Patent Application Number 2009761.4
BACKGROUND
At present, the only way we can get into space is with space rockets
which are extremely expensive and dangerous. For this reason people
are looking for alternatives and one of the most outrageous ideas is
the Space Elevator. The idea being to lower a cable down from a
geostationary satellite (35,786 km or 22,236 miles high) so space
cargo can climb up this cable. The problem is that it is totally
unpracticable with today’s technology as you need a cable so long
62,000 miles,100,000 km to go to a counter weight, beyond
geostationary orbit, that it will break under its own weight.
Some people have proposed building a
building a tower up into space but it would be a gigantic project
that would be as difficult as the Space Elevator. As you will have to
deal with tremendous compression forces and made it extremely wide at
the base, at least 10 miles (16 kilometres) or more, to prevent it
toppling over or being blown down by the wind. But this is only true,
if conventional building methods are used.
Then there is the proposed ThothX Tower which is just a giant balloon
12 mile high. It would be so large that a runway can be built on top
of it, but the design has problems with strong winds and 12 miles
high is still well short of what is needed.
There are also space companies who are attempting to launch space
rockets from aircraft. The problem with this is that the highest an
aircraft can take a space rocket is about 7 miles. Whereas most
satellites orbit the Earth between a 120 to 200 miles high. So 7
miles up is not a big advantage and this is why many space
organizations don’t consider an air-launch.
A tube or mast would be a lot smaller and cheaper than a massive
tower but the objections to this, is that a mast has to be held up
with guy cables to prevent the wind blowing it over, and there is a
limit in how high you can take them. The highest was the Warsaw
Radio Mast which was 646 meters, or 0.4 of a mile in height.
Then there still be a problem of compression forces that will bend
and buckle the mast if it goes up too high. Nowadays we have light
materials like carbon fibre. Though it will be epoxy resin that is
mixed with carbon fibre, that will be taking the compression load,
and manufacturers claim it can be made harder than concrete. Then
there are lighter materials like graphene which hasn’t been mass
produced yet. Although many pressure vessels are made from composite
material like steel or aluminium reinforced by carbon fibre. Metals
have the advantage of being as strong in tension as they are in
compression.
But this is not the only problem, any slight bend in the tubes, will
be made far worse by the compression forces bearing down on it. Then
there is the problem of the tube from being blown over by strong
winds like gales and hurricanes.
It is these problems that need to be solved, to make a Space Tube
possible.
ABSTRACTION
Pressurised tube
All the problems of a space tube that can reach up into space, can be
solved with a pressurised tube, lighter building materials and active
support. Although the pressure in a pressurised tube can help resist
downward compression forces and buckling the walls of the tube. It
still has the weight of an extremely long tube bearing down on it.
But the pressurised air in the tube can also provide sideways and
upwards force to keep the tube vertical and counter compression
forces. It is this that will take the place of guy cables to keep the
tube upright. So how high can something like this go? It seem it can
go up a very long way.
Nowadays people can buy compressors and pressure tanks for air-guns
and scuba gear that compress air up to 4,500 psi or 300 bars. As
normal air pressure at sea level is about 14.5 psi, or 1 bar, if the
tube at ground level is pressurised by compressors, then it will be
possible to keep high air pressure a long way up an extremely long
tube.
The troposphere is about 7 miles or 12 kilometres high, so in theory
if the tube at the base is pressurised to 4,500 psi or 300 bars, the
troposphere could be extended up in the tube, 300 times that height,
which will be 2,100 miles or 3,600 kilometres high. This is as high
as geostationary orbit. Though the pressure at the top of the
troposphere and therefore the tube, will be about only 10% of the air
pressure at sea-level.
But industry uses pressure vessels with far greater air pressure, for
instance, titanium pressure vessels are capable of holding between
30,000 psi to 200,000 psi. A Space Tube with 43,500 psi or 3,000
bars at its base could deliver normal sea level pressure up to
geostationary height. So it suggests it can be done, a extremely long
pressurised tubes that can be extend a long way into space, with
today’s technology.
Although in theory, a pressurised tube could make it all the way up
to geostationary orbit, it will be a big project costing a lot of
money. So before doing that, there is a more modest target that would
be a lot easier and cheaper, and that is low orbital height of 120
miles high (190 kilometres). A pressurised tube of 300 bars could
probably deliver between 1-2 bars of air pressure at that height.
While 30,000 psi or 2068 bars would deliver 7 times that amount of
air pressure.
So a pressurised tube can deliver to this orbital height, the upper
stage of rockets, that do not have to be fired up there by really
large throw-a-way rockets. At that height, it can accelerate
horizontally with no air resistance and without needing to push
upwards enormous fuel tanks a hundred miles.
The objection to this, is that surely an extremely high tube would
fall over and normally that would be true. But a pressurised tube can
use a variety of different ways to to keep it vertical, while at the
same time provide upwards lift to counter compression forces. The
pressurised air in the tube can be vented outside to give both
sideways and upwards push, to the whole structure.
The thrust of compressed air can be increased with electric
propulsion like Arcjets, Resistojets or even a Ion drive. These can
be powered from electric cables from a ground based power station.
Electric fans or propellers can also use the compressed air to give
greater push where the atmosphere is too thin for propellers to
operate. Even lighter-than-air gases like methane or hydrogen can be
pumped up the tube and the gases can be burnt in combustion chambers
along with compressed air, to blast out with the thrust of a
jet-engine.
Venting air out of the tube will create a strong upwards air current
and this can be utilized, with fixed curved blades shaped like a fan.
As the air comes up the tube the fixed blades will turn the air
sideways creating upwards lift or use autorotation rotors. Downward
facing aerofoils can also use the upwards air currents in the tube to
give sideways push to help keep the tube upright.
Also, lightweight reaction wheels can be used. These are used by
satellites like space telescopes to turn the satellite in whatever
direction that is needed, by changing the speed of their spin.
Although they are light weight they can be very powerful if the
revolutions are high. Which they can be, if using electricity from
electrical cables from the ground.
Reaction wheels are used not only on satellites but people can use
them to balance things like poles. So they would be perfect to
balance a tube in the thin air of the upper atmosphere above the
weather where there are no strong winds. Though in the
troposphere where there will be less an issue about weight, reaction
wheels can be made heavier to have the power to counter any swaying
movement by the tube.
Though probably downward facing aerofoils
would probably be more effective in the pressurized air of the lower
tubing. While reaction wheels will be more effective further up as
the air pressure in the tube decreases.
DETAILS
Probably the best way to engineer a tube like this is to build it
similar in shape to the Eiffel Tower, with a wide base and a cone
like shape going up to top of the troposphere and then a straight
tube after that. But a wide cone, could dramatically add cost to the
whole project so a straight tube would be easier to build and can be
kept upright in the troposphere with jet thrusters, heavy weight
reaction wheels or downward facing aerofoils.
Jet thrusters will have more power than any strong wind like gales,
cyclones or the jet-stream blowing against the tube. The gases can
be burnt in combustion chambers along with compressed air, to blast
out with the thrust of a jet-engine. There can be 4 or 5 of them
around the tube with perhaps gimbaled
nozzles and only used when the wind becomes too strong for reaction
wheels or aerofoils. There will have to be more on the tube that is
really needed, in case, some of them don’t work properly when
switched on.
Obviously it wouldn’t be a good idea to have these thrusters on all
the time and they can be used only where there are strong winds. They
can be controlled by movement and pressure sensors, gyroscopes,
computers, anemometers and wind vanes. Nowadays, technology like this
is used to keep small multi-copters stable, as well as rockets as
they leave the launch pad.
An
alternative to jet thrusters are fans, compressed air from the tube
can be boosted by a fan or propeller when vented out of the tube.
The problem with this, is that there will be a big difference in
pressure between the pressurized air in the tube and the air outside
the tube, especially if it is in the thin air of the upper
atmosphere. So the air will come out of the vent holes extremely fast
and so it would need a extremely high speed propeller to be propel
this air even more quickly.
The way around this is to vent the air downwards
into a diffuser,
a cone shaped tube, which will decelerate and expand the air. Then a
fan or propeller just inside the wider mouth of the cone, can
accelerate the air once again, giving more lift.
Above the troposphere the tube will be above the weather so
hopefully gas jets won’t have to be used. The thrust of compressed
air can also be increased with electric propulsion like Arcjets,
Resistojets or even a Ion drive. On spacecraft these are powered by
solar panels which are limited in power. Whereas a Space Tube
wouldn’t have any such restrictions as electric jets can be powered
from electric cables from the ground. The advantage of electric jets
is that they would be far less bulky than a large diffuser and fan
and there is no need to pump gas up the tube if using gas jets. All
that is needed is an electric cable to power them.
Some people might object that venting air out of the tube will
greatly reduce its air pressure, and it will to some degree. But if
the amount of air escaping is controlled and calculated, then the
compressors on the ground can compensate for the lost air and keep
the pressure high by having more compressors, pump extra air into the
tube.
Although pressurised tubes made from carbon fibre will be able to
resist downwards compression forces to some degree, a tube of a
hundred miles or more, will become extremely heavy. So any upwards
lift that can be gained with any type of thrusters or fixed vanes
will be make it possible for the mast to be longer. All these things
will be needed to keep the tube upright and resist downward
compression forces.
So the supply of compressed air is important but will be drained off
to power thrusters of various types, but this is not as bad as it
seems. The water supply in any town is being drained off all the time
by all the houses and businesses in the town. Yet the water industry
can still keep the water pressure consistent through the use of water
towers.
The same will be true in a Space Tube, providing the compressors can
keep the pressure in the tube consistent on the ground, then air will
always flow upwards to to replace any air vented out of the tube. So
there needs to be pressure sensors in the tube, so if the pressure
has decreased, then computers will automatically switch on more
compressors.
But if that is not enough and too much air is vented out of the tube,
then the air pressure on the ground can be increased. This means the
lower tubes need to be stronger so high pressures can be used. Which
is not a bad thing as the lower tubes need to be strong to resist
downward compression forces anyway. So the air pressure can be
extremely high in the lower tubing but made a lot less higher up, by
venting air and so being able to have lighter tubing in the upper
atmosphere.
Venting air out of the tube will also have another advantage, as it
will create a upward current of air that can be used to help lift the
tube. Curved vanes shaped like fan blades but fixed to the walls,
will deflect the up coming air sideways and create lift. This will
also create a vortex effect in the tube and this can be utilized by
another fixed fan above it, angled in the opposite direction, which
can use the upwards spinning air to create even more lift. There can
be any number of these fixed vanes going up inside the tube.
The fixed vanes will slow down the air but it will be only a
temporary effect as the air will speed up because of the air pressure
underneath it, and the air being vented from the tube above it. The
design of these fixed vanes may have to change to deal with different
air pressures. Near the base the high air pressure will be greater
than surface water, so the design of the vanes would probably look
more like ship’s propellers and will be as powerful, in the high
air pressure. But further up the tube the air pressure and speed of
the upward air will decrease and so the design of the fixed vanes
will have to change to be the most efficient in these conditions.
Instead of fix vanes autorotation rotors can be used instead. This is
how helicopters can glide if they lose power, the rotors are angled
downward so the rotors can turn and give the helicopter lift.
Autogyros do the same thing. This would probably give more lift than
fix vanes. Though the advantage of fix vanes is there is no moving
parts, so nothing can go wrong with them.
The upward flow of air can also give sideways push through downward
facing aerofoils. Some people would question if aerofoils would work
in an enclosed tube but we have to remember that aerofoil designs are
tested in wind tunnels. Which are enclosed tubes of either a square
or round shape, where they measure the lift of these aerofoils in
these tunnels.
There are two ways of doing this. The first is to put the downward
facing aerofoil in ball-bearing or ball-roller rings around the inner
surface of the tube. So the aerofoil can be turned in whatever
direction to counter any swaying movement or the force of the wind.
They would have to be symmetric aerofoils like the tail fins of an
aircraft, so it can turn like a tail fin to give sideways lift, in
either direction or go into a vertical neutral position when the tube
is stable. Although this would be an efficient design it would be
hard to get to, if anything goes wrong with it. As it will be within
a pressurised tube that humans can’t access.
The alternative to this, would be to have two downward facing
aerofoils, at a 90 degrees angle to each other. So both aerofoils can
work together to counter any sideways movement by the tube from any
direction. There can be a reasonable gap between them to lessen the
turbulence created by the lower aerofoil on the upper one. This
design wouldn’t be so efficient, but less that can go wrong with
it. The turning shaft that creates the angle of attack for the
aerofoils, can go right through the walls of the tube to servo motors
and computers on the outside of it. This then means the set-up is
partly repairable if anything goes wrong with it. Again it will be
guided by movement and pressure sensors, anemometers and wind vanes.
Gas jets would give both a upwards as well as a sideways push but
they would have to be switched on all the time to do this. Though if
needed, perhaps if the gas that is burnt is hydrogen which means
mostly water will come out of its exhaust, and that might be more
acceptable. Perhaps they can be use only when a spacecraft or some
other cargo is being lifted up the tube to give it more stability and
the ability of the tube to carry up a heavier cargo.
In the lower tubing fixed vanes and downward face aerofoils will be
very effective in the pressurized fast moving air. But further up the
tube, the speed and air pressure will gradually drop away and
reaction wheels will then become more effective in keeping the tube
vertical.
There is a case for making the base of the tube wider than the top
which will help keep up the pressure in the tube, the higher it goes.
But this will make constructing the tube complicated and more
expensive, while straight tubing will be a lot easier and any gains
by reducing the diameter of the tube can be compensated for, by
increasing the air pressure at the bottom.
Then there is the problem of transporting spacecraft up in the tube
and there are many options. One possibility is to have another tube
within the main tube and spacecraft can be transported within it, at
normal air pressure. Or perhaps even push a spacecraft up with
compressed air. In the 19th and 20th centuries
there was pneumatic tube transport, where mail was transported
through tubes by air pressure. Air pressure trains were proposed
then, but were never successfully built.
The only problem with this, is that it is another extremely long tube
will greatly add to the weight to the whole structure. Though
surprisingly it will also add a upwards force. Because if the bottom
of the tube is off the ground, then it will float upwards.
The pressure in the tube will be more than surface water and so a
hollow tube can float in it. If there is a gap between the bottom of
the inner tube and the ground and the outer tube is pressurised to
something like 300 bars. Then there will be a upwards pressure of 300
bars underneath the tube while the other end of the tube is open and
in space, so there won’t be any counter pressure on top pushing
down, although there will still be the weight of an extremely long
tube.
The fixed curved vanes and downward facing aerofoils can go around
the inner tube in the gap between the inner and outer tube, fixed to
the walls. Another advantage it could have is that because spacecraft
will be going up inside the tube then rotors can be used on the
outside of the tube, to keep the tube upright in the troposphere
rather than use jet thrusters.
Taking a spacecraft up on the outside of the tube would be difficult
as it will have to go pass thrusters and reaction wheels. The way
around this is to put the reaction wheels out of the way, inside the
tube. Though this will mean the reaction wheels operating in
compressed air with air friction slowing them down. But that
shouldn’t be too much a problem as it will only use up a little
more electricity. Or the reaction wheels can be boxed in with panels
around them.
The bigger problem is that if any break down, then it would be very
difficult to get to, to repair them. But this is also the problem
with reaction wheels on satellites and there is not a lot that can go
wrong with them. Though some have gone wrong on satellites, but
manufacturers now have the knowledge of why they went wrong.
Even gas thrusters can put inside the tube with only the nozzle
outside, though thrusters can also be pointed downwards on the side
of the tube and so won’t stick out too far. And any side push can
be obtained with thrust vectoring. So the nozzle can be manipulated
to move in different directions. This is possible with VTOL aircraft
and gimbaled nozzles on rockets. Though the nozzles on these jets
need to be always angled away from the tube to prevent any damage.
Then there is the problem of that taking up a spacecraft on the
outside will unbalance the tube and there needs a counter weight,
like another spacecraft, on the other side. The spacecraft can use
the crawlers invented for the Space Elevator to climb up the outside
of the tube, but using bars or rails instead of cables. It can also
be powered from a small electric rail like a train using a
pantograph to transfer power from electric line or
track to the vehicle.
The problem of needing two spacecraft going up together to balance
the tube, can be solved by the spacecraft being pushed up in some
form of climbing vehicle, which has its own thrusters and reaction
wheels on it, to balance it. There will be a limit in how heavy a
payload a tube can take up into space but that can be greatly
increased by rocket power. The vehicle can have on it, first of all,
rockets designed to work best in the thick atmosphere of the
troposphere, or use a jet engine.
So the rocket will be on the vehicle and the nozzles angled so it
doesn’t damage the tube or anything it is pulling up. As at the
same time it is pulling up a train of fuel tanks and using the fuel
in the tank at the bottom first. Then as each tank’s fuel is used
up, it can be released and allowed to drop down the climbing rail.
Along with the rockets or jet-engines that are no longer needed. As
it goes into the upper atmosphere, it will now it will now use a
rocket optimised for the stratosphere and higher and so take it up to
the top of the tube.
The descent of fuel tanks and rocket or jet motors, can be slowed
down and stop near the ground by magnetic brakes, that are used by
drop towers in funfairs. As the rocket is supported by the tube it
doesn’t have to try to obtain escape velocity, while punching
through the thick air of the troposphere, carrying tons of fuel. It
can go up a lot more slowly.
The vehicle will also be using the power of electric motors from
electricity from the ground delivered by and electric rail and a
pantograph, so it won’t be only be dependant only on the rocket
alone for upwards push. Then when the vehicle has delivered the
spacecraft it can also drop to the ground and its fall will again be
stopped by magnetic brakes near the ground. As the tube is stronger
near the ground more weight can be pushed up, but then as the fuel
tanks drop down, the weight will decrease but at the same time, the
tube becomes more lightly built. So a pressurised tube could deliver
genuine reusable rockets and fuel tanks.
Although by having a tube near low orbital height a rocket should be
launched horizontal. But it would be complicated to do this. So it
would be better to still launch a rocket vertical with again nozzles
angled away from the tube and when the rocket is clear of the tube,
to then use side thrusters or reaction wheels to turn the rocket
nearly horizontally in space. Then switch to full power to obtain
orbital speed.
Although a runway might be possible if a large amount of compressed
air can be delivered to the top of the Space Tube. Then this
compressed air can be vented downwards through a number of vents
underneath the runway to support it. Electric jets or fans using the
compressed air, along with long braces from the tube, will also be
help to support it. Though it will also need a small crane or hoist
on the runway to turn the spacecraft horizontally.
A large platform on top of the tube can be used for many other things
like different types of telescopes or house scientists who want to
study space.
Another big advantage of going up on the outside of the tube is that
the climbing rails can take up a viewing platform as well. Nowadays
there are observation towers with a moving observation platform right
around the tower. So to have a observation platform that can go right
up into space would be a great tourist attraction.
There will have to be a big gap between the viewing platform and the
outside of the tube so it can pass thrusters, gas pipes, electric
cables and sensors. A moving platform would also be a great help for
maintenance to allow workmen to access the thrusters, cables, pipes,
computers etc. If anything go wrong. It can also take up scientists,
as well.
There are a few complications having one tube and perhaps some of
them can be solved by having three or four tubes. The big advantage
of this is that all the tubes can be tied together with struts and
braces like a lattice mast, giving it structural stability. Then
rockets and other cargoes can be transported up between the tubes and
large reaction wheels can be put on the outside of the mast attached
to either the struts or tubes.
Perhaps in the troposphere large rotors can replace large reaction
wheels. These would be more powerful in dealing with strong winds and
perhaps could replace gas jets. They could be attached to each tube
and be able to turn 90 degrees or 120 degrees, (depending if it is a
3 or 4 tube mast). It would also help to have reversible rotors that
can move air backwards or forward depending on the direction of the
wind. It would also help to stagger the height of the rotors so the
turbulent air from one rotor won’t interfere with another one.
It would even be a bit help with maintenance as one tube can be shut
down and worked on, while it is being supported by the other three
tubes that are still active.
The only drawback with this is that one large tube will have far more
compressed air in it, for the same weight than 3 or 4 smaller tubes.
So therefore have more power to overcoming compression forces by
venting more air downwards. This means a compressed tube lattice
mast, may not be able to go as high as just one large single tube
unless the the compressed air inside the smaller tubes is a lot
higher.
So just one large tube is the best solution because of the
power-to-weight ratio, even if it creates a few complications like
sending up space cargo on the outside of the tube. The
power-to-weight ratio will also increase by making the diameter of
the tube larger. This is because the area of a circle will increase a
lot more in relationship to its circumference.
BUILDING A SPACE TUBE
The obvious material to construct it all would be carbon fibre as it
is used in pressure vessels and is between four and five times
lighter than steel, while holding in the same amount of pressure.
Though graphene and other new materials could be even better, once
they are mass produced. The trouble with carbon fibre is that
although it has high tensile strength it is not so strong in
compression. This suggests that there might be a case for using
metals which are as strong in compression as in tension. So perhaps
aluminium reinforced with carbon fibre in a geometric truss design
might be a possibility.
Steel and other hard metals can also be used in joints and around the
holes where the thrusters are fixed to the tubes and perhaps even
used for the lower tubes. There will be greater internal pressure
near the ground than at the top, so the tubes can be made heavier at
the bottom and lighter as it rises higher. Then
there is the problem of building it. There is no way it can be built
like a normal building, it would be impractible to have steeple jacks
constructing it, in the tratosphere, in space suits. So a better way
is build the top first then jacked it up and then put tubing put
under it and jacked it up again, and so on.
That creates another problem because the lightly constructed top
tubes will have to go through strong winds of the troposphere. So the
best way to deal with this, is to build the more robust tubes of the
troposphere first.
The less joints for the whole tube, the better, because joints add
weight and air can leak from them. Carbon fibre tubes can be joined
together with a inner ferrule tube but it is important that the tube
can sway and move without breaking. The problem with carbon fibre is
that it is a very stiff material so some of the joints need to be
able to move. So there has to be some play in some of the joints and
the gaps filled with rubber O-rings.
So to build it with long tubes it best to build it in a tall building
that is wide enough to lift upright tall tubing and start off with
the tubes near the top of the troposphere. So this tube will be
jacked up to the top of the building and another tube put underneath,
and so on, but sooner or later the tube will encounter strong winds
and need jet thrusters to keep it upright. Things like fixed vanes,
downward facing aerofoils cannot be put in at this stage of the
constrution. While reaction wheels can only be used on the outside
of the tube. So this means temperary rotors can also be used as well
to keep the tube upright.
The problem with jet thrusters is they have been designed to work in
compressed air. There are a few way to tackle this problem. The first
is to have small jet engines instead of jet thursters. Though at a
later date the jet-engines will have to be removed and thrusters take
their place. Or use rotors or propellers to keep the tube upright.
The final way, is to pressurise the tube as it is being constructed.
Which will mean putting a temperory cap on the top troposphere tube.
The
only way to do this would be to pressurize the whole building. But
no human can work in air that is pressurized too much, so the
construction will have to be done with robots, like used in car
factories. The tubes will have to be brought into the building
through a long air-lock and the tubes fixed together with
quick-action couplings.
On
top of the building there will be a pipe the same diameter as the
couplings. The tube is pushed up these pipes to a platform above.
Now, the diameter of the tubes and the couplings are going to be
different which means when the couplings come out of the top of the
tube, the gap is filled with two halves of a metal plate with two
half circles cut out of them, that are pushed together with hydraulic
pressure to fill in the gap. It can be opened again when the next
coupling comes up.
Once
the tube is above the platform the side thrusters can be put on. The
thrusters will be an issue because compressed air will be rushing out
of the holes they go into and the pressure will badly hurt any human
that got in the way. So when the vent holes appear above the
platform, the thrusters will again have to be fixed into place with a
robot using hydraulic power, either screwing them in or again using
quick-action couplings.
Once
the more robust tubes are constructed the lighter tubing above the
troposphere can be construct inside the troposphere tube. This then
will mean that upper atmosphere tubing will have to be of a smaller
diameter to fit inside the troposphere tube. One objection to this
and that is the upper atmosphere tubing could block off the vent
holes feeding the thrusters of the troposphere tube. But upper tubing
will have its own vent holes in them and there has to be a gap to put
in coupling joints.
This
will mean there has to platform at the top of the troposphere tube.
But that can be a viewing platform taken up on climbing rails.
Working in the thin air of the upper atmosphere is not a job for
humans so again it will need robots to do this. The lid on the top
troposphere tube will have to be taken off and the top tube pushed
through which would have its own lid on it. Robots again will put on
the side thrusters when their holes appear above the platform as well
as electrical cables, motion sensors and computers.
It
it was decided to put a platform or runway on top of the tube then it
will be best to be build it now. As the tube becomes longer it will
become heavier and will probably need all the downward thrust of all
the thrusters to help lift it up so more tubes can be put underneath
it. It will certainly need this lift when the final part has to be
lifted up out of the troposphere tube and fixed to the top of it.
Then
there will be the problem of putting fixed vanes, downward facing
aerofoils and perhaps heavy duty reaction wheels in the troposphere
tubing. The lighter reaction wheel will have already been put into
the tube above the troposphere along with fixed vanes and aerofoils.
All these things can be taken into the tube through the airlock, then
taken up the inside of the tube with the same climbing platform used
to lift the final section of tube. So there will have to be climbing
rails inside the troposphere tube.
It
will be the same if it was decided to have a inner tube to take up
spacecraft. The inner tube can be built with the upper outer tubing
in the upper atmosphere tubing. Then the inner tube in the
troposphere tube can be put in afterwards along with fixed vanes and
aerofoils as well as a air-lock near the bottom. Then all the
pressurized air in the inner tube can be released.
The
same principles can apply if building a lattice mast out of
pressurized tubing. The tubes can be joined on top of each other in
the part of the building that has compressed air in it. Then the
struts, braces, rotors, reaction wheels and thrusters can be put
together when the four tube come out of four holes on the top of the
compressed air section.
There
is a case for putting a light outer tube over the pressurized tube to
cover things like electrical cables, gas pipes, computers and
sensors. This can be put on later using the maintenance platform. The
problem is that in a tube of a hundred miles, even a light outer
covering can end up weighing many tons overall. Though all things
fixed to the outside of the tube will need some sort of covering so
it might be an option.
FUTURE POSSIBILITIES
The
tube or mast can be used like a satellite and broadcast TV and radio,
as well as being used like a weather satellite or observatory. Once a
tube going up to low earth orbit has been built and in operation,
then the experience of doing this will make it possible to know if
going further is feasible.
One of the big problems for a Space Tube is the number of satellites
and space junk in orbit. The Space Tube will be going at the speed
the Earth rotates at about a 120 miles in height. Satellites and
space junk will be moving at speeds up to 17,000 mph, so a Space Tube
would be a sitting duck. Whereas anything below low Earth orbit will
end up falling back to Earth and burning up. This suggest a Space
Tube would be safer being below low Earth orbit.
Although there is big benefit to get to geostationary orbit but that
is 35,786 kilometres or 22,236 miles high. This will mean being able
put satellites in orbit with just thrusters. It also means the Space
tube could transport cargo back to Earth without needing heat
sheilds. Which will make space mining possible.
Perhaps the tube can avoid any satellites and space junk by swaying.
After all a tube over a hundred miles high or more, can sway a long
way side by side. So the thrusters can move the whole tube a many
meters to get out of the way of anything in orbit that might crash
into it. This might be possible if everything in orbit is tracked.
Though the mast will still be in danger of very small space junk like
small pieces of metal that can puncture the walls of the tubes.
Though workmen on the maintenance platform can probably fix any hole
in the tube there is a danger of space debris doing more damage than
that.
So the tube will probably need a Whipple Shield that protects many
satellites today, but also adds to their weight. So the tube will end
up with a lighter outer tube. Though the effectiveness of the Whipple
Shield might be increased with air pressure between the shield tube
and the main tube.
It may be possible for the Space Tube to get to higher by simply
making it larger. An 8 meter diameter tube would have a circumference
of 25 meter and a area of 50 square meters, so the area would be
twice the circumference. Whereas 16 meter diameter tube would have a
circumference of 50 meters but have a area of 202 square meters. So
the area would be 4 times the circumference.
This means that as the tube diameter increases the volume of air in
the tube will increase more than the weight of the tube. So the
increasing the diameter of the tube will make the power-to-weight
ratio higher. This suggests the way to make the Space Tube more
effective is to just build them larger. Although lighter building
materials like graphene and a increase in air pressure within the
tube, will also help.
A larger tube might allow a pneumatic tube to be put inside it and it
can be used like a giant air gun. So a spacecraft can be accelerated
up the tube using air pressure underneath it, without needing rocket
propulsion.
Perhaps the Space Tube might make the Space Elevator possible. They
could work together where the Space Tube reaches a height where a
cable from a Space Elevator to the Space Tube will be of a length
that won’t break. One advantage of this is that a cable is less
likely to be hit by space junk than a large tube, at orbital height.
CLAIMS
1) High air pressure can be extended all the way into space in a
extremely long tube pressurized by compressors from the ground.
2) The air pressure in the tube can be used to give both upwards and
sideways force to keep the tube upright and overcome downward
compression forces from the weight of the tube.
3) Upwards and sideways force in the tube is created by venting the
air out of it, or using the upwards current of air, created by the
venting, to give aerodynamic push by fixed vanes or aerofoils.
4) Gas jets, electric thrusters, fans, propellers, fixed vanes,
autorotation rotors, aerofoils and reaction wheels guided by
computers, gyroscopes and sensors can also be used to keep the tube
upright and help overcome downward compression forces.
5) Rockets, spacecraft, cargoes, observation platforms all can be
transport up to the top of the tube into space.
6) The Space Tube can be used to broadcast TV and radio as well as
weather data and even telescopes of various kinds can be put on top
of it, on a large platform.
7) A Space Tube and Space Elevator can work together so a cable from
a Space Elevator can be lowered to the Space Tube and so shorten the
length of cable from the Space Elevator.
8) A Space Tube can have a pneumatic tube inside it to push up
spacecraft with air pressure.