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The real bonus is that you leave your engine at home, where it may be reused for other launches.
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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Hope nothing goes wrong, lest it makes directed energy take-downs of missiles look like a sparkler compared to a fireworks display.
I'm sceptical about the ability to beam sufficient power from a 1km² antenna to the heat exchanger on a rocket moving as fast as it will be. I'm also more than a little dubious about the author's understanding of the reasons that we have multiple-stage rockets in the first place - they're far more efficient than single-stage ones, for two reasons. Only one of which applies to liquid fuelled rockets.
Firstly, if you split the fuel into two tank/motor assemblies you can get rid of 1/2 of the total fuel tank weight after you jettison the first stage, you also lose some of the length, which improves the rocket's Cd. Admittedly, you need to carry several engine modules for a liquid fueled motor and the associated stage couplings, or an extra nozzle for solid fuelled ones, but the penalty of either of these is outweighed by the reduction in weight of everything that was dumped after stage-burnout.
Secondly, and not important here - if you multi-stage solid-fuel rockets, the fuel in your second stage will produce more peak thrust and specific impulse than it would if it were in a larger single stage. Why? Simple, the solid fuel is housed within the reaction chamber. As the fuel burns, the volume inside the chamber increases which leads to lower pressures, which then leads to slower burn-rate, that further decreases the pressure in what is a vicious cycle.
This can be seen in any number of commercial multi-stage rockets of the 'small' variety. The infamous BUK is multi-stage, yet it has an operational ceiling of just 22,000 meters. To send it as high with a single stage would cost and weigh more. It would also be detrimental to the missile's maximum velocity.
This is such simple and basic stuff. I'm rather bemused by the fact that my standard retort in such a situation is entirely invalid, since this actually is rocket science.
"When I was 5 years old, my mother always told me that happiness was the key to life. When I went to school, they asked me what I wanted to be when I grew up. I wrote down 'happy'. They told me I didn't understand the assignment, and I told them they didn't understand life." - John Lennon
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All of that's true (although the bit about the changing volume of a solid fuel rocket's combustion chamber's irrelevant to this design); but that bit that you're missing is that staging adds a huge amount of complexity to designs and is something that we only do because the low specific impulses of current rocket fuels mean we have no choice.
Specific impulse is a term that goes in the exponent if you're calculating the mass fraction of a rocket that needs to be made of fuel to reach it's destination; which means that even fairly modest increases to it will result in large shifts in the mass fraction.
Pulling the equations out of wikipedia[^] gives the mass fraction as: 1-e^(-delta_v/v_effective), and v_effective = g * i_sp For a low earth orbit you need a delta v of 7000 m/s; plugging the numbers into google gives a theoretical mass fraction of 0.91[^] for fuel with a specific impulse of 300 seconds (typical for a hydrocarbon fueled rocket), 0.81[^] for a Isp of 425 (hydrogen fueled rocket), an Isp 600 would improve the ration to 0.69[^].
With conventional liquid fueled rockets, that's roughly the same as the ratio between the first stage of the rocket and everything else; which is why the performance numbers they're expecting actually do make an SSTO a viable design.
Keeping the beam from the radar array tight enough to avoid wasting most of the power is potentially a major challenge; however beyond the general rule that a larger phased array makes a tighter beam possible I don't know enough about their design to make an estimates of how feasible this would be.
Did you ever see history portrayed as an old man with a wise brow and pulseless heart, waging all things in the balance of reason?
Is not rather the genius of history like an eternal, imploring maiden, full of fire, with a burning heart and flaming soul, humanly warm and humanly beautiful?
--Zachris Topelius
Training a telescope on one’s own belly button will only reveal lint. You like that? You go right on staring at it. I prefer looking at galaxies.
-- Sarah Hoyt
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 Ahhhhhh.
Absolutely correct - by the sounds of it I have indeed absurdly underestimated the added complexity of staging. It was always so insultingly easy to muti-stage Estes rockets. Heck, I've made from scratch an entire air-frame, fuel and motors (except for casings, which take too long to dry and harden) and fired it in the same day more times than I can remember. Seeing a rocket made from A4 printer paper and balsa wood kick over sideways as the first stage separates and then come zooming overhead at about 500 Km/h on the third stage always was good for a giggle. (after one got over the fear for one's safety and the shame of the results of a poor coupling) But such is life when the extent of ones coupling hardware is a piece of scotch tape - considerably harder to ensure a clean break than when using LSCs as the big boys do.
Didn't even think to research the weight of the first-stage vs the rest. I've also directed a little more effort towards finding out more about phased arrays. Hmm, interesting.
Thanks for the reply. It's been the most interesting subject and material I've had the pleasure to read about since the story of the pentaquarks last week. 
"When I was 5 years old, my mother always told me that happiness was the key to life. When I went to school, they asked me what I wanted to be when I grew up. I wrote down 'happy'. They told me I didn't understand the assignment, and I told them they didn't understand life." - John Lennon
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There is understandably a lot of excitement around what the IoT means in terms of our everyday lives: the proposed environmental benefits, money savings and increased business efficiencies are well documented. Expectations are high, but are they being met? In fact, will they ever be met? "Take nothing on its looks; take everything on evidence. There's no better rule."
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Windows 10 Home updates coming to a PC near you, whether you want them or not. It will also make you eat your veggies, and exercise more often
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My wife who uses windows 8 opted in for win10 update almost as soon as she got the notice, I'm going to sue her as a test bunny.
I really don't like this because I like to keep my computer mine and I don't want app suggestion or what I like to call it commercials on my computer. Yet I realize that I can't sit with windows 7 forever. My home computer is nearing a critical point where it's going to need a reinstall to remove all the clutter/crap/straight up sh*t it has accumulated in every corner and going Windows 10 seems like it would save having to do the switch later but at the same time why do they keep coming with all this crap?
Every time I'm starting to lean towards windows 10 something new comes up that makes me say no and at the same time doubt myself. If I was guaranteed they wouldn't push bloat ware it would probably help me with my little problem of skipping updates because I cant be bothered and I'm paranoid.
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I'm really curious about the reaction of people who love Windows 7. Because, in many aspects, Windows 10 doesn't offer any benefits for those users, except for the performance enhancements maybe. But that's just the internals, if you look at the front-end, a lot of functionality is in fact going away or incomplete: The Windows 10 Start menu is inferior to the one in Windows 7, Settings and Control Panel still live side-by-side... For people on Windows 7 who don't care about all the app and cloud stuff... I don't know, I'd just tell them if you care about performance and can live with the changes, or maybe if you're a gamer and want to be on the bleeding edge with DirectX 12, you can start using Windows 10 right away. Otherwise, there is no need to be in a rush. Windows 7 is supported for a few years to come. I'd suggest to wait at least until next year and see how Windows 10 will evolve. I mean, let's face it: If you checked out the Insider builds, the OS is far from being finished and polished. There are a lot of subtle inconsistencies and driver issues.
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In other words I should also keep my wife away at least for a few months at the minimum. She does game and care about gaming but just mmo games where she can create girls in skimpy outfits and it's going too be a long time before she gets a dx12 card.
But there is still the risk she will opt in anyway, she is an avid iphone user and despite having a 5s she still downloads every new update even thou I warn her it will only slow down her phone and eat up more memory. Bah, couldn't they just announce that they would keep win7 around forever instead?
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Once games start supporting it, DX12 will speed things up even on cards a few years old. MS doesn't require devs to write separate code paths for each DX level they support; an older card won't get all the new extra eye candy options; but the low overhead APIs that give most of the speedup will be supported for anything released in the last few years.
http://www.extremetech.com/extreme/207598-demystifying-directx-12-support-what-amd-intel-and-nvidia-do-and-dont-deliver[^]
Did you ever see history portrayed as an old man with a wise brow and pulseless heart, waging all things in the balance of reason?
Is not rather the genius of history like an eternal, imploring maiden, full of fire, with a burning heart and flaming soul, humanly warm and humanly beautiful?
--Zachris Topelius
Training a telescope on one’s own belly button will only reveal lint. You like that? You go right on staring at it. I prefer looking at galaxies.
-- Sarah Hoyt
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Does a hd 5850 from around 2009-2010 count as the last few years. I swear that monstrosity sound like a jumbo jet even when it's idling.
Attracts dust also. A lot.
But you do make DX 12 sound very interesting.
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That's more than a few years old; to the point that I'm mildly surprised it's still working. It's also two years and two architecture generations older than the oldest architecture AMD's initial DX12 drivers will be supporting; and unfortunately it appears that the VLIW4 (and presumably the older VLIW5) architectures were too rigid in design to make the newer APIs work. nVidia is supporting higher end cards back to 2010; but they've got a major advantage in having switched to a more general purpose architecture first
Did you ever see history portrayed as an old man with a wise brow and pulseless heart, waging all things in the balance of reason?
Is not rather the genius of history like an eternal, imploring maiden, full of fire, with a burning heart and flaming soul, humanly warm and humanly beautiful?
--Zachris Topelius
Training a telescope on one’s own belly button will only reveal lint. You like that? You go right on staring at it. I prefer looking at galaxies.
-- Sarah Hoyt
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The Flash Player update released Tuesday not only fixed two vulnerabilities that were being targeted by attackers, but added additional protections that will make entire classes of security flaws much harder to exploit in the future. Bwahahahaha! Oh, they kill me.
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Did they turn-on the automatic memory management ? 
Patrice
“Everything should be made as simple as possible, but no simpler.” Albert Einstein
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The security firm Symantec just released its monthly report for June, and it's got some good news for spam fighters. "Don't make a fuss, dear. I'll have your spam. I love it."
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Is it because the quantity of SPAM has been reduced or because the quantity of other emails are increasing?
Decrease the belief in God, and you increase the numbers of those who wish to play at being God by being “society’s supervisors,” who deny the existence of divine standards, but are very serious about imposing their own standards on society.-Neal A. Maxwell
You must accept 1 of 2 basic premises: Either we are alone in the universe or we are not alone. Either way, the implications are staggering!-Wernher von Braun
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Microsoft promises the traditional decade, or as long as the hardware can handle the OS, whichever comes first. Or until they announce Windows 11
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Or they might be counting in binary!
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OK, so the main difference here is that you will get updates (i.e., features) as well as support for 10 years. Previously it was updates just within the 5-year mainstream support period, right? Caveat being that your PC can handle any increase in system requirements.
Kevin
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If you truly think your electronics have been invaded by an evil spirit, there's someone who will take your call — Reverend Joey Talley — a Wiccan witch from the San Francisco Bay Area who claims to solve supernatural issues for techies. "She turned me into a newt!"
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Windows 10 has a secret screen recording tool that can be used to capture on-screen activity as a video file. Coming soon: conspiracies about its "real purpose"
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Might be useful, and "secret" is a bit misused in this case.
Geek code v 3.12 {
GCS d--- s-/++ a- C++++ U+++ P- L- E-- W++ N++ o+ K- w+++ O? M-- V? PS+ PE- Y+ PGP t++ 5? X R++ tv-- b+ DI+++ D++ G e++>+++ h--- r++>+++ y+++*
Weapons extension: ma- k++ F+2 X
}
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[^] I don't want to have something I am wearing, or carrying, broadcasting; and yes, I do realize that even my entry-level Samsung cell-phone (not a smart-phone) does that.
Yes, I am becoming more and more an old curmudgeon, perhaps like Howard Hughes, but without the money, the penthouse, or the Mormons 
«I want to stay as close to the edge as I can without going over. Out on the edge you see all kinds of things you can't see from the center» Kurt Vonnegut.
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Off and on we have things in common. Who'da figured?
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "As far as we know, our computer has never had an undetected error." - Weisert | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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BillWoodruff wrote: Yes, I am becoming more and more an old curmudgeon
No, you're not even nearly paranoid enough.
Once most of the people can be tracked, we will have world-peace. Anyone opposing the idea will be disposed of by some drone.
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
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