmill belt. To
the observer standing beside the treadmill, the car is motionless. If the
driver placed his hand out the window, he would feel no wind even though
his "speed" as indicated by the speedometer may be 100 miles per hour.

This is very similar to your example of running on the treadmill. You did
not feel a relative wind in your face because you were stationary relative
to the observer standing beside the treadmill. The reason you were
stationary is you generate your propulsion by moving your feet against the
ground (or belt, in this case) and the belt is moving in the opposite
direction and same speed of your "travel". Like the car, your speed is
measured by how fast your feet move from front to rear and they match the
speed of the belt to cancel out each other.

Now, replace the car and runner with an airplane. The airplane derives its
propulsion from its engine pushing air from front to back. None of this
energy is sent to the wheels to propel the airplane. The speed of the
airplane is measured by the flow of air past the airplane, not the turning
of its wheels. As the airplane's engine spools up to takeoff power, air is
forced from front to rear and the plane moves forward regardless how fast
its wheels are turning. The observer standing beside the treadmill would
notice the treadmill speed up, the airplane's wheels turn twice as fast as
normal, and the airplane move forward (not stationary).

Speed is relative and the key here is the means of propulsion. The
airplane's speed is measured by how fast the air is moving past it, not by
how fast its wheels are turning or how fast the ground is flashing by.
None of the airplane engine's energy is transmitted to the wheels to
generate speed. All of the airplane's propulsion is derived from moving
air (otherwise it would never stay in the air after takeoff). Since the
treadmill has very little effect on the air (and what little effect it
does have actually helps the airplane generate more lift), the airplane
will indeed takeoff in the same distance it normally would use without the
treadmill. However, the airplane wheels would be turning at twice their
normal speed at the time of takeoff.


Try this experiment:

Take a toy car and attach it to a string. Tie the other end of the string
to a small spring scale. Place the car on the treadmill belt and hold the
scale in front of the car while you turn on the treadmill. Observe nearly
zero (essentially 1G) force being exerted on the string/scale. Speed up
the treadmill (for simplicity, let's say you set it to a constant 10mph)
and you'll observe no significant difference in force exerted on the
string (the only additional force is the friction of the car's axles). Now
gently pull the string/scale forward. As long as you maintain a 1G force
on the string, the car will continue to accelerate.

Now, to the observer standing beside the treadmill, was the car stationary
or moving forward? It's speed was certainly not zero as the car most
definitely moved from rear to front of the belt. What was the speed of the
car relative to the "driver" sitting inside the toy? The wheels would be
turning faster than 10mph. If the "driver" were to put his hand out the
window, how fast would the air be moving? Much slower than his wheels
would say he's moving, but faster than the driver I mentioned at the
beginning of this post.

Replace the toy with the mythical airplane above, replace your arm with
the airplane's engine (and propeller, if appropriate), then replace the
string with the airplane engine mounts. You should now be able to
visualize why the airplane sitting on that giant treadmill would most
definitely takeoff.

If not, I wish you good luck and safe flight. You'll need it.

--
John T


Thank you for your reply. Here is my .02, it would seem that the plane never
actually moves in respect to the observer no matter how fast the treadmill
moves, the plane will just take off like it is hovering and then slowly
accelerate away?

I guess I'll have to set this up and try it, I do have a few RC planes
laying around and I have a treadmill so I guess I'll know one way or
another, unless Mythbusters beats me to the punch.

-------------------------------------------------------
DW

"Darkwing" theducksmailATyahoo.com wrote in message
...

"John T" wrote in message
...
"Darkwing" theducksmail"AT"yahoo.com wrote in message


First, the question posed in the link by the OP of this thread is an
incorrect variation of the original. The original problem asks: "A plane
is standing on a giant treadmill. The plane moves in one direction, while
the treadmill moves in the opposite direction and at the same speed as
the plane. Can the plane take off?"

As has been explained, placing a car on the question's treadmill would
result in a stationary vehicle relative to the observer standing beside
the treadmill. The reason is the car derives its propulsion through the
wheels sitting on the treadmill and the speed of the car is measured by
how fast the wheels are turning. The faster the wheels turn, the "faster"
the car moves. However, this is only relative to the treadmill belt. To
the observer standing beside the treadmill, the car is motionless. If the
driver placed his hand out the window, he would feel no wind even though
his "speed" as indicated by the speedometer may be 100 miles per hour.

Hmm. That presumes that "at the same speed as the plane" means "as fast as
necessary to cancel the forward motion." If you take your car analogy and
apply it to the plane, then the treadmill must try to run backwards as fast
as necessary to cancel forward motion - which is, Ah, let's just say
difficult.

To be consistent with your conclusions about the plane's motion, then the
car would also move. Using the object's motion as the defining parameter to
determine the treadmill speed, then a stable state can be reached with
either
1) a plane with forward motion X, treadmill with motion -X, wheels
spinning at 2X, thrust applied to achieve speed X
2) a car with forward motion X, treadmill with motion -X, wheels
spinning at 2X, thrust applied to achieve speed 2X

Accelerate either the plane or the car with X from 0 to, say, 65. The plane
will take off. The car will drive off the end of the treadmill.

John T


Thank you for your reply. Here is my .02, it would seem that the plane
never actually moves in respect to the observer no matter how fast the
treadmill moves, the plane will just take off like it is hovering and then
slowly accelerate away?

I guess I'll have to set this up and try it, I do have a few RC planes
laying around and I have a treadmill so I guess I'll know one way or
another, unless Mythbusters beats me to the punch.

-------------------------------------------------------
DW


DW,

None of the people that believe the plane will fly say that it will fly with
no forward motion. The claim is that the plane will accelerate to flying
speed in spite of the treadmill moving in the opposite direction.

Here is my .02, it would seem that the plane never
actually moves in respect to the observer no matter how fast the treadmill
moves, the plane will just take off like it is hovering and then slowly
accelerate away?

How about we make life easy for the moment and forget about the
treadmill. The airplane is magnetically suspended over the runway. No
part of the plane is touching the runway at all. It's all done with
electromagnets. (and for the nitpickers, let's ignore linear induction
motor effects).

The (otherwise ordinary) plane is magnetically suspended over the runway
with nothing touching the runway at all. Can the plane take off? How
does it do so?

Jose
--
"There are 3 secrets to the perfect landing. Unfortunately, nobody knows
what they are." - (mike).
for Email, make the obvious change in the address.

("Jose" wrote)
The (otherwise ordinary) plane is magnetically suspended over the runway
with nothing touching the runway at all. Can the plane take off?


Yes. But, ...Lord only knows what direction he's heading. g


Montblack

"Montblack" wrote in message
...
("Jose" wrote)
The (otherwise ordinary) plane is magnetically suspended over the runway with
nothing touching the runway at all. Can the plane take off?


Yes. But, ...Lord only knows what direction he's heading. g

The thrusters will take care of that, until the inertial dampeners take effect.
g
--
Jim in NC

("Darkwing" wrote)
Thank you for your reply. Here is my .02, it would seem that the plane
never actually moves in respect to the observer no matter how fast the
treadmill moves, the plane will just take off like it is hovering and then
slowly accelerate away?


Not unless the plane's "wheels" are coupled to the shaft of a gyro's rotor.

Try this one:

You're in a Class B airport terminal.
You're on roller-skates, Rollerblades, a skateboard... whatever.

You find yourself on an (evil) moving sidewalk - facing the wrong way.
The (evil) sidewalk ALWAYS matches your wheels' forward speed.

Someone moves a huge Hollywood 'film set' fan, in a few feet behind you.
They point the fan at your back and turn it on.

You hold open your jacket to make a sail (...like kids at the ice skating
rink have done for ages)

1. Will you get blown down to the far end of the moving sidewalk - your
destination?

2. Will you remain in the same spot - relative to the wall - no matter how
hard the giant fan blows?

3. Forgetting the fan, if you try pulling yourself forward using the
stationary handrails, will you in fact move forward? Or will the (evil)
moving sidewalk thwart your forward motion by speeding up? Or will your
upper body pull itself forward, while your feet remain behind ...(or
stationary, relative to the wall and the handrail)?

4. How is this the same as the airplane and the treadmill question? How is
it different?


Montblack

"Montblack" wrote in message
...
("Darkwing" wrote)
Thank you for your reply. Here is my .02, it would seem that the plane
never actually moves in respect to the observer no matter how fast the
treadmill moves, the plane will just take off like it is hovering and
then
slowly accelerate away?


Not unless the plane's "wheels" are coupled to the shaft of a gyro's
rotor.

Try this one:

You're in a Class B airport terminal.
You're on roller-skates, Rollerblades, a skateboard... whatever.

You find yourself on an (evil) moving sidewalk - facing the wrong way.
The (evil) sidewalk ALWAYS matches your wheels' forward speed.

Someone moves a huge Hollywood 'film set' fan, in a few feet behind you.
They point the fan at your back and turn it on.

You hold open your jacket to make a sail (...like kids at the ice skating
rink have done for ages)

1. Will you get blown down to the far end of the moving sidewalk - your
destination?

2. Will you remain in the same spot - relative to the wall - no matter how
hard the giant fan blows?

3. Forgetting the fan, if you try pulling yourself forward using the
stationary handrails, will you in fact move forward? Or will the (evil)
moving sidewalk thwart your forward motion by speeding up? Or will your
upper body pull itself forward, while your feet remain behind ...(or
stationary, relative to the wall and the handrail)?

4. How is this the same as the airplane and the treadmill question? How is
it different?


Montblack


It's basically the same question with the same ambiguities. The crux of most
of the hilarious debate is really over what defines the speed of the
treadmill. It seems like a more interesting puzzle if the treadmill (or evil
moving sidewalk) tries to match the forward speed of the object on the
wheels resulting in the wheels simply spinnning at twice the speed of the
forward movement of the object.

The other interpretation, which leads to an impossible solution, is that the
treadmill moves to counteract all forward motion - which results in a
treadmill accelerating to infinite speed (or until the wheels explode which
ever comes first).
--
-------------------------------
Travis
Lake N3094P
PWK