DusterBoy Posted February 26, 2010 Report Share Posted February 26, 2010 Okay, for now they're only toys but check out. So, now it's just a question of scaling up. . . Quote Link to comment Share on other sites More sharing options...
mattingly Posted February 26, 2010 Report Share Posted February 26, 2010 Re: Laser launched rockets ...wth frickin' sharks on their warheads! Quote Link to comment Share on other sites More sharing options...
Old Man Posted February 26, 2010 Report Share Posted February 26, 2010 Re: Laser launched rockets So, now it's just a question of scaling up. . . If by "scaling up" you mean "weaponize", I'm all for it. Quote Link to comment Share on other sites More sharing options...
DusterBoy Posted February 27, 2010 Author Report Share Posted February 27, 2010 Re: Laser launched rockets By scaling up, I mean making it able to launch a manned vehicle. Bear in mind that Jerry Pournelle wrote about this in "A Step Further Out Pt2" published in 1979! Quote Link to comment Share on other sites More sharing options...
Yansuf Posted February 27, 2010 Report Share Posted February 27, 2010 Re: Laser launched rockets I recall seeing a televised demonstration of laser propulsion that appeared identical to this system over a decade ago. Quote Link to comment Share on other sites More sharing options...
shadowcat1313 Posted February 28, 2010 Report Share Posted February 28, 2010 Re: Laser launched rockets Jordin Kare has been working on this for years, course he was also one of the folks behind the laser based bugzapper project M$ funded Quote Link to comment Share on other sites More sharing options...
ajackson Posted March 4, 2010 Report Share Posted March 4, 2010 Re: Laser launched rockets By scaling up' date=' I mean making it able to launch a manned vehicle.[/quote'] Might take a while. Minimum laser power for laser launch into orbit is on the order of 100 kW/kg (of payload), and reaching that lower limit is unlikely. There's something of a shortage of lasers capable of producing several hundred megawatts continually for multiple minutes. Quote Link to comment Share on other sites More sharing options...
DusterBoy Posted March 16, 2010 Author Report Share Posted March 16, 2010 Re: Laser launched rockets Yeah, but that's just engineering. If we want it enough, we'll find a way. Quote Link to comment Share on other sites More sharing options...
austenandrews Posted March 16, 2010 Report Share Posted March 16, 2010 Re: Laser launched rockets In what context would this be the most efficient way to get something aloft? Honest question; I don't know the limits of the concept. Quote Link to comment Share on other sites More sharing options...
McCoy Posted March 16, 2010 Report Share Posted March 16, 2010 Re: Laser launched rockets Might take a while. Minimum laser power for laser launch into orbit is on the order of 100 kW/kg (of payload)' date=' and reaching that lower limit is unlikely. There's something of a shortage of lasers capable of producing several hundred megawatts continually for multiple minutes.[/quote'] Then let's get a bunch that can deliver a pulse and recharge, ready to go again when their turn comes around. In what context would this be the most efficient way to get something aloft? Honest question; I don't know the limits of the concept. Biggest advantage is your power supply can stay on the ground. You can use, say, the energy of a nuclear reactor without having to lift a nuclear reactor. Much better than sitting on top of tons of high explosives and lighting a match. Quote Link to comment Share on other sites More sharing options...
Kraven Kor Posted March 17, 2010 Report Share Posted March 17, 2010 Re: Laser launched rockets Stupid question... would this work if your source laser was mounted on the ship? Or would you just tear the laser mount off the back of the ship? Quote Link to comment Share on other sites More sharing options...
dmjalund Posted March 17, 2010 Report Share Posted March 17, 2010 Re: Laser launched rockets Stupid question... would this work if your source laser was mounted on the ship? Or would you just tear the laser mount off the back of the ship?Are you talking about having the laser on the ship targeting another part of the ship, then no acceleration will happen. However, you could use a laser as a thruster, where you use E = mc2 (and Momentum of light = E/c) to cause accelleration, you would required a very high power Power Source to make any decent acceleration Quote Link to comment Share on other sites More sharing options...
Cancer Posted March 17, 2010 Report Share Posted March 17, 2010 Re: Laser launched rockets And the Kzinti Lesson applies. The beam will be impressive in power and destructive capacity. As in, several orders of magnitude more than those little flashlights you were thinking of for armament. Quote Link to comment Share on other sites More sharing options...
Lawnmower Boy Posted March 17, 2010 Report Share Posted March 17, 2010 Re: Laser launched rockets One megawatt of beamed power/kg of payload in orbit. I'm beginning to rethink the idea of this being safer than sitting on high explosives and lighting a match. Also, the proponents seem to be a bunch of cultists. Never a good sign in technology. Ooh! IPad! Quote Link to comment Share on other sites More sharing options...
Cancer Posted March 17, 2010 Report Share Posted March 17, 2010 Re: Laser launched rockets Yeah, you can scratch out a back-of-the-envelope calculation for photon rockets and end up with appalling numbers. For a vehicle the mass of the Space Shuttle, if you want enough thrust to accelerate you at 1 gee (which is enough to levitate you above the surface of the Earth; you need a little more thrust to lift you to orbit) your rocket power requirement is about 10^15 W. FWIW, that power requirement exceeds the world electricity generation capacity in 2006 by a factor of several hundred. Quote Link to comment Share on other sites More sharing options...
austenandrews Posted March 17, 2010 Report Share Posted March 17, 2010 Re: Laser launched rockets FWIW' date=' that power requirement exceeds the world electricity generation capacity in 2006 by a factor of [u']several hundred[/u]. That's what prompted my question. For the amount of power we're talking about, it seems like some sort of railgun would be infinitely more efficient. Quote Link to comment Share on other sites More sharing options...
pinecone Posted March 17, 2010 Report Share Posted March 17, 2010 Re: Laser launched rockets I recall seeing a televised demonstration of laser propulsion that appeared identical to this system over a decade ago. Yep, me too...I think it was funded by NASA..... Quote Link to comment Share on other sites More sharing options...
pinecone Posted March 17, 2010 Report Share Posted March 17, 2010 Re: Laser launched rockets In what context would this be the most efficient way to get something aloft? Honest question; I don't know the limits of the concept. In theory it should be Very good....you don't have to haul a metric b-load of fuel with you....just to burn it up. So the lift per KW is much better... Quote Link to comment Share on other sites More sharing options...
McCoy Posted March 18, 2010 Report Share Posted March 18, 2010 Re: Laser launched rockets Yeah, you can scratch out a back-of-the-envelope calculation for photon rockets and end up with appalling numbers. For a vehicle the mass of the Space Shuttle, if you want enough thrust to accelerate you at 1 gee (which is enough to levitate you above the surface of the Earth; you need a little more thrust to lift you to orbit) your rocket power requirement is about 10^15 W. FWIW, that power requirement exceeds the world electricity generation capacity in 2006 by a factor of several hundred. Is that based on light pressure alone, or using the laser to heat reaction mass? Quote Link to comment Share on other sites More sharing options...
gewing Posted March 18, 2010 Report Share Posted March 18, 2010 Re: Laser launched rockets Is that based on light pressure alone' date=' or using the laser to heat reaction mass?[/quote'] you beat me to it. I have seen a couple of different concepts over the years, iirc. Photon pressure- only good for small items or in Doc Smith level stuff (okay, Mote in God's Eye did use it with a solar Sail also, but...) I seem to recall proposals that would heat air inside the chamber to expand it as a form of jet engine also proposals to feed a "fuel source" into the chamber, and heat/ignite it with the laser. I still prefer mass drivers for earth to orbit launch, or space elevators of course. now from the Moon, maybe solar powered lasers could be used... Quote Link to comment Share on other sites More sharing options...
RexMundi Posted March 18, 2010 Report Share Posted March 18, 2010 Re: Laser launched rockets Dean Ing had an interesting approach to Laser Propulsion in the book Big Lifters. Very good read by the way. Man Kzin wars see's some Laser Propulsion stuff in the beginning as well. Certainly some potential there. ~Rex Quote Link to comment Share on other sites More sharing options...
Cancer Posted March 18, 2010 Report Share Posted March 18, 2010 Re: Laser launched rockets Is that based on light pressure alone' date=' or using the laser to heat reaction mass?[/quote'] Light pressure. Heating reaction mass is something else entirely. Quote Link to comment Share on other sites More sharing options...
RexMundi Posted March 18, 2010 Report Share Posted March 18, 2010 Re: Laser launched rockets As much as what I hate Wikipedia here's a link with a few Laser Propulsion system thingies for those not in the know http://en.wikipedia.org/wiki/Laser_propulsion ~Rex Quote Link to comment Share on other sites More sharing options...
Kristopher Posted March 18, 2010 Report Share Posted March 18, 2010 Re: Laser launched rockets "Scaling up" isn't the simple, easy step it's often made out to be. Look up the actual mass / weight of the objects being lifted by lasers currently. Quote Link to comment Share on other sites More sharing options...
StGrimblefig Posted March 18, 2010 Report Share Posted March 18, 2010 Re: Laser launched rockets My impression from the video (s -- I watched a couple of the related ones in English as well) is that the laser is focused by the shape of the underside of the craft to superheat the air flowing through the vents in the body, causing a rapid expansion of that air that pushes against the body of the craft and produces the thrust. This presents the practical use of the craft with two major problems: 1) The craft is limited to use where the density of air is great enough to provide the necessary thrust. So, no orbital lifting. 2) the laser must be directly underneath the craft, and lined up properly, or it will at best produce unbalanced thrust, which would drive it further, or completely, out of alignment with the laser, and back into gravity's persistent embrace. So, no flying on windy days. Or near the jet stream, if you can even fly that high. It is an interesting technology, but it doesn't seem very useful. Quote Link to comment Share on other sites More sharing options...
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