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Space

Private Rocketplane Test A Success 283

Posted by michael
from the x-prize-or-darwin-award-whichever-comes-first dept.
HobbySpacer writes: "XCOR announced the success of the first phase of flight tests for the EZ-Rocket. In the most recent flight, Dick Rutan fired both of its rocket engines to take off and reach a speed of 160knots and an altitude of 6200 feet. The vehicle is a Long-EZ kit plane modified to hold twin 400 lb thrust rocket engines fueled by isopropyl alcohol and liquid oxygen. The project is not aimed at a homebuilt EZ-Rocket but will demonstrate safe and reliable rocket propulsion. The primary goal is development of reusable launch technology that leads next to a high altitude sub-orbital rocket vehicle for space tourism, rocket racing (e.g. vertical drag racing at air shows) and the X-Prize competition."
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Private Rocketplane Test A Success

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  • Pointless (Score:3, Insightful)

    by kin_korn_karn (466864) on Thursday October 04, 2001 @11:50PM (#2390800) Homepage
    Rockets are the most inefficient method of propulsion that's still in use, a better goal would be figuring out an entirely new propulsion system that could apply to everything. Speaking of which, what's the latest on Ginger?

    And furthermore, who cares about "vertical drag racing"? Drag racing cars is fun because it's something everyone can relate to. Very, very few people can relate to racing rockets.
    • Wrong! (Score:2, Informative)

      I do not know what kind of efficiency you mean, but in terms of energy efficiency rockets are actually very good. A rocket engine transforms about 90% of the chemical energy of the propellants to kinetic energy. This is excellent.

      The total energy efficiency of an orbital rocket can be defined as the potential energy of the empty rocket in orbit divided by the chemical energy in the propellants. Even here rockets are not that bad.

      If you have a hydrogen powered rocket with a specific impulse of 4300m/s and a total delta-v of 9000m/s, your mass ratio is 8.109, so the propellant weighs 7.109 times as much as the empty rocket. But the empty rocket has a specific kinetic energy of about 30 MJ/kg, whereas the propellants only have a specific chemical energy of 11MJ/kg. The total efficiency is thus 30/(7.109*11)=0.38. Not too bad, eh?

      The reason rockets are still so expensive is that most current rockets are direct descendants of ballistic missiles where cost was not important. And the shuttle is a f***ing joke.

      regards,

      tuttle
    • Re:Pointless (Score:5, Informative)

      by Rogerborg (306625) on Friday October 05, 2001 @11:26AM (#2392199) Homepage
      • Rockets are the most inefficient method of propulsion that's still in use, a better goal would be figuring out an entirely new propulsion system that could apply to everything

      Got any ideas? Once you're at the edge of the atmosphere, you're pretty much limited to using a self contained reaction motor.

      Ground laser launching relies on superheating air, plus it's only been used to shove vehicles directly up, so it's basically a really cool but expensive way to replace July 4 bottle rockets. A more viable alternative is turning beamed EM into electricity then powering magnetohydrodynamic motors that superheat air, but you still have that pesky problem that you are relying on an atmosphere to get your speed.

      You could accelerate the vehicle in a rail gun or rocket sled until it reaches orbital velocity while it's still on the ground. Ballpark figure, at a (barely) survivable 20g, you'd need a 150km track to reach the 7.73km/s orbital velocity of a typical shuttle mission, ignoring air resistance. Except you can't ignore air resistance, because at 7.73km/sec at 1 atmosphere, you'd burn the vehicle to a toasty crisp.

      Even if you postulated antigrav, you still need to generate lateral acceleration to achieve orbital velocity, which again requires a self contained rocket, or an atmosphere.

      A beanstalk (space elevator)? Heck, maybe we've already got the technology to do it, but we're not going to, not for a long, long time.

      So, really, if you've got any ideas about what to use as an alternative to rocketry today, let's hear them. I'm fresh out.

      • Well...if beamed EM to electricity is viable, then how about using that to heat self-contained propellant? Sure, it's technically still a rocket, but most of the reaction energy comes from outside the ship, so it's not 100% self-contained.

        Or, once you get going at a high enough Mach, atmospheric friction will turn air into plasma. Use standard magnetic controls to keep this plasma off of your craft, trapping the plasma so it itself is what impacts even more air and turns it into plasma, then send this plasma out the back. Basically a more ambitious version of the SR-71's "aerodynamics only seal up when heated by fast travel".

        And, of course, there's direct interaction with the Earth's magnetic field - though that takes a lot of power, especially at those (relative to significant magnetic field strength) low altitudes where the atmosphere exists.
      • Ground laser launching relies on superheating air, plus it's only been used to shove vehicles directly up, so it's basically a really cool but expensive way to replace July 4 bottle rockets.
        That doesn't make sense. Isn't going up the hard part? Consider the S1-C Stage [nasm.edu] used in the Apollo missions. It expended 5 millionpounds of fuel just to lift the rest of the hardware out of the mesosphere. This compares to 1 million pounds get the rest of the way, and a few thousand pounds to get back. Finding a more efficient alternative to such a large, expensive, non-reusable vehicle wouldn't complete eliminate the need for rockets, but it would certainly make a big difference in the cost of space exploration!
          • That doesn't make sense. Isn't going up the hard part?

          Uhhh... no. Going sideways at 7.73 km/s is the hard part. Once you hit that speed (assuming you don't burn up, which you would, so you have to accelerate as you rise out of the atmosphere), you'll rise to 300km and stay there. If you just rise to 300km with no angular speed, you'll come straight back down again. Not much use for putting satellites into, what's the word... orbit.

          • OK, I'm no engineer, and I never really looked at this idea before I read your jibe. But if I understand this explanation [osd.mil] of laser propulsion, there's no reason the thrust has to be strictly vertical. The thrust comes out of a nozzle, just as with a chemical rocket.
              • if I understand this explanation [osd.mil] of laser propulsion, there's no reason the thrust has to be strictly vertical. The thrust comes out of a nozzle

              ...in theory. The last that I heard, Lightcraft are still at the stage of shooting tiny disks straight up in the air, with no nozzles or lateral motion.

              Actually, that's not strictly true, the disks do experience lateral forces - when the reflective base fails catastrophically in one area and explodes, or when the disks pick up a wobble and tumble out of the air.

              It's a truly appealing idea, but (again, AFAIK) the practice is lagging way, way behind the theory. I'm having a hard time picturing them getting anything into orbit without dropping it or frying it to a crisp.

              Perhaps our best hope is that Son of Star Wars spins off some useful technology in this area.

              • So laser propulsion has a dubious background and a poor track record. So did rocketry at one time. You could argue that rocketry still has a poor track record. In any case, I think it's silly to pre-judge all the alternatives to rocketry as pure pipe dreams.

                Excuse me if this comes across as a flame, but you only seem to want to look at arguments that LP is a boondogle. Did you even look at the link I provided before? Or have you seen these proposals [llnl.gov]?

                None of which means I care for all the "Star Wars" nonsense that seems to be associated with alternative propulsion technologies. Weapons of mass destruction can't be handled by some fancy technofix. But perhaps thats what really has hurt oddball systems like laser propulsion: they have an unfortunate association with folks motivated by nationalistic ideology or military career-building -- not a geninuine interest in space exploration.

                But this association shouldn't prejudice us against the very idea of finding alternatives to rockets. As the guy who started this thread pointed out, it's a damned inefficient means of propulsion. A serious return to space just isn't going to happen until we find an alternative.

                  • you only seem to want to look at arguments that LP is a boondogle. Did you even look at the link I provided before

                  Er, yes, and I've looked at all the pretty concept art that looks like it's been done by the same guy that drew all those flying cars back in the 1950's.

                  Again, I really like the idea of light propulsion, but the reality is a long, long way off. That's not to say that we shouldn't pursue it, only that we should be careful about throwing money at it just because it's appealing and exciting. The results (so far) simply don't justify it. Once it works reliably for simple toys, then I'd be 100% behind scaling it up, but the proof of concept has to come first.

      • Re:Pointless (Score:3, Informative)

        by Catbeller (118204)
        The "rocket sled" (actually a linear induction motor used as a railgun of sorts, also called a mass driver by Gerry O'Neill and company, and first dubbed a "catapult" by Heinlein and something totally else by Clarke) doesn't have to accelerate the ship to orbital speed. That's ludicrous.

        It merely has to replace the first stage, and that only requires a few miles of track, an upwardly sloping mountainside, and a few G's of acceleration. One the ship leaves the mouth of the catapult, it's moving fast enough for a very small fuel tank to kick it all the way to orbit -- not to mention the fact that at mountain height, it's past a goodly chuck of the atmosphere pretty quickly.

        It's surprising how little ship you need to achieve orbit once you get rid of the first few miles and get some speed buildup. The ship is SMALL.

        A catpult would prolly use maglev, be pretty cheap once the thing is built, and only require electricity to operate instead of rocket fuel. And it is reusable to a ridiculous degree.

        • Let me run "a few miles" at "a few G's" by my (admittedly rusty) physics, rounding up to the nearest power of ten (as tradition dictates ;-) ).

          Let's say 10km @ 100m/s2 (~10G). s=1/2at^2, t^2=2s/a, t^2 = 20000/100 = 200, t = 14.14s, so v = t * a = 14.14 * 100 = 1.4 km/s, and you need 7.73 km/s for a 300km orbit.

          What am I missing? Is this really a big enough fuel saving to justify building and maintaining 10km of track?

          I'm not trolling, I do actually agree that this is the most practical solution we have right now, but I can't get the maths to work out.

          • Wow -- actually that's a pretty short track for orbital velocity!

            Well, you couldn't get orbital speed in the atmosphere, so the track doesn't have to be that long.

            We build interstate highway systems that need rebuilding every few years, and no one notices the cost. The track would cost tens of millions, maybe hundreds of millions. The first one would, any way, because it's all new engineering and that means mistakes and redos. The successor catapults would be cheaper.

            Back to the answer: you only need to get the ship going a bit -- and I don't have the maths, just the studies over the years by NASA, the National Space Society, endless seminars, fifty years and more of maths, starting with Sir Arthur Clarke -- you need to get the ship up the first few miles, and moving at a few hundred miles per hour, to totally eliminate the need for a first stage. Remember, the first stage is the biggest, and the reasons for that are that it's in the densest part of the atmosphere, and is lifting not only the entire structure of the successor stages and the the orbital craft, but it's OWN weight and the weight of its fuel, an enormous sum.

            And don't forget, you can't get it going too fast, or sonic booms play havoc with the catapult, and friction fries the ship itself. No, you can't get orbial velocity in the atmosphere... but you can get the puppy moving pretty fast before the rockets kick in.

            Kick out the first stage, and you can have your spaceplane without a giant fuel tank and strap-on boosters. Something the size of a big Lear jet, maybe.

            Also, if you want to launch unmanned vehicles, you could harden the payload to take many more G's, and boost that acceleration UP, getting a huge piece of orbital velocity out of the way.

            Piece of trivia: remember "When Worlds Collide", the George Pal SF movie of the fifties? They used, yup, a railway up a mountain to get the ark up to speed before the rockets cut in. I remember watching that image as a kid...

            The maths and studies have been done over and over again, and they are buletproof.
    • Hey, when you come up with a propulsion system that has T/W > 1, let me know. Until we can get off the ground with something else, the really cool and exotic [and, yes, efficient] stuff--like ion propulsion, ram jets, et cetera--is going to be the domain of spaceflight only. Even then, you're going to have to get that stuff up there somehow. Too bad people are so scared of using fission to provide heat energy for conversion into propulsion [and onboard power]. That could make things really easy, actually ...
  • by ekrout (139379) on Thursday October 04, 2001 @11:54PM (#2390814) Journal
    In the most recent flight, Dick Rutan fired both of its rocket engines to take off and reach a speed of 160knots and an altitude of 6200 feet.

    If your last name was Rutan (read "Rootin'"), you should not name your kid Richard (or encourage the nickname Dick!). This is common sense.

    Thankfully, Bart & Lisa's prank calls to Moe on The Simpsons should discourage future "Hugh Jass"s, "Ivana Tinkles"s, and "I.P. Freely"s.

  • by Nindalf (526257) on Thursday October 04, 2001 @11:55PM (#2390818)
    Think of how much money goes into car racing. Rocket racing would be an incredible spectacle.

    This could easily lead to full funding for the transitional stage of private rocketry before the obvious profit potentials of orbital flight.
    • Think of how much money goes into car racing. Rocket racing would be an incredible spectacle.

      Yes, but think about the audience for auto racing - namely rednecks. Rednecks like auto racing because they drive too and watching people drive cars fast apparently makes them think their dick will become larger when they drive their trucks fast. I say apparently because I don't know since I think auto racing is boring and stupid.

      Rocket racing won't have an audience because rednecks *don't drive rockets*. Despite the obvious phallic look of rockets, rednecks will not go to rocket races in droves.

      Furthermore, auto races are confined to small stadiums where the cars tediously go around and around the same tiny track many times. Rockets cannot be confined to such a small sanitized "track" and instead will blast-off in a few seconds never to be seen again. I suppose rocket racing is more akin to the even more boring drag racing [draglist.com] which has a much smaller audience.

      Geeks, the only remaining potential audience for this will go to something significant like STS [nasa.gov] launches. STS = the space shuttle program for those not in the know.

      That leaves redneck geeks as the only people who will go to rocket races!

    • Rocket racing would be an incredible spectacle ... but it'll be hard to get much detail. You'll have to watch from far away for safety and perspective reasons--if you have ever been to any CART or NASCAR race, you know you just feel the cars go by you, really.

      As for profit potentials, I'll agree that they exist, but at this point, no one's put up the money to make it happen. That we've seen scads of money thrown after bad business ideas in the last 25 years tells me something about the risk/reward function on private orbital flights.

  • Once this gets going, I can see corporate sponsorship coming in, in a big way. Sort of like what we see in auto racing right now.

    The visions of certain very big companies influencing the designs and the paint jobs of the rockets inspires scary visions.

    never mind the obvious upgrades on jokes like "If company X designed ABC"

  • Rocket Racing? (Score:2, Insightful)

    by Millyways (262662)
    Is it just me or does anyone else think that pushing the limits of rocket design technology at public airshows might not be in the best interests of public safty?

    In conventional top fuel drag racing when things go wrong which they often do it can often result in part flying off 100's of meters into the air. Dragsters by their very nature are stressed to the limits of their durability, in order to get that little bit faster than the next guy.

    I don't think we want distasters reminisant of the challenger disaster happening at airshows before we decide this is a bad idea.
    • Re:Rocket Racing? (Score:3, Interesting)

      by Alien54 (180860)
      Is it just me or does anyone else think that pushing the limits of rocket design technology at public airshows might not be in the best interests of public safty?

      The best thing would be a one way run away from a crowd, say out into a desert.

      Just make sure the chutes do not fail.

      Sound like something that could be cool out in a place like Death Valley.

  • Unit conversions (Score:3, Informative)

    by metricman (265010) on Thursday October 04, 2001 @11:57PM (#2390826)
    160knots = 296 km/h
    6200 feet = 1890m
    400 lb = 1779N

    A cool feature for slashcode would be automatic unit conversions.
    • Please get the units right. These are measures quoted in the article, rended into the confusing metrics, for people insisting on using that system.

      160 knots = 160.1023 knots (metric)
      6200 ft = 1889.76 m.
      400 lb = 1.779 kN.

      Areal and nautical speeds are measured in knots, not miles per hour, or km/h or cms. Force of engines is measured in kilonewtons, not newtons.

      But what would you convert the units into? Metric, or regular.

      The whole idea of metric is that we should put all of our eggs in the one basket, so that people with certian brain defects would not be able to understand it. I found little logical in it to understand what people see so wonderful in it, and I have studied it for thirty years now.

      • You have trouble with metric? Whats so hard about powers of ten?
        Take temperature for example:
        Imperial, freezing is at 32, boiling at 212
        celcius, freezing at 0, boiling at 100

        distance
        12 inches to the foot, 3 feet to the yard, 5000 and change feet to the mile, anyone know how long a furlough is?

        10 mm to the cm
        100 cm to the meter
        1000 meters to the kilometer

        1000 ml to the liter

        miligrams, grams, kilograms
        its obvious what these are just from the name.

        Imperial uses ounces for both wieght and volume!

        Metric features a uniform system of naming:
        mili - thousandth
        centi - hundreth
        kilo - thousand
        etc...

        Metric is MUCH simpler than imperial. The same obstinace that has the whole world speaking english is the only reason the USA hasn't switch to metric.
        • Re:Unit conversions (Score:2, Interesting)

          by os2fan (254461)
          Imperial, freezing is at 32, boiling at 212
          celcius, freezing at 0, boiling at 100

          Nothing special about these temperature points. The only one that matters is absolute zero = 0. I mean, there are 180 degrees fahrenheit because of historical accident, but at least Fahrenheit adjusted his scale so that fractions would not occur in normal use. The original Roemer units were four times the size. (ie Fahr / 4 both size and scale).

          Reameur scale is at least logical in that its degrees represent the increase in volume as 1000 units of alcohol are heated. It ranges from 0 to 80.

          Without further comment, the Celcius temperature had freezing at 100, and boiling at 0. The current scale was called Centigrade, but Celcuis was coopted when everyone forgot about the mark I fiasco.

          AngleYes, the wonderful simplicity of the metric system, which was intended to replace all measures, did supprisingly poor on angle and time. Despite the so-called decimal advantage, and that the kilometre was intended to be a centisimal minute at the surface of the earth, and so replace nautical mile, neither the decimal division of the quadrant, or day took off. When you calculate the speeds in decimal days, you will start to see the silliness of unrestrained decimals:

          1 km/h = 2.4 km/H = 0.24 m/S, and
          1 mph = 4 km/H = 0.4 m/S.
          Speed limit in usa = 55 mph = 220 km/H.
          (1d = 10 H = 1000 M = 10000 S.

          Distance. A furlong is 660 feet, as anyone can see. A mile is clearly 5280 feet, as it should.

          Imperial ounces don't exist. They're avoirdepoise, troy, or fluid ounces. The context defines the missing adjective. Just as it does with cubic, square and linear measure.

          And while you're at it, I notice that you are supprisingly silent on mill, a length, angle and volume, or K, a number, temperature, distance, mass, speed. The truth is, that relying too heavily on a matrix naming does lead to lots of confusion. We won't even go into the prefixes like deci vs deka.

          10 mm to the cm
          100 cm to the meter
          1000 meters to the kilometer

          1000 ml to the liter

          It is of course interesting here, that apart from preaching how the metric system uses prefixes and so forth, how the "centilitre" is noticably absent. Even more so the nightmare of deci- vs deka, hecto, or Myria-. Oh well. There goes consistancy.

          Both systems suffer from the Roman weight-fraction legacy. An uncia was a 12th measure, this gives the foot of 12 inches, and the troy lb of 12 ounces, and an hour of 12 ounces. Mind you, any metric unit divides into 1000 mills. Depending on context, the builder's mill is the mm, where the chemist's mil is a ml. And we won't even worry about "gammas", a mass and magnetic field, and "lambdas" a volume, and "micros" a mass, not to be confused with "microns", a length, or "ohm", a capacity and resistance unit, or "farad" (a capacatance) vs "faraday" (any of a number of electrical charge units).

          Metric is still bound by the same sorts of mentality that drives the imperial system. One talks of millions of kilometres, not *gigametres, or "tonnes", not "Megagrams". So much for "logic". Mind you, the names are wildly long that people look for shorter names.

          And we won't even worry too much about a large number of special symbols that you need to express its units (eg raised 2, 3, greek Omega, mu). Like, you can't write sq m, you have to put m^2. Where I can write ft or Ft or FT, mm, Mm and MM can be milli or mega- metres.

          What's even more impressing is that the prefixes are both patchy, and overload letters, for example, m and M differ by nine orders of magnitude (milli, and mega), and somewhere we got to squease a third m for micro into this lot. Luckily, we can steal the greek mu for this end.

          The whole prefix multiple system has been coopted into computing, where one can use K as 1000 or 1024, depending on what your needs are. Megs, Gigs and so on are simply K*K, K*K*K &c. So a 1.44 MB floppy is actually 1.44 * 1000 * 1024. Hmmm.

          Metric is MUCH simpler than imperial.

          I seriously doubt this, too. The numbers that metric are easier to convert between one and another unit, but I can not seem to recall doing conversions from capacity to volume units all that often, that rough rules could not handle. But to achieve this simplicity, much had to be sacraficed.

      • Re:Unit conversions (Score:3, Informative)

        by marm (144733)

        The whole idea of metric is that we should put all of our eggs in the one basket, so that people with certian brain defects would not be able to understand it. I found little logical in it to understand what people see so wonderful in it, and I have studied it for thirty years now.

        Umm, no. The beauty of metric, or rather the more modern form of metric called SI (Systeme Internationale) is that:

        a) multiples of a unit are always in base 10, so it is obvious that 27km = 27000m, and it is just as simple to write that in scientific notation (i.e. 27km = 2.7x10^4m) - you try telling me what 27 miles is in feet without reaching for a calculator

        and b) there is a small set of measured base units (there are 7 - metres, kilograms, seconds, amperes, kelvins, moles and candelas) and every other unit used throughout science and engineering is directly derived from these base units without any fudging

        Quite apart from the obvious benefits for calculation, it also makes things much easier to understand in your head - you only need to know the size of the 7 base units to be able to have some idea of exactly what each derived unit means. Also, if you are sticking to SI notation to the letter, it is plain from the name of the derived unit exactly how it is derived from the base units.

        Really, it is perfectly logical, and a heck of a lot simpler to learn than the old Imperial or Imperial-derived systems, where there were about 3 times as many different base units. Science has adopted SI worldwide, partly for its ease and simplicity, and yes, partly because scientists want to be able to understand each other. In most countries, engineers have also adopted the system for similar reasons, and even the general populace understands most of it thanks to everyday things being measured in SI units or multiples of - masses in grams or kilograms, volume in litres, distances in metres or kilometres.

        Anyway, in SI Units...

        160 knots = 82 ms^-1 (metres per second)
        6200 ft = 1900 m (yes, this one was right :)
        400 lbf = 1800mkgs^-2 (meters per kilogram per second, aka newtons)

        All conversions rounded to 2 significant figures... now, who's going to be the first to complain about the use of significant figures? ;)

        • You forgot a few other niceties:

          Volume: one litre is the volume of 1000 cubic centimeters (i.e. 10cmx10cmx10cm cube). How many of you can tell me how "large" one gallon is, physically? Could you guess how many gallons are in your swimming pool just by the dimensions... in your head?

          Kilogram: the mass of one litre of pure water. How much does a gallon of water weigh???

          Metric Tonne: the mass of one cubic meter of water. How many Imperial Tons does your swimming pool weigh?

          I can easily visualize things in terms of metric units... but it's very difficult to do so with Imperial units. I see this as a great aid in any sort of mental gymnastics.

          MadCow.
          • From 1900 to 1963, the litre was 1000.028 cu cm.

            Gallon = cube side 6.522 inches. But I don't need to work in cubes by itself. I fl oz = cube side 0.1 feet.

            Kilogram: the mass of one litre of pure water. How much does a gallon of water weigh???

            One gallon is 10 lb water.

            How many Imperial Tons does your swimming pool weigh?

            An imperial ton is very nearly 36 cu ft: ie 1 fathom * 1 fathom * 1 foot. If you insist on a cube, try 3.3 ft or 39.6 in, or 5 links, they're all the same.

            I can easily visualize things in terms of metric units... but it's very difficult to do so with Imperial units. I see this as a great aid in any sort of mental gymnastics.

            You must have went to sleep during the arithmetic lessons.

        • SI (Systeme Internationale)

          Isn't this a dead give-away. System = collection of units used together: International = hodgepodge designed to clip the wings of foreign aspirations. Enough said

          ..it also makes things much easier to understand in your head..

          Actually, you would more easily understand the intensity of a kilometre-candle, (ie a candle at a kilometre), rather than a metre-microcandle, (ie a millionth of a candle at a metre), which is what a microlux is all about. Also, an acrefoot is an easier volume to grasp than a Megalitre, although they're the same size. People convert sheets of paper into stacks miles high because thousands and millions can not be grasped.

          7 base units

          CGS had only three, and seemed to work OK with that. I've used systems with one base unit. All this means is how many equations you plan to leave out of the derived theory.

          They only have seven, because the the system is a botch-up that they HAD to have 7. The mole was only invented as a base because SI did not want to use the coherent kilomole. The base unit "Ampere" depends on the size of the metre and kilogram, but the "Henry per metre" is free of such dependancies. Yet the "Ampere is afforded the status of "base unit". The size of the candela depends on the square metre, but the lux does not.

          Sad about the mass unit having a derived name ...

          you try telling me what 27 miles is in feet

          Don't have to. Because I don't do that sort of conversion at all. Really.

          be able to have some idea of exactly what each derived unit means

          Some is the operative word here. Rationalisation throws a spanner in the works. 1 C translates into 12.566 C, if flux is being refered to.

          Really, it is perfectly logical, and a heck of a lot simpler to learn than the old Imperial or Imperial-derived systems, where there were about 3 times as many different base units.

          The imperial system has three base units; yard, pound and gallon. All the rest are supplemental. Somehow, three by seven is three. Good one.

          Also, if you are sticking to SI notation to the letter, it is plain from the name of the derived unit exactly how it is derived from the base units.

          I did way better with no units, in a google system. In essence, 1 s = 1e100, 1 m = 1e1100, 1 kg = 1e73300, 1 A = 1e32100. Decimal prefixes are just added in: 1 cm = 1e1098. Do unit and exponent calculations all in the same column. The units are far enough apart that you can do the unit sums and exponents with a calculator, and you don't have to remember individual dimensions.

          yes, partly because scientists want to be able to understand each other

          The pre-metric system used by scientists was Paris feet. Not having a precise widely used measurement system does not hinder much of science.

          Why measure volumes in litres. Doesn't the cubic metre cope with this??? No. Volumes are derived from the linear measures, and are very hard to reproduce. Capacity is done by bulk comparison, and is very easy to use: ergo, litres, gallons, bushels.

          Also, if you are sticking to SI notation to the letter, it is plain from the name of the derived unit exactly how it is derived from the base units

          And from this, we can see immediately how "Weber" is derived from "Metre", "kilogram", "second", and "ampere". Get real.

  • by Telek (410366)
    can someone tell me why they're not interested in using balloons at all for reusable launch vehicles? It would make far too much sense to me since it's essentially free and lightweight, and a lot LESS expensive than dumping humungous feul tanks into the ocean after every launch. You can get up very high, ditch the balloon, then use attached rockets to fill you the rest of the way. You could even use reusable balloons with hot helium instead in case you need to lift too much weight for just hot air to raise.
    • Looks like it's moderators on crack day today.

      If you want to get into orbit, or leave Earth entirely, the crucial thing you have to do is go really fast. Altitude is pretty much irrelevant except that aerodynamic drag slows things down more at lower altitudes.

      The only difference than launching from a balloon at altitude would be the slightly reduced aerodynamic resistance, negligible compared to the cost, complexity, and risk of building a floating launch platform :)
      • Actually, a balloon first stage is incorporated into a number of fairly credible amateur rocket designs. By using a balloon to bypass the heaviest 15-20 miles of the atmosphere, you're cutting down not only on drag, but distance. This means you have to carry considerably less fuel, leading to a smaller, cheaper, and possibly more reliable design. It probably won't be used for getting large multi-ton objects into space, but for a small one-two man capsule, or a small satelite, a balloon launch makes a good deal of sense.
      • One other thing:

        if you can get 16km up (which is pretty easy even with a large load) you've cut out a LARGE portion of the density of the atmosphere. For every 16km up you're down to 1/10th of the density. So 16km up is 0.1atm and 32km up is 0.01atm.

        Needless to say 90% reduction in density leads to _significantly_ less air resistance. Now although air resistance is not a huge drag (no pun intended) it does play a part. Add to the equation now that you're 16km up without using any feul, and you have that much more potential energy to use to get up to speed.

        And the risk of building that is ... negligable. These things are, by definition, aerodynamic. If you drop the plane straight down all you have to do is pull back on the yoke and pretty soon you'll be flying vertical again. The balloon has to do nothing more than just drop the rocket.
    • by Gorobei (127755) on Friday October 05, 2001 @12:47AM (#2390964)
      The main reason is the FAA. If you want to be a high alt attempt, you need to file a lot of paperwork concerning your flight plan and risks to populated areas/foreign airspace. In theory, you could get approval for an orbital shot from two places in the USA (Black Rock and Alaska,) if you have a self-destruct device on board. Note that a self-destruct doesn't make the rocket vanish, it just puts the debris in a safe zone. Now, if you want to float to 120,000 feet before launch, your debris zone is about the size of the Pacific Ocean. You don't get approval, end of story.
      • cool sounds like an interesting response.

        however I don't understand why your wreckage zone is that much higher.

        and besides, if you launch from near the ocean and float out into international space, do you still have those problems? surely if you're over the ocean you don't need to worry too much about debris falling on people. Nasa routinely dumps stuff all over the ocean all the time, it can't be that hard to make it a reasonably targeted zone.
        • The wreckage zone is much bigger for two reasons: you may need to abort during the climb to launch alt, and you don't know where the launch will take place.

          Assuming a 4 hour climb, you may pass through the jet stream (giving you a speed of 100 mph or more) and then get pushed around by the stratospheric winds. You might have travelled 300 miles or more in a relatively random direction. From this unknown location, you fire your rocket. In this thin air, it easily reaches Mach 4 and starts to go off course. You abort, and put the debris into a nice lob in the thin air. This gives you an additional couple of hundred miles in a random direction.

          Ok, I exaggerated a bit - the debris zone is in the 100,000 square mile range: the FAA wants numbers that show the chance of hitting a ship is .1% or so, airplane 1 in ten million or so. Plowing in foreign soil is a no-no. In theory, you could get the waiver, but it still seems easier to just tank up a big dumb booster, ideally launched from White Sands or similar, so you can avoid the FAA red tape.
    • I think you are refering to a "rockoon".

      http://www.friends-partners.org/mwade/lvs/rockoo n. htm

      They were invented by Dr. Van Allen and some of his associates. They were only for sounding rockets, which explore the upper atmosphere but don't go into orbit. If you want to go into orbit, you still need a lot of horizontal velocity so the rockoon is not as handy for that.
    • JP Aerospace [jpaerospace.com] "America's OTHER Space Program" is doing this very thing. They used balloons to carry a launch platform and rocket to 26,000 ft where they launched the rocket. Now they're currently working up to being able to launch from 100,000 ft.
  • ah Crap! (Score:3, Funny)

    by OO7david (159677) on Friday October 05, 2001 @12:20AM (#2390888) Homepage Journal
    Now, not only do I have crapily modified cars running down main street fridays and saturdays, but now I also have to deal with these jerks interruptin my flight!? I don't want to see a rocket with a 4' muffler, it's not cool. I don't care if your rocket has a Vtec engine. I want to fly safely from point A to point B, much as I would like to drive from point A to point B without having your terrestial counterpats fly past me at 100+ mph.

    Honestly, kids these days.
  • by Anonymous Coward
    The first tourist in space got to stay on the ISS for a couple days and he was using a well tested reliable vehicle (Soyuz). The tourists of these sub-orbital rockets would get minutes (at most hours) in a cramped vehicle, is it worth the risk ? Although I agree with the concept of stimulating creativity for designing sub-orbital re-usable vehicles, keep in mind that these "tourists" would still be essentially strapped to a liquid oxygen bomb and that if "civils" start going into space what does that say about the gruelling Astronaut selection performed by NASA and all the space agencies that produce astronauts (Russia, ESA, CSA, NASDA,ISA etc.) These people (astronauts) give up a good part of their life to get a trip into space. Challenger was the first to fly a "tourist" on the crew and we know what happened. NASA then cancelled all civil/commercial endeavors using the shuttle ever since... In my opinion the risks are too great to let just anyone fly in these vehicles. (as payloads mind you) -I am tempted to use the cliche "Talk about the Wrong Stuff"
  • life during wartime (Score:3, Interesting)

    by motherhead (344331) on Friday October 05, 2001 @01:06AM (#2390991)

    The primary goal is development of reusable launch technology that leads next to a high altitude sub-orbital rocket vehicle

    Could a missile fired from sub orbit on an (relatively) inexpensive platform such as this one, actually knock out a satellite?

    Yes I realize that the missile would have to be expensive enough with it's payload and whatever guidance it would need to find it's target.

    But if these things can be made as cheaply as they say, I wonder if small governments (okay i am sicking of typing the "T" word) could use this kind of technology to cause a lot of mayhem.

  • Rotary Rocket gone (Score:3, Informative)

    by Animats (122034) on Friday October 05, 2001 @01:28AM (#2391019) Homepage
    Rotary Rocket is gone. Sad. They had a launch vehicle that was supposed to go suborbital, and probably would have worked. The helicopter-type landing system passed flight test. Another Rutan airframe design, by the way. [rotaryrocket.com]

    The big problem was that the new engine concept didn't work out, and using off the shelf engines doomed the thing to suborbital flight, for which there is no commercial market.

  • Nice try dick, but you're not the first [darwinawards.com]

  • article text (Score:2, Informative)

    by FrenZon (65408)
    it seems like the server's going down (or it could just be australia's crap old ADSL) So here's the body text, fear my karma-whoring or something.

    Mojave, October 3, 2001: XCOR Aerospace today announced that it has successfully completed the first phase of its flight test program for the EZ-Rocket. The EZ-Rocket is the world's first privately built rocket powered airplane.

    At 0900 hours today the EZ-Rocket took off from the Mojave Civilian Flight Test Center to an altitude of 6,200 feet before gliding back to Runway 30. The EZ-Rocket is powered by twin 400 pound thrust rocket engines designed and built by XCOR Aerospace. The flight test program passed its first milestone by flying with both engines for an engine run time of 96 seconds and total flight time of five minutes and twenty seconds.

    Retired United States Air Force Lieutenant
    Colonel Dick Rutan


    XCOR's test pilot is retired United States Air Force Lieutenant Colonel Dick Rutan, a Vietnam veteran and world-famous test pilot. "I ignited one engine and the crew said everything looked good, so I lit the second engine and we started moving," said Lt. Col. Rutan. "As I rolled down the runway Mike Melvill flew overhead in another Long-EZ and served as chase plane. The plane took off 1,200 feet down the runway and once airborne the vehicle rapidly accelerated to 160 knots. The rocket power provided positive, firm acceleration. Once we started running out of liquid oxygen I shut down both engines. Mike inspected the airplane visually and reported it was clean with no leaks. We entered a standard flame-out [landing] pattern and glided back to the runway."

    The EZ-Rocket is a research and development test bed for XCOR. "Routine operations must be the primary criterion for rocket engine development," said XCOR Chief Engineer Dan DeLong. "Our approach is to build safe and reliable rocket engines first, then progress to the higher performance needed for orbital launch vehicles."

    XCOR president Jeff Greason said, "We passed a major milestone today. This is a significant technical achievement for a variety of reasons. First, once you get two engines working in combination it is significantly easier to cluster more engines for larger vehicles. Second, we were able to keep the engine and fuel flow running smoothly during the flight."

    The official roll-out and flight demonstration of the EZ-Rocket will take place this November at Mojave airport. Check the XCOR (www.xcor.com) web site in the next few days for details on the event.

    EZ-Rocket Specifications
    The EZ-Rocket is a modified Long-EZ homebuilt aircraft. The aircraft is powered by twin 400 lb thrust regeneratively cooled rocket engines and fueled by isopropyl alcohol and liquid oxygen. The EZ-Rocket includes an external composite fuel tank and an insulated internal aluminum liquid oxygen tank. The modifications were performed at XCOR Aerospace's Mojave, CA shop. Tests are performed at the Mojave Civilian Flight Test Center.

  • by warpeightbot (19472) on Friday October 05, 2001 @02:48AM (#2391134) Homepage
    It looks like Buzz Aldrin's got some competition now.... Buzz had been going at it with the idea of adapting existing missile tech in clusters to form a cheap booster for commercial space.... but it looks to me like he was using the cathedral method of design. Big and slow.

    On the other hand, it looks like the Rutan brothers are using something like Extreme Programming to build rockets... build up little by little, test daily, twice, three times a day, use existing airframes as testbeds (Dick Rutan could fly a LongEZ in his sleep, and probably has by now :) .... and you know damn good and well that when they get a reliable product they're gonna release it as a kit.

    (drum roll please)

    Open Source Aviation!

    No, I'm serious... when you buy a kitplane, you get the source (plans, etc.), and you are perfectly free to hack'em, and post your results and sell the resulting product. (Kindof a BSDish license... 1/2 :) The original 2-seat pusher LongEZ became the 4-seat Velocity, the taildragger Quickie, and inspired the commercial LearStar and Beechcraft StarShip designs.

    Yeah, aircraft design is kinda like doing something the size of Mozilla.. but once you've got something working (and the VariEze/LongEZ designs have been around for... well, the old VariViggen (the granddaddy of all homebuilt canards) the Museum of Flight was registered in 1972, so.... and once you've got something it's dead easy to do incremental improvement and even rapid prototyping.

    They've been doing this on a shoestring budget (I know how the Rutan brothers work, that's how they built Voyager) for about two years now, and they've got a bird in the air alreddie... where the Zoche folks have been at this aerodiesel thing for six years now, and still don't have anything flying... which is a reflection of the design philosophy; Zoche is going for an FAR-23 certified engine up front, where XCOR is happy to get something off the ground in a safe manner... in much the same way as Netscape would write this huge thing ground-up and only release it when it was all done as opposed to Mozilla pumping out milestone after milestone as things gradually started working...

    In short, real-world, non-code-geek example of why bazaar-style development works.

    • At least it's not running windows... makes you wonder about those crashes, and blue (red?) screens of death...
    • by Chris Y Taylor (455585) on Friday October 05, 2001 @11:03AM (#2392102) Homepage
      I hate to break this to the programming community, but you did not invent the philosophy of "open source" or the "bazaar vs. the cathedral."

      Science has had an "open source" component for pretty much as long as there has been modern science. Everybody works on some little bit of the problem (figuring out how the universe works), and when they have something they think is reasonable they publish it for everyone else to critique. Such publications may not technically be free, because you have to subscribe to the journals, but in reality if you go to any science library you can get free access to them. Really, the philosophy of finding mistakes by releasing code as "open source" so that a lot of other people can look at it and tinker with it is the same old philosophy behind peer-review and publication of scientific papers. The "open source aircraft design movement" exists; it is called "Journal of Aircraft" and is delivered to my home every couple of months.

      This may get me modded down, but I think that "open source" is just Computer Scientists figuring out something that the other branches of science have already known for a very long time. Getting new developments into the public domain and letting other researchers bang around on them will yield even newer and better developments. One team of people locked away in isolation is not nearly as likely to develop a workable product (which for science would pretty much be a model of everything in the universe.)

      That said, I don't think the idea of developing aircraft the same way that you develop programs is a good idea, because they are NOT the same sort of things. I'm sure you all know the joke about if Airplane development went like Computer development then we'd already have hypersonic transport aircraft with world spanning range that the average person could afford to own and operate... and they would explode once every week or two killing everyone on board. Aircraft Theory and Aircraft Conceptual Design and Aerodynamic Behavior and other such things are generally done as public science and/or published in journals and presented at conferences (i.e. "open source"). When it gets time to actually design the aircraft, this is done with a relatively small, closed team of people. There is a good reason for this. Airplane and rocket crashes kill people. Pick up a copy of The Right Stuff and read the first chapter. Such things ARE tested regularly. They are tested methodically and often. In wind tunnels and CFD code and on the ground and finally in the air. They are tested with methods and in progressions that were proven to work with VERY costly (in dollars and lives) prior experience. You could call it "extreme programming" for aircraft. Aircraft design is also complex. Simply moving the battery from the front to the back of a plane this size can invalidate all previous flight test data, so it is with good reason that the development is done by people who know the whole picture intimately (a difficult thing for a hobbyist to do). And, many aircraft design groups don't want their detail designs and their "tricks of the trade" to be open source because they are proprietary or classified. Yes, other sciences have "Closed Source" projects, too; but unlike in computer science, they tend to usually be offshoots and niche developments with the bulk of science being "open source" (to use CS lingo). Even big, private company laboratories in other scientific fields publish a lot of "open source" scientific material. Not only do they realize the value of having it reviewed and verified by other scientists "for free," but they also understand the importance of such publication in maintaining their organization's prestige in their industry and in recruiting the best new talent.

      Aerospace has had "open source" for almost 100 years now. Physics has had it since the days of Newton and Galileo. Computer scientists, welcome to the club. Just don't think the rest of us haven't known about this for a long time... and stop tacking the phrase "open source" on everything. Try terms like "peer review" and "in the public domain" on for size; maybe you'll sound less socialist and the public will take it more seriously.
      • Yet another reason to prefer the term Free Software :-)

        Seriously, though, I think the innovation of free software is that it takes what had been hoarded as property (finished, marketable products) and makes it as free as basic research.

        Of course, maybe that's because, in software, one can apparently take something with the quality of bad undergraduate research and sell it...

      • Very insightful comment. As you point out, modern science is based on the free exchange of ideas. This shouldn't come as a suprise to anyone with a technical education.


        However, there is one major difference between the general scientific community and the Open Source movement: scientists share abstract ideas, whereas OSS shares a useful, consumable product. An openly published physics paper is really only useful to other physicists. An openly published computer program is useful to anyone with a computer -- you don't have to be able to understand the source code in order to execute the program.

  • by deathcow (455995) on Friday October 05, 2001 @02:57AM (#2391145)
    I find it unbelievably strange that John Carmack (of Doom,Quake fame) is also building a rocket capable of transporting humans. He's made a ton of progress. His company: Armadillo Aerospace [armadilloaerospace.com]
  • by ruszka (456169)
    Not sure if it's been posted yet, but a guy out in Oregon is also working on something related to this.. Goes by RocketGuy [rocketguy.com]

    Everything he's worked on and gone through is pretty damn interesting, worth the read if you haven't heard of him.. He's set to launch in May of next year
  • I'm very suprised to see nobody else in this forum recognize the name "Rutan." The Rutan brothers, especially Dick, are huge figures in experimental aviation. The Design that was modified for this experiment was originally created by Dick. As were many other novel and very successful airplanes. Among them were the "Voyager" aircraft that circled the globe unrefueled. He also has an "nonsymetrical" twin engined, twin hulled aircraft that carries eight people, goes 300mpg and is fully aerobatic. Trust me, this guy knows his stuff and is quite unlikely to win the Darwin arward. Not saying can't, but given this guys intelligence and experience, I don't believe he could ever be a candidate.
  • In 1986 Dick Rutan flew his "Voyager" around the world, non-stop, in 9 days [dickrutan.com]. In 1997 he flew his Long-EZ around the world, with many stops, in 80-or-so days [dickrutan.com]. Now with his EZ-Rocket [dickrutan.com] maybe could now fly round the world, with refuelling stops, in (what?) a day?

    Meanwhile, previous Long-EZ customer's will love this the Rocket-EZ. John Denver could've killed himself [256.com] much quicker in one of these. And James Gleick could make another - high speed - attempt on his own life [wired.com] too.

    Regards, Ralph.

  • While I have no doubt that the rocketplanes test was a complete success, I do have some issues with its ultimate goal of low cost reusable orbital operations. Two 400lb rockets just arent going to cut it. Figure the plane wieghs in at 10 tons fully loaded, thats 20000 lbs of fuel, rocket and pilot, and wings. Wings are good for getting you up off the ground, which this demonstrated, but they really become a liability above say mach 3-4 and they are obviously completely useless once in space. Keep in mind that they only got up to about 160knots or maybe 200mph. Orbital velocity is 14000 mph. you need alot more oomph than 800 lbs of thrust to put you into a stable orbit.
    • You cluster dozens of the rockets. Much better, because redundancy gives you a better chance of not-dying.

      Also, Rutan and co. are working on bigger engines. This was a testbed. And it worked! Good engineering and testing == success.

      Rutan is god.

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