Can a Plane on a Treadmill Take Off?

"Flyingmonk" wrote in message
oups.com...
Depends on the airplane, certain lpanes are built in such a way that
they can actually attain enough lift just from the prop wash alone.

Other than the ones we call helicopters, I've never heard of such a thing.

Care to elaborate?

"jesse" wrote in message
ups.com...
"One of the posters raised the issue of what would happen when the
aircraft
returned for landing."

If the belt were moving backwards at the speed of the aircraft when it
touched down, it would be similar to landing with that much tailwind,
basically, your ground speed would double you airspeed at touch down.

All that would happen is that the wheels would have to turn faster to
accomdate the treadmill. Just as they do at takeoff. There's not really
any difference between the two scenarios.

Other than the ones we call helicopters, I've never heard of such a thing.

Care to elaborate?

Already rephrased my statement.

The Monk

"Don Tuite" wrote in message
...
but what
is the point of the original question in that case? Is it just to
trap a sloppy reader into thinking it's all about a crackpot VTOL
methodology?

I think the more interesting point is to notice the implications of not
transmitting force through the wheels. Even people who know that planes and
cars differ in that way may fail (at least at first) to draw the appropriate
conclusion about what happens to the treadmill plane when it applies takeoff
power.

--Gary

"cjcampbell" wrote in message
oups.com

"An airplane on a runway sits on a conveyer belt that moves in the
opposite direction at exactly the speed that the airplane is moving
forward. Does the airplane take off?" (Assuming the tires hold out, of
course.)

The conveyor belt is simulating groundspeed. How many of you fly airplanes
by reference to groundspeed?

--
John T
http://sage1solutions.com/TknoFlyer
Reduce spam. Use Sender Policy Framework: http://spf.pobox.com
____________________

"Morgans" wrote in message
...

You will find that you will be taken more seriously around here, if you
continue you attempts at correctly (minus a few typo's) written posts.
The small mistakes will always creep in, it seems, no matter how hard we
all try. In this case, a small one was there,

Many people helped my as I was .....

but I'm almost sure there is a mistake in me post. It is a rule, I was
told. g

Yup. In addition to writing "you attempts" and "me post", you misspelled
"typos" (apostrophes are not used to form nonpossessive plurals). Also, the
comma in the first sentence is incorrect. It indicates that the dependent
clause is parenthetical, but in fact that clause is integral to the sentence
(the sentence means something substantially different if the clause is
removed). The Chicago Manual of Style gives these examples to illustrate the
distinction:
She ought to be promoted, if you want my opinion.
We will agree to the proposal if you accept our conditions.

--Gary

"Michael Ware" wrote

Yes, but an airplane isn't propelled by its feet.

This is where everyone who seems to think that the airplane will fly is
getting confused.

The method of propulsion doesn't matter. You can drive an airplane down the
runway by driving its wheels just like a car and it will still reach takeoff
airspeed and fly briefly. The propeller is only important once you are
airborne, because you need something to pull you through the air.

The bottom line is this - you cannot take off without first moving across
the ground unless the wind (airmass movement relative to the ground) is
blowing hard enough to give you sufficient airspeed to fly without moving.
In this case, once you take off your airspeed will immediately begin to
decrease unless you are using a prop to pull you through the air, or a
tether to hold you there (relative to the ground).

Example - a floatplane is sitting in a river that is moving at 30 mph (hey,
it's a fast river!). There is also a wind blowing down the river at 20 mph.

If the floatplane is anchored and facing into the wind, it has an airspeed
of 20 mph. If you release the anchor and use enough engine power to get the
plane going through the water upstream at 30 mph you will be standing still
with reference to the shore, and your airspeed will be 20 mph. If the river
was flowing at a rate in excess of the maximum speed of your airplane, then
you could never move forward going upstream with reference to the shore, and
your airspeed would never exceed 20 mph, even at full throttle. If you
fully understand this then you would know that you could shut your engine
down, face downstream, and take off and fly briefly.

BDS

"alexy" wrote

If the conveyor keeps the airplane standing still relative to the ground,
then it cannot take off.
Yeah, but the original statement of the problem made no such claim.

Alex - here is what the statement said:

"An airplane on a runway sits on a conveyer belt that moves in the
opposite direction at exactly the speed that the airplane is moving
forward. Does the airplane take off?" (Assuming the tires hold out, of
course.)

The plane cannot move forward - that means that it is standing still to me.

BDS

"BDS" wrote in message
m...


"An airplane on a runway sits on a conveyer belt that moves in the
opposite direction at exactly the speed that the airplane is moving
forward. Does the airplane take off?" (Assuming the tires hold out, of
course.)

The plane cannot move forward - that means that it is standing still to
me.

BDS


You are taking the statement 'a conveyer belt that moves in the opposite
direction at exactly the speed that the airplane is moving
forward' to mean that somehow there is a force being applied to the mass of
the aircraft, equal and opposite the thrust generated by the propellor. The
only place the treadmill can exert any force an the airplane is the only
place the treadmill is touching the airplane: the wheels. Any motion of the
treadmill belt will be translated into rotation of the wheels. This will not
prevent the aircraft from moving forward, through the air and taking off.

"BDS" wrote

This is where everyone who seems to think that the airplane will fly is
getting confused.

Nevermind - I finally get it.

DUH!!

BDS