Can a Plane on a Treadmill Take Off?

wrote in message
oups.com...
What an inane thread! I am amazed at how many people are arguing about
such a silly subject.

There's nothing wrong with being interested in a brain-teaser.

Get a life people!

Oddly, your own busy life leaves you time not only to read a thread you're
not even interested in, but also to post here announcing your lack of
interest.

--Gary

Gary wrote:
What an inane thread! I am amazed at how many people are arguing about
such a silly subject.

There's nothing wrong with being interested in a brain-teaser.

Get a life people!

Oddly, your own busy life leaves you time not only to read a thread you're
not even interested in, but also to post here announcing your lack of
interest.

It is just another way for Dean to tell us that his life is much more
fulfilling than ours Gary. lol

The Monk

An idea that popped into my mind...
ywo subject question lines...
1. Can a plane on a treadmill take off?

2. Can a plane take off from a treadmill?

In the first instance, the airplane is attached to the
treadmill and would have to lift the weight and shape of the
treadmill. In the second, the airplane would behave
differntly depending on whether the treadmill was powered or
just a belt on rollers.
a. If just a belt on rollers, the engine thrust would drive
the airplane forward until it was not on the treadmill
anymore, thus it would have air movement over the wings and
would take-off. If the brakes were not locked, either or
both the tires and treadmill would "roll." If the brtakes
were set, the treadmill would roll and the airplane would
likely come to a stop when it departed the treadmill unless
it was alrady at flying speed.
b. If the treadmill was powered [and everything was timed
in sync] the belt would be accelerating rearward and the
engine thrust would be pulling forward at the same rate,
thus the airframe mounted wigs would have near zero airspeed
and lift and would not fly.
b1. If the treadmill was powered and ran forward, it would
act as a catapult and launch the airplane or at least
assist.


Hey, let's build a really big treadmill and try several
different airplane types, such as a Helio, a Maule, a Cessna
Caravan, and a C5 [a really big treadmill] and see what
happens.


--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"Flyingmonk" wrote in message
oups.com...
| Gary wrote:
| What an inane thread! I am amazed at how many people
are arguing about
| such a silly subject.
|
| There's nothing wrong with being interested in a
brain-teaser.
|
| Get a life people!
|
| Oddly, your own busy life leaves you time not only to
read a thread you're
| not even interested in, but also to post here announcing
your lack of
| interest.
|
| It is just another way for Dean to tell us that his life
is much more
| fulfilling than ours Gary. lol
|
| The Monk
|

"Jim Macklin" wrote:


b. If the treadmill was powered [and everything was timed
in sync] the belt would be accelerating rearward and the
engine thrust would be pulling forward at the same rate,
thus the airframe mounted wigs would have near zero airspeed
and lift and would not fly.

Just to "set the hook" here, are you saying that it will be possible
to have the conveyer move backwards fast enough that the plane remains
still, even under full power, and with no brakes on?
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

"alexy" wrote in message
news
Just to "set the hook" here, are you saying that it will be possible
to have the conveyer move backwards fast enough that the plane remains
still, even under full power, and with no brakes on?

I thought you had already established that it would be possible, and that
the treadmill speed is "somewhat below the speed of light"? You didn't
appear to solve the "materials integrity" aspect of the problem, but that
seems like a minor quibble.

Pete

"Peter Duniho" wrote:

"alexy" wrote in message
news
Just to "set the hook" here, are you saying that it will be possible
to have the conveyer move backwards fast enough that the plane remains
still, even under full power, and with no brakes on?

I thought you had already established that it would be possible, and that
the treadmill speed is "somewhat below the speed of light"? You didn't
appear to solve the "materials integrity" aspect of the problem, but that
seems like a minor quibble.


No fair; that's the next question, not to be asked out of order!! ;-)

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

"Peter Duniho" wrote:

"alexy" wrote in message
news
Just to "set the hook" here, are you saying that it will be possible
to have the conveyer move backwards fast enough that the plane remains
still, even under full power, and with no brakes on?

I thought you had already established that it would be possible, and that
the treadmill speed is "somewhat below the speed of light"? You didn't
appear to solve the "materials integrity" aspect of the problem, but that
seems like a minor quibble.

You know, there is a fallacy in my reasoning that I am surprised no
one has called me on. We are used to aerodynamic drag, which increases
as the square of velocity. But if my memory of high school physics is
correct (and if Newton hasn't changed his mind in the last 40
yearsg) the friction between two bodies is a coefficient of friction
times the force normal to the motion (i.e., the weight of the plane).
No component for the relative velocities of the two bodies! So the
drag due to wheels is small, and speeding up the conveyer will not
increase that small drag, at least until you get to the "noise"
elements that make the idealized drag model imperfect.

I guess that by _accelerating_ the conveyer, you could make the plane
use all of its power for a short while providing the angular
acceleration to the wheels, but you very quickly get to relativistic
speeds, without ever reaching a steady state tradeoff for the
engine/prop's thrust.

Much easier to just read the problem as stated, and have the conveyer
only move as fast backwards as the plane moves forward!!

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

"alexy" wrote in message
...
You know, there is a fallacy in my reasoning that I am surprised no
one has called me on. We are used to aerodynamic drag, which increases
as the square of velocity. But if my memory of high school physics is
correct (and if Newton hasn't changed his mind in the last 40
yearsg) the friction between two bodies is a coefficient of friction
times the force normal to the motion (i.e., the weight of the plane).
No component for the relative velocities of the two bodies!

Hardly seemed worth it, given the opportunity to equivocate on the point.
In particular, while the idealized friction drag remains static relative to
speed, that ignores the possibility for change in the materials as the
friction heats them. Expansion may create a higher normal force (depending
on what part expands faster), and thus higher frictional drag. It also
ignores aerodynamic drag around the surface of the tire.

While I haven't bothered to calculate what these increases would be, it
seems safe to say that it's *possible* they would rise fast enough to offset
the available thrust before reaching the speed of light.

Basically, in an arm-chair, lay-person discussion like this, practically
*anything* is possible as you approach the speed of light. So why not just
invoke that, and ignore the details?

Pete

Another pilot slips into the tar pit.

"alexy" wrote in message
news
"Jim Macklin" wrote:


b. If the treadmill was powered [and everything was timed
in sync] the belt would be accelerating rearward and the
engine thrust would be pulling forward at the same rate,
thus the airframe mounted wigs would have near zero airspeed
and lift and would not fly.

Just to "set the hook" here, are you saying that it will be possible
to have the conveyer move backwards fast enough that the plane remains
still, even under full power, and with no brakes on?
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked
infrequently.

sure, in our imaginary world. in the real world nobody will
try this so mechanical limitations are unimportant.


"alexy" wrote in message
news | "Jim Macklin"
wrote:
|
|
| b. If the treadmill was powered [and everything was
timed
| in sync] the belt would be accelerating rearward and the
| engine thrust would be pulling forward at the same rate,
| thus the airframe mounted wigs would have near zero
airspeed
| and lift and would not fly.
|
| Just to "set the hook" here, are you saying that it will
be possible
| to have the conveyer move backwards fast enough that the
plane remains
| still, even under full power, and with no brakes on?
| --
| Alex -- Replace "nospam" with "mail" to reply by email.
Checked infrequently.