When Bad Ideas Meet: CNT and the Space Elevator

None of the idiots that ever came with this idea ever thought of angular velocity and the energy required to atain it think of an equivalent of Coriolis effect when going up the elevator. Amount of energy that need to be imparted on an object remains this same regardless how is this energy imparted. Object on a stationary orbit generates zero pull on a string attaching it to fixed point on earth so it would be useless. Object would have to be higher then stationary orbit to exert some useful pull it would then tend to lag earth rotation an effect that would have to be compesated by pull of the string and made worse by any object moving up the string add to it atmosferic drag that would have to be compesated for on a continous bases (antypassates). All this is just a tip of an iceberg of the tip of my tongue.

Yours, Karol Karolak P. Eng.

Quoting Guest: "None of the idiots that ever came with this idea ever thought of angular velocity and the energy required to attain it think of an equivalent of Coriolis effect when going up the elevator."

At the ascend speeds (120 mph) that they are talking about, this is not really a problem. To reach the height of the Space Station will take about 2.5 hours and the angular velocity is pretty slow - it's 490 odd m/s, not much more than the 460 odd m/s that we have at the equatorial surface. (Remember, the elevator is not in orbit, it simply rotates with Earth).

What is more, that small increase in kinetic energy is 'stolen' from Earth's rotational energy, to be given back when the elevator comes down again. At 120 mph ascend speed, going up to geostationary altitude will take about a week, so the Coriolis forces will be tiny, while the energy 'stolen' from Earth will be pretty huge.

So, if a suitable material can be found, maybe the idea is not so crazy after all…

Thanks Roger for that posting, mmm my absolute all time favourite topic. "To Reach the Stars" Now you simply must check out good old Wikipedia on this one, At Cambridge in the early 1980's "The Space Fountain" was a hot topic of conversation.

http://en.wikipedia.org/wiki/Space_fountain

The advantage is clear, ultra-strong materials are not required, and a space fountain can be located at any point on a planet's surface, instead of just the equator, and can be raised to any height required. Its major disadvantage is that it is an active structure , and so requires constant power input to remain aloft

Wikipedia needs an 'edit' as it describes a space fountain as a massive tower, The origional concept as I recall was for a closed loop cable, internal mass suspended in a vacuum and propelled by linear motors, would 'brake' on the up journey, and 'accelerate' on the down. The braking energy(minus losses) could assist the acceleration of the downward projectiles. As the loop could be joined most of the way, these losses could in theory be reasonably small. High temperature superconduction may reduce this even more.

To quote Wikipedia,

"The concept originated in a conversation on a computer net in the 1980s when some scientists who usually work in artificial intelligence, Marvin Minsky of MIT and John McCarthy and Hans Moravec of Stanford, were speculating about variations on the skyhook concept with some scientists at Lawrence Livermore National Laboratory who usually work on laser-initiated fusion, Roderick Hyde and Lowell Wood. As a means of supporting the upper end of a traditional space elevator at an altitude much less than geostationary, they proposed a ring of space stations hovering 2000 kilometers above Earth, motionless relative to the surface. These stations would not be in orbit; they would support themselves by deflecting a ring of fast-moving pellets circling Earth. The pellets would be moving at far greater speed than the orbital velocity for that altitude, so if the stations stopped deflecting them the pellets would move outward and the stations would fall inward."

Check out this link for all the abstracts on the subject, Paul Birch's "Orbital Ring Systems and Jacobs's Ladders" is very interesting. (page 11 of 17)

As we are in an "Off the Wall" forum(goody goody), has anybody thought of "Castles in the Air" or even "Cities in the Air" a cubic kilometer of displaced air would be 1,290,000 tonnes. maybe less, as humid air is paradoxically less dense.

The problem is, what are you going to displace all that air with that isn't heavier than air anyway? If it is vaccuum, there must be a (heavy) rigid structure. If humans will be aboard, they will require air to breathe and air pressure to keep our blood from boiling off or our bodies from exploding if most of the interior is a vaccuum. OK, so we wear pressure suits or stay in small pressurized living quarters.

Are you talking about a terantic (larger than gigantic) airship lifted by hot air balloons or helium cells? (NO hydrogen, Remember the Hindenburg!).

Just how would you float your Castle/City in the Air? This might be an "off the wall" forum, or "outside the box" thinking, but it still needs to be science or engineering-based to have a semblance of reality instead of just plain fantasy.

STL you write,

"Just how would you float your Castle/City in the Air? This might be an "off the wall" forum, or "outside the box" thinking, but it still needs to be science or engineering-based to have a semblance of reality instead of just plain fantasy."

Nearly twenty years ago at a local I.C.I. research facility, we had loads of fun at the I.C.I.'s expense whipping up egg albumin into a foam 'a la marangue confection'. Then we folded in all sorts of powdered clays and glazes etc. The fun bit was opening the Kiln door, The blocks of vitrified foam floated about a bit till they cooled down. They had practically no strength at all, and were extremely fragile structures. but still lighter than air when hot. The holes/cavities in the middle were much bigger than those at the surface. We figured the stuff might find an application in high efficiency loft insulation, where multiple layers of heat reflective aluminium sheet are placed between the rafters. This ceramic foam could act as a spacer layer.(fireproof as well)

Pi 'D' squared is the surface area of a sphere. 4/3 Pi r^3 the volume. In a race, cubic volume is always one exponent ahead of surface area. so as heat can only escape from an exterior surface, the bigger(within engineering contraints) the better. If the bulding blocks of our 'Out of the Box' project are themselves 'Air Buoyant' the more the merrier. So in effect the challenge is to make the 'bricks' so to speak, strong enough.

OK allow a hundred metre diameter structural sphere with a 'hot air' to 'ambient air relative density of 1/1.29 ie each cubic meter displaced delivers a kilogram of lift. That restricts the engineer to an average of 16.7 kilos per square meter of sphere surface area. if buoyancy is to be achieved, however the presumably geodesic structure weight distribution is allocated. I could live with less than 16.7 kilos to keep the pipe dream pipe puffing smoke rings.

A last thought, if these spheres, however big, were packed into the walls of a much larger structure, and the interior of the large structure was maintained at a moderately high temperature, the entire 'City' could be inhabitable. I would like weather forcasting to be a little more reliable than at present before embarking on more than just an architectural model, perhaps with a prize on offer to the best design. (mmm, must contact the Carnegie Corporation and rattle a can in front of their noses)

OOps Silly me "Stand for an hour in the corner with a dunce cap on...1/1.29!!!! but I hope the reader knows what I mean.

My problem with the concept is that the life of a carbon fiber
cable would be limited due to its passage through the Van Allen
belts ioizing radiation. The specialized bonds would be broken and
the cable degraded.

Even were this not the case, a slow passage through this region
is not likely to be at all salutory for the traveler.

I suppose that the vibrations in the highly stressed cable system
could be dealt with, but would not expect the problem to be simple.
Input of any primary, or harmonic frequency would have to be carefully
avoided.

I also question what would happen to the electrical impulse generated
as the conductive, (?), cable passed through the earths magnetic field.

That's a new one on me, I always thought the earth's magnetic field rotated with the earth? but boy oh boy, what a lightning conductor! Never mind the Van Allen Belt, the tight wads at the Wall Street Belt are going to be a big problem. I like the Paul Birch project from the "The British Pipe Dream Society"

Orbital Ring

Ref: Paul Birch, "Orbital Ring Systems and Jacob's Ladders - I", Journal of the British

Interplanetary Society, Vol. 35, pp. 475-497, (1982).

Ref: Paul Birch, "Orbital Ring Systems and Jacob's Ladders - II", Journal of the British

Interplanetary Society, Vol. 36, pp. 115-128, (1983).

Ref: Paul Birch, "Orbital Ring Systems and Jacob's Ladders - III", Journal of the British

Interplanetary Society, Vol. 36, pp. 231-238, (1982).

Description: Loop located in low circular equatorial orbit moving slightly in excess of orbital

velocity. Excess velocity supports stationary tethers connected to the Earth. Stationary tethers

connect to the ring by magnetic levitation. Low orbit is used to obviate the necessity for very

high strength materials. Various additional features describ

I'm surprised that nobody mentioned the Aerovator idea (or did I miss the post?)

Thanks, for that, absolutely brilliant! it's gone streight to my 'favourites', (off the wall stuff) I just love immaginative propositions, thinking out of the box. So often these wacky ideas have born fruit, even if only spin-off applications. 'Aerovator' a new concept to play with. great!

Thanks again Jorrie, The link has been forwarded to the Boss. Merlin Hay. We were chatting about this earlier this year. (P.S. Merlin is head of H.M.'s Scottish Household) 'Aerovator' may become a hot topic of small-talk at a forthcomeing Garden Party, Who Knows? maybe with some Top Brass and a few Boffins in attendance? We can but hope.