Hypersonics Overhype

Build a tower 15 miles high? Umm, please correct me if im wrong, but this
is not possible using current materials technology. Concrete/steel/titanium
construction will only get you up to about 8 miles, and then you would have
to be satisfied with a zero-weight loading at the top of a significantly
tapered structure. Base something like 5 miles wide for the 8 mile high
structure!

Not to mention that such a construction project would be a bit....pricey.

I'm not a structural engineer, but it seems to me that an 8 mile high tower
doesn't need to be a solid structure. You could have a 5 mile wide base with
lots of space between the supports. The rest of the effort would be to get the
scram jet to fly at lower altitudes to meet the tower half-way. It also helps
if the base of the tower starts at 2 miles above sea level. Mount Everest is 5
miles high, one might build a maglev track up its slope, that would be cheaper
than building an 8-mile high tower and it would bring jobs to the local
Nepalese economy.

Tom

We are not even up to half a mile and for very obvious reasons - there is
utterly no need for such. I mean - gosh, what the heck would you use all that
space for?


Launching a scramjet. The tower would exist solely to launch the scramjet,
there would be no offices, and no multiple elevators to stop at the midlevels.
The only people to stop their would be the maintenence crew. Most people would
be interested in ascending to the top as quickly as possibly. If the load is
too much for the scramjet to bear, it can be encase in a heat shield until it
ascends to sufficient altitude after leaving the track and then ejected so that
it can operate in thinner air. The initial speed would have to be fast enough
so that its still moving at sufficient velocity when the appropriate altitude
is reached.

Tom

How would you overcome wind and gravity?

Eric


Inertia. Make sure the object leaves the track at sufficient velocity such
that, accounting for wind resistance and gravity, it is still traveling at high
enough velocity when the right altitude is reached for the scramjet to operate.

Tom

"Sander Vesik" wrote in message ...

And a mile being 52x0 feet ( forget the value of x, but it was not 0),
its not even exactly 17 miles.

http://www.google.com/search?q=90,000ft+in+mi

But here's my suggestion:
http://www.google.com/search?q=90,000ft+in+km



--
__ “A good leader knows when it’s best to ignore the __
('__` screams for help and focus on the bigger picture.� '__`)
//6(6; ©OOL mmiv :^)^\\
`\_-/ http://home.t-online.de/home/ulrich....lmann/redbaron \-_/'

You might find that there aren't any suitable locations to build such
a beast. For example, you might find the right mountain, but it may
be located in an area that's largely inaccessible.

This discussion is pointless anyway. In the near term, this doesn't
do anything for *cheap* access to space.

Jeff

I have a cousin who spent some time in Nepal in the shadow of Mount Everest, he
got there, so it is accessible.

Tom

lid (John Savard) wrote in
:
... I was thinking
that a 20 mile high artificial mountain, if it were possible to build
one without it flowing like taffy,
.
.
.
The fact that the base might be, say, 125 miles wide, would not be a
big deal, just site the tower somewhere where land is cheap.

"Building" a mountain 20 miles high will require a material with a
significantly better compressive strength than any natural mineral on
earth. Compensating for this by using a very gentle slope (your "125 miles
wide" base) will put sufficient stress on the local tectonic plates that
you will trigger a regional subsidence. Earthquakes galore!

There is a very sound reason why mountains on earth are limited in height.

Artificial materials, having compressive strengths many times more than
rock, can build a more slender building. But keep in mind this general
rule: Double the building's height, and you increase its weight by 8. A
building's mass is approximately proportional to the third power of its
height, when the height exceeds that at which a monotone cylinder of the
construction material fails to support its own weight.

By this rule your 20-mile-high building would be some 468552 times heavier
than the twin towers were. Meaning it would cost about 250 years of the
complete US GDP.

On 2 Apr 2004 21:19:11 +0200, in a place far, far away, Marvin
made the phosphor on my monitor glow in such a
way as to indicate that:

There is a very sound reason why mountains on earth are limited in height.

Yes, and it has nothing to do with compressive strength.

Artificial materials, having compressive strengths many times more than
rock, can build a more slender building.

What materials have compressive strength many times more than rock?

TKalbfus wrote:
Build a tower 15 miles high? Umm, please correct me if im wrong, but this
is not possible using current materials technology. Concrete/steel/titanium
construction will only get you up to about 8 miles, and then you would have
to be satisfied with a zero-weight loading at the top of a significantly
tapered structure. Base something like 5 miles wide for the 8 mile high
structure!

Not to mention that such a construction project would be a bit....pricey.

I'm not a structural engineer, but it seems to me that an 8 mile high tower
doesn't need to be a solid structure. You could have a 5 mile wide base with

This does not help signifcantly with the problem at hand.

lots of space between the supports. The rest of the effort would be to get the

It would make more sense to have the upper parts look like this. The higher
you are the more youwant it to be both lightweight and resistant to wind.

scram jet to fly at lower altitudes to meet the tower half-way. It also helps
if the base of the tower starts at 2 miles above sea level. Mount Everest is 5
miles high, one might build a maglev track up its slope, that would be cheaper
than building an 8-mile high tower and it would bring jobs to the local
Nepalese economy.

Ha ha ha ha ha. So not only do you want to build a two orders of magnitude
higher building than has been built before, you also want to build it in an
inpossibly remote place with incredibly large logistics problems not to
mention no local materials or workforce for it.


Tom

--
Sander

+++ Out of cheese error +++

TKalbfus wrote:

I'm not a structural engineer, but it seems to me that an 8 mile high tower
doesn't need to be a solid structure. You could have a 5 mile wide base with
lots of space between the supports. The rest of the effort would be to get the
scram jet to fly at lower altitudes to meet the tower half-way. It also helps
if the base of the tower starts at 2 miles above sea level. Mount Everest is 5
miles high, one might build a maglev track up its slope, that would be cheaper
than building an 8-mile high tower and it would bring jobs to the local
Nepalese economy.


You ever see "Murder On The Orient Express" where the train gets stuck
due to an avalanche on the tracks?
Okay, now our scramjet Orient Express is going up the side of Mount
Everest when the sound of its acceleration startles a Yeti searching
for the bodies of frozen climbers on the mountain's summit (this being
the Everest Yeti's current primary food source; having completely
replaced the rich supply of Tibetan Buddhist monks that were its staple
before the Chinese arrived, and whose prayer wheels made such amusing
toys for Yeti young), which then trips over one of the 800 or so
National Geographic Society flags that cover the mountain top like a
forest- the Yeti falls, dislodging that dread _first snowflake_....which
common knowledge assures us must inevitably lead to an immense
avalanche.... an avalanche which then engulfs the launch track as the
scramjet ascends.
We now cut to the scene of the gleeful Yeti as it jumps up and down in
delight at the fireworks show above it, and the rain of human body parts
descending from the sky like heavenly manna into the snow around it.

Pat :-)

TKalbfus ) wrote:
: How would you overcome wind and gravity?
:
: Eric
:

: Inertia. Make sure the object leaves the track at sufficient velocity such
: that, accounting for wind resistance and gravity, it is still traveling at high
: enough velocity when the right altitude is reached for the scramjet to operate.

No, the wind and gravity are questions about the structure not the ramjet.

Eric

: Tom