...100 MW of Space Solar Power ...per single launch!
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From: jimp on 17 Dec 2009 00:35 In sci.physics "Greg D. Moore \(Strider\)" <mooregr_delet3th1s(a)greenms.com> wrote: > <jimp(a)specsol.spam.sux.com> wrote in message > news:lc3ov6-5mp.ln1(a)mail.specsol.com... >> In sci.physics "Greg D. Moore \(Strider\)" >> <mooregr_delet3th1s(a)greenms.com> wrote: >>> <jimp(a)specsol.spam.sux.com> wrote in message >>> news:fqrnv6-6so.ln1(a)mail.specsol.com... >>>> >>>> For existing things there is the concept of minimum enroute altitude >>>> which ensures you are above all the obstacles for a significant >>>> distance. >>>> >>>> There is no getting above an energy beam from space. >>>> >>> >>> And yet people still fly into the ground or buildings. Again, it's the >>> pilot's fault. Not the build, ground or beam. >> >> Apples and oranges. >> >> How do you avoid something that is invisible to all existing aviation >> sensors? > > Same way pilots avoid no-fly zones now. They consult their maps and NOTAMs > and fly around them. > >> >> While flying VFR, obstacles are avoided by eyesight and altitude, neither >> of which will work with an energy beam from space. >> > > Pilots flying VFR avoid no-fly zones now. I'm not sure why in the future > you think they're suddenly going to become stupid. > > In any case, at the energies discussed, the power levels just aren't that > dangerous. If the energy density is low enough to be safe, it isn't high enough to be particularly usefull. -- Jim Pennino Remove .spam.sux to reply.
From: jimp on 17 Dec 2009 00:37 In sci.physics Jonathan <Home(a)again.net> wrote: > > <jimp(a)specsol.spam.sux.com> wrote in message > news:ls1mv6-hrf.ln1(a)mail.specsol.com... >> In sci.physics Jonathan <Home(a)again.net> wrote: >>> >>> "BradGuth" <bradguth(a)gmail.com> wrote in message >>> news:6b4a5e28-24e8-423a-89d4-94a3d2e10e6a(a)x5g2000prf.googlegroups.com... >>> >>> >>>> 64% all-inclusive efficiency isn't half bad, >>> >>>> Getting so much created, deployed and serviced is likely going to >>>> consume most every megawatt of energy it produces, and then some. >>> >>>> Is this energy going to cost us $1/kw.h? >>> >>> It doesn't really matter, the greater benefit would be >>> the effect on all other energy sources. >> >> Yes, it does, and a lot. >> >> The cost of electricity increasing by a factor of around 5 would be >> an economic catastrophe. >> > > The initial costs are not so important, what counts is the > new /trend/ that would be established. Space Solar Power > would be very expensive at first, but over time would become > steadily ...cheaper... and more ...plentiful. Adding clean energy If the delivered price isn't on a par with other sources, it goes nowhere, ever. -- Jim Pennino Remove .spam.sux to reply.
From: jimp on 17 Dec 2009 00:43 In sci.physics Peter Fairbrother <zenadsl6186(a)zen.co.uk> wrote: > Alain Fournier wrote: > However there would be other benefits to starting a space-based economy, > for instance things can be made in space which are impossible or > expensive to make on Earth Name something that is impossible to make on Earth or would be cheaper to make in space for which there is an actual market. I hear this arm-waving claim from the space cadet crowd a lot, but no one seems to be able to identify a product. -- Jim Pennino Remove .spam.sux to reply.
From: Pat Flannery on 17 Dec 2009 03:08 Rick Jones wrote: > > I don't think that "a plane might fly through the beam" is a > sufficient reason to veto SSP, yet, just how far out into the boonies > are power plants these days? Sure, you want these things out in the > sticks, but the farther out, the more of your hard-earned, somewhat > expensive, space-electricity you lose to terrestrial transmission > losses right? They've gotten better at long distance power transmission, but even with losses from transmission you can still decrease the overall power load needed for the whole nation in a major way. Some cities (Las Vegas, Nevada and Phoenix, Arizona come to mind) are ideally located in or near deserts so transmission length wouldn't be much. Up here in North Dakota, an area of farmland could be easily set aside for this purpose without noticably affecting crop production levels, as the state is 89% farmland by area anyway. > Would the chocolate bar in your pocket start to melt?-) > > http://en.wikipedia.org/wiki/Microwave_oven#History It would depend if the microwaves got inside the aircraft via non-metallic parts, such as composite structures or plastic canopies or windows. Aircraft that emit high power radio or micro waves like the EA-6 Prowler ECM aircraft have metallic coatings on their canopies to keep the possibly dangerous levels of energy out of the cockpit: http://www.flickr.com/photos/brentc2/3710662562/ The F-117 and B-2 use the same type of coatings to prevent enemy radar from coming right through the canopy and reflecting off of the crew and equipment inside, to preserve the aircraft's stealth. A side benefit of this is that it should also block UV rays, so the pilot wouldn't get sunburn in flight at high altitude. Thin gold plating has been used on space helmets to protect the astronauts from hard UV exposure during EVAs. Pat
From: Pat Flannery on 17 Dec 2009 05:00
Peter Fairbrother wrote: >> When these systems were first proposed in the 1970s-80s the favored >> launch system was a massive single or two-stage-to-orbit vehicle that >> did a vertical takeoff and landing. One design used no less than >> twenty F-1 engines, all firing during ascent, and six firing for landing. > > That's a different sort of system, a very large one and not winged. > >> Building a horizontal takeoff and landing or vertical >> take-off/horizontal landing first stage for the size payload required >> to make it economical would be daunting, as it would probably dwarf a >> C-5B Galaxy as far as size and weight went. > > I'd try stick to something which could still land at an airport - which > means a maximum of about 450 tons MTOW for a HTHL, and 1000 tons for a > VTHL (it only has to land, empty). I'm trying to get some ballpark figures on the weight per kilowatt of the ISS solar arrays, as they are about as lightly made as possible to be structurally sound in space, and in that way you could get some order of magnitude figures on what a large SPS would weigh. Unfortunately, the weight figures I find are for the solar arrays and associated equipment in the ISS node they are attached to as it's carried aloft, rather than just the solar arrays themselves. Anyone have data on the weight of just the panels themselves? Using the reflectors and Brayton cycle generators you suggested are a open question as far as weight goes, as nothing like that has been deployed in space other than the big parabolic reflectors used to intercept microwave signals by the NSA. Details on those are classified, but the recently launched "Mentor" might be around the size for something used on a SPS: http://www.globalsecurity.org/space/systems/trumpet.htm That's estimated to be 350 feet in diameter and weigh 10,000-13,000 pounds. You point something 350 feet across at the sun in space, and you will indeed get a lot of thermal energy to run a Brayton cycle engine. > > Using Lox/kero first stages and LOX/LH2 second stages a 1,000 ton VTHL > could launch maybe 25-30 tons, and a 450 ton MTOW HTHL could launch > maybe 8-9 tons into equatorial LEO. > > The difference is partly from scale, and partly because a HTHL would > probably need to take off from an airport on jets rather than rockets - > but this also means a HTHL TSTO booster stage can go-around, and loiter, > on the landing approach. > > > I favour the lighter system, about a 450 tons MTOW HTHL SSTO - about the > MTOW of a 747, but a bit smaller. It also means you can use existing > aircraft parts for eg landing gear, flap actuators, and so on. One problem here is physical size of the parts you can carry into orbit via something of this size. A SPS is going to be very large in size, and the larger the individual parts you can carry to it, the easier and quicker it will be to assemble. > > Also a HTVL has to be carrier from the airstrip to the expensive launch > pad, then winched from horizontal to vertical between flights. The > lighter VTVL option just uses an existing airfield. I've heard of HTHL and VTHL like the Shuttle but never HTVL, as that means your wings are going to be useless on the way back down, unless you are going to carry something like a ROMBUS aloft and launch it in flight. > > Also, since most booster designs >> that use this design philosophy try to get up to around Mach 6-7 >> before they release the orbital stage, you are going to have a huge >> square-foot area of thermal protection materials that will need going >> over after every flight to check them for damage, and that's a real >> pain in the rear with even the far smaller Shuttle as far as man-hours >> go. > > John Carmack once said that the first stage should just go up and down, > and the second stage should do the translation - but I don't entirely > agree. > > The Shuttle TPS is made from carbon-reinforced-carbon, foamed silica > tiles, and silica blankets in order of heat rejection capacity. CRC and > foamed silica are very fragile, although silica blankets aren't nearly > so fragile. > > A winged first stage, even with a Mach 6-7 horizontal component, has to > dissipate less than a *tenth* of the energy per unit mass than a Shuttle > re-entry. Ever see what Mach 6.7 did to the X-15?: http://www.youtube.com/watch?v=wHuBsBOF4R8 And that was with a Inconel X structure covered with a ablator layer. > > While it would some sort of TPS, we are not talking about the kind used > by Shuttle, something much simpler and much more robust would be enough. > We are talking about less than the silica blanket end of the range, not > CRC or foamed silica. You get a rip in that silica blanket during ascent, and it could peel off of the vehicle's exterior. Also, since the winged stage is going to be at suborbital velocity during descent, lower heating might be combined with higher g loads as it gets down into the denser atmosphere quicker than something descending out of orbit. During Shepard's suborbital Mercury-Redstone flights, the capsule hit 11.6 g's during its descent into the atmosphere after reaching Mach 6.94. Even with wings to turn some of that descent velocity into horizontal flight distance, the HTHL first stage is going to have to have a very strong (i.e. heavy) structure to take the g loads during descent. Also, during descent, unless you figure out a way to turn the winged booster around 180 degrees to fly back to the launch site while keeping inside of its structural limits, you are probably going to end up landing on the far side of the Atlantic if you take off from KSC, or on the east coast if you take off from Edwards AFB. So now you have to get the booster back to the starting point. > > Also there isn't such a need for ultra-light weight in the TPS [*] so a > much heavier TPS could be used. There are several possibilities, and in > general it is quite do-able. It's a bit of a challenge but not in any > way a deal-breaker. > > [*] it's a first stage, a bit of extra mass here has much less effect on > overall performance than a bit of extra mass on a second or orbiting stage. > >> The fewer flights you need to get all of the materials for the SPS >> into LEO (it can be moved slowly out to GEO via ion engines once >> assembled, and building it in LEO really cuts back on assembly crew >> launch costs, as well as removing the radiation threat to the assembly >> crew from solar storms) the better from a economic viewpoint, > > NO NO NO! The number of flights is not relevant, the cost for the total > mass launched is the important metric (okay there are other > considerations like minimum component size and assembly costs, but > that's the most important one). A whole pile of launches equals a whole pile of infrastructure to support between launches, like on the Shuttle. And that eats up money fast. Even if you can get turnaround time between launches of individual vehicles down to a really short period of time, say 3-4 days, and despite the lower stage being able to use a robust and heavy TPS, there is still the reusable top stage to consider - that is going to reenter from orbit and will need a lightweight TPS like the Shuttle and need looking at between flights. > Large is not necessary if you can fly several times per day - I envisage > a 10 ton payload HTHL TSTO flying once every 90 minutes from a ground > site to a location in orbit with three launchers, giving a turnaround > time of 4.5 hours. You couldn't even get the cargo aboard it, restack the two stages, and refuel it that fast, much less check it out and make sure it's ready to fly again. 747's have a turnaround time between flights of around 3 hours, and that's without loading and hoisting a C-141 onto the top of one. Even the von Braun ferry rocket designs of the 1950's had a turnaround time of five days, not five hours. The shortest Shuttle turnaround time was eight weeks, although the design originally specified fourteen days, so you are counting on your launch system having 1/128 the turnaround time of the Shuttle's original specs. I can see reducing turnaround times, but two orders of magnitude seems a bit much. > Yes, that sort of thing could be done - my preferred system returns the > second stage engines, electronics, RCS and (maybe) LOX tank, but the LH2 > tank is left in orbit for either living space or constructional > material. There are other possibilities. Now, let me get this straight...parts of a second stage are going to come back...get recovered...and installed on a new second stage...which then gets loaded with cargo...restacked on the flyback first stage...fueled...and launched...in 4.5 hours? And that doesn't even include the time of ascending to orbit, unloading the cargo in orbit, and the upper stage's parts descending back to Earth. Without the help of Dr. Who and the TARDIS this ain't going to work. :-D Pat |