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

"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

"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

"Darkwing" theducksmailATyahoo.com wrote in message
...
This looks like a job for the MythBusters!!!

*Yawn*

That would be a boring show. Either they'd have to fill 19 minutes with the
construction of the treadmill itself, or they'd have the airplane taking off
in the first 30 seconds, leaving them with 19 minutes of filler at the end.

You don't need MythBusters. You just need a little knowledge of physics and
some common sense.

Pete

"Peter Duniho" wrote in message
...
"Darkwing" theducksmailATyahoo.com wrote in message
...
This looks like a job for the MythBusters!!!

*Yawn*

That would be a boring show. Either they'd have to fill 19 minutes with
the construction of the treadmill itself, or they'd have the airplane
taking off in the first 30 seconds, leaving them with 19 minutes of filler
at the end.

You don't need MythBusters. You just need a little knowledge of physics
and some common sense.

Pete


Okay Mr. Cynical, I sent an email off to the Mythbusters explaining this
whole thing and a link to the Google Groups thread so we'll see if they pick
it up and show it on the program.

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

In article ,
"Darkwing" theducksmail"AT"yahoo.com wrote:

Okay Mr. Cynical, I sent an email off to the Mythbusters explaining this
whole thing and a link to the Google Groups thread so we'll see if they pick
it up and show it on the program.

doubt it. It's not a myth.

--
Bob Noel
Looking for a sig the
lawyers will hate

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

If we take the statement, "The conveyer belt is designed to exactly
match the speed of the wheels, moving in the opposite direction", to
mean that the plane can not move forward, because some how the conveyor
is moving so fast the wheel friction becomes great enough that the
engine thrust can not over come it. Obviously this isn't going to
happen, but if it were, I think we can all agree that the conveyor would
be moving extremely fast, several hundred MPH if not thousands of MPH.
Now consider a 150 foot wide, 10,000 foot long conveyor moving at that
speed. Would that not cause enough air to move with it that there would
be enough air speed for the plane to lift off? Of course once that
happened, the wheels would quickly stop, as would the conveyor and the
air. Then with no forward ground speed, the plane would probably fall
because it could not accelerate as fast as the "head wind" was dying.

How's that for an interesting twist?

--
Chris W
KE5GIX

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"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

You're standing on the conveyor wearing a pair of roller skates. The rope
you are holding
is attached to the rear bumper of a truck. The truck is on the ground and
begins to move
away from you. As you begin to move forward the conveyor begins to turn
backwards
to match the wheel's speed. (Here's another point... as long as the wheels
are rolling and
not sliding the conveyor is "matching the wheel's speed". Just depends on
the observer's
reference frame whether the conveyor is moving or even needs to move to meet
the
conditions of the problem.) Eventually the truck will pull you off the end
of the conveyor.
Just substitute a propeller coupled to the atmosphere for the truck's wheels
coupled
to the ground. The conveyor is irrelevant.

Ok, how about this one. Everyone knows pilots love a tailwind.

You have a giant fan mounted on a truck positioned behind the airplane.
The fan blows air towards the airplane, helping it to accelerate down
the runway (literally blowing it down the runway) while the truck
follows, keeping up with the airplane. Pretty soon the plane will be
thundering down the runway and the pilot pulls back on the yoke.

Does the pilot have to wait until the airplane's speed down the runway
is twice Vr before he can take off?

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.