FYI: Dec 12 MythBusters: Airplane Hour

"Morgans" wrote in message ...


Well, all but Shawn Tucker's plane. I think he could make the turn in less time than .1 second, from the crazy crap I
have seen him do!
--
Jim in NC


Shawn ends up with bug splats on the wing trailing edge!

"Gladrock" wrote in message
...

I'm amazed that this argument is happening. You are arguing about the
behaviour of a non-existent aircraft doing something that real aircraft
cannot do. Why don't you discuss what a real aircraft, turning downwind at
a normal rate will do. Every pilot has to make a downwind turn entering
the pattern, it appears to be a fairly survivable manoeuvre.

I believe I am pointing out how the non flying public sees the problem, in
their heads.

They do not understand that as the turn is made over time, it accelerates
with the air mass, so nobody can tell the difference.

A plane exhibiting the characteristics I pointed to is how they see the
problem unfolding.
--
Jim in NC

"Gladrock" wrote:

I'm amazed that this argument is happening. You are arguing about the
behaviour of a non-existent aircraft doing something that real aircraft
cannot do. Why don't you discuss what a real aircraft, turning downwind at a
normal rate will do. Every pilot has to make a downwind turn entering the
pattern, it appears to be a fairly survivable manoeuvre.

Unlike a 0.1 second 180 degree turn (effectively the same as going
from 140 knots to zero in 0.1 seconds). I suppose the whole point
would become moot since the PIC would e splattered all over the
cockpit.

OTOH, the only way that most people can get their arms around this
concept is to reduce it to absurd levels (which the 0.1 second U-turn
is, of course).

I like to use the example of flying a toy helicopter inside a bus to
describe the concept of downwind turns. Doesn't really matter how
fast the box full of air is going, the helicopter will behave the same
(minus the effects of accelerating the bus, of course).

Mark "how many G's is that?" Hickey

"Morgans" wrote in message
...

"Gladrock" wrote in message
...

I'm amazed that this argument is happening. You are arguing about the
behaviour of a non-existent aircraft doing something that real aircraft
cannot do. Why don't you discuss what a real aircraft, turning downwind
at a normal rate will do. Every pilot has to make a downwind turn
entering the pattern, it appears to be a fairly survivable manoeuvre.

I believe I am pointing out how the non flying public sees the problem, in
their heads.

They do not understand that as the turn is made over time, it accelerates
with the air mass, so nobody can tell the difference.

A plane exhibiting the characteristics I pointed to is how they see the
problem unfolding.
--
Jim in NC

I willing to bet that the non flying public looks up and sees a plane and
thinks, hmm.. a plane, without giving any thought at all to flight in
various attitudes.

On Dec 9, 9:03 am, "Blueskies" wrote:
"Maxwell" wrote in ...

"B A R R Y" wrote in messagenews:ghrnl3h2rm847jvivviio87sa7arlkjvo7@4ax .com...
On Sun, 9 Dec 2007 09:12:27 -0400, " Vacant lot
wrote:

I don't understand the premise of the conveyor belt thing. If you are
talking about thrusting an aircraft forward, like a catapult, you already
know the answer, and if the belt is running so the the wheels of the
aircraft are spinning madly while it stays still then again you already know
the answer. What are they trying to prove?

If it were so cut and dried, why does it generate threads of several
hundred messages here? G

Only because there are one or two nit pickers on here.... G

Maybe we should start the thread drift right here and now....

You know, people would fully understand that a plane on a treadmill will not start flying if we had a good educational
system. Liberal use of aerodynamic principles leads to stall spin accidents, and everyone knows the dreaded downwind
turn was by global warming...- Hide quoted text -

- Show quoted text -

Dude, you can't be serious with that educational system crap. Yes, the
American public education system could use some help, but I'm a
college senior and I can't tell you **** about aerodynamics

On Dec 9, 1:54 am, James Sleeman wrote:

safely land an airplane and if a plane can take off from a conveyor belt

Oh lordy, here we go again, I sense an enormous thread coming.

It started in 1931. Look at patent number 1824346.

I think that a plane could be doing 70kts due north and be going south
..1 second later without missing a beat.

Morgans wrote:
Ah, but if you are flying near stall with the wind, and the wind suddenly
slows, will you stall?
Yes -- Your momentum needs to catch up with your new (reduced) airspeed.

.OR.
If you are slow on approach, into a gusty head wind, and a gust suddenly
resides, will you stall?
It depends on how much margin you have between stall and airspeed to
begin with. If the margin is less than the (now non-existent) gust, you
will stall. Otherwise, you will see a sudden increase in sink rate. I
guess it might not be fair to call it a stall.

Everyone, remember that this is not a real airplane, but instead it is a
theoretical airplane, like in physics class, where they tell you to figure a
problem without any friction being taken into account.

This airplane was going 70 knots (airspeed) north, with a 30 knot wind out
of the north, and it suddenly, and instantly is going to be going south, in
.1 second.

That means it had 40 knots worth of momentum. When that sudden reversal of
direction takes place, it will have the same momentum, for that first
instant of reversed flight, until the wind blowing at its back starts to
blow on it and accelerate it. That means the 40 knots of momentum will have
the airspeed component of the tailwind subtracted from it, so 40 knots minus
30 knot wind means it will see an airspeed (only for an instant) of 10
knots, until the tail wind plus the thrust starts accelerating the plane
back to its original airspeed of 70 knots.

I would agree that the airplane would develop a VERY serious sink rate.
Would that be a stall, though? g

On Dec 8, 10:20 pm, buttman wrote:
On Dec 8, 9:32 pm, Jim Logajan wrote:

"Jamie and Adam take wing to test if a person with no flight training can
safely land an airplane and if a plane can take off from a conveyor belt
speeding in the opposite direction. Tory, Grant, and Kari jump on some
Hollywood-inspired skydiving myths."

Quoted from the Discovery channel schedule:http://dsc.discovery.com/tv-schedule...=1.13056.24704....

(My local paper's weekly TV schedule has just the brief summary "Landing a
747" so I presume the plane they attempt to land without training is a 747.
Will be interesting to see if they try the real thing and are not limited
to a simulator.)

I'm really anxious to see this episode, because apparently they filmed
the treadmill myth at my home airport.

What is the tredmill myth based on? Is the assertion that an aircraft
takes flight because of the speed of the tires?

-Robert

"Robert M. Gary" wrote:
What is the tredmill myth based on? Is the assertion that an aircraft
takes flight because of the speed of the tires?

Cecil Adams dealt with the treadmill myth in the following column:

http://www.straightdope.com/columns/060203.html

And about a month later dealt with it again:

http://www.straightdope.com/columns/060303.html

I can only hope that the Myth Busters properly interpreted the original
problem statement and did not confuse it with one of the variants floating
around the net.

I also hope that they have a "Science Content" discussion that points out
the importance of clearly understanding the problem statement.

Dave wrote:
I think that a plane could be doing 70kts due north and be going south
.1 second later without missing a beat.


As it passes over the North Pole?