Need Numbers to Complete Crazy Idea Proposal[slingshot to orbit]

On Dec 20, 7:00 pm, PD wrote:
On Dec 18, 3:07 pm, The Translucent Amoebae
wrote:



If you're just going to respond to this to add that this is a stupid
idea,
Then please try to restrain yourself...

OK

The idea is to put a single astronaut in a suit, or very small
capsule, into low Earth Orbit, for 2 or 3 trips around the Earth.
Cost ???

First:
Build a HUGELY HUGE, REALLY HUGE, WITH THE IDEA OF BEING HUGE IN
MIND...
Helium Balloon Shaped like a Donut. Oriented while in use, so that the
Hole in the Donut is Perpendicular to The Earth. So looking up, you
could see Space, looking down, you would see The Earth.

Second:
You build a Platform under the Balloon with a common Rubber Tube
Slingshot attached,
So that when the Balloon is at it's apogee, which is aided by heating
the helium in the balloon,
You slingshot the astronaut into orbit, through the hole in the
balloon.

Third:
The Balloon is tethered to the Earth by a very strong fishing line, So
that the helium in the Balloon is cooled, and the donut is reeled in,
for reuse.
---
My original idea, before the fishing line idea, was to add some
shutters to the balloon that would close after use, and on their
surfaces, of the blinds, would accumulate enough space dust that it
would eventually descend to the ground, where the blinds would be
opened, to launch another astronaut into orbit...
But even i thought was stupid.

So--
Obviously this is a crazy idea, but i'm much more interested in how
difficult it would be,
That is; Just how much trouble would it be to make it work...
Rather than Negative Nellies just telling me to Shut Up.

Thanx!

The numbers tell you in an eyeblink how crazy this really is. That's
the value of being able to do back-of-the-envelope calculations -- you
can dismiss dumb notions quickly.

Orbital velocity is about 16,000 mph, or about Mach 21. You need that
speed to get into orbit no matter how high the launch point is. That
is, if you managed to get the astronaut all the way to orbital
altitude in the balloon, you'd *still* have to fire him at 16,000 mph.
Now, the human body can tolerate an acceleration of about 6 gees for a
duration of several seconds. Any higher acceleration or longer
duration and you damage the astronaut, which would not go over well on
the evening news. Getting to 16,000 mph (23,400 ft/s) at 6 gees takes
about 120 seconds or a full 2 minutes of sling-shot slinging. Now you
can calculate how long the bungee cord has to be to sling an astronaut
from rest to 16,000 mph over a 2 minute sling. You may be amused to
obtain the result that the stretch distance of that rubber band has to
be about 1,400,000 feet, or 270 miles, which is about 3 times further
than the orbital altitude you're trying to get to. So unless you want
to dig a hole 260 miles deep to stretch back a rubber band far enough
to launch an astronaut 90 miles in the sky and not turn him into a
spacesuit full of blood sausage, I'd say you have a feasibility issue.

Compound this with the fact that helium is actually a pretty rare
substance on the earth. You want a really really HUGE HUGE helium
balloon, but you've got no idea (I guess) whether there's enough
helium available to fill that HUGE HUGE helium balloon up.

Now, I hope that isn't being too much of a Negative Nellie.

PD

Agreed you probably would not want to do this with a manned ship. But
let's suppose it was only for cargo. Hardened computer chips in some
artillery shells can withstand accelerations of 10's of thousands of
g's. At this acceleration the distance now would only be in the 10's
of meters range. The question now is are there materials that could
withstand this kind of stretching to induce such high velocities?
This page gives some values of strength of materials and velocities
that could be withstood by the materials:

STRUCTURAL MATERIALS.
http://www.islandone.org/LEOBiblio/SPBI1MA.HTM

The "characteristic velocity" listed in the table is the maximum
speed the material could withstand if you wanted for example to make a
flywheel of this material. You see to get up to orbital velocity in
the range of 7000 to 8000 m/s only buckyball material, same as for
carbon nanotubes, would suffice IF you wanted to do this by for
example twirling the craft at high speed in a circle with a rope made
of the material.(However, it might be you could get higher than the
speeds listed by using tapering.)
But it is not clear to me this "characteristic velocity" is the right
speed to use for the idea of using a stretched elastic band. It might
instead be the longitudinal sound speed in thin rods listed on the
"STRUCTURAL MATERIALS" page. And this speed for several high strength,
low weight materials already in common use is higher than orbital
velocity.
A related question could you use these high longitudinal sound speeds
to induce propulsive mass to high exhaust velocities? A possibility:
have a molecularly thin plate sticking up perpindicularly to the rod.
Then as the molecules were vibrating at the high speed the plate would
be made to move back and forth also at the very high speed. Then a gas
used for the fuel could be made to move at high speed by being pushed
by the plate. You would need to remove the gas from the plate once it
reached the highest speed.


Bob Clark

Dear Robert Clark:

"Robert Clark" wrote in message
...
....
Agreed you probably would not want to do this with a
manned ship. But let's suppose it was only for cargo.
Hardened computer chips in some artillery shells can
withstand accelerations of 10's of thousands of g's. At
this acceleration the distance now would only be in the
10's of meters range. The question now is are there
materials that could withstand this kind of stretching to
induce such high velocities?

What is the point? They will vaporize passing through the
atmosphere. Perhaps you did not notice that even the tenuous
atmosphere at 60 miles was enough to vaporize a space shuttle at
less than full orbital speed. And you want to do this speed at
ground level?

David A. Smith

On Dec 21, 12:08 am, "N:dlzc D:aol T:com \(dlzc\)"
wrote:
Dear Robert Clark:

"Robert Clark" wrote in message

...
...

Agreed you probably would not want to do this with a
manned ship. But let's suppose it was only for cargo.
Hardened computer chips in some artillery shells can
withstand accelerations of 10's of thousands of g's. At
this acceleration the distance now would only be in the
10's of meters range. The question now is are there
materials that could withstand this kind of stretching to
induce such high velocities?

What is the point? They will vaporize passing through the
atmosphere. Perhaps you did not notice that even the tenuous
atmosphere at 60 miles was enough to vaporize a space shuttle at
less than full orbital speed. And you want to do this speed at
ground level?

David A. Smith

No, rockets to orbit already reach such high speeds at this
altitude.

BTW, here is a list of alternative methods of launching to orbit
including "slingshot" methods:

Earth-to-Orbit Transportation Bibliography, February 18, 2005.
http://www.islandone.org/LEOBiblio/


Bob Clark

Dear Robert Clark:

"Robert Clark" wrote in message
...
On Dec 21, 12:08 am, "N:dlzc D:aol T:com \(dlzc\)"

wrote:
Dear Robert Clark:

"Robert Clark" wrote in message

...
...

Agreed you probably would not want to do this with a
manned ship. But let's suppose it was only for cargo.
Hardened computer chips in some artillery shells can
withstand accelerations of 10's of thousands of g's. At
this acceleration the distance now would only be in the
10's of meters range. The question now is are there
materials that could withstand this kind of stretching to
induce such high velocities?

What is the point? They will vaporize passing through
the atmosphere. Perhaps you did not notice that even
the tenuous atmosphere at 60 miles was enough to
vaporize a space shuttle at less than full orbital speed.
And you want to do this speed at ground level?

No, rockets to orbit already reach such high speeds
at this altitude.

No they don't. They hit mach 7 to 12 at those same altitudes.
And you want to hit orbital velocity in "10s of meters"? Rockets
lift up first, to get clear of some atmosphere, then they tilt
over to gain orbital momentum. You can't "flick" something
straight up at orbtial speed plus, and end up in a circular
orbit. There is no path that contains a point on the surface,
that won't contain another point on the surface on the next
orbit. Unless you hit escape velocity, or apply *lots* of thrust
in some other way than slingshotting.

David A. Smith

On Dec 21, 9:02 am, "N:dlzc D:aol T:com \(dlzc\)"
wrote:
Dear Robert Clark:

"Robert Clark" wrote in message

...



On Dec 21, 12:08 am, "N:dlzc D:aol T:com \(dlzc\)"

wrote:
Dear Robert Clark:

"Robert Clark" wrote in message

...
...

Agreed you probably would not want to do this with a
manned ship. But let's suppose it was only for cargo.
Hardened computer chips in some artillery shells can
withstand accelerations of 10's of thousands of g's. At
this acceleration the distance now would only be in the
10's of meters range. The question now is are there
materials that could withstand this kind of stretching to
induce such high velocities?

What is the point? They will vaporize passing through
the atmosphere. Perhaps you did not notice that even
the tenuous atmosphere at 60 miles was enough to
vaporize a space shuttle at less than full orbital speed.
And you want to do this speed at ground level?

No, rockets to orbit already reach such high speeds
at this altitude.

No they don't. They hit mach 7 to 12 at those same altitudes.
And you want to hit orbital velocity in "10s of meters"? Rockets
lift up first, to get clear of some atmosphere, then they tilt
over to gain orbital momentum. You can't "flick" something
straight up at orbtial speed plus, and end up in a circular
orbit. There is no path that contains a point on the surface,
that won't contain another point on the surface on the next
orbit. Unless you hit escape velocity, or apply *lots* of thrust
in some other way than slingshotting.

David A. Smith

This page gives the velocity and altitude of the STS-30 space shuttle
mission at main engine cutoff (MECO) as 24,286 ft/s, Mach 22.70, or
7360 m/s, and 362,243 ft, 68.6 miles:

Aerospaceweb.org | Ask Us - Solid Rocket Booster Jettison.
http://www.aerospaceweb.org/question...ft/q0183.shtml

The shuttles last step to its final orbit is provided by onboard fuel
and engines after the SRB's and external tank have been jettisoned.

Also, there have been plans to use high velocity cannon launchers
even from the surface to send small satellites at or near orbital
velocity. There was also recently discussed a plan to do this using
magnetic fields to accelerate a craft around in a ring until it
reached orbital velocity.
Actually for the launch from a helium balloon idea you couldn't get
as high as 60 miles since the highest such balloons can reach is about
150,000 ft about 30 miles. Still the air friction and drag at this
altitude wouldn't be insurmountable obstacles as long as you could
reach sufficient velocity since well thought out proposals for doing
this even exist for launch from the surface.


Bob Clark

On Dec 21, 8:15*am, Robert Clark wrote:
On Dec 21, 9:02 am, "N:dlzcD:aol T:com \(dlzc\)"
wrote:





Dear Robert Clark:

"Robert Clark" wrote in message

...

On Dec 21, 12:08 am, "N:dlzcD:aol T:com \(dlzc\)"

wrote:
Dear Robert Clark:

"Robert Clark" wrote in message

....
...

Agreed you probably would not want to do this with a
manned ship. But let's suppose it was only for cargo.
Hardened computer chips in some artillery shells can
withstand accelerations of 10's of thousands of g's. At
this acceleration the distance now would only be in the
10's of meters range. The question now is are there
materials that could withstand this kind of stretching to
induce such high velocities?

What is the point? *They will vaporize passing through
the atmosphere. *Perhaps you did not notice that even
the tenuous atmosphere at 60 miles was enough to
vaporize a space shuttle at less than full orbital speed.
And you want to do this speed at ground level?

No, rockets to orbit already reach such high speeds
at this altitude.

No they don't. *They hit mach 7 to 12 at those same altitudes.
And you want to hit orbital velocity in "10s of meters"? *Rockets
lift up first, to get clear of some atmosphere, then they tilt
over to gain orbital momentum. *You can't "flick" something
straight up at orbtial speed plus, and end up in a circular
orbit. *There is no path that contains a point on the surface,
that won't contain another point on the surface on the next
orbit. *Unless you hit escape velocity, or apply *lots* of thrust
in some other way than slingshotting.

*This page gives the velocity and altitude of the STS-30 space
shuttle mission at main engine cutoff (MECO) as 24,286 ft/s,
Mach *22.70, or 7360 m/s, and 362,243 ft, 68.6 miles:

At altitude. Out of the atmosphere.

In the atmosphere, it travels much slower. Down near the surface of
the Earth.

...
*Actually for the launch from a helium balloon idea you couldn't
get as high as 60 miles since the highest such balloons can
reach is about 150,000 ft about 30 miles.

With negligible loads.

Still the air friction and drag at this altitude wouldn't be
insurmountable obstacles as long as you could reach sufficient
velocity since well thought out proposals for doing this even
exist for launch from the surface.

The problem is, that you need a massive power source to power the
catapult, and you will literally blast your balllon to tiny shreds by
recoil at mach numbers proportional to your "lauched divided by
launcher mass". You have a massive object that will come crashing
back to Earth, so you will need to recover the launcher too.

I wanted to do a magnetic catapult with a nice long ramp, releasing at
about 2-3 miles altitude, and couple the release with a soliton
generated at the ramp exit, into which the launch vehicle is
injected. Still need non-trival engines to "circularize" the orbit,
but, not quite so much fuel would need to be lofted...

David A. Smith