World Wide Web links regarding mass fluctuation from other people than Star-Drive.
From another thread:"Lastly, for said colonial program, VASIMR would be just as effective as your notional reactionless drives. As would nuclear pulse drives."VASIMR is nothing close to the performance possible with even a rudimentary MLT or UFG if we can trust the unverified figures to date.
Quote from: GI-Thruster on 07/15/2009 02:52 amFrom another thread:"Lastly, for said colonial program, VASIMR would be just as effective as your notional reactionless drives. As would nuclear pulse drives."VASIMR is nothing close to the performance possible with even a rudimentary MLT or UFG if we can trust the unverified figures to date. It is, however, more than enough to do the job. Which is really all that counts, for this particular instance. Sure, getting there super-fast would be nice, but it offers only iterative (minor, in this case) advantages over the VASIMR's projected transit time of a few weeks. Both are such improvements over the (already workable, we believe) current time of 180 days that there really is not much to choose from, especially since VASIMR is (as was stated) already moving into field prototypes.In many cases, and I think this is one, the Soviets were right: "Best is the enemy of good enough". I think we can work with VASIMR (if not current rockets) until a better candidate emerges (and matures). Certainly we shouldn't wait for it/them.
GI Thruster:I've been busy, but since you need some MLT verses VASIMR data here it is in a nutshell. The VX-200 has a thrust to power efficiency of ~1.0 Newton per 50.0kW of input power or inversely it's 2.0x10^-5 N/Watt. The Mach-2MHz demonstrated a 5x10^-3 N/7 watts input or 7.14x10^-4 N/Watt. That is already a factor of 7.14x10^-4 / 2.0x10^-5 = 35.71 times more energy efficient than a optimized conventional electrodynamic ionic rocket design. Yes, the MLT's lifetime was only 15 minutes of runtime verses the weeks to months required, but it gives one an idea of where these gravinertial thrusters can go once we fully understand and optimize the material science for them. In other words, 1.0 Newton per Watt G/I field based MLTs and/or UFGs will be buildable in the long term. The question is how long will it take to get there and that depends on how much time and effort we can throw into their development.BTW, propellantless drive is a misnomer IMO. Instead, they should be called a recycled propellant drive since they require a small amount of mass for these mass fluctuations to occur in that is recycled for reuse after every excitation cycle is competed, in much the same way a piston is reused on every rotational cycle of an internal combustion engine.
Quote from: MichaelF on 07/15/2009 03:46 amQuote from: GI-Thruster on 07/15/2009 02:52 amFrom another thread:"Lastly, for said colonial program, VASIMR would be just as effective as your notional reactionless drives. As would nuclear pulse drives."VASIMR is nothing close to the performance possible with even a rudimentary MLT or UFG if we can trust the unverified figures to date. It is, however, more than enough to do the job. Which is really all that counts, for this particular instance. Sure, getting there super-fast would be nice, but it offers only iterative (minor, in this case) advantages over the VASIMR's projected transit time of a few weeks. Both are such improvements over the (already workable, we believe) current time of 180 days that there really is not much to choose from, especially since VASIMR is (as was stated) already moving into field prototypes.In many cases, and I think this is one, the Soviets were right: "Best is the enemy of good enough". I think we can work with VASIMR (if not current rockets) until a better candidate emerges (and matures). Certainly we shouldn't wait for it/them.I haven't seen a spacecraft design for mars transit using VASIMR that didn't include a fission reactor. I'd love to believe someone somewhere can convince POTUS to support flying a fission reactor to Mars but somehow I'm not quite there. . .
Quote from: GI-Thruster on 07/15/2009 02:52 amFrom another thread:"Lastly, for said colonial program, VASIMR would be just as effective as your notional reactionless drives. As would nuclear pulse drives."VASIMR is nothing close to the performance possible with even a rudimentary MLT or UFG if we can trust the unverified figures to date. It is, however, more than enough to do the job. Which is really all that counts, for this particular instance. Sure, getting there super-fast would be nice, but it offers only iterative (minor, in this case) advantages over the VASIMR's projected transit time of a few weeks. Both are such improvements over the (already workable, we believe) current time of 180 days that there really is not much to choose from, especially since VASIMR is (as was stated) already moving into field prototypes.
Quote from: Star-Drive on 07/15/2009 03:47 amGI Thruster:I've been busy, but since you need some MLT verses VASIMR data here it is in a nutshell. The VX-200 has a thrust to power efficiency of ~1.0 Newton per 50.0kW of input power or inversely it's 2.0x10^-5 N/Watt. The Mach-2MHz demonstrated a 5x10^-3 N/7 watts input or 7.14x10^-4 N/Watt. That is already a factor of 7.14x10^-4 / 2.0x10^-5 = 35.71 times more energy efficient than a optimized conventional electrodynamic ionic rocket design. Yes, the MLT's lifetime was only 15 minutes of runtime verses the weeks to months required, but it gives one an idea of where these gravinertial thrusters can go once we fully understand and optimize the material science for them. In other words, 1.0 Newton per Watt G/I field based MLTs and/or UFGs will be buildable in the long term. The question is how long will it take to get there and that depends on how much time and effort we can throw into their development.BTW, propellantless drive is a misnomer IMO. Instead, they should be called a recycled propellant drive since they require a small amount of mass for these mass fluctuations to occur in that is recycled for reuse after every excitation cycle is competed, in much the same way a piston is reused on every rotational cycle of an internal combustion engine. And do you have any relative mass/thrust numbers? I think VASIMR is around 300 kg for 5 N thrust.
Quote from: GI-Thruster on 07/15/2009 03:53 amQuote from: MichaelF on 07/15/2009 03:46 amQuote from: GI-Thruster on 07/15/2009 02:52 amFrom another thread:"Lastly, for said colonial program, VASIMR would be just as effective as your notional reactionless drives. As would nuclear pulse drives."VASIMR is nothing close to the performance possible with even a rudimentary MLT or UFG if we can trust the unverified figures to date. It is, however, more than enough to do the job. Which is really all that counts, for this particular instance. Sure, getting there super-fast would be nice, but it offers only iterative (minor, in this case) advantages over the VASIMR's projected transit time of a few weeks. Both are such improvements over the (already workable, we believe) current time of 180 days that there really is not much to choose from, especially since VASIMR is (as was stated) already moving into field prototypes.In many cases, and I think this is one, the Soviets were right: "Best is the enemy of good enough". I think we can work with VASIMR (if not current rockets) until a better candidate emerges (and matures). Certainly we shouldn't wait for it/them.I haven't seen a spacecraft design for mars transit using VASIMR that didn't include a fission reactor. I'd love to believe someone somewhere can convince POTUS to support flying a fission reactor to Mars but somehow I'm not quite there. . .Since any manned mission to Mars perforce requires a fission reactor along anyway (for surface operations)....might as well go for two.
a ME Thruster driven vessel would be buildable on earths surface akin to building a shuttle orbiter or ocean going vessel in an industrial setting. It would be buildable for a 200-600 million dollars, at most, versus 100 billion for a VASIMR ship.
Quote from: mlorrey on 07/18/2009 06:42 pma ME Thruster driven vessel would be buildable on earths surface akin to building a shuttle orbiter or ocean going vessel in an industrial setting. It would be buildable for a 200-600 million dollars, at most, versus 100 billion for a VASIMR ship.You mean this rocket here will cost 100 billion?