Fuel Efficient Five-Gear Rocket Engine Designed 122
Roland Piquepaille writes "Georgia Tech researchers have had a brilliant idea. Rocket engines used today to launch satellites run at maximum exhaust velocity until they reach orbit. For a car, this would be analog to stay all the time in first gear. So they have designed a new space rocket which works as it has a five-gear transmission system. This rocket engine uses 40 percent less fuel than current ones by running on solar power while in space and by fine-tuning exhaust velocity. But as it was designed with funds from the U.S. Air Force, military applications will be ready before civilian ones. Here is how this new rocket engine works."
pun intended (Score:3, Funny)
That must make for some pretty awesome burnouts.
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point missed (Score:3, Insightful)
DS1 had something like this (Score:3, Informative)
<rant>
I really hate the front-page article, because it makes no distinction between the payload boost from a lighter stationkeeping system and the payload increase which would result from
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I'd be OK with blocking all of Pipsqueak's submissions.
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Solar? (Score:1)
Re:Solar? (Score:5, Interesting)
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Re:Solar? (Score:5, Informative)
There is very little sunlight where Voyager probes [wikipedia.org] were supposed to go:
Sounds like a no-brainer to me : use conventional rocket engines to escape earth, and then switch to solar/ion drives.
Indeed there is little novelty in this.
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To tell the truth, I'm glad to see so many stories recently that talk about increased efficiency in anything we do. The less ene
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Ion engines run for months on end at low thrust but high efficiency, so the acceleration adds up when you are going, say, from one planet to another. They are not useful for launching anything to orbit.
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But Americans can only drive automatics! ;-) (Score:4, Funny)
(ducks and grins)
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In Soviet Russia rockets still launch you.
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The Border Patrol does tend to prefer them, but there are a great many people not affiliated with Immigration and Customs Enforcement.
Re:But Americans can only drive automatics! ;-) (Score:5, Funny)
I guess if I bought a cool enough car she might learn. But then it's chicken and egg - how can I get this cool car without using a lot of our money, which I'd need permission to spend on a car that she can't drive?
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That is the #1 reason to buy a stick shift, at least when it comes to friends wanting to borrow your car. It gives you the perfect way to say "No, you moron, you'll only wreck it or get me a parking ticket" without actually saying it and being impolite. Instead, you just say, "Wow, I didn't know you could drive stick," and then they say, "Oh damn, I forgot about that. Hmm, I wonder if Bob would let me borr
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Oh, hang on - they never get taken off road, do they? You're quite right. Carry on.
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yeah, but can it go into reverse? (Score:2, Funny)
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"Second favorite thing in the universe" (Score:2)
Xyz (Score:5, Informative)
For all the rest: Beware beware! This is a Roland post! Last link goes to his page!
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Amazing Technology (Score:3, Insightful)
40% less fuel usage means less fuel needed to get into space, meaning a lighter rock; saving even more fuel. This will also drastically reduce the cost of getting into orbit as well, meaning more satellite based technology in the near future. This is an all around good thing.
I do wonder if this technology will go the route of the automobile or the bicycle. Staying at five gears or heading for twenty-one?
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For a car, this would be analog to not having gears and staying all the time at most fuel efficient rev-count.
Uhm (Score:5, Insightful)
Apart from the fact that no technical details are described about this new technology, and that "gears" makes no sense at all in a rocket, and thus the comparison got tiring even the first time they used it, the authors of the article couldn't even make up their mind about what this invention is intended for. In the heading they talk about rockets for launching satellites, but everywhere else in the article, they talk about "satellite engines" used in orbit, which are apparently some form of improved ion-drive, completely useless for launch vehicles.
This is just silly. To illustrate how silly it is, we could just as well have an article about how a new toaster will use multiple stages to toast, just like rocket engines have multiple stages to orbit. This can potentially lead to up to 40% reduced cost of toasting toast, and potentially, making toast in deep space more of a reality, as well as in other energy-starved places. Then we can include a drawing of a hairdryer to "explain" it, and continue to explain that while commercial applications are a few years off, the new toaster will soon be ready to used for military infrared signalling.
Recommended Tag (Score:1)
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The analogy was probably come up with by the PR department at the university. I had a similar experience with a project I did for my PhD work. We were using execution replay to efficiently do a forensic post-mortem analysis. The PR department called my advisor, and after a long discussion, came up with the analogy of a "security camera". This was in the University's press release, which got copied to all the major news outlets. It was even used in an interview the BBC did with my advisor.
The analogy w
And now for something completely different... (Score:3, Interesting)
A conventional rocket motor chucks out lots of hot, ionized gas. In the lower atmosphere, this comes out as a long, thin flame. As the atmosphere gets thinner, the gas can fly out sideways. You have the paraboloidal bells at the base of the rocket with try an convert this sideways motion of the plasma into downward motion, so you get as much forward momentum as you can. However, the gas in the bells is colliding with itself as much as with the engine walls,
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aerospike engine (Score:4, Informative)
Aerospike Engines (how they work) [aerospaceweb.org]
Aerospike Engine (history) [wikipedia.org]
Linear Aerospike Engine (see the "efficient at all altitudes" section) [nasa.gov]
Rocket engines [nasa.gov] are more efficient (see: specific impulse [wikipedia.org])when the exhaust velocity of the escaping gas is higher. The shape of the bell of the "traditional" rocket nozle is static and thus operates at maximium efficiency at a particular altitude. The linear aerospike engine makes one side of it's bell continuously variable -- by using the air as one side of the nozle and taking advantage of the changing atmospheric pressure as the rocket ascends. The rocket engine will then have a continuously variable, uh, "transmission", to borrow the terminology of this discussion which beats a five-speed hands down. : )
The article summary, the RP/ZDNet press release rehash, and indeed the original press release itself are all very poorly written.
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The idea behind assisted ram
Re:Uhm (Score:5, Informative)
But, KE = mv^2 (or P=rho*v^2 in this case) The power available (photovoltaic, chemical, nuclear-electric, etc.) is relatively constant, so the density of the exhaust gasses (and therefore the thrust since it goes like momentum T={mass flow rate}*v) goes way down at higher exhaust velocities.
High-thrust, low impulse would be "first gear" and only needed for launch. It is the maximum flow rate, and obviously uses up propellant like nobody's business. Orbital transfers would use the "fifth gear" mode as once in orbit, there is no atmosphere to rise out of before turning tangentially to the ground, the energy source (solar power) is relatively unlimited over time, and continuous thrust is even more efficient than even the ever useful hohmann transfer.
There are maximally energy efficient thrust modes between max flow and max velocity depending on orbital velocity, but with a continuous source of energy, the life limiting factor is actually propellant, and since it's not easy to resupply to a spacecraft, it's usually better to be miserly with the thing you can't replace and run all the time in high-Isp (specific impulse) mode.
AND the engine's not even new. It's not even a completed version of a recent project like VASIMR. It's a Hall thruster, which impressive though they are, are mature enough to have actually flown already. Not to mention that it will probably never be capable of the kind of thrust needed for launch.
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I too had an issue at first with the article--but then I saw at least one point: if a satellites maneuvering fuel can be reduced, there is less mass that needs to
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So, if they make it (Score:1, Funny)
so erm... (Score:1)
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Less mass. More energy. Same acceleration. The energy is free up there.
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Say what? (Score:5, Interesting)
1. high-thrust mode is hugely less efficient than low-thrust mode, or
2. there is a considerable fuel cost to starting and/or stopping the motor.
If neither applies, then you would simply run the motor at high thrust for shorter periods of time, without the added expense of a low-thrust mode.
The article wasn't what you might call detail-oriented, but this is some sort of electric ion propulsion scheme, which achieves high specific impulse (~3000sec, accd. wikipedia) and so optimising for efficiency makes sense. But it's still an ion drive, so there'll be no takeoffs in its future. At least not takeoffs from anything with a gravitational well deeper than an asteroid.
So we have an article about a thing. Only the article doesn't say what it is or what it's good for. I think I'll keep getting my space news from not-ZDnet, thanks.
Re:Say what? (Score:5, Informative)
Modern satellites are inserted into orbit using kerosene or hydrogen or hydrazine, with some oxidizer (liquid oxygen for example.) These fuels contain both the energy and the reaction mass, and require nothing but a nozzle and a few pumps to work, and they are very powerful.
Once in the orbit, many satellites can be moved a little using a very limited amount of fuel that is stored in the satellite, and once used up the fuel can't be replenished. Sometimes it may be just compressed gas. It would be very useful to replace these with ion engines; the only trouble with them is that it will take a year to move a satellite from one orbit to another, since the thrust of an ion engine is measured in grams, and typically satellites weigh a ton. Try pushing your car with a feather, gently :-)
Ion engines are efficient because of throwing your precious reaction mass away at low speed it accelerates individual molecules to a very high speed, and saves the reaction mass for future use. The energy for this is provided by an external source; typically, only nuclear sources are sufficiently powerful to provide a reasonable thrust, but of course a solar panel will do as well, if you have plenty of time.
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Stupid summary, incoherent article and unoriginal idea. I guess Roland couldn't find anything good but needed his weekend ad money.
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I count two engines and no gears in your description though, so I don't think it's what the article is talking about.
I'm not certain of that however, because even the Georgia Tech article repeatedly talks about this engine being useful during takeoff. The initial claims could be simply bad phrasings of something true: less mass needed for maneuvering == less fuel on the launchpad == more space for payload. But then it says "Satellites using the Georgia Tech engine to blast off ca
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They Avoided the P Word Again (Score:4, Insightful)
Is this a competition? Is there a prize?
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I hope that last word didn't blow your stack, but when you need a "big word", you need a "big word".
(Wow, this is hard. How did he manage this [muppetlabs.com]? It would take me a year, I swear, and I used five, not just four.)
Soooo... it's another VASIMR? (Score:4, Interesting)
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It's impossible to tell for sure from the lies and confusion in the article, but it seems like it may be optimized for station-keeping while at the same time being useful for the final orbital insertion or orbital transfer burn.
But what would a "science journalist" be doing without writing an article that was full of ridiculous contradictions,
Old News (Score:3, Informative)
It seems to have a similar principle to VASIMR [wikipedia.org] engines. Basically, they can adjust the specific impulse in flight, higher specific impulse giving lower thrust but better efficiency.
Of course, the thrust that an engine like the one described would output is miniscule. It would not be useful for launch vehicles, but only for keeping satellites in orbit. That said, if you can reduce the amount of fuel a satellite uses by 40%, you can keep it up there for almost twice as long, which is never a bad thing.
nope (Score:5, Insightful)
Not *physical* limits (Score:2)
It's about *cost* limits, both monetary and pay-load.
Fuel engine can accelerate as much we want (at least as you said, within relativistic limits). But to do so, I needs a lot of fuel.
The whole idea that a lot of scientist have, including this project, is to use fuel engine only for take off, when a lot of energy is needed to overcome gravity and lift the ship, and then switch to a ion engine that can both
- be powered by solar pannels, thus not needing as much fu
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...except for the amount of fuel you carry.
Remember, kids, there aren't any gas stations in space!
--Rob
Maybe ... (Score:2)
A reverse gear could be useful for reusable satellites.
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Misleading. (Score:2)
Clarification of article (Score:5, Informative)
The Georgia Tech press release [gatech.edu] is slightly less misleading than the various summaries derived from it.
The GA Tech news blurb explains it better (Score:1)
[Georgia] Tech's significant improvement to existing xenon propulsion systems is a new electric and magnetic field design that helps better control the exhaust particles, Walker said. Ground control units can then exercise this control remotely to conserve fuel.
So they've improved the degree to which one can regulate the output of conventional ion thrusters. Better thrust control means better fuel efficiency, so you need less fuel to do the same work as before.
Can someone buy this Roland guy some books (Score:2)
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Really misleading. (Score:5, Insightful)
If your energy comes from solar panels (so it arrives if you want it or not) or a nuclear reactor (so fuel and propellant are separate), you should try to use propellant as efficiently as possible, accelerating it to the maximum speed that the engine design allows. To control the total momentum produced by the engine you can just run it for a longer or shorter time.
2. Drawing in the article makes no sense, unless it's missing something important. If electric and magnetic fields' directions are as shown (electric along the axis, magnetic along the radius), electrons' trajectories will be, depending on the initial speed, spirals around the axis of the device, or , more likely, loops returning them to the anode, not spirals around circles shown on the drawings. They would look like those spirals if those circles were magnetic field caused by the current produced by ions, but then this field should be significantly stronger than the radial magnetic field.
3. There should be something accelerating electrons, or this engine will end up charged negatively, decelerating ions that leave it until the whole process stopped with a large cloud of positive ions hanging behind it. The drawing shows cathode that supposedly emits electrons, and direction of the electric field suggests that cathode is much larger than shown of that there is another cathode, but it still doesn't show why this cathode emits electrons. It may be in a way of the stream of ions, so it's hot from being bombarded by them, or it may be an electron cannon, like in CRTs, or both, but the drawing shows neither. If the electrons going in circles are outside the engine, as opposed to how they are shown inside it, it kinda makes sense considering that ions leaving the engine produce circular magnetic field, but then the drawing misplaces it inside the cylindrical engine, where magnetic field is in a completely different direction.
See http://www.nasa.gov/centers/glenn/about/history/ip sworks.html [nasa.gov] for comparison.
4. Any ion engine can regulate the speed of its exhaust -- it's determined by electric field's strength that is in its turn determined by voltage/position of electrodes. Maybe they have invented some other way to regulate it, for example, by changing the magnetic field, but it's not what the articles claim.
5. Ion engines can't launch satellites by themselves -- even if they are used at some point, the vast majority of the energy passed to the satellite is produced by chemical engines. Ion engines can be used to adjust orbit, or to accelerate in the process of interplanetary travel, but they are useless for initial launch that requires huge amount of energy to be released over a short time. Optimizing the use of fuel for orbit adjustment may reduce the initial mass of satellite (by the amount of fuel or ion engine propellant saved over the lifetime of the satellite), what in its turn can decrease the amount of fuel used for launch.
However at the point when satellite reaches the orbit most
Capt'n! (Score:3, Funny)
Captain > Sure they can.. *presses clutch*... hey! ensign! pull that large lever over there will ya!
*ensign pulls huge lever with a lot of effort*
*clunk*
Captain > Don't they teach people at the Academy how to put a star ship transmission into overdrive anymore? Sheesh..
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Living in New Jersey, fighting villains from afar. (Score:2)
More efficient - 4 "gears" (Score:2)
Nooooooooo (Score:2)
How Rockets work (Score:1)
One of the things that limits how efficient a rocket can be is whether or not you have living things on board. If you do then you have to limit the acceleration so part of the payload isn't smeared against the back of the cabin and is still breathing when you get to where you want to go. That means that you have to spread the acceleration over a longer period of time than absolutely necessary. That in
Concept already in use (Score:4, Informative)
"Geared" Rocket Engine is probably bi-modal (Score:1)
I read the article carefully and looked at the diagram and it appears to me that the design is a bi-modal design. The engine either operates as a standard ("first gear") rocket engine using standard fuels, or it switches to an ionic engine ("fifth gear") that is driven by electricity and a supply of xenon gas.
If this is actually the design, this engine will not save fuel for a standard satellite launch platform, as the standard launch vehicle is jettisoned once the satellite reaches orbit. It might achiev
Stalling (Score:1)
Is it me, or is this article retarded? (Score:1)
Other direction (Score:2)
Wow, I didn't know aerospace borrowed drivetrain technology from cars. I thought it was only the other way around [allpar.com].
Roland Piquepaille: the next John Katz? (Score:3, Insightful)
I remember that I changed some parameter when Katz was crapping up our message boards so I wouldn't have to even see his posts. Is that possible under the current incarnation of the site? How do I do it?
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As for reverse...gravity takes care of that.
Grump
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40mph in 1st gear? Boys, boys, boys, we obviously don't drive the same vehicle [europe-machinery.de]...
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Considering that both TFAs couldn't even decide whether this advancement relates to launch vehicles, LEO satellites, or deep space probes... I think we can safely overlook the confusion over the number of totally inapplicable mechanical torque-to-speed conversion devices contained.
Good catch, though, you beat me to it - Even staying within the sad analogy to gears, they describe this as a five-speed that skips right from first to fifth. I think I'd avoid using the links as technical
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Every design I'm aware of which tried to use air-breathing engines eventually concluded that they'd be better off with pure rockets for that reason... air may be 'free', but drag really hurts when you're travelling twelv
components of a system (Score:1)
I think maybe this might work, a 5 stage complete system, airbreathers at two places in the launch stack, where they might work the best.
1) and so on to 5...airbreather (mothership, a normal big modified plane) to normal rocket(dropped and fired, mothership returns for landing), t
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question (Score:1)