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Essentially total impulse is the total amount of momentum, and by extention velocity, change capability a vehicle has with a full load of propellant. It's measured in Newton X Seconds (Ns), which in turn is force times time. For example, if a given vehicle has a total impulse of 10 Ns, that would mean it could sustain a newton of force for ten seconds, or vice versa, or any other combination of the two that when multiplied together equal ten, provided of course the engine can throttle to that value. Naturally, a rocket with a smaller total impulse (such as SpaceShipOne) cannot change its momentum (and thus usually velocity) as much as one with a high total impulse (such as the Saturn V first stage).
On the other hand, specific impulse is, as GCN noted, a measure of efficiency. Specific impulse measures the amount of momentum change you can achieve not out all fuel on the vehicle, but for a given amount of propellant. By contrast isp is measured in Newton X Seconds/Newtons, usually just abbreviated to Seconds. In other words, specific impulse measures the number of newtons (or pounds if you prefer English units) of thrust you can get from a kilogram (or pound-mass) of propellant.
In rocketry specific impulse and the rocket equation are probably the two most critical principles involved. The rocket equation: MR= e^delta-V/isp, where MR= mass ratio, delta-V is total velocity change, and isp is the specific impulse of the rocket's engines, determines how much of a rocket's starting mass will have to be fuel in order to reach a given velocity change. In order to go from a standing start at a temperate lattitude to low-Earth orbit, a minimum velocity change of 8 km/s is required, but engineer's usually have to deal with around 9 km/s of delta-V after factoring in losses due to atmospheric drag, steering, and the time a rocket spends going straight up after launch burning fuel but not adding to its tangental (orbital) velocity. This is an immutable law of the universe that must be addressed in order for any rocket to work in its intended role.
The rocket equation is so demanding of orbital launch vehicles, whether or not single-stage-to-orbit (SSTO) LVs are possible is a subject of hot debate. Going to orbit is easy in multiple stages because each stage only has to deal with a smaller portion of the total delta-V, but a single stage has to deal with the whole thing up front. As the rocket equation dictates, the amount of propellant a rocket needs increases exponentially as delta-V increases linearly, which is why Robert Zubrin says "engineers will kill to get delta-V down and isp up." Modern rocket engines are very close to the theoretical specific impulse limits of their fuels, which for liquid oxygen and hydrogen is about 4.5 km/s (around 470 s, guesstimating without a calculator). Until there's a breakthrough in something such as airbreathing engines or a revolutionary new propulsion system that variable won't get much better.
So, plugging these variables into the rocket equation one sees that an SSTO launch vehicle burning oxygen and hydrogen can have no more than about 15% of its starting mass be tanks, engines, electronics, payload, everything but the fuel. That's no problem for an expendable LV, but for a reusable one, perhaps carrying a crew capsule, ouch. It's a tight squeeze. GCN and I have intensely debated whether or not it's possible to develop such a reusable SSTO launch vehicle for a price of under a billion dollars or so. Expensive or cheap, such a rocket will be extremely difficult to make.
This is why specific impulse is sooooooooo important for rocket scientists.
Treb, I just hope for their sake of course that another earthquake doesn't strike. But for OUR sake I hope one (especially of a high magnitude) doesn't occur on the 4th of July, or the 5th. Those rumors that perhaps the U.S. is planting bombs on the ocean floor and detonating them to get at the Muslims population would start up again. :-\
--Cindy
What rumors? That's a pretty crazy rumor to try to get someone to believe. The most powerful nuclear weapons ever created don't even approach the tiniest fraction of the raw power released on the Boxing Day earthquake. Powerful as H-bombs may be, a few dozen pounds of fusing deuterium cannot possibly come near the power of billions and billions of tons of crunching, grinding bedrock. Besides, sure seems like one heck of a waste of a bomb. :;):
It really is a shame that the Jitterbug went out of fashion. Back in November our school musical was Grease and I had an absolute blast during the dance scenes. The problem is that, even when a great song for jitterbuggin' comes on, nobody knows how to dance to it, it takes longer than five seconds to learn how. It's an important skill, to know how to jitterbug, just in case of an emergency. After all, everyone already knows how to macarana and electric slide, would one more decent dance be so hard to learn?
Then again, this is coming from someone who's idea of nice music consists primarily of disco and video game soundtracks.
"Gosh, well that's a tough problem," Barkley said, unconciously raising a hand to scratch her head. The Air Force Academy ring on her right hand glinted the purple end of the visible light spectrum off its cool Amythest surface.
"Any suggestions?" Meadows inquired with a dejected, haggard expression. Barkley's crystal green eyes were fixed on the flatscreen, her mind racing to come up with a set of numbers that might finally satisfy the problem at hand.
"I would say... start with one, after all that's the first positive integer. Then, how about two and 72? That's e. After that, you can go ahead and use two, 13, and 64, my birthday numbers." Meadows noded and input the numbers into the online lottery retailer. "Are you shure you can still play out here, John, isn't the lottery kinda limited to one planet?"
"Well, I suppose it doesn't hurt to try," he responded.
"Shure seems like a waste of five dollars to me. What good is $100 million on Mars, anway?" Meadows smiled and let out a somewhat annoyed chuckle and that second comment.
"So, February 13, 2104, I guess that's the big day you turn-"
"Please," Barkley intervened, seeing ahead to where this was going, "I don't even want to think about that now." Turning 40 was of course nothing nowadays like what it was 100 or 150 years ago. Back then you were old. Now the only significance 40 had was that it was halfway to 80, in turn halfway to the average lifespan of 160. For someone in Barkley's shape the date especially didn't mean anything, but to this day it still carried some stigma of old age, of senility just around the corner, however unfair a notion that was. Some cultural elements just don't die easy, Barkley thought to herself.
"Don't you need to get back to writing that quarterly report?"
"Yeah, but I'm doing all right with that," Barkley stated, waving off the question. In truth she absolutely loathed the whole idea of the quarterly reports, it was such a waste of time, but it was the only way the government would ever let them fly. "Anyway, I'm off to get a Diet Dr. Pepper, then it's back to work."
The problem with trying to scale up from entry-level suborbital travel to orbital flight is that there is very little of practical commercial value in between the two ventures. Mach 4 suborbital flight is great for tourism, and mach 25 orbital flight is good for launching satteltites, orbital tourism, maintaining space stations, colonization, etc. If a good, viable market can be found in between the two delta-V extremes, it will be much easier to scale from suborbital as is being done right now by Scaled Composites to real low-cost orbital.
A good next step after SpaceShipTwo-class vehicles might be two-stage semi-reusable launch vehicles. The first stage, probably a spaceplane like Black Colt or the X-34, achieves a delta-V of around mach 15 at 100 miles, where it releases an upper-stage that gives the payload the rest of the kick it needs to reach orbit. That's nearly two-thirds of orbital velocity, and around one-fourth to one-third of orbital energy. Another possibility for such a vehicle would be rapid point-to-point travel for military or airline applications. There's actually probably a good amount of marketability to a Mach 15-capable rocketplane, so this might be a good next step for the alt space industry.
From there it will be much easier to develop the technology needed for orbital travel. That is, much of the technology could be reused from the previous vehicle for the new orbital version. This is another possibility for the alt space industry to consider.
In my age group/geographic area "sweet" seems to have been mostly phased out with the equally-non-sensical "tight." Also, "dope" is synonymous with "really cool," and "ride" will work just as well as "car." This allows for some awkward sentences such as "Dude, that ride's tight dope!" I suppose if you averaged the ages of Cindy and me you'd come up with a 20-something at the age of 27.5, if that counts. And androgynous for good measure.
"Synecdoche" (sin-eck-doh-key) is one of the literary terms we went over while covering Macbeth earlier this year. We're now done with that unit, save for the oral interpretations that will come next Monday after we all return from spring break. Rght now I'm just trying to enjoy my week off (w00t!). Before leaving we were all given a copy of Tess of the D'Urbervilles, and told that if we wanted to we could start flipping through it. So far it's a very interesting book, it has that quality of movies like Master and Commander and October Sky, you really feel like you're back in the mid-Victorian era. Pretty cool (as far as I can tell that term's not going away).
Assuming that the Falcon I can operate as cheaply as is claimed by Spacex it should be the death of all competition in the commercial small sattelite LEO market. The problem is that this is an extremely small market as it currently stands. If miniturization technology progresses far enough perhaps some of the current market on slightly larger LVs can be grabbed, and Spacex might be able to convince customers to forgo launching multiple payloads on larger launch vehicle and use the Falcon instead. Without government-sponsored payloads, however, it will be much more difficult for them to stay afloat.
For example, the Vega will be far more expensive to operate and probably less reliable than the Falcon I, but will automatically have 100% of the market share for ESA-sponsored light payloads. Spacex must grab the American market from Orbital Sciences and the Pegasus or else they'll never see much of a return on their investment. Or perhaps having such a low-cost launch vehicle will open up a much wider market for commercial payloads. It's a possibility, but I'm rather skeptical of it happening right now.
Perhaps my thinking for coming up with a sub-$1 billion figure for RLV SSTO development is somewhat flawed, but I'll try to explain it as best I can. From what I've learned it appears that single-stage to orbit flight is not actually that difficult to do, but making the launch vehicle reusable is extremely difficult. The reason is that current aerospace technology is good enough to allow a kerosene/LOX launch vehicle to have an empty weight about 6% of its GTOW (I prefer using percentages over mass ratios, but that's just me), almost good enough for SSTO flight, and a hydrogen/LOX LV to have an empty weight around 8-10% of its GTOW, good enough right off the bat to be an SSTO.
However, there's quite a difference between and expendable launch vehicle and a reusable one. Naturally expendables don't have to deal with heat shields, landing gear, or airframes sturdy enough to withstand many flight cycles. This is where the subject becomes sticky, because we know that the tanks, engines, guidance systems, and pressurization systems can be made light enough, but we don't know if the other systems such as the TPS and land gear can be for SSTO flight. Powered landing systems require a substantial amount of fuel to be carried, I'm not sure that RLV SSTO designers using only today's technology could get away with that amount of dead mass. Parachutes might be lighter but are a great inconvienance to use if the vehicle is to be reused. I'm a fan of using lifting body airframes, as they require no fuel on landing, can land at conventional airports, and might only add a small amount of mass to the total vehicle. It remains to be seen, however, if any of these approaches can work without an advance in current technology.
My thinking was that, assuming that no advance over current technology is required, it should cost perhaps $800 million or so to develop an RLV SSTO. That would require using mostly technology from a current or near-future LV such as the Falcon V. Modify it to run on hydrogen, make the engines super-reusable, and solve the TPS/landing gear problem and it could work. I don't doubt that a clean-sheet approach a la the DC-Y would cost around $6 billion, but I'm talking about using mostly recycled technology. It all hinges around whether or not that pesky TPS/landing gear situation can be resolved.
Moreover, there really is a difference in the cost efficiency of private industry versus government contracts. The Falcon I and all applicable infrastructure development was created for about $50 million (if only it would actually fly...). The DC-X was created for just about $60 million. Overall the difficulty of designing the two vehicles might have been just about the same. This would mean that Spacex (alt. space) came in at being 16.7% more efficient than McDonnell Douglas (big three aerospace). That alone isn't too impressive, but the difference in practicality of these two ventures is staggering. The DC-X was a prototype technology demonstrator, the Falcon I is a low-cost semi-reusable launch vehicle. Spacex was able to create the Falcon I for this price because it wasn't afraid to simply recycle old technology when it was effective enough for the job. This is how a low-cost RLV SSTO will have to be built if it is done.
In the end, the only way either side will be proven right is if it's actually done.
I wouldn't worry if I were you. English is intellectually considered a Germanic language, but that doesn't really do justice to the language. There are hundreds if not thousands of intricate dialects of English scattered throughout the world, each of which has assimilated and incorporated other nearby languages. Just as the US is considered (at least by us Americans) as the political "melting pot" of the world, English is the linguistic melting pot. Pretty much everyone knows what a "valley girl" is, so long as they live around Southern California or Arizona. Outside of that region very few would recognize that piece of slang. As for deadhead, I'm not quite sure myself what that means, but it's part of a song, so whatev.
"Take it easy,
Take it easy,
Don't let the sound of your own wheels
Drive you crazy,
Lighten up, while you still can,
Find a place to make your stand,
And take it easy"
-The Eagles
Heh heh, I love that song. Hey, speaking of odd pieces of slang, a while ago in English we had a discussion on synecdoches. We of course covered the usual synecdoches you hear in everyday coloquial conversation (like car=wheels, clothes=threads, where a whole is represented by one of its parts), and my teacher mentioned one I had never heard before, girl=skirt. Of course, nowadays if you called someone a "skirt" a lawyer would jump from behind a bush and put you in court for sexual harrasment fast enough to make your head spin, but has anyone else here heard this idiom before?
I know it's a bit late, but here's another chance to go analyze someone's dreams. What exactly does it mean when you have a dream in which you walk into a poorly-lit subway car, sit down with a friend and have a nice conversation about absolutely nothing (ie in Seinfeld) for about five or six hours with her? It beats me. I can't remember a single thing we talked about but I do know that it was pleasant and went on for hours and hours dream time, though I imagine it was a couple of minutes real-world time. I do remember that the conversation strayed over to the subject of me needing to be more spontaneous just as I woke up. Odd, eh? :;):
"Inner valley girls?"
Long story.
Actually it's not, I just made it up. A "valley girl" is someone from the SoCal/west coast region who talks in the stereotypical dialect of 90s American teenagers. You know, says "like" every three words, and their idea of intellectual vocabulary includes words like "totally," "gnarly," "tubular," etc.
Anyways, I once by accident said "like" about five times in a sentence along with many of those above vocab words while talking to a guy in French class and muttered "Whoa, I'm just talking like a valley girl today." So perhaps "inner valley girl" as in the fun-loving, shop-till-you-drop surfer in all of us. Like your "inner child," but like totally fur real awesome, dudes!
Hey, it's the apropos. If you want serious discussion go to "Human Missions." I just come here to ramble and say whatever happens to pop into my mind at the most inopportune moments. Maybe you learned something. It's a theoretical possibility.
...What I am saying is that you are a AltSpace-crazed quack that real aerospace professionals will never take seriously (nor should they) if you believe in this dreamer nonsense... a hydrogen SSTO with brand new engines RLV for $800M? A joke, not a possibility. Kistler can't even get their TSTO kerosene rocket with antique engines to fly for that kind of money.
Even assuming that I am a crazy alt.space-hugging quack who has a tenuous-at-best grasp on reality, it would seem that I come out ahead here. You claim that I resort to wishful thinking and falacies to back up my points. You on the other hand resort to insults and name calling. I have absolutely ZERO respect for you as an opponent in this debate now, GCN. If your side of the argument is so obviously correct to every single person who was not born yesterday and lives on this planet, you ought to be able to defend yourself without name-calling. This isn't the playground, we're adults here. If you want to insult people do that somewhere else.
Yes yes yes, we're all very aware that hydrogen is much less dense than kerosene. But much smaller quantities are needed to reach a given delta-V as well. Tank stretching is necessary, but not a vehicle-killing amount. The Atlas first stage was capable of reaching orbit in a single stage after dumping two of its engines, and that burned kerosene. With hydrogen and oxygen no advance over current technology is needed for SSTO flight.
Better insulation will be required as well, but this is not a killer either. Insulation technology is highly mature and remember that an RLV SSTO will only need to carry its load of hydrogen for a couple of minutes. If the hydrogen is pumped into the launch vehicle about ten minutes or so before launch that makes it very difficult for the hydrogen to boil off and minimizes ice formation.
An engine that burns hydrogen will require higher-strength materials to cope with the much hotter exhaust temperatures. How is that grounds for a tenfold increase in development cost? We like to think that these analyses can tell us exactly how much a given increase in reusability and reliability will increase the cost of development, but they can only go so far. No one has ever built an engine of sufficient resusability for an RLV SSTO and because of this there is no example to cite costs from. Any estimates of the cost of such rocket development are educated guesses at best.
Let's pause for a moment and think about the TPS subject. Imagine this. At the bottom of the vehicle a plate of beryllium-copper alloy is placed with holes cut into it just the right size for the engine bells. To cover the engines during re-entry retractable doors made of the alloy lock into place. In between the plate and the base of the fuel tank (or crew capsule) is an empty space filled with vacuum. Since the doors will be open during the whole ride to orbit, creating a vacuum in this space is as simple as letting all the air leak out during launch and sealing it up tight while in orbit. The beryllium-copper will be able to survive reentry temperatures (its the stuff that usually causes damage when sattelites de-orbit) and the vacuum space would insulate the rest of the vehicle. Has anyone considered this possbility for a TPS? Perhaps it could work. The point is that there is no fundamental law of nature that dictates that a heat shield must be expensive and incovenient.
If it were possible to launch from the same desert the SSTO lands in that would eliminate the transport problem. Edwards comes to mind as a place this might be possible, but I doubt the FAA would be very keen on launching away from the coast. What about using parafoils? Parafoils would allow the vehicle to land on a runway like an airplane, in Florida right next to the launch site as well. Of course, no one's ever demonstrated a parafoil big enough for the job yet, but it is another possibility to consider. The landing gear issue is a tricky one to solve, but that is no reason to assume that it will automatically cost a mystical $6 billion to develop the rest of the vehicle.
Being closed-minded never got anyone anywhere.
Am I the only one of us sporatic contributers, who thinks that our "Replies" are being hurried out of "New Posts" and into "New Mars forums" too quickly to be read from one day to the next? What are the rules, if there are any--or do I detect a subtle form of (gasp) censoring afoot?
I'm probably one of the most sporatic of the bunch, and it does get frustrating at times. When you don't post daily or nearly daily your posts are often smushed to the back of the queue making it difficult to keep up. I mostly just skim after a long abscence or just gloss over topics entirely. There are days, for sure, when I look at someone with a daily post average of above 5 (!!!!!) and think, "I should be doing that," but pragmatically there's no reason to. There's just so many things to do, so little time, for those of us who can make the commitment to New Mars to post daily that's great but for people like me I'm happy to just jump in when I'm comfortable.
Probably not censorship. -Longish pause-. So what do y'all think about abortion? Heh heh, that's about as big a can of worms as you can possibly open, fell free to respond if you dare. For serious contenders only. :;):
Less controversially, I think we could all benefit if we were more in touch with our inner valley girls. I try to keep in touch with mine, it's quite breathtaking, really. Ahem.
Mission Commander's Log, May 6, 2103:
I think I've come up with a plan that's fool proof. Hopefully. Maybe.
Treb, the Chyrsians, and Lord Vlork's flock has had access to all of our technology data for some time now and it would appear that any edge we have over them has evaporated. However, what they didn't bet on is that I have exclusive access to highest-level security tech dvelopment documents. Nobody, not Gryphon, not Meadows, nobody knows this but me, which is pretty cool.
One of the key points on our negotiations with the Chyrsians was that our new digital doppler radar units are foolproof and incapable of error, they can detect anything. While that's true, it's incomplete. Back at MIT they've just finished the plans for a new prototype jamming system that can conceal something even from these instillations they've set up. I'm not quite sure I fully understand the technology behind it, but it has something to do with destructive interferance with the initial radar waves, and doing this without alerting the sensor of the presence of active cancelling. I had Meadows in engineering stereo-lith a few of the units for me, they're really quite innocuous looking unless you know what goes on inside one.
Tonight I'm going to assemble a team of a few negotiators and troops for our assault on Lord Vlork. He has far too much manpower for us to defeat him purely through burte force of course, but that's not what I'm trying to do. We'll sneak into his palace, surprise him, and have a nice friendly chat about a ceasefire. Going at the rover's maximum efficiency speed if we head out by 22:00 tonight we can reach his base by 8:00 tomorrow morning. If he balks, we upload a virus into the palace that kills all computer controls on everything. The LSS, the air conditioning, water purifiers, everything will go wacko on Vlork if he doesn't feel like cooperating. If things really get hairy we can always bug out and dissappear. At least, that's the plan...
-Lt. Col. Tiffany Barkley
In the crystal black darkness of a Martian night, the rover set out for the northwest. As the hours wore on it passed checkpoint after checkpoint and scores of killbots, all of which were as blind to the rover as human senses are to radiation. Slowly the Sun illuminated a layer of Cirrus clouds and the deep blue and teal colors of a Martian sunrise. The rover continued on at its breakneck pace, attempting to outrun the ability of the myriad sensors' detection. Finally, it reached its destination.
Lord Vlork's palace was a rather unflattering building considering the expectations one might have from its name. In essence it was a hut dug into the rim of the caldera of Olympus Mons, that archaic leviathan against which all other volcanoes in this star system are measured. The view was great, overlooking the former and possibly future shore of the Boreal Ocean to the north and the vast chasm of Olympus's caldera to the south, but the palace itself was unimpressive. A small, visitor's center look-alike sat at the ground floor of the palace, filled with stairs and elevators and rabbot sheds.
Under the cover of their radar cloak, the rover parked mere feet from the door of Vlork's palace. With military precision six suited astronauts piled out of the vehicle and flung open the door. Upon equalizing pressure, they bolted down the stairs, following the kindly-painted directions to the palace throne. Surprisingly barely anyone filled this top layer, and those who did paid no attention to anything at all, merely muttering unintelligable incantations.
Upon reaching the throne room, the team became aware of the power of Vlork. The room, an immense chamber rivaling that of the largest caves on Earth (indeed it was a former lava tube, a relic from the volcano's more youthful days), was filled with nearly the density of a Nazi rally of hooded priests and nuns chanting praises to Vlork. In an instant the team could have been swallowed up and eliminated by the crowd, but for Vlork's command to halt them.
Vlork, like his palace from the outside, was rather unimpressive. He was hunched over, wrinkled with age and barely coherant enough to utter a sentence, much less command the largest force on the planet (no offense :;): ). Upon viewing this sight the team marched forward to his throne, visors up to conceal their emotions and where they glanced. One of them, bearing a nametage "T.Barkley" bounced under the weak gravity directly to Lord Vlork's seat.
Abruptly the lead settler flipped up a golden visor, revealing the face of a woman in her mid thirties. She then went so far as to flip up the glass entirely, choosing to breathe the same air as that of Vlork and his flock. The astronaut pushed a lock of muddy-brown hair back, looked Vlork over with deep piercing emerald eyes and cleared her throat.
"Hi, the name's Tiffy Barkley."
She extended a gloved hand to the ancient dictator.
Hmm. The DC-X argument is rather compelling. Maybe it's not possible to build a "perfect" SSTO for under several billion dollars. But there are other elements to consider.
The Falcon I first stage could very nearly be an SSTO as it is. IIRC its empty weight is 6% of its gross takeoff weight which is just -this- close to allowing SSTO flight for a kerosene/LOX launch vehicle. Assuming the tank were stretched and the fuel replaced with liquid hydrogen or methane it's reasonable to think that such a stage could lauch a reasonable amount of payload as a percentage of its GTOW.
Now, the Falcon I has cost roughly $50 million to design and build, and it ought to be flying any day now. The Falcon V uses almost exactly the same engines (slightly uprated thrust versions), so the cost for engine development for a Falcon V-class SSTO would be very low. Musk claims that Merlin engines have demonstrated excellent reusability in tests, though now I suppose we just have to take his word for it. The Falcon V's tank is bigger than that of the Falcon I, yes, but ultimately it has just about the same level of complexity. Pretty much all of the subsystems will likely be common technology between the launch vehicles.In other words, the Falcon V will probably cost just about the same as the Falcon I to develop, ~$50 million, or $75 million with a healthy cost margin thrown in.
It's reasonable to think that for $75 million a small alt. space company with healthy investment can create a semi-kinda-reusable launch vehicle with a payload capacity of 20,000 lbs to LEO and man-rating for a small amount of extra development. That's certainly a start. For $75 million a vehicle capable of launching up to 20,000 pounds and crew capsules for about $1,000 per pound can be developed. That won't set the world on fire but it will definately rock the aerospace industry.
Of course, this has little to do with SSTO development, but bear with me. The development program for the Merlin has cost somewhere in the range of $25 million likely, at most. An equvalent engine that burns LOX/LH2 with super-ultra-great reusability might cost, what, four times as much? Sure, a hydrogen-burning enigne has a much higher isp than a kerosene-burning version, but would the former be much more complex. I'm not quite sure myself, but I would be skeptical of any claims that higher-quality fuels entail an enormous cost increase in development. Then again, I usually try to be skeptical about everything.
That reusability component is the devil in the details, though. How reusable would a "hydrogen merlin" be? How reusable are they to start with? How much resuability is necessary? There are so many variables it is impossible to come up with a highly accurate prediction of what such an engine's cost would be, and even if we knew the factors it'd still be quite tricky. To my educated layman's eye $300 million seems to be a reasonable amount for the development of a decent SSTO-worthy main engine. And so this is how I came to the conclusion that it might be possible to develop an SSTO-quality engine for $300 million, not $3 billion. Just a possibility. Apparently.
Other components for our SSTO will probably cost just about the same as what they cost for the Falcon V, so let's appropriate $50 million for that. The crew capsule part will be another tricky part for development, but how tricky exactly? Assuming your formula that cost increases with the square of complexity and a Falcon I costs $50 million to develop, according to the asertion that it will cost about $2 billion for the crew capsule requires the capsule to be six and a half times as complex as a small semi-reusable launch vehicle. It will be complicated, but six and a half times as complicated as a top-of-the-line sattelite launching machine? That does not seem reasable to me. I see no reason why it will cost more than $300 million for the capsule.
This still leaves the heat shield and landing gear. Everybody hates the shuttle's TPS, but is it really that bad? On an RLV SSTO one would not have to worry about debris from an external tank puncturing it or tiles breaking off due to vibrations from SRBs, vastly reducing the danger of the system. Granted, the maintainance times are absolutely atrocious, but if you really streamlined the operation and tailored it to lean operating costs rather than keeping NASA technicians gainfully employed the turn-around times could be vastly reduced. Enough for "real" RLV SSTO operations? Who knows. It's another variable. In any case, let's include another $200 million for this system.
Finally, for the landing gear. Why not just use a parachute? Assuming the vehicle has an empty weight in the 50,000-70,000 pound range parachutes might still be used effectively. In places like the Bonneville Salt Flats there's nothing but huge swaths of utterly flat land for miles and miles and miles, perfect for landing a giant parachute-landed rocket. Some rather pedestrian shock-absorbers at the bottom of the vehicle would be quite enough for absorbing the impact, and the whole system of parachutes, shocks, and gear would weigh in as a very small portion of the vehicle's empty weight. After landing the crew inspects the tiles, repacks the parachutes, examines the equipment to ensure that everything is cherry, and you're off again. A turn-around time of one week or perhaps less is plausible. That could be reduced to less than a day with a new, better TPS.
What I am saying is that it is possible, just possible, to design, build, and fly an RLV SSTO for about $800 million assuming that previous semi-reusable vehicle infrastructure is already in place. This would be a DC-X style rocket with a GTOW of 600,000 pounds, six hydrogen/oxygen engines in the Merlin class, an empty weight of 60,000 pounds, and a payload capacity to LEO of 8,000-10,000 pounds. Certainly not in the Proton-class, and really flirting with the edge of shuttle-intensive ground ops, but this is do-able. And moreover, assuming that our company merely builds the vehicles and can find four customers a year who will pay a price tag of $200 million, a bargain-basement price $75 million less than an A380, such a rocket would be an enormous profit generator. Those profits could be fed into the next generation of bigger, badder, better SSTOs. If one works progressively, this should be possible, for much less than you might think at first glance.
Well, maybe "romantic" isn't quite the right word. Let's see, "wicked awesome" has already been used, how about "captivating?" Personally I've never had any problems at all with security at the metal detectors or watching the planes, but again I don't fly very much. I love to just watch the whole proccess, to see the mechanics buzzing around the plane before boarding, the pilots running over checklists inside the cockpit, the feel of the slightly damp aluminum of the fuselauge (I always make sure to touch the outside of the plane as I enter, sort of a habbit of mine). There's a great adrenaline rush when the attendants slam and latch the door shut and the cabin subtlely (sp?) shifts to bleed air, then begins to taxi away. Last November when I went to New Mexico I had brought along a book and some homework thinking I would be bored out of my mind after a little while at the airport, but I was so excited I never even touched either. Then again, this is the kind of stuff that gets me pumped (and ranting), most people just don't see the attraction I suppose.
Since my family never really goes on vacation anywhere I've decided to do it myself this summer. I'm paying for the bulk of a 10-day trip to England and Scotland chaparoned by my history teacher. That's four flights within ten days of each other (we'll first be flying to either Chicago or New York before going to London and the same on the way back from Glasgow), w00t (more modern slang)! I really don't understand why some of the other expedition (I prefer that term over "trip") members are so worried about the trans-Atlantic flight, I can't wait! Just imagine, nothing but ocean and some clouds for thousands of square miles to the horizon. I imagine it helps one get a better grasp of the concept of infinity. Whenever I fly I am absolutely glued to the window, so I'll be very happy if the rest of the group fights over the isle seats. I always go for the windows. Anyways, that's my rather inexperienced, romantic (do'h! I'm not supposed to say that!) take on the matter.
Another part of that website that bothered me was the comparison between the Saturn V and the SASSTO. Right at the top of the page it bore a picture of an exploded view of the Saturn V staging with a note that "everyone (who exactly is that?) knows REAL rockets aren't SUPPOSED to look like this..." That's just plain insulting to everyone who was involved in the development of one of the greatest pieces of engineering in the history of the human race, IMHO. Rockets aren't supposed to look like that!? It's real! What else do you want? I just happen to get highly offended at art for art's sake, art that is created design priorities first, asthetics later (ie Saturn V) is far far far better. Reality rules. I just don't get why everyone tries their darndest to get away from it. Just look at some of the top images from the Hubble. No artist in the world has ever created something that comes near approaching the awe-inspiring beauty of those images, because reality is far better than any fantasy world we can create. I for one like this world.
Well, that's just my venting for today. I of course wouldn't try to impose any of my opinions on you. I'm just stating them excessively vocally.
-(Brushes self off. Straightens hair and collar. Gets back to work)-
Mission Commander's Log, May 3, 2103
Today we began our negotiations with some character who calls himself "Trebuchet," the leader of the Chrysians. From what I can piece together they are the decendants of about a fourth what's left of the original colony's population. They reside in TempleBar and surrounding homesteads out on Chryse Planitia, with the remainder of the colony either living underground at Hellas Basin or throughout the Tharsis Region. Apparently those Tharsians are the ones to watch out for. The Tharsians are religious fanatics who follow a former leader of the Compassionate Fascism Movement who's given himself the title Lord Vlork. At least, that's Trebuchet's story.
The negotiations got off to a rocky start, as Treb insisted that we salvage Viking 1 (a stone's throw away from TempleBar) for parts to repair the rover. After I of course declined we got into a heated argument that continued until we finally agreed to give them the remainder of our unsalted pretzels in exchange for protection of the site in the future. And so the First Viking Peace Talks were underway.
Most important we agreed to create a united front against Lord Vlork's forces. Since Vlork was apparently the one launching most of the attacks against us (sattelite data seems to confirm this) I'm just fine with this clause, but I prefer to avoid agression at all costs. Hopefully he won't attack us and we won't attack him and everything will be just cherry, but my money's on him making an offensive within a month. We'll be ready.
In exchange for a significant construction force to augment and fortify Von Braun Station we have consented to share all technology. The plan is to create a much larger powerplant and iron refinery at TempleBar and revamp our diamond plant here at Von Braun. That way we'll have plenty of energy, lasers, and manpower when Vlork comes around. The Chrysians already are building a navy, and hopefully we'll be able to greatly increase their development in this area. We'll be ready for anyone who wants trouble.
More than anything else I would like to see a halt to all of this rather pointless agression. It really sucks to be stuck in the middle of all this, but hopefully if we can fend off Lord Vlork we can convince him not to mess with us and just leave us alone. At least now the guys back on Earth actually know what's going on over here. I really hope Mars is big enough for all of us, but I'm starting to wonder.
I dunno, the creators of that site seem to have a tenuous grasp of reality. I was thumbing through the section "Future Flight," avoiding the urge to pound my head painfully against the keyboard. "Believe it or not, flying used to be romantic, adventurous..." blah blah, the same old rubbish. Am I the only one that still thinks flying is really wicked awesome!? Probably. The next time you're on an airliner (I'm lucky, I'll be on several this summer. I've only been on heavy metal flights a handful of times in my life) just pause for a moment and think about what's going on. Hundreds of thousands of pounds of thrust propelling hundreds of people riding half a million pounds of aluminum and composites miles upward into the sky. Riding in shirt-sleeve comfort at 39,000 feet with nothing more than some bleed air and a nice pressurization system. I don't care if I'm not pampered with extravagant luxuries, the flight in of itself is the attraction.
Moreover, why were any technical assides labeled "boring technical details?" The technology and the details are what make it fun! You skip that and there's no point in discussing the matter in the first place. Sure a picture of the whirlpool galaxy from the Hubble is nice eye candy even to a layman, but if you truly understand what's going on in there it becomes an awe-inspiring miracle of nature, not just a pretty picture. Details are everything. Maybe I just like getting brain candy more than most people.
At any rate, that site annoys me. Sorry if I'm ruining your tomorrow (I wrote this at 11:53, so probably no one's going to read it today).
Mission Commander's Log, April 30, 2103:
Well this is just lovely. I came home from a local excursion only to find the base totally trashed, many of our infrastructure personell either killed, captured, or scared into hiding in rabbit lockers. The rabbits are acting funny, too, oddly enough.
Clearly base security alone is not enough. We need to go out and find what in the net these guys want and how to turn them in our favor. Tomorrow I'm taking the long-range rover up to the Chryse radio source, with no weapons. Our sources indicate that the locals appriciate pacifism and openess. It's a calculated gamble, yes, but from where I sit it seems to be the last option.
-Lt. Col. Tiffany Barkley
Mission Commander's Log, April 18, 2103:
Dr. Gryphon continues to insist that these crazy cyborgs are the best way to defend the base. I'm not so sure, but I figure they can't help, though to be perfectly honest they bug the crap out of me. Once again the engineering team has proven their worth, the base is fully online after only a little over a month. I've put security on 24-hour watch over the station, and I've been talking to Meadows on extending the complex underground. We have no idea what the bleep is going on here, so we ought to have a base at least as safe as those archaic missle silos from 140 years ago.
Did I say defending the base? Good greif, what a difference a month makes. 40 days ago no one could have possibly expected to see this invasion of rabbots and killer drones we've had. Our motives have shifted entirely from exploration to defense. Oh, well, I guess you have to be secure before you can explore.
I've decided to place the base on limited power use so that our batteries are 100% charged at all time. If we get a sudden spike in rabbot encounters, we'll be ready for it. I'm afraid it may hurt morale, but we'll all just have to make sacrifices. God, what I would give for a nice warm bubble bath. There's just no time anymore.
-Lt. Col. Tiffany Barkley
Mayflower-2 LAN e-mail:
From: TBarkley@olympus.net
To: DGryphon@olympus.net
CC: JMeadows@olympus.net, VPatel@antares.net
Subject: Rabbots, Robots, Formalities
Body:
Dr. Gryphon, I would like to know how much longer you intend to deploy the cyborgs. With the radio transmissions coming from Chyrse we know that there's someone out there with similar technology who could potentially mess with your code and turn them against us. Plus, they're probably a surefire way to tick off the locals, so please only deploy them as long as you feel necessary.
I would like to try to make contact with the Chrysians as soon as possible, so please prepare our ham radio transmitter asap. Also, I know that someone here must speak either French or Dutch; if you know anyone who can translate those poorly-sung show tunes I'd greatly appriciate it. We have to get into their minds, figure out what they want, before we can fend them off. And can someone please tell me what in the world is happening around Olympus Mons?
It is critical that we get a solid defense network up right now, so please don't let anything deter you from accomplishing that. I know I've been pushing everyone lately but you're all doing wonderfully and I promise that as soon as we get the caves hollowed out and pressurized and the refinery up to level two capacity you'll get a break. Just stay with me these next two or three weeks.
One more thing, enough with the formalities. I realize that this is a military/governmental program, but guess what, they're not here. We need any morale boost we can get, and formalities certainly don't help, so I'm ending the dress code (unless you go outside of course :;): ) and this stupid military ranking system. Tiffany or Tiffy will be fine in the future. Enough with "Col. Barkley," for now. We're on an alien planet, the last thing I want anyone dealing with is paperwork and a ranking system. Leave the paperwork to me when quarterly report time comes around in May.
-Tiffy
Nonsense, the Falcon-I is a puny toy barely capable of orbital flight at all. Its first stage is no more reuseable then a Shuttle SRB, which isn't reuseable, its refurbishable. "Reuseable" doesn't mean "try to fish it out of the ocean without breaking it and hope the salt water didn't kill the turbopumps." Which you would have to dismantle, check, and test... gee, now what does that sound like? (*coughShuttlecough*) ...Five of them on Falcon-V too. And how many times as any of Elon's rockets flown?
It is going to cost a billion dollars to design a passenger-carrying crew vehicle which uses off-the-shelf docking adapter/airlock, avionics, engines, LSS, and so on which won't have to somehow carry the big flimsy upper stage back down too... Oh, thats for the RUSSIANS to build something like that, a vehicle that would win the "Americas Space Prize."
20% more to develop a launch vehicle that is ~5 times as powerful? Rediculous. The new launch pad will cost that much alone.
"it should be possible to make a true-blue SSTO RLV for $300-400 million."
Perhaps you recall the DC-I RLV concept that Burt at Scaled Composits had a hand in? $6Bn. Small lift-body space planes (baby HL-20) will likly cost around half that at least, and thats just for the crew vehicle with no launch vehicle development.
"$300M-400M" is clearly wishful thinking.
File this under better-late-than-never.
The Falcon I first stage is a bit different than a shuttle SRB. True, some refurbishing would be necessary, but nothing near the complex proceedures needed to use an SRB again. The Merlin is a much simpler machine than an SSME (gas-generator cycle rather than preburners, pintle injection system, demonstrated reusibility...), so there are much fewer parts to check. Dismantle a turbopump, relatively simple for a gas-generator engine, run some water through to make sure it works, clean it up, and you can use it again. X-ray the tank to make sure there are no cracks and its ready to go again. This results in a turn-around time of a week or two without a shuttle standing army of technicians. Not as good as an airliner, but definately better than shuttle level reusability.
Why exactly will it cost at least a billion dollars to develop the crew capsule? You threw out a figure and a laundry list of technical parts without an evidence for this figure. Don't take it personally, man, I'm just asking how you came up with a billion dollars. As far as I can tell, assuming the crew capsule is twenty times as complex and difficult to develop as the SS1 cabin it should take about $200-300 million to create. That's probably on the high side.
First of all, I think that's "ridiculous" you ment to say. Assuming a new launch vehicle uses essentially the same technology as a previous launcher, just a scaled-up version, it shouldn't be that much more expensive to develop. A new 737 version and an A380 cost about the same to bring from CGI model to rollout, despite the quite large difference in scale.
You yourself have pointed out before that Scaled just constructed the tanks for the DC-X. They didn't even design them, they were just assembled in Scaled Composites's factory after they were given the plans from McDonnell Douglas. These costs you keep citing are always those incurred by cost-plus dealings between dinosaur big-three aerospace companies and NASA or the Air Force. Costs will always be quite lower, even orders of magnitude lower, for Alt. space companies because they fundamentally operate differently and more efficiently. The reason you don't see very many successful alt. spacers is because they can't even get the small bare minimum capital needed for vehicle development in the first place. They really can do things cheaply.
With this in mind, there is clearly a factual basis for a $300-400 million figure for an SSTO RLV. Disagree with me all you want but pretty please with a cute little red cherry on top don't accuse me of consciously forgoing logic and giving in to wishful thinking. That's not what I do.
It's starting to look like the whole argument is pretty moot anyway. NASA is sloughing funds from across a wide range of missions, Hubble is just the most publicly-visible. It's likely that Voyager, Ulyssess, Hubble, and many other ongoing missions will go the way of JIMO in order to pool more funds for the VSE. Not the most desirable outcome, but it's what we have to live with.
I'm certainly not a fan of dumping Hubble, but it looks like that's what the issue is going to come to no matter what. Hopefully a mission like HOP will be launched to fill the gap.
Happy 35th Graeme, may you continue your enlightening tenure at Ares Express for many more birthdays to come!
Slowly four shimmering dots on the horizon ballooned both in size and brightness. One by one they flared to almost painful brightness, sending soft wishpering sonic booms to the microphones of several recon robots. Under gossamer sheets of kevlar and plastic they slowed down dramatically, to little more than the speed of an average early-21st century car on a highway. Spaced five hours apart, the Olympus, the flotilla's flagship, then the Antares, Lowell, and Opportunity came to a screeching halt on plumes of plasma-hot hydrogen peroxide.
Immediately following the flotilla's landing that fine early summer morning, the quartet of ships unpacked and began setting up base under the salmon-pink Martian sky. It was a risky business, colonization, and the 200 daring astronauts from NASA, the Air Force, and Boeing knew it. But, they believed, the potential benefits of conquering this planet, and finding out what happened to the ill-fated previous expedition, would be well worth the potential costs.
Mission Commander's Log: March 27, 2103:
Thank goodness EDL was a non-event. What followed was certainly not. After landing we started unpacking base, just as proceedures dictate, but ran into a bit of a snag. Five sentry robots of some sort attacked the crew, before we could get the lasers out. We were able to destroy them, but it sure gave medical a wake-up call. Patel examined of one of the bots and said that it didn't match anything in the original colony's payload manifest. Left unsaid was that the robot looked like nothing that either Boeing or the Air Force had ever been involved with, but I could tell that was what we were both thinking.
Obviously someone is still down here, but who? There are so many questions; are they still alive? Is this some remnant of a nasty fued between two factions of colonists? As soon as Meadows and the rest of the engineering team confirms that all LSS subsystem loops are closed with growth room for the minimum colony expansion requirements I'll send a team out to Hellas to see what exactly is going on over there. Meantime we'll be exploring the local Valles Marineris. So far we haven't been able to find any remnant of the prevoius Von Braun station except for a few scraps of metal and what look like crudely-made shotguns. Either the last crew totally killed itself or decided to leave... and leave no trace of their existance. Beyond that I don't even want to speculate before we look at Hellas.
The pressure here is high enough that you don't even need a spacesuit to walk around, but I don't want to be the first to try that. On our first foray into the Valley we found that the Shenandoah River is flowing again, that was a bit of a shock. According to MSL's observations, that river hasn't flowed for over 2 billion years, but I suppose that it shouldn't be too surprising that it's going again considering the vastly increased surface pressure. This place is absolutely incredible. On the surface it seems like a dump, red rocks, red sky, dry dusty and low-pressure, but... there's just something about it. I have no doubts in my mind that it is our destany and duty to settle this place. I know it sounds weird, but after we landed, this place immediately just felt like home. The view from Shenandoah certainly doesn't hurt. We absolutely cannot afford to let this mission fail, it is critical to our species that we succeed.
-Lt. Col. Tiffany Barkley
OOC: I'm guessing that the Yu Knights were the original colonists that didn't follow Lord Vlork? And Lord Vlork is Cobra Commander? To all colonists of Hellas Basin, bring it on! Oh, yeah, and if anyone new wants to jump in feel free to join my side, because right now it looks like I'm all by myself.
Post 400!!!!
w00t!!!! :laugh:
I don't have the slightest clue what's going on here. Considering that the topic has now slipped out of the first page of the "Free Chat" section and seems to be losing interest, I hope you guys don't mind if I go ahead and jump in.
Mission Commander's Log, March 11, 2103:
We finished re-packing the sails today, right on schedule. In two weeks the floatila will be landing, and maybe we'll finally find out what in any world has happened to Mars. I went over the procedures for atmospheric entry again with John Meadows, our cheif flight engineer, this afternoon; all the preparations are coming together nicely. Fortunately we haven't had to use the diamond-electric lasers the colony department of NASA insisted on including the payload manifest, at least for now. The results from the Antares's atmosphere observations are in, confirming telescopic view from Earth. Mars's atmosphere has swelled like a tick ever since we lost contact with the first colonists, whatever in God's name happened to them is wreaking havoc with the whole planet. Unless of course, they're behind it.
This time we'll be doing it right. We'll be landing at Von Braun Station in the Shenandoah Valley, right where the last colonists touched down first. That should give us a good indication of what happened to them; I can't wait to see the Valles Marineris for myself. There seems to be some activity in Hellas Basin, I'll make a note to send an expiditionary crew to go check it out. In the meantime we'll just have to hope for the best and try to piece together what went wrong, and do it right this time as well. It'll be difficult, for sure, but I've been stuck on this ship for the last three months. Let's get down there already!
-Lt. Col. Tiffany Barkley
Okay, I had absolutely no idea in the world on what date this was supposed to be set in, so I just guessed. Feel free to point out any plotholes I may have just opened up. So, who wants to go next?