What happens if you fly towards space ?

will you enter earth´s orbit?

With the proper ship you would be exiting earths orbit.

"Stan J. Lefosi" wrote in message
om...
will you enter earth´s orbit?

Stan J. Lefosi writes:

will you enter earth´s orbit?

You are in orbit at any time you are in free fall, so even if you jump
off a curb, you're in orbit until you hit the ground.

If you mean a stable orbit that decays only very slowly, you need to get
above the atmosphere to achieve that. This implies that you need a
spacecraft rather than an aircraft. Aircraft require air for their
engines, and for the aerodynamic phenomena that provide lift to keep
them suspended in the air. Beyond a certain altitude (usually from
30,000-90,000 feet, depending on the aircraft), there isn't enough air
to maintain lift and/or power the engines, and so you can't go any
higher than that, which prevents you from reaching a stable orbit (you
can still go into orbit at lower altitudes, but friction from the air
will cause your orbit to decay almost immediately).

To get clear of the atmosphere, you need something with a power source
that is independent of any need for air, such as a rocket, and you need
a power source that can provide all the necessary lift on its own,
without relying on any aerodynamic phenomenon.

Normally, then, if you fly towards space in an _aircraft_ (not a
spacecraft), eventually you'll run out of power or air, and you'll fall
back towards Earth. You may or may not be able to regain controlled of
the aircraft and resume normal powered flight after you've returned to a
lower altitude. It's tricky because at high altitudes you have
virtually no control over how an aircraft behaves (none of the control
surfaces really work), and you may go spinning uncontrollably back
towards the ground. In the right kind of aircraft with a competent
pilot, though, it is possible to regain control and return safely.

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i've had a 777 over chicago at 90,000 feet, no glide, lift, or power - just
free falling to earth like a skydiver. - and i couldn't regain control

the fun of FS04 on a rainy day

You may or may not be able to regain controlled of
the aircraft and resume normal powered flight after you've returned to a
lower altitude. It's tricky because at high altitudes you have
virtually no control over how an aircraft behaves (none of the control
surfaces really work), and you may go spinning uncontrollably back
towards the ground. In the right kind of aircraft with a competent
pilot, though, it is possible to regain control and return safely.

Mxsmanic wrote in message
...
Stan J. Lefosi writes:

will you enter earth´s orbit?

If you mean a stable orbit that decays only very slowly, you need to get
above the atmosphere to achieve that. This implies that you need a
spacecraft rather than an aircraft. Aircraft require air for their
engines, and for the aerodynamic phenomena that provide lift to keep
them suspended in the air. Beyond a certain altitude (usually from
30,000-90,000 feet, depending on the aircraft), there isn't enough air
to maintain lift and/or power the engines, and so you can't go any
higher than that, which prevents you from reaching a stable orbit (you
can still go into orbit at lower altitudes, but friction from the air
will cause your orbit to decay almost immediately).

You also need to be going very, very fast. Fast, as in 17,000mph fast.
Mach 25 fast. Basically, during a rocket launch, your spacecraft starts out
going almost straight up. It does this to get out of the atmosphere (which
would cause drag and heating and other nasty effects), and then pitches over
so it's basically flying horizontal. This is where all the speed is
required, and once your orbit is circular, you shut off the engines. From
there, you can change your orbit by using the engines in bursts (called
"burns"), the direction of which is specified by the laws of physics.

Tune2828 writes:

i've had a 777 over chicago at 90,000 feet, no glide, lift, or power - just
free falling to earth like a skydiver. - and i couldn't regain control

the fun of FS04 on a rainy day

I've done that, except with a 737. Typically the airframe is
overstressed on the way back down. Either you end up going too fast, or
you shear off the wings while trying to level out, or you get into weird
oscillations between semi-stable flight and vertical movement.
Fortunately, it's not a problem that is ever likely to arise in real
life, since getting up to 90,000 feet in a 737 would be problematic to
begin with.

I've noticed similar problems and instability when trying to
substantially exceed the service ceiling for the aircraft, even well
below 90,000 feet.

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Bob Martin wrote:

You also need to be going very, very fast. Fast, as in 17,000mph fast.
Mach 25 fast.

And if you manage to get up to 25,000mph, you'll leave to Earth's gravity well
entirely and won't go into orbit at all. At least, not around Earth.

George Patterson
You can dress a hog in a tuxedo, but he still wants to roll in the mud.

To get into orbit, your ship has to move at a speed high enough so that
the Earth's gravity can't "catch it" and bring it back down. Gravity
gets weaker as you get further away from a massive object like Earth, so
the speed required to break away is called "escape velocity". It works
out to about 7 miles per second (around 25,000 MPH) for a human-scale ship.

No known airplane except the Space Shuttle can reach this kind of speed,
and only then with an extremely large amount of fuel and some serious
rocket power strapped on! The wings, of course, have nothing to do with
getting up - they're only useful coming down.

If you can't get to escape velocity, you can't truly escape Earth's
gravity no matter how high you fly - even if you've got engines that
don't use air (rockets). In fact, if you don't want to completely leave
gravity well around Earth, your ship will have to maintain "orbital
velocity" just to circle the Earth - about 17,000 MPH for a satellite.
To be "in orbit" essentially means that you are constantly falling but
always "missing" the Earth!

-Scott

Scott Lowrey wrote:

To get into orbit, your ship has to move at a speed high enough so that
the Earth's gravity can't "catch it" and bring it back down. Gravity
gets weaker as you get further away from a massive object like Earth, so
the speed required to break away is called "escape velocity". It works
out to about 7 miles per second (around 25,000 MPH) for a human-scale ship.

Nope. If you get that fast, you won't go into orbit at all. What you have to do
is get high enough and fast enough that your centrifugal pseudo-force balances
Earth's gravity. That's less than escape velocity.

George Patterson
You can dress a hog in a tuxedo, but he still wants to roll in the mud.

Scott Lowrey writes:

To get into orbit, your ship has to move at a speed high enough so that
the Earth's gravity can't "catch it" and bring it back down.

To get into orbit, you must place your craft in a free-fall trajectory
that does not intersect with the Earth's surface or atmosphere. This
requires that you first get many miles above the planet's surface (in
order to avoid the atmosphere) and then move in a direction tangent to
the surface until the path of your free-fall trajectory misses the
Earth.

In practice, this means that you must reach an altitude of at least 185
km. The speed required tangent to the surface in order to enter a
stable orbit depends on your altitude, but at 200 km the speed is about
15,300 kt (yes, really!), or nearly 8 kilometres per second. Getting
that high and going that fast requires tremendous acceleration in order
to be achievable, and air-breathing craft cannot manage it.

Gravity gets weaker as you get further away from a massive
object like Earth, so the speed required to break away is
called "escape velocity". It works out to about 7 miles
per second (around 25,000 MPH) for a human-scale ship.

Escape velocity won't put you in orbit; escape velocity is the minimum
velocity required to leave the Earth's gravitational field faster than
it can decelerate you. If you can manage to reach a speed of 22,000 kt
at the surface of the planet, you'll zip right out of the Earth's
gravity and on into space. However, if you try this without leaving the
atmosphere first, only the burnt-out cinder of your craft will remain by
the time it gets out of the atmosphere, thanks to friction. Best to try
it only after getting above the atmosphere at lower speed.

If you can't get to escape velocity, you can't truly escape Earth's
gravity no matter how high you fly - even if you've got engines that
don't use air (rockets).

If you have unlimited propulsive power, you can escape gravity at any
speed, even at walking speed. The problem is that any propulsion system
with this kind of power and endurance would be too heavy to lift itself,
so in practice it can't be done (with current technology). The only
other option, then, is to accelerate so much that you can coast out of
the Earth's gravity without any additional propulsion. The faster and
harder you can accelerate, the more efficiently you can accomplish your
escape.

To be "in orbit" essentially means that you are constantly falling but
always "missing" the Earth!

Exactly. If the Earth were a dimensionless point with the same mass, it
would be virtually impossible to _prevent_ anything from going
immediately into orbit.

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