Solar-pumped laser power transmission, a way to dramatically decrease launch costs?
in [Physics]
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From: William Mook on 8 Mar 2010 08:57 On Mar 7, 8:16 pm, Fred J. McCall <fjmcc...(a)gmail.com> wrote: > I think you get some idea of how 'good' Mookie's numbers are by the > simple fact that he claims that SSTO is 'NOT POSSIBLE' with > conventional propellant types. There's lots of data out there from > people who are actually knowledgeable in the field (unlike Mookie) > that says otherwise. > > For example: http://www.dunnspace.com/alternate_ssto_propellants.htm > > Or perhaps:http://www.reactionengines.co.uk/downloads/JBIS_v56_108-117.pdf > > Mookie thinks that an ability to do arithmetic is sufficient to > 'prove' things. It's not. > > William Mook <mokmedi...(a)gmail.com> wrote: > > :On Mar 7, 12:50 pm, "J. Clarke" <jclarke.use...(a)cox.net> wrote: > :> On 3/7/2010 11:53 AM, Marvin the Martian wrote: > :> > :> > :> > :> > On Sat, 06 Mar 2010 21:21:37 -0700, Fred J. McCall wrote: > :> > :> >> Marvin the Martian<mar...(a)ontomars.org> wrote: > :> > :> >> :On Sat, 06 Mar 2010 11:43:21 -0800, William Mook wrote: : > :> >> :Actually, I think Mr. Mook's idea has merit. : > :> > :> >> Of course you do. Can you spell 'sock puppet'? Yeah, I thought you > :> >> could. > :> > :> > You're an idiot, McCall. Another damaged ego posting drivel to > :> > Sci.physics in the hopes of feeling important. > :> > :> > NASA has been looking into laser transfer of energy for propulsion since > :> > at least 1976. > :> > :> >http://hdl.handle.net/2060/19760014427 > :> > :> Yep, and it doesn't address the main driver in launch costs. > :> > :> All these schemes aimed at saving gas are worthless until gas is the > :> major cost driver. > : > :Its cost of lift, not gas per se. Cost of lift has to do with the > :cost of the vehicle. That has to do with empty vehicle weight. > : > : > :So, you can see we're not talking about the cost of propellant, we're > :talking about the cost of the SYSTEM > : > :Consider; > : > :Here are the performance of some of the technologies we've either used > :or discussed in this group. First we list the exhaust speeds > :attainable, and then we list the thrust to weight of the engine, and > :then structural fraction of the airframe to carry the propellant > : > :Propulsion Technology: > : > :Solid Propellant Chemical Rocket: 2.5 km/sec exhaust speed, 100:1 T/ > :W, 5% structural fraction > :Hypergolic Propellant Chemical Rocket: 3.2 km/sec exhaust speed, 70:1 > :T/W, 7% structural fraction > :Cryogenic Propellant Chemical Rocket: 4.0 km/sec exhaust speed, 70:1 T/ > :W, 12% structural fraction > :Nuclear Thermal Rocket (Solid Core): 8.0 km/sec exhaust speed, 10:1 T/ > :W, 15% structural fraction > :Nuclear Thermal Rocket (Gas Core): 12.0 km/sec exhaust speed, 7:1 T/W, > :15% structural fraction > :Nuclear Pulse Rocket: 20.0 km/sec exhaust speed, 5:1 T/W, 5% > :structural fraction > :Laser Pulse Rocket: 50.0 km/sec exhaust speed, 20:1 T/W, 5% > :structural fraction > : > :So, let's see what impact these figure have on the size and complexity > :of a vehicle that lofts 60 tonnes into LEO. > : > :The Shuttle masses 1,400 tonnes at lift off and carries 24 tonnes into > :LEO. So, a system 2.5x more massive would loft 60 tonnes into LEO and > :mass 3,500 tonnes - which corresponds with a 2.5 stage Cryogenic > :system described below (external tank is half stage). > : > :The Proton UR500 masses 540 tonnes at lift off, and lofts 12 tonnes > :into LEO. So, a system 5x more massive would weigh 2,700 tonnes at > :lift off and loft 60 tonnes into LEO - which corresponds with a 3 > :stage hypergolic system described below. > : > :Reference Vehicle: > : > :Payload: 60 tonnes, > :Ideal Delta Vee: 9.2 km/sec > : > :So, we construct the following table - > :Empty Weight Sizes the cost of the vehicle, > :Take off Weight sizes the cost of the launch center. > : > :Technology Propel Struct Stage Pay Vehicle Take Off Weight Empty > :Weight > : > :Solid > : 4 stage 0.601 0.060 0.338519 0.013132 4,568.98 274.14 > : 3 stage 0.707 0.060 0.233269 0.012693 4,726.97 283.62 > : 2 stage 0.841 0.060 0.098817 0.000965 62,179.99 3,730.80 > : 1 stage 0.975 0.060 NOT POSSIBLE > : > :Hypergolic > : 4 stage 0.513 0.084 0.403075 0.065488 916.20 77.22 > : 3 stage 0.616 0.084 0.299246 0.026797 2,239.07 188.72 > : 2 stage 0.762 0.084 0.153235 0.003598 16,675.41 1,405.50 > : 1 stage 0.944 0.084 NOT POSSIBLE > : > :Cryogenic > : 4 stage 0.437 0.134 0.428419 0.078633 763.04 102.46 > : 3 stage 0.535 0.134 0.330273 0.036026 1,665.45 223.65 > : 2 stage 0.683 0.134 0.182351 0.006064 9,895.24 1,328.79 > : 1 stage 0.900 0.134 NOT POSSIBLE > : > :Nuclear Thermal (solid core) > : 4 stage 0.250 0.250 0.500137 0.125102 479.61 119.90 > : 3 stage 0.318 0.250 0.431586 0.080390 746.36 186.59 > : 2 stage 0.437 0.250 0.312705 0.030578 1,962.22 490.55 > : 1 stage 0.683 0.250 0.066637 0.000296 202,772.68 50,693.17 > : > :Nuclear Thermal (gas core) > : 4 stage 0.174 0.293 0.532725 0.151185 396.86 116.22 > : 3 stage 0.226 0.293 0.481629 0.111722 537.05 157.28 > : 2 stage 0.318 0.293 0.388729 0.058741 1,021.44 299.14 > : 1 stage 0.535 0.293 0.171702 0.005062 11,852.94 3,471.22 > : > :Nuclear Pulse > : 4 stage 0.109 0.250 0.641366 0.263826 227.42 56.86 > : 3 stage 0.142 0.250 0.607844 0.224582 267.16 66.79 > : 2 stage 0.205 0.250 0.544534 0.161463 371.60 92.90 > : 1 stage 0.369 0.250 0.381284 0.055430 1,082.45 270.61 > : > :Laser Pulse > : 4 stage 0.045 0.100 0.855042 0.625118 95.98 9.60 > : 3 stage 0.059 0.100 0.840510 0.593784 101.05 10.10 > : 2 stage 0.088 0.100 0.812105 0.535595 112.02 11.20 > : 1 stage 0.168 0.100 0.731936 0.392120 153.01 15.30 > : > :The laser pulse system has an empty vehicle mass 10 to 16 tonnes > :versus a 4 stage hypergolic system massing 78 tonnes empty. A four > :stage hypergolic system is the lowest cost existing technology, which > :is reflected in the launch costs of the Chinese and Russian systems. > :A three stage cryogenic system is 3x more expensive - which again is > :reflected in the experience of the USA, Europe and Japan. A laser > :system once developed will be 1/20th the cost of a Cryogenic system > :and 1/7th the cost of a Hypergolic system - assuming single use throw- > :away. A reusable system, reused 100x will be 1/700th the cost of the > :lowest cost system available today. > : > :You can see we're not talking about the cost of propellant, we're > :talking about the cost of the SYSTEM Fred, is nuts. He's saying that a rocket with a 4.0 km/sec exhaust speed and 13.4% structural fraction can be made into an SSTO rocket. It can't. He'd know that if he knew how to do the calculations, which he obviously doesn't. GIven these exhaust velocities and structural fractions - SSTO is not possible. These values are based on actual data, they are soundly based. This is supported by the fact that there are no systems flying today that are SSTO. The SSTO programs supported by NASA over the past 25 years are regarded generally as failures. Also, flight systems derived from SSTO research may not have the reliability and safety required for piloted operation. One expert said, we are trying to achieve the structural fraction of eggs (5% to 7%) - we shouldn't be surprised if the results are as fragile as eggs. The destruction of a leading edge on the space shuttle made of reduced carbon composites by a piece of foam flying at subsonic speeds killed the SSTO program for NASA leadership because the reduced structural fractions were going to be achieved by extensive use of RCC throughout the vehicle. SSTO is not possible with today's performance with cyrogens. None exist. According to Fred, that makes them fictional. Even so, the engineering argument is compelling. Shoud we spend a significant amount of money to slightly improve these performances and achieve SSTO? I think not. Because total cost isn't radically reduced. That's because vehicle size is not reduced, and performance remains largely the same. So, we are better off investing in laser rockets, which is my point. Let's look at SSTO program as approached by NASA for the past 25 years and see what might be possible if we assume someslight improvements in structural fraction and performance. The argument is sound. Slight advances in the art, might make SSTO possible. Reduced structural fractions to say 7%, and increased exhaust velocities as achieved with flourine oxygen engines - to 4.5 km/sec from lift off through ascent - and we have a single stage capability. The numbers given these slightly improved numbers are; Ve=4.5 km/sec u = 7% Propellant Fraction 0.87055 Structure Fraction: 0.07000 Payload Fraction: 0.05945 Which is interesting. Obviously if structure were to rise to over 12.945% we would have no useful payload and SSTO is not possible. Since I assumed 13.4% structural fraction in my cryogen case, and 4.0 km/sec no useful payload is possible with those assumptions - which is all that meant - and which Fred is trying to lie to us and say I meant something more than that. For this SSTO system - which is only possible if exhaust speeds are 4.5 km/sec throughout the flight cycle, and only possible if structural fractions of 7% are attained, a vehicle that lofts a 60 tonne payload to LEO would mass 1,009.2 tonnes and mass 70.7 tonnes empty. A two stage system with the same performance is smaller overall. 714.4 tonnes take off weight, 50.0 tonne structural weight - with far more chances of success if performance or structural fraction capabilities slip slightly. So, with a program dedicated to improve structural fraction from 13.4% to 7% and to improve engine performance from 4.0 km/sec to 4.5 km/sec we have the following for a 60 tonne payload capability; 4.0 km/sec - 13.4% TOW structure 4 stage 763.04 102.46 3 stage 1,665.45 223.65 2 stage 9,895.24 1,328.79 1 stage NOT POSSIBLE 4.5 km/sec - 7.0% 2 stage 714.4 50.0 1 stage 1,009.2 70.6 Total launch infrastructure remains about the same as a three or four stage cryogen rocket of the older performance type, and total vehicle cost is cut in half. The big issue is reusability. Can a vehicle built with a very small structural fraction by flown again and again and again reliably? If its easy to break, or even easy to dent, its not going to have the robustness, or low cost that we're seeking. Even so, assuming we do our jobs right, it might be possible to attain an SSTO capability, with no reduction in overall costs from a four stage capability using the older technical approaches. Apply the improved capabilities to a two stage system and we might cut costs by 30% or more. Applied to our Mars mission example from the previous post we can see that total numbers are not radically changed by this approach. Even if we cut costs in half, we still only get a footprint mission on Mars for $100 billion in a decade- after spending a decade and another $50 billion developing the technology. Far better to pay the russians to adapt their launcher technology to the task and get the whole footprint on Mars done in four years and $50 billion . So, this discussion of SSTO emphasizes my original point. For $30 billion and a few years research, we can radically transform space launch and our relationship to the cosmos while solving our energy problems and raw material problems.
From: William Mook on 8 Mar 2010 08:57 On Mar 7, 8:17 pm, Fred J. McCall <fjmcc...(a)gmail.com> wrote: > William Mook <mokmedi...(a)gmail.com> wrote: > > :On Mar 7, 2:13 pm, Fred J. McCall <fjmcc...(a)gmail.com> wrote: > :> Marvin the Martian <mar...(a)ontomars.org> wrote: > :> > :> :On Sat, 06 Mar 2010 21:21:37 -0700, Fred J. McCall wrote: > :> : > :> :> Marvin the Martian <mar...(a)ontomars.org> wrote: > :> :> > :> :> :On Sat, 06 Mar 2010 11:43:21 -0800, William Mook wrote: : > :> :> :Actually, I think Mr. Mook's idea has merit. : > :> :> > :> :> Of course you do. Can you spell 'sock puppet'? Yeah, I thought you > :> :> could. > :> : > :> :You're an idiot, McCall. Another damaged ego posting drivel to > :> :Sci.physics in the hopes of feeling important. > :> : > :> > :> Coming from a nymskull sock puppet, that's really quite funny. > :> > :> : > :> :NASA has been looking into laser transfer of energy for propulsion since > :> :at least 1976. > :> : > :> :http://hdl.handle.net/2060/19760014427 > :> : > :> > :> Yes, I know they have, sock puppet. And they're still not even > :> considering building such a vehicle. That ought to tell you > :> something, if only you were sane. > :> > :> We now return you to your regularly scheduled Mookery of reality. > :> > : > :Marvin, you can't win! lol. > : > > That's the first thing you've posted that has been even approximately > accurate, Mookie... > > -- > "Some people get lost in thought because it's such unfamiliar > territory." > --G. Behn Yeah, Fred, you are a damaged personality! haha
From: William Mook on 8 Mar 2010 09:03 On Mar 7, 8:51 pm, Fred J. McCall <fjmcc...(a)gmail.com> wrote: > William Mook <mokmedi...(a)gmail.com> wrote: > > :250 flights requiring 250 expendable launchers to support a dozen > :interplanetary craft, which requires a space station on orbit put up > :with another 250 launches with 250 flights - costing $210 billion+ - > :to put 80 people into the vicinity of Mars and 20 people on the > :surface - on a 3 year mission - is an exciting and difficult project > :spanning a decade or more. > : > :It would be exciting and inspiring and uplifting. Yet its practical > :impact would be questioned still. > : > :This is the typical mission to mars with hypergolics. > : > > Nonsense! > > 1) Nobody sane is talking about using hypergolics for a Mars mission. vonBraun is insane too? I must be in good company. > 2) Nobody sane would send 100 people on the mission and then only land > 20 of them. So, you're saying vonBraun is insane too? Interesting. > 3) No space station is required. What does Mookie think one is > necessary for? Riiight - so you haven't read Operation Mars - got it. > 4) Putting 24 people on Mars (more than Mookie postulates) requires > only four copies (or fewer if equipment from prior missions is used) > of the Reference Mission. That's 16 launches, total, not the **500** > that Mookie claims. How are you keeping your cryogens from boiling away? What do you do if there is a mechanical failure enroute? > 5) Putting 100 people ON MARS (the total of Mookie's 'into the > vicinity' and 'on the surface' numbers) can be done in 68 launches > (102 people on the surface of Mars), not the **500** that Mookie > claims. So, you're saying the total cost of a Mars mission using your approach is? What? Substantially less than $200 billion? What is the cost you are estimating and why? > I think that gives you a pretty good idea of just how many truckloads > of salt you should take Mookie's fantasy numbers, following, with. > 'Imagine', indeed, since that's as close to actuality as his claims > come. Nonsense. Please give the basis of your calcuations. Whatever the assumptions are use them - and then compare them in the same way to what laser and nuclear can do - and it will prove my point - investing in laser is the way to radically transform our relationship to the cosmos. > :Now consider laser propulsion on the same scale. > : > :Imagine 1000 reusable launchers costing 1/7th that of the hypergolic > :launchers so cost $60 billion. These each fly to mars using laser > :light sails after a laser lauch, and return in 3 weeks. Each vehicle > :carries 600 people. Each passenger incurs a cost of $2,000. Each > :vehicle used 12x per year and has a 40 year life cycle. 1,000 > :vehicles costing $60 billion plus another $40 billion for laser > :infrastructure - cost 1/2 the 'footprint' mission with hypergolics. > :This fleet of 1,000 reusable vehicles execute 12,000 flights per > :year. So, a flight leaves every 43 minutes from somewhere on Earth. > :1,000 vehicles operating out of eight space ports around the world, > :would have 3 outbound flights per day, and 3 inbound flights per day. > :In a year 7.2 million people would visit Mars and if each paid $5,000 > :the operate generates $36 billion each year on the $100 billion > :invested. > : > :Would 7.2 million people each year pay $5,000 and 3 weeks to visit > :Mars? Well, there are 200x as many air passengers each year. So, > :we're talking about a very select clientele, despite the volume. > : > :This would be even more inspiring and uplifting, and transform life on > :Earth, and our relationship to our frontier. > : > :So, its not just about propellant cost - its about system cost and > :system performance achievable for the dollars we're spending and what > :we're getting back for those dollars in terms of a changed world.
From: William Mook on 8 Mar 2010 11:29 On Mar 8, 10:46 am, Fred J. McCall <fjmcc...(a)gmail.com> wrote: > William Mook <mokmedi...(a)gmail.com> wrote: > > :On Mar 7, 8:16 pm, Fred J. McCall <fjmcc...(a)gmail.com> wrote: > :> I think you get some idea of how 'good' Mookie's numbers are by the > :> simple fact that he claims that SSTO is 'NOT POSSIBLE' with > :> conventional propellant types. There's lots of data out there from > :> people who are actually knowledgeable in the field (unlike Mookie) > :> that says otherwise. > :> > :> For example:http://www.dunnspace.com/alternate_ssto_propellants.htm > :> > :> Or perhaps:http://www.reactionengines.co.uk/downloads/JBIS_v56_108-117..pdf > :> > :> Mookie thinks that an ability to do arithmetic is sufficient to > :> 'prove' things. It's not. > :> > : > :Fred, is nuts. He's saying that a rocket with a 4.0 km/sec exhaust > :speed and 13.4% structural fraction can be made into an SSTO rocket. > :It can't. He'd know that if he knew how to do the calculations, which > :he obviously doesn't. > : > > In other words, Mookie is rigging the numbers to come out the way he > wants them to, just like he does with his 500 launches required Mars > missions. > > : > :GIven these exhaust velocities and structural fractions - SSTO is not > :possible. These values are based on actual data, they are soundly > :based. This is supported by the fact that there are no systems flying > :today that are SSTO. The SSTO programs supported by NASA over the > :past 25 years are regarded generally as failures. > : > > I see. Mookie knows better than the experts, writing in the cites I > gave. > > : > :Also, flight systems derived from SSTO research may not have the > :reliability and safety required for piloted operation. One expert > :said, we are trying to achieve the structural fraction of eggs (5% to > :7%) - we shouldn't be surprised if the results are as fragile as > :eggs. > : > > And which 'expert' would that be? Is his name "Mook"? > > : > :The destruction of a leading edge on the space shuttle made of > :reduced carbon composites by a piece of foam flying at subsonic speeds > :killed the SSTO program for NASA leadership because the reduced > :structural fractions were going to be achieved by extensive use of RCC > :throughout the vehicle. > : > > Absolute bullshit. > > : > :SSTO is not possible with today's performance with cyrogens. None > :exist. According to Fred, that makes them fictional. > : > > Actually, you might want to go do some looking at this. The old Atlas > was damned near an SSTO. Much less fictional than your imaginary > maunderings. > > : > :Even so, the engineering argument is compelling. Shoud we spend a > :significant amount of money to slightly improve these performances and > :achieve SSTO? > : > :I think not. Because total cost isn't radically reduced. That's > :because vehicle size is not reduced, and performance remains largely > :the same. So, we are better off investing in laser rockets, which is > :my point. > : > > Mookie thinks a totally untried technology will be CHEAPER to develop > than merely enhancing what we have. No doubt he started running 9.5 > second 100 meter dashes before he learned to walk. > > : > :Let's look at SSTO program as approached by NASA for the past 25 years > :and see what might be possible if we assume someslight improvements in > :structural fraction and performance. > : > :The argument is sound. Slight advances in the art, might make SSTO > :possible. Reduced structural fractions to say 7%, and increased > :exhaust velocities as achieved with flourine oxygen engines > : > > Once again we see Mookie jiggering the numbers. One of the cites I > gave him specifically ruled out things like fluorine engines and had > no problems getting to an SSTO. > > : > :- to 4.5 > :km/sec from lift off through ascent - and we have a single stage > :capability. The numbers given these slightly improved numbers are; > : > :Ve=4.5 km/sec > : u = 7% > : > : Propellant Fraction 0.87055 > : Structure Fraction: 0.07000 > : Payload Fraction: 0.05945 > : > :Which is interesting. Obviously if structure were to rise to over > :12.945% we would have no useful payload and SSTO is not possible. > :Since I assumed 13.4% structural fraction in my cryogen case, and 4.0 > :km/sec no useful payload is possible with those assumptions - which is > :all that meant - and which Fred is trying to lie to us and say I meant > :something more than that. > : > > So you jiggered the numbers to make your pet fiction look better. > Anyone surprised? > > Now he's going to go into a dance that makes it look like it's all > about exhaust velocity. It's not. SSTO is probably actually easier > with lower exhaust velocity fuels because you can lose all the mass > margin required for handling cryo fluids in large quantities. A > non-cryo fuel can have tank masses as low as 1% of the fuel weight. > LH2 usually requires something up around 10%. LOX with any of a > number of non-cryo fuels will double your payload to LEO. > > : > :For this SSTO system - which is only possible if exhaust speeds are > :4.5 km/sec throughout the flight cycle, and only possible if > :structural fractions of 7% are attained, a vehicle that lofts a 60 > :tonne payload to LEO would mass 1,009.2 tonnes and mass 70.7 tonnes > :empty. > : > :A two stage system with the same performance is smaller overall. > :714.4 tonnes take off weight, 50.0 tonne structural weight - with far > :more chances of success if performance or structural fraction > :capabilities slip slightly. > : > : > :So, with a program dedicated to improve structural fraction from 13.4% > :to 7% and to improve engine performance from 4.0 km/sec to 4.5 km/sec > :we have the following for a 60 tonne payload capability; > : > : 4.0 km/sec - 13.4% > : > : TOW structure > : 4 stage 763.04 102.46 > : 3 stage 1,665.45 223.65 > : 2 stage 9,895.24 1,328.79 > : 1 stage NOT POSSIBLE > : > : 4.5 km/sec - 7.0% > : > : 2 stage 714.4 50.0 > : 1 stage 1,009.2 70.6 > : > :Total launch infrastructure remains about the same as a three or four > :stage cryogen rocket of the older performance type, and total vehicle > :cost is cut in half. The big issue is reusability. Can a vehicle > :built with a very small structural fraction by flown again and again > :and again reliably? If its easy to break, or even easy to dent, its > :not going to have the robustness, or low cost that we're seeking. > : > :Even so, assuming we do our jobs right, it might be possible to attain > :an SSTO capability, with no reduction in overall costs from a four > :stage capability using the older technical approaches. Apply the > :improved capabilities to a two stage system and we might cut costs by > :30% or more. > : > :Applied to our Mars mission example from the previous post we can see > :that total numbers are not radically changed by this approach. Even > :if we cut costs in half, we still only get a footprint mission on Mars > :for $100 billion in a decade- after spending a decade and another $50 > :billion developing the technology. Far better to pay the russians to > :adapt their launcher technology to the task and get the whole > :footprint on Mars done in four years and $50 billion . > : > :So, this discussion of SSTO emphasizes my original point. For $30 > :billion and a few years research, we can radically transform space > :launch and our relationship to the cosmos while solving our energy > :problems and raw material problems. > : > > Utter hogwash. Just look at what Mookie claims can be developed for > that $30 billion and just what a crock it is becomes obvious to > everyone but Mookie. He thinks it takes almost twice as much money to > make small improvements in what we already do than it does to come up > with a combined laser launcher and 1g lightsail combination. > > The man is obviously batty as a belfry. > > -- > "Ordinarily he is insane. But he has lucid moments when he is > only stupid." > -- Heinrich Heine Interesting that thorughout all of Fred's objections he doesn't provide any numbers of his own, or any real rationale for his commentary. That speaks volumes. Fred knows nothing of the rocket equation or how to use it to estimate system performance or put it together in any meaningful way.
From: Marvin the Martian on 8 Mar 2010 12:43
On Sun, 07 Mar 2010 13:06:57 -0800, William Mook wrote: > Marvin, you can't win! lol. McCall is a first class idiot. The only way you don't win is if you don't killfile that jackass. |