Can a Plane on a Treadmill Take Off?

"jesse" wrote:

when you walk on a treadmill, do you have any significant
airspeed(minus wind and fans)? you are moving forward relative to the
treadmill belt only, your airspeed is zero, sure your legs are moving
at say three miles per hour, and the treadmill belt is moving three
miles per hour the opposite way, but without airspeed you have no
lift(assuming your arms were airfoils). its not that complicated
people. the thrust of the airplane is only used in most cases, to
provide a movement of air over the wings to cause lift. if the supposed
airplane is stationary to the air, regardless how much thrust is being
used to "keep up" with the treadmill, no lift will be created, try it
with an rc plane on a real treadmill if you dont believe me. Im not
calling anyone stupid, but didnt everybody learn in PP ground school
that ground speed has nothing to do with airspeed and the associated
lift? thats one of the first things, the most basic of things that i
was taught. im done with this topic. enjoy, let the roasting begin!
Jester
PP-ASEL
A&P

some people apparently have a hard time reading.

"a conveyer belt that moves in the
opposite direction at exactly the speed that the airplane is moving
forward."

When the conveyor belt is moving backwards at 80mph, how fast is the
plane moving? Hint: there is no mention of how fast the plane is
moving relative to the conveyor belt. If the plane is moving forward
at 80mph, is it likely to have enough airspeed to fly?

If you are still confused, when the plane is moving forward at 80mph,
the conveyor will be moving backwards at 80mph, and a speedometer that
measures off of tire rotation would indicate the plane's speed (before
getting airborne) as 160mph, the speed relative to the conveyor.
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

and a speedometer that
measures off of tire rotation would indicate the plane's speed (before
getting airborne) as 160mph, the speed relative to the conveyor.

While an airspeed indicator would indicate zero.

-Robert, CFI

"Robert M. Gary" wrote:

and a speedometer that
measures off of tire rotation would indicate the plane's speed (before
getting airborne) as 160mph, the speed relative to the conveyor.

While an airspeed indicator would indicate zero.

-Robert, CFI
Only if there is an 80 mph tailwind.
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

Only if there is an 80 mph tailwind.

If the plane is rolling 80mph against a conveyor going 80mph back the
difference would be zero.

-Robert

"Robert M. Gary" wrote:

Only if there is an 80 mph tailwind.

If the plane is rolling 80mph against a conveyor going 80mph back the
difference would be zero.

True. But I was referring to the problem stated, that the conveyor was
moving the same speed and opposite direction to the speed and
direction that the plane was MOVING, not this different scenario in
which the conveyor was moving the opposite direction and same speed to
that at which the plane's tires were turing.

--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

Robert M. Gary wrote:
Only if there is an 80 mph tailwind.


If the plane is rolling 80mph against a conveyor going 80mph back the
difference would be zero.


BUT-what is the total friction force from the wheels? Certainly it's
less than the thrust from the engine--I mean, that's what wheels are
designed for, to have as little rolling friction as possible. So let's
add this up... forces acting on airplane are thrust, aerodynamic drag,
and an essentially negligible amount of drag from the wheels. Add it
up, and since the thrust is greater than the drag (as it would be on a
normal takeoff) the airplane accelerates. As I said in another post,
since wheels are designed for minimal friction, just pretend that they
are frictionless, and therefore not even there (anti-gravity airplane).
What is the conveyor belt going to push against now?

What is the conveyor belt going to push against now?

The conveyor belt is pushing against the force of the prop through the
air but we don't care. The problem stated that they are doing 80mph, we
shouldn't worry about how the plane is able to do 80mph on the belt.

-Robert

No. The plane is moving forward at 80mph. The wheels are the only thing
feeling the 160mph effect of the treadmill. This isn't a ground propelled
vehicle.

--
-------------------------------
Travis
"Robert M. Gary" wrote in message
ups.com...
and a speedometer that
measures off of tire rotation would indicate the plane's speed (before
getting airborne) as 160mph, the speed relative to the conveyor.

While an airspeed indicator would indicate zero.

-Robert, CFI