#21
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poor man's rocket
Peter Fairbrother wrote:
Actually they would be utterly stupid to spend $100M on the sat. The only reason why a sat that has a few $100k of functionality can cost $100M is that the overall mission cost is lower bounded by the launch cost. Um, no. a good sized chunk of the cost is in the engineering needed to make it last for years in a hazardous environment. Even with launch costs drastically reduced, it's not clear how much satellite costs can fall for commercial birds. (Few of them can tolerate extended outages, as such outages can cost millions of dollars a day.) Even if costs fall, and lead time falls, (and the two are not unrelated), you have the non trivial task of storing the spare, and you have the time it takes to reach geosync for commo birds. D. -- The STS-107 Columbia Loss FAQ can be found at the following URLs: Text-Only Version: http://www.io.com/~o_m/columbia_loss_faq.html Enhanced HTML Version: http://www.io.com/~o_m/columbia_loss_faq_x.html Corrections, comments, and additions should be e-mailed to , as well as posted to sci.space.history and sci.space.shuttle for discussion. |
#22
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poor man's rocket
"Paul E. Black" wrote:
Joann Evans wrote: Peter Fairbrother wrote: Remember, we make no such distinctions with aeronautical or maritime transportation.... We do in postage. I usually do not pay more for invitations, bill payments, etc. because the US postal system is good enough. Once in a while I do pay more to have a lower chance of problems (like when I sent our family's 120-yr old Bible across the county back to my Aunt). With postage, you usually pay more for faster delivery times, and/or confirmed delivery to a specific individual, not an increased certainty that it will be delivered *at all.* Even at book and magazine bulk rates, you're making the assumption that it *will* eventually reach the addressee. The mail rides the same 'man-rated' planes that you or I do. I think there would be a market for very high reliability launch and high reliability launch. If I couldn't afford a 'high-reliability' launch outright, I'd try to share a launch with one that's going essentially where I want to go. Amateur Radio satellites generally get launched like this. |
#23
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poor man's rocket
"Derek Lyons" wrote:
Peter Fairbrother wrote: Actually they would be utterly stupid to spend $100M on the sat. The only reason why a sat that has a few $100k of functionality can cost $100M is that the overall mission cost is lower bounded by the launch cost. Um, no. a good sized chunk of the cost is in the engineering needed to make it last for years in a hazardous environment. Even with launch costs drastically reduced, it's not clear how much satellite costs can fall for commercial birds. (Few of them can tolerate extended outages, as such outages can cost millions of dollars a day.) Even if costs fall, and lead time falls, (and the two are not unrelated), you have the non trivial task of storing the spare, and you have the time it takes to reach geosync for commo birds. That's somewhat questionable. Most likely, cheaper launches and less robust satellites would result in different satellite designs which allowed them to more easily hand off services to each other (think about the last time you noticed passing from one cellular phone cell to another). In that case "spares" aren't quite the right way to look at it, more like "excess capacity". And then you just have to worry about having enough excess capacity to guarantee service until you can launch more satellites (which, with cheap launchers might not be a long wait). Even so, there are some pretty fundamental economic reasons behind short-lifespan capital assets. Not the least of which is the tax code, which frowns on such things, more or less. An economists, which I'm not and never plan on being, could probably tell you about the interplay between asset lifespan and various other costs. But my gut tells me that lifespans for expensive capital equipment is almost always best kept at above several years rather than only a few years or less than a year. Now, on the other, other hand, I am unconvinced that cheaper satellites need necessarily be shorter lifespan satellites. And I can imagine especially that greater mass bugets and more frequent full-up design testing (both of which depend on cheaper launch) could quite easily make up for more expensive design, construction, and components. And, on the other, other, other hand! Most of the cost of a satellite is in the design and testing phase. Motorolla showed how to build satellites, state of the art satellites, in production line fashion at fairly low unit cost. In such cases the unit cost approaches the unit incremental cost (actual construction labor and component cost) as the design and testing overhead costs get amortized over much larger numbers of units. Today with only a few satellites sold or launched a year those overhead costs make up sizeable chunks of the unit cost. Now, if a satellite line is set up for mass production (and that's a big if) then it's possible to take advantage of low cost yet low reliability launchers by building more satellites than you need, knowing that some will not be launched successfully. Now, the disadvantage of this is that it only really pays off for bulk satellite purchases, and then it mostly pays off in the reverse direction (more satellites per dollar, rather than fewer dollars per satellite, yes, there is a difference). For a network of satellites this is a no- brainer (and it is more or less *exactly* what Iridium and Globalstar did) but for launching a single commsat or even a few commsats, it's too risky to make sense. I think that's enough hands for now. |
#25
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poor man's rocket
"Christopher M. Jones" wrote:
I think that's enough hands for now. I've run out of fingers to keep track of the hands... But you pretty much got a synopsis of a summary of a condensed version of the issues right. It's far more complex than most people think, and the financial and hardware tradeoffs are interrelated in a variety of complex ways. (And that's without the additional complexity of trying to project the costs and other issues into the future.) D. -- The STS-107 Columbia Loss FAQ can be found at the following URLs: Text-Only Version: http://www.io.com/~o_m/columbia_loss_faq.html Enhanced HTML Version: http://www.io.com/~o_m/columbia_loss_faq_x.html Corrections, comments, and additions should be e-mailed to , as well as posted to sci.space.history and sci.space.shuttle for discussion. |
#26
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poor man's rocket
"Christopher M. Jones" wrote:
My second point is actually more important with regard to the satellite industry in the present and near future and relates to insurance. There's more in your message I'll address later (how much later, I dunno, I have a reunion of my submarine crew this weekend), but one I want to toss out first; Insurance is *not* a panacea. Even with insurance, a failed launch (whether rapid disassembly or failure to reach a useful orbit), can leave you in a lurch. Insurance money in hand can't replace a lost bird in the short term (modulo mass produced birds). A bird in hand can't replace a bird in orbit in the short term (modulo launch delay decreasing). Therefore, even with insurance, a company with few birds can be caught in a bad corner if one of them fails to launch. There are no 'loaner cars' in the space business currently or in the foreseeable future. D. -- The STS-107 Columbia Loss FAQ can be found at the following URLs: Text-Only Version: http://www.io.com/~o_m/columbia_loss_faq.html Enhanced HTML Version: http://www.io.com/~o_m/columbia_loss_faq_x.html Corrections, comments, and additions should be e-mailed to , as well as posted to sci.space.history and sci.space.shuttle for discussion. |
#27
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poor man's rocket
toby peers wrote in message ... I've posted an idea for a peroxide powered turbo-prop vtol spaceplane on the halfbakery website at: http://www.halfbakery.com/idea/prope...rocket_20plane I've included a link to an aerobatic plane that can fly vertically in sustained flight (someone else has included a link to a biplane equivalent), a link to Glen Olson's pogo page and a link to Armadillo Aerospace but i couldn't find a link to a self standing, simple explanation of a 'walter style' peroxide turbine. Does anyone know of a site which I could include a link to? I found a link to a rocket-turbine car. The engine was a gas-generator powered turbine drive called a turbonique. http://www.almar.easynet.be/turbonique.htm Does anyone know if anyone ever tried puting one of these engines in a plane (either to power a propeller or a ducted fan)? Toby |
#28
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poor man's rocket
Penguinista wrote
Still, a jet powered first stage dropping of ~mach 3 could make sense. Been looking at this a bit more, and it seems to me that a jet/rocket first stage might be even better for a reuseable TSTO. A back-of-an-envelope design: Suppose you have a 50 ton OEW (operating empty weight) plus ten tons flyback fuel piloted jet/rocket "Lifter", and a 60 ton lox/LH2 second stage with a MR of 4.4. It makes sense to use lox for the first stage rocket as we have it on-hand, and we'll use "hydrocarbon" as the fuel. If we take a MR of 2.45 for the lifter rockets, that's 295 tons, and add 45 tons "hydrocarbon" jet fuel for the first stage, giving a MTOW (max take-off weight) of 340 tons. That gives us 16,000 lb payload to LEO. The only problem is the dry weight of the lifter. Typically airliners have a MTOW/OEW of about 2-3 as opposed to our 6.8. Could it be done? The fuselage is only about half the diameter and half the length of a comparable jet. The wings can have a higher loading, and we can sneak in a bit of rocket power for takeoffs. The jet engines can be lighter than normal (no fans, lower performance and power) and we don't need floors, windows, loo's, seats etc. Everything else is well within modern technological limits, I've allowed good margins and double the usual mass for the second stage engine, so we can really develop an immediately reuseable engine with a long lifespan. The lifter rocket engines are a bit unusual, but I won't go into that here, save to say that they are initially cheap and mostly reuseable, later becoming totally reuseable. Second stages come in two types, an unmanned satellite-launch "Cargo" stage and a manned "Spacebus", both using the same wholly-reuseable engine. They are both 3.5 m diameter, the Cargo is the usual cylinder and the Spacebus orbiter is a cylinder with wings that fit into the wings of the lifter. Both are totally enclosed by the lifter until separation. The lifter is piloted, and man-rated initially as an experimental vehicle. We start off just using the unmanned Cargo, giving sat launch income and paid-for test flights, before developing and flight rating a manned arbiter. The Cargo stages return the engine and other expensive bits (by using an ablative heatshield/ parachute, and discarding the empty tanks) so we can reuse the engines, and use the inspection data to develop our second stage engine into a really reliable reuseable before risking a manned flight. The tanks burn up on (separate) re-entry. It's about as safe as a jet. If the lifter rockets fail, we dump fuel and land. If an unmanned second stage fails then we lose the sat in the ocean If a manned second stage fails it returns to base and lands. Even a catastrophic engine failure need not be fatal, depending on design and magnitude of catastrophe. Looking at the flight path, Stage iMass oMass dVhor Vhor Height tons tons m/s m/s km Taxi 340 340 0 250 0 (Earth's rotation) Lifter jet 340 295 250 500 10 Lifter rocket 295 120 1500 2000 160 Cargo 60 13.6 5800 7800 180 the jets take us to 10 km and ~250 m/s, pretty much at a dawdle. The lifter rockets start at 10 km high so the bells can be optimised for vacuum operation, giving better overall isp. They are back on the ground within hours for the engineers to work on them. No real speed is reached before we get high, decreasing max q on the Lifter The Lifter takes us to 160 km with a coast, during which separation occurs in near-vacuum. The entire second stage is enclosed inside the first stage until then, so the second stages experience no aerodynamic forces on ascent, meaning lighter weight, no shroud is needed for Cargo, and a manned second stage orbiter only has to withstand re-entry forces. Cryogenic insulation can be in the lifter, not on the Cargo or orbiter. Required investment would be around $700 million, but there are some WAG's in there. -- Peter Fairbrother |
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