meiza - 3/10/2006 6:36 PMYou still need to circularize the orbit, one can not do orbital launch with a pure gun (the orbit intersects Earth's surface). And there has to be lots of that 2000 gee supporting track: if the exit velocity is 8 km/s, it's 20 kilometers just for the ring (not counting the ramp) or with 10 km/s velocity, 32 kilometers / 20 miles. And the ramp has to be huge too, for 30 degree elevation it has 1.7 to 2.7 km of track and rises 1.6 to 2.5 km from the ground (depending on exit velocity). Such freestanding structures don't even exist. One has to find a pretty fitting mountain for the exit ramp, or then build the ring completely or partially deeply buried into the ground, which I'm not sure if it has been done either.
Sling Fan - 3/10/2006 7:12 PMMXER beats this hands down...and has more abilities.
bhankiii - 3/10/2006 5:18 PM"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." And a small rocket on the tail adjusts the orbit.
hop - 3/10/2006 9:36 PMThey mention the possible use as a weapon, but it's hard to see what advantage it has over traditional ballistic missiles. It does have the significant disadvantage of being a single large, fixed target that could rendered completely useless with a nuke or a small amount of well placed conventional explosives. Or a well placed brick, for that matter...
bhankiii - 4/10/2006 1:18 AMQuotemeiza - 3/10/2006 6:36 PMYou still need to circularize the orbit, one can not do orbital launch with a pure gun (the orbit intersects Earth's surface). And there has to be lots of that 2000 gee supporting track: if the exit velocity is 8 km/s, it's 20 kilometers just for the ring (not counting the ramp) or with 10 km/s velocity, 32 kilometers / 20 miles. And the ramp has to be huge too, for 30 degree elevation it has 1.7 to 2.7 km of track and rises 1.6 to 2.5 km from the ground (depending on exit velocity). Such freestanding structures don't even exist. One has to find a pretty fitting mountain for the exit ramp, or then build the ring completely or partially deeply buried into the ground, which I'm not sure if it has been done either.The track is circular - 2km across, so extreme distances aren't required --"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." And a small rocket on the tail adjusts the orbit.
meiza - 4/10/2006 5:23 AMHuh? 1 km radius and 2000 gees, that makes the velocity 4.4 km/s. That's only like a first stage. You don't "adjust" the orbit, you have to actually do over half of the delta vee still, and that's not even counting the aerodynamic losses. And I don't know about the direction of the velocity either. You probably need a two stage solid. And you have to keep the six kilometer track in a vacuum etc...
meiza - 3/10/2006 4:36 PM... And the ramp has to be huge too, for 30 degree elevation it has 1.7 to 2.7 km of track and rises 1.6 to 2.5 km from the ground (depending on exit velocity). Such freestanding structures don't even exist. One has to find a pretty fitting mountain for the exit ramp, or then build the ring completely or partially deeply buried into the ground, which I'm not sure if it has been done either.
PurduesUSAFguy - 10/10/2006 7:17 AMI don't see such a system as being very useful for launching microsatilites, such a satilite would have to be superhardened to withstand that many Gs making it too heavy to launch, not to mention as was previously mentioned the thermal protection required for such a launch process.I do however, see this as being a tremendously usefull weapon system to help replace our aging bomber fleet. This system has all the advantages and capabilities of an ICBM armed with a unitary depleted uranium kinetic warhead without the tens of millions in cost of a Trident D3 or Minuteman booster. 300kilos of depleted uranium hitting your breeder reactor (*cough*iran) at mach 20 is enough to ruin your day. Also you don't have to just be doing unitary deep penetrators, imagine if the heat sheild is wraped in explosive cord to petal at lets say 2 kilometets altitude to disperse thousands of tungstun flechetes. That would be one devistating anti armor or anti personal strike.
And if you can do that, why not go on into space?
PurduesUSAFguy - 10/10/2006 5:17 AMI do however, see this as being a tremendously usefull weapon system to help replace our aging bomber fleet. This system has all the advantages and capabilities of an ICBM armed with a unitary depleted uranium kinetic warhead without the tens of millions in cost of a Trident D3 or Minuteman booster. 300kilos of depleted uranium hitting your breeder reactor (*cough*iran) at mach 20 is enough to ruin your day. Also you don't have to just be doing unitary deep penetrators, imagine if the heat sheild is wraped in explosive cord to petal at lets say 2 kilometets altitude to disperse thousands of tungstun flechetes. That would be one devistating anti armor or anti personal strike.
Marcus - 10/10/2006 1:56 PMQuote And if you can do that, why not go on into space?We are signatories to the Outer Space Treaty which forbids the installation of WMD's in orbit. Whether a precision munition with the kind of KE you're talking about is a WMD or not is debatable.Just in general, I have to say that the weaponization of LEO is a really bad idea. It wouldn't take too many ASAT engagements to put enough untrackable debris in orbit to deny everyone access for a very long time.If the monkeys must throw rocks at each other, please keep it ballistic.
TyMoore - 11/10/2006 1:38 PMIn any case, for a launch ring to work it must use somekind of magnetic levitation as no mechanical support could possibly sustain sliding velocities in excess of 1 km per second, let alone 10km per second. And the only way that could be done would be to use magnetic repulsion because natural compression of magnetic fields increases repulsive forces--so it has a natural positive feedback--but still requires active damping of oscillations. The forces exerted to repell the projectile off the track are enormous: F=mv^2/rFor a mass of 100 kg, moving in a circular track with radius of 1000 m, and tengential velocity 10^4 m/s, requires exerting :F=10MN (about 2.25 million pounds of force.)Even using a magnetic sled and using the Meisner Effect to cause it to repell from a superconducting track, the required magnetic field pressure will probably force the trapped magnetic flux to exceed the superconductor's Critical B-Field strength. Exceeding the critical B-field will break apart the Cooper pairs in a superconductor and that causes a superconductor to transition to normal conduction states. If this were to happen, the sled would collide with the repulsive track within milliseconds...A magnetic launch track would either require a very, very large ring (something bigger even than 50km radius) or will require a lot of energy storage and a track maybe 2-50 km in length. Still an expensive endeavour, but certainly possible as a way of transporting large quantities of material into space such as the Mass Driver concepts for the surface of the moon.