Can a Plane on a Treadmill Take Off?

There will be airspeed felt by the plane in the area of the propellor
wash. Out of the prop wash, since the plane is not moving relative to
the surrounding air, there will be no relative wind felt by the
airplane. The airplane MIGHT take off, but it will not be a normal
takeoff, at least not for a normal airplane with 36' wingspan and a 6'
propellor. I really don't think there is enough information to know the
answer for sure. Too many unknowns.

This is one of these "frame of reference" problems.

I dont know what all the fuss is about. The plane will not takeoff for
the reason that the all the plane is doing is keeping stationary. In
actual fact the trust thats produced is not producing thrust, its only
compensating from the drag thats pull the aircraft back. (treadmill) in
order to take off the plane must superexceed the opposing force and
establish that trust actually does exceed drag. hence the the plane
must build up momentum (in the correct direction)

correct ?

Barry...

Taxi is just nomenclature for the airplane moving along the ground.
"Takeoff run" would be more correct I guess, but in this case things
are so weird, as it is ambiguous whether the plane is going to takeoff
or not.

Ok, in relevance to Dougs post... we are both correct !!! apart from
the down wash from the small propeller, they will not be any airflowing
over the rest of the wings... why ??? Because the airplane is not
moving !!!! its only compensating for the exstreem backward force, as i
said its only standing still, and standing still doesnt get you
anywhere. you need momentium.

It however, would be possible if you have a plane with an exceedingly
small wing span, very low stall speed and a big propeller to generate a
downwash to cover the entire wing. As you know your aillerons are
situated at the outer section of the wings, if you have no downwash
over them it will stall and not turn leading to a temporary lift and
then crash.

Barry

If the treadmill is stationary and the belt speed is equal
to the required take-off speed, the airplane will have zero
airspeed if it is "moving" in relation to the belt, the
airplane is moving, the prop has thrust and is balancing the
rearward movement of the belt. The tires are rolling, but
the airplane is stationary and there is no airspeed or lift.



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James H. Macklin
ATP,CFI,A&P

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"Doug" wrote in message
oups.com...
| Taxi is just nomenclature for the airplane moving along
the ground.
| "Takeoff run" would be more correct I guess, but in this
case things
| are so weird, as it is ambiguous whether the plane is
going to takeoff
| or not.
|

First I'm not a pilot.... But the engine is providing thrust, not driving
the wheels like a car. The airplane is gonna move regardless of what speed
the wheels are or are not turning. What the wheels do is only slightly
relevant if at all unless you're holding the brake....and even that wouldn't
matter if you're on a treadmill. Second.....are we talking about a
treadmill or a conveyer belt? The treadmill may or may not move at all
relative to the world if it's the "classic" kind ... (i.e. non-motorized).
Depends on whether the wheels or treadmill has better bearings.

"Morgans" wrote in message
...

"Doug" wrote in message
oups.com...
What is keeping the airplane's speed up with the conveyor belt? The
propeller. Said propeller moves air. Air causes lift. The problem is
more complicated than it seems to be at first read.

Another way to say it; it had better be a long conveyer belt, cause the
prop
is pulling the plane forward, without caring how fast the wheels are
going.
That will make the necessary airspeed to lift off.
--
Jim in NC

See Custer Channel-wing [Google] and reaction controls.


"The Flying Scotsman" wrote in
message
ups.com...
| Ok, in relevance to Dougs post... we are both correct !!!
apart from
| the down wash from the small propeller, they will not be
any airflowing
| over the rest of the wings... why ??? Because the airplane
is not
| moving !!!! its only compensating for the exstreem
backward force, as i
| said its only standing still, and standing still doesnt
get you
| anywhere. you need momentium.
|
| It however, would be possible if you have a plane with an
exceedingly
| small wing span, very low stall speed and a big propeller
to generate a
| downwash to cover the entire wing. As you know your
aillerons are
| situated at the outer section of the wings, if you have no
downwash
| over them it will stall and not turn leading to a
temporary lift and
| then crash.
|
| Barry
|

Paul Tomblin wrote:
In a previous article, "jesse" said:
Ok, so all of us do not comment on his site, or well maybe that would
be better, does this guy really not have any sense to know that the
ground speed is completely irreleveant to aerodynamics(thinking of the
threads about 152s with 0 or negative ground speed)? whatever....
airspeed is zero, no lift, no fly.

Hopefully the people commenting on his site aren't as stupid as you.


Paul...dont look now, but that airplane is NOT flying off the ground
until the AIRSPEED is up...the treadmill is only moving the TIRES, that
means diddly squat to an airplane.

Damian

My friend and i were discussing this. There is not enough information
in the orginal question to determine anything. Depending which way you
argue the various variables, it could work either way. The people who
are saying the plane will fly are saying that the prop pushes against
the air and thus will eventually fly, the people who are saying that
the plane will not fly are assuming that the prop(or jet) is only
giving enough thrust to equalize the resistance on the wheels bearings
etc, thus the plane will stand still. define some variables, define
speed(wheel speed, ground speed, air speed) the original poster(at
cecils site) didnt give us enough info, and used the term speed and
move in more than one way. he also a plane standing on a runway, then
it moves, but then the conveyor moves. which is it buddy? if the plane
starts to move, it will take off. uh oh, here i go again, getting lost
in the details, now i think it will take off. its almost akin to
asking, if you fire a gun into a crowd will you kill someone. a lot of
people would say yes. what if the bullet went between people, what if
it was a blank, what if it was a blank and then some guy had a heart
attack, what if superman stopped it. define variables and argue it
either way, the answer is yes and no, it depends, and thats the
wonderful thing about these questions, it gets us to think, thats why
we are the top of the food chain. animals might have said, i dont care
weather it takes off or not, im outta here so it doesnt eat me. other
animals might have tred to eat it. aluminum or wood or fiberglass or
steel is not very edible to us, so we talk about it. its a great world
isnt it! if you need to be right to prove your intelligence, go on
jeopardy. to me, i gotta go flying, and i havent seen any conveyor
belts at OUN, so im outta here!
Jester

"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.
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