Posted on 10/03/2006 2:51:24 PM PDT by blam
Huge 'launch ring' to fling satellites into orbit
16:00 03 October 2006
NewScientist.com news service
David Shiga
A ring of superconducting magnets fires a projectile off a ramp at 8 kilometres per second, fast enough to reach orbit (Artist’s conception: J Fiske/LaunchPoint)
A cone-shaped shell would protect the payload during its passage through the atmosphere into space, and includes a rocket at the back end to adjust its trajectory (Illustration: J Fiske/LaunchPoint Technologies) An enormous ring of superconducting magnets similar to a particle accelerator could fling satellites into space, or perhaps weapons around the world, suggest the findings of a new study funded by the US air force.
Proponents of the idea say it would be much cheaper than conventional rocket launches. But critics warn that the technology would be difficult to develop and that the intense g forces experienced during launch might damage the very satellites being lofted into space.
Previous studies have investigated the use of magnets to accelerate satellites to the high speeds required for launch. But most have focused on straight tracks, which have to gather speed in one quick burst. Supplying the huge spike of energy needed for this method has proven difficult.
The advantage of a circular track is that the satellite can be gradually accelerated over a period of several hours. And the setup is technologically feasible and cost effective, suggests a recent, preliminary study of the idea funded by the air force's Office of Scientific Research.
The air force has now given the go-ahead for more in-depth research of the idea. The two-year study will begin within a few weeks and be led by James Fiske of LaunchPoint Technologies in Goleta, California, US.
The launch ring would be very similar to the particle accelerators used for physics experiments, with superconducting.
(Excerpt) Read more at newscientistspace.com ...
Heinlein also used something like this located in India (IIRC) in "The Moon is a Harsh Mistress"
For example, if this thing has a 10 meter circular cross-section, you'd need to be able to evacuate about 2.5 million m3 to a very good vacuum, similar to what's found in space -- in a structure that's flexing in response to a 1300 G point load. Good luck with that.
Next, when you open the door to let this thing out, there's gonna be that nice shock wave caused by air racing in to fill the vacuum. Whole lotta buffeting going on there -- launch accuracy will suck, assuming that the thing doesn't just tumble and fragment.
And don't forget the part about screaming through the atmosphere at Mach 20+. The thermal requirements are gonna be killer.
:)
Two undesirable things would be happening as the launch sled circled for hours: heat would build up; and increasing amounts of energy would be wasted on overcoming air resistance.
Perhaps a more optimal design would incorporate a larger sled, and a larger rocket and more rocket fuel. This would enable a quicker launch, at lower speeds & lower g forces. The rocket could provide the final boost at very high altitudes, where there is very little air resistance.
Google is your friend...
Fellows.....it can go around more than once......much lower g's.
Niven also had some sort of anti-gravity inertial damper machine. IIRC. It's been 20 years.
It's like the fair ride where you stand against the wall, it spins around, and the floor drops down. Except it spins so fast - your body turns into a puddle.
The lateral g-forces would be enormous. Most satellites are designed with a single direction high g-load in mind for launch.
Not sure how this would play out. The Moon is a different animal though. For years, there have been proposed designs for a mass driver to lift payloads to space.
Imagine a power plant (nuclear would be ideal -- it's a good base-load provider) built in the center of the ring. During peak hours, the plant sends juice over the wires as usual. Off peak, the plant feeds excess power into the ring's accelerator magnets. Instead of lofting a spacecraft into orbit, the ring magnets use the juice to accelerate a conductive body (say an iron slug) to the maximum speed mentioned in the article, 10 km/sec. Since Ek=mv2/2, a 10 kg slug traveling at 10000 m/sec will have a instantaneous kinetic energy of five hundred million Joules. The power plant then closes off the power to the ring magnets. Due to induction, the speeding slug will then cause a current to flow back through the circuit, converting its energy of motion into about 139 kW/h of instantaneous electrical energy. Figure 50% loss through the system and that's roughly 70 kW/h of tappable electrical power per slug -- enough power to meet an American home's electrical needs for several weeks!
Now imagine the entire ring filled with such slugs. At a diameter of 10km, the power ring would have a circumference of 31.4 km, give or take a few centimeters. Assume the slugs are of equal size (90 cm, say); with a 10 cm gap between slugs, the ring could hold 34, 906 slugs, making its total instantaneous electrical energy storage potential an astounding 2,443,400 kW/H (2.44 gW/h) -- enough stored energy to power a city of seventeen thousand homes for a month!
In addition, the power ring would (through losses) generate a good deal of heat energy. By careful design, the cooling system could make use of this "waste" heat to provide cogeneration energy for other uses.
Of course, if the levitation magnets fail or the physical structure of the ring is compromised, the slugs will impact the ring walls, depositing all 17,453,000,000,000 Joules into the surface of the earth — the equivalent of a nuclear explosion of a little over four kilotons. Ouch!
All this is just a thought experiment, of course. I am no kind of engineer and I may be overlooking one or more important objectons to the use of high-speed magnetic-levitation rings as power storage devices. (And I also may have the math wrong.) Still, it's an interesting idea, I think.
You don't say!
Curvature radius of at least 1000 miles, so you might as well make it straight.
Then, you still have the problem of getting any appreciable positive z-dot (vertical velocity), on a launch ramp of workable size, without mashing the occupants into dinosaur cartilege.
That could throw the earth off it's axis, possibly even out of it's orbit.
What about the EMP effects to the projectile?
That was one of the most disgusting ads on TV
Dude, that really doesn't seem right. 1.96 RPS across a 10km circle is not going to give you 1300G's. Are you talking about centrifugal or centripedal accelerations?
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