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

Looks like airplane treadmill problem, regularly a spark for flame wars
on R.A.P., has made it into the mainstream.

http://pogue.blogs.nytimes.com/

Let the arguing begin!

- Ray

"Ray" wrote in message
...
Looks like airplane treadmill problem, regularly a spark for flame wars on
R.A.P., has made it into the mainstream.

http://pogue.blogs.nytimes.com/

And handled with every bit as much intelligence and consideration as we've
seen here. Which is to say, there's no shortage of people convinced that
the airplane won't take off, even though it will.

Let the arguing begin!

Why? Haven't you had enough by now?

"Ray" wrote in message ...
Looks like airplane treadmill problem, regularly a spark for flame wars on
R.A.P., has made it into the mainstream.

http://pogue.blogs.nytimes.com/

Let the arguing begin!

- Ray

That would depend on what has the greater resistance,
the air in front of the plane or the belt on the treadmill.
If it was harder for the plane to push through the air in
front of it then the plane would merely roll stationary
on the treadmill.
If the resistance of the treadmill rollers was greater
than the air in front of the plane then the plane would
push forward thereby achieving lift through air flow
passage over the wings.

You can equate it to an airboat in a river.
Will the river push the airboat down stream or
will the propulsion of the engine move it forward?

Just my two cents worth....

David
Greer, SC

"FLAV8R" wrote in message
...
That would depend on what has the greater resistance,
the air in front of the plane or the belt on the treadmill.

No, it would not depend on that at all. Both of those effects are creating
a resistance in the same direction, and thus are additive. Which one is
greater is irrelevant. The only relevant question is whether they combined
exceed the thrust from the engines.

They don't even come close to doing that, and so the engines can easily push
the airplane forward to a high enough speed for flight.

[...]
You can equate it to an airboat in a river.
Will the river push the airboat down stream or
will the propulsion of the engine move it forward?

It's similar, yes. Except that the drag due to friction from the treadmill
is miniscule, whereas hydrodynamic drag is significant.

Pete

"Peter Duniho" wrote in message
...
"FLAV8R" wrote in message
...
That would depend on what has the greater resistance,
the air in front of the plane or the belt on the treadmill.

No, it would not depend on that at all. Both of those effects are
creating
a resistance in the same direction, and thus are additive. Which one is
greater is irrelevant. The only relevant question is whether they
combined
exceed the thrust from the engines.

They don't even come close to doing that, and so the engines can easily
push
the airplane forward to a high enough speed for flight.

[...]
You can equate it to an airboat in a river.
Will the river push the airboat down stream or
will the propulsion of the engine move it forward?

It's similar, yes. Except that the drag due to friction from the
treadmill
is miniscule, whereas hydrodynamic drag is significant.

Pete


As pictured, the runway is much to short, which is just as well since the
uprights of the treadmill would impinge on the wings. bfg

Actually, I agree that the drag from the treadmill is trivial. Therefore,
if sufficient distance was provided to accellerate to an appropriate
airspeed, the only problem would be the maximum speed rating of the tires.

Peter

"Ray" wrote in message
...
Looks like airplane treadmill problem, regularly a spark for flame wars on
R.A.P., has made it into the mainstream.

http://pogue.blogs.nytimes.com/

Let the arguing begin!

- Ray

It is a trick question. The obvious assumption being that the plane will
not move, therefore no airflow over the wings. The plane, however WILL move
down the runway. The propeller or the jets will pull or push on the air and
move the plane. The wheels are not providing the moving force, the reaction
of the thrust mechanism against the air is.

One of two things would happen before the plane took off though, the
bearings in the planes wheels would burn up or the motor driving the
treadmill would burn up. The control system is in an infinite feedback
loop. The plane would move due to the forces described above and the
treadmill would try to speed up, so the wheels would move faster, then the
treadmill would move faster etc etc etc......

"Ray" wrote in message ...
Looks like airplane treadmill problem, regularly a spark for flame wars on
R.A.P., has made it into the mainstream.

http://pogue.blogs.nytimes.com/

Let the arguing begin!

It is truly amazing how many clueless people have commented on the problem. MX
should go hang out there. He would look like a rocket scientist.
--
Jim in NC

"Peter Duniho" wrote in message
...
"Ray" wrote in message
...
Looks like airplane treadmill problem, regularly a spark for flame wars
on R.A.P., has made it into the mainstream.

http://pogue.blogs.nytimes.com/

And handled with every bit as much intelligence and consideration as we've
seen here. Which is to say, there's no shortage of people convinced that
the airplane won't take off, even though it will.

Let the arguing begin!

Why? Haven't you had enough by now?


It seems that the "non-believers" think that the treadmill is somehow
holding the airplane back.
The way that the problem is posed on the blog states that the treadmill
matches the wheel speed of
the airplane. ("The conveyer belt is designed to exactly match the speed of
the wheels, moving in the
opposite direction.") If friction is taken into consideration then one of
four conditions can exist.
1. no thrust (or not enough thrust to overcome frictional forces) ...
neither the plane nor the conveyor are moving.
2. minimal thrust... the wheels and conveyor are moving but the conveyor
drags the plane backwards.
3. just enough thrust to match friction forces... the airplane remains
motionless relative to the earth but the wheels
and conveyor are moving a little faster.
4. more than enough thrust.... the airplane accelerates until it can take
off. The conveyor also accelerates to match
the wheel's speed until lift off when the wheels rotate to a stop and
the conveyor, somehow sensing this, also
comes to a standstill.
The treadmill's speed is dependent on the wheel's speed, not the other way
around.

"Ray" wrote in message
...
Looks like airplane treadmill problem, regularly a spark for flame wars on
R.A.P., has made it into the mainstream.

http://pogue.blogs.nytimes.com/

Let the arguing begin!

- Ray

This looks like a job for the MythBusters!!!

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

"Peter Duniho" wrote in message
...
"Ray" wrote in message
...
Looks like airplane treadmill problem, regularly a spark for flame wars
on R.A.P., has made it into the mainstream.

http://pogue.blogs.nytimes.com/

And handled with every bit as much intelligence and consideration as we've
seen here. Which is to say, there's no shortage of people convinced that
the airplane won't take off, even though it will.


Nope the plane won't take off.

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