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New Molecule Could Lead To Better Rocket Fuel
MithrandirAgain writes "Trinitramid is the name of the new molecule that may be a component in future rocket fuel. This fuel could be 20 to 30 percent more efficient in comparison with the best rocket fuels available today, according to researchers (abstract). The discovery was made at the Royal Institute of Technology (KTH) in Sweden. 'A rule of thumb is that for every ten-percent increase in efficiency for rocket fuel, the payload of the rocket can double. What's more, the molecule consists only of nitrogen and oxygen, which would make the rocket fuel environmentally friendly. This is more than can be said of today's solid rocket fuels, which entail the emission of the equivalent of 550 tons of concentrated hydrochloric acid for each launch of the space shuttle,' says Tore Brinck, professor of physical chemistry at KTH."
From TFA:
"It remains to be seen how stable the molecule is in a solid form," says Tore Brinck.
And until then, this is a premature press release to be criticising the shape shuttle solid rockets.
Someone must need to re-up on their grant.
The key part being "solid". Solid rocket fuels are notoriously inefficient compared to liquid fuels.
From the sounds of this stuff, assuming that 20-30% is closer to 30% than to 20%, we're talking roughly 75% as efficient as Hydrogen, and somewhat less efficient still than kerosene...
"I do not agree with what you say, but I will defend to the death your right to say it"
in small words the shuttle has 2 systems pushing it into orbit
1 the huge tank thing and the jets on the tail of the shuttle
2 those skinny rockets on either side of the huge tank thing
the huge one is hydrogen/oxygen the others are a solid rocket booster (btw thats where the name SRB comes from)
the SRB is just like a model rocket only bigger LOTS BIGGER and this is the fuel being replaced
(note for actual rocket scientists this is the post-it(tm) version so the details are a bit fuzzy)
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I tought that the revolutionary molecule that would help with rocket propulsion would be thiotimoline
In even smaller words: Nothing you said addresses the parent posts questions.
If telephones are outlawed, then only outlaws will have telephones.
Rocket fuel was a big research area in the 1950's. Dozens of very good chemists spent a whole load (hundreds of millions of 1950-size dollars) trying to make better rocket fuels.
( One of them wrote a informative and funny book about that time and place ).
The short summary is: Yes, you can make higher oomph rocket fuels and oxidizers with more oxygen in them.
But a lot of the formulas are impractical as:
(0) They were already discovered years ago, and discarded, but chemists don't like to write up their failures, and researchers don't like to read old moldy research summaries anyway.
(1) They're waaay too expensive to make, even for military uses.
(2) They are highly toxic, even more toxic than the widely-used hydrazines, which can kill you in several interesting ways.
(3) They're so unstable, you have to keep them under impossible conditions, like no sound, no vibrations, no light, and under a part per million of crud in the perfectly-smooth and unscratched nickel-plated tanks.
(4) They can't be stored for more than a day or so before the fuel or oxidizer starts decomposing itself or the tank walls.
(5) Too many of the researchers were vaporized while handling the stuff. Literally. Truly. Completely. That tends to make it hard to find substitute researchers to continue working with the same stuff.
(6) For military applications, you need a fuel that can be handled by raw recruits, stored for many months, be pumped quickly into not always totally clean rocket tanks, kept in those loaded rockets for days to months, and tolerate wide temperature swings. These requirements alone disqualify a large percentage of really zippy fuels and oxidizers.
The odds are pretty high against this "new" compound being all that new, or it passing the basic requirements for fuel or oxidizer.
Over the decades, chemists have come up with dozens of molecular structures that would make "the perfect rocket fuel" or "the perfect explosive" (both qualities are closely related). If only they would be stable enough to prevent accidental explosions ("It remains to be seen how stable the molecule is in a solid form"). And be possible to produce in hundreds of tons ("The scientists have also managed to produce enough of the compound in a test tube for it to be detectable.") And most important of all, cheap enough to compete with existing propellants.
Until these problems can be addressed, this "breakthrough" is just another octanitrocubane
http://en.wikipedia.org/wiki/Octanitrocubane
It's a chemical tour-de-force to synthesize difficult structures like this in the first place, and in that sense, the researchers may have made a valuable contribution to the field of synthetic chemistry, but if you expect rockets with quadruple payloads based on this molecule to be lifting of by 2015, well, don't hold your breath.
See also: http://en.wikipedia.org/wiki/2,4,6-Tris(trinitromethyl)-1,3,5-triazine
Then it is being speculated that (a) the synthesis can be scaled up to produce a few hundred tonnes in a cost-effective way, (b) the stuff is stable enough to not decompose explosively if you shake it too hard, and (c) can be burnt in a controlled way to make it suitable as a rocket fuel.
A long shot. Unfortunately, it seems to be necessary nowadays to speculate about far-fetched applications in fundamental research, since the fact that a new compound consisting of just 4 nitrogen and 6 oxygen atoms is synthesized that has never been seen before, is not considered to be interesting by itself.
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The big drawback is that once they're lit you have no control, you can't turn them off, or even throttle them down.
Something I've always wondered, if one of the shuttle's SRBs fails to lit and the other one starts up, what happens?
By the rocket equation, mass fraction is determined by velocity and exhaust velocity is driven two things; the mass of the molecules being put out and the pressure/temperature of the combustion chamber. The latter is limited, as once you get to about 100 atmospheres and 3000K you start to run out of materials to make the combustion chamber out of. Thus, molecule mass is the real driving factor - which is why despite the truly horrific engineering problems it entails, liquid hydrogen is a highly valued rocket fuel.
In fact, because molecular mass is so important, H2/O2 rockets are run fuel rich, sacrificing some combustion efficiency in order to leave some unburned hydrogen in the exhaust and reduce its average molecular mass.
So it doesn't matter how much energy you can get out of this new compound. It will only spit out oxygen, nitrogen and nitrous oxides, all far more massive than the hydrogen and water vapour you get from rockets in use at the moment. Sure, breaking down this molecule in optimal conditions might yield enough energy that the reaction products would have more velocity than the exhaust of a H2/O2 rocket, but there is a reason chemists don't build rockets; these researchers aren't taking into account the kind of unobtanium combustion chamber walls you would need to utilise such an inferno.
If we can put a man on the moon, why can't we shoot people for Apollo-related non-sequiturs?
A quick google search and voilà!
More advanced solid rocket motors can not only be throttled but also be extinguished and then re-ignited by controlling the nozzle geometry or through the use of vent ports.
It is by the juice of the coffee bean that thoughts acquire speed, the teeth acquire stains. The stains become a warning
The big drawback is that once they're lit you have no control, you can't turn them off, or even throttle them down.
Something I've always wondered, if one of the shuttle's SRBs fails to lit and the other one starts up, what happens?
Even though you can't turn off the booster you can detach it and use the range safety device to self destruct it. Have a look at "Space Shuttle Abort Modes" on Wikipedia.
That's true of the main engines, but not the solids. The explosive bolts holding the shuttle to the pad are fired before the SRBs are lit.
Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
And the hold-down bolts are designed so that the thrust from the SRB would cause them to stretch and break loose, even if the pyrotechnic fasteners never fired.
To answer the original question, a launch where only one SRB fired would be an unsurvivable disaster. The asymmetric thrust would cause the shuttle to cartwheel into either the launch tower or the surrounding area.
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This is a potential replacement for the fuel used in the solid rocket boosters, not the main engines.
While the main engine burn LH2 and LOX, emitting nothing but steam, the SRBs burn a rubbery mix of ammonium perchlorate, powdered aluminum and a polymer binder. They emit a pretty nasty exhaust stream, containing hydrogen chloride and aluminum oxide, among many other compounds.
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Odds are the RSO wouldn't be able to fire the charges in the 100 mS it takes to exceed load limits due to an asymmetrical SRB firing.
Doesn't really matter, because everyone dies either way: the shuttle will crash and burn if it's on the pad with one SRB missing. All you have to do is ensure you destroy the SRB before it goes flying off across Florida and crashes into a bus full of nuns and orphans on their way to Disneyland.
Funny, a different article on wikipedia (Space Shuttle Abort Modes) claims that: "The SRBs cannot be turned off once ignited, and afterwards the shuttle is committed to take off. "
Wikipedia is contradicting itself? Noooooooooo!! *headasplode*
> Wikipedia is contradicting itself?
No. There are extinguishable solid-fuel rockets. The shuttle SRBs are not among them.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
Yeah, basically. However SRMs are incredibly reliable in terms of lighting off. They are crap in many other respects, but I can't think of an instance where a vehicle launched from a pad like the shuttle had an ignition failure in an SRB.
Basically the drill is at T - 6 the SSMEs start. At that point it is still possible to abort. Once all 3 SSMEs are running at full power the clock hits 0, something like 6 pyro igniters in each SRM fires them up, and then maybe 500ms later the hold down bolts blow.
As for range safety, the RSO is basically 'finger on button' during launch. It probably would take a half a second or something to flip up the cap and push the button. There's no automatic way, or accidental way those can go off. The self destruct basically blows a couple holes in the top of the SRM, at which point it will go completely to pieces on its own. Interestingly I actually worked on the box responsible for this stuff. It is pretty impressive. Made out of a 12"x12" brick of aluminum, hogged out to form a case, with some boards mounted in slots in the aluminum, and then the whole thing is potted full of engineering epoxy. It is basically the one 100.00000% reliability subsystem on the whole stack. The spec is basically "this cannot fail, period". Designing it and verifying it met spec was a pretty interesting project.
"Malo periculosam, libertatem quam quietam servitutem." -- Jefferson
" What's more, the molecule consists only of nitrogen and oxygen, which would make the rocket fuel environmentally friendly."
I'm not saying that the byproducts of combustion will be dangerous but just because it is composed of only nitrogen and oxygen does not automatically make it "environmentally friendly". One of the major components of smog also consists of only oxygen and nitrogen. It's nitrogen dioxide.
Nitrous oxide is also made up of only Nitrogen and Oxygen. Would we want that mixed into the air we breath? The very thought has me ROTFLMAO.
Have gnu, will travel.
Most modern solid-fuel rockets use pretty much the same fuel as the shuttle SRBs. It's cheap, stable and reliable but it does produce a lot of goop and the ISP could be better. If this stuff is stable it might make an excellent replacement for ammonium perchlorate oxidizer.
Shuttle SRBs are more expensive and less reliable than equivalent liquid boosters. This is the main reason why SpaceX is only using liquid engines in the Falcon-9. ULA uses solid boosters for extra thrust on the Atlas V, but these solids are cheaper and more reliable than Shuttle SRBs. In addition, based on recent conference papers, I think they want to get away from solids in their next generation of rockets.
So why is NASA planning on using boosters based on the lower performing, more expensive, and less reliable Shuttle SRBs in their new Heavy lift rocket? This is because the Utah Congressional delegation is lobbying heavily for the company that makes the SRBs. The Utah senators inserted text into the continuing resolution that NASA is currently operating under that they claim prevents NASA from even doing trade studies to consider any alternatives to using the Shuttle SRBs.
Solids might have made sense in the 60s, but with current technology they are no longer needed except in a few specialized applications for robotic planetary exploration spacecraft.
There are 10 types of people in this world, those who can count in binary and those who can't.
LH2/LOX engines will perform better than this new compound no matter what. The only way to get better performance than LH2/LOX (for a chemical rocket) is to change the oxidizer.... maybe liquid ozone... or Fluorine. Fluorine is the best oxidizer you can get. Problem is that it tends to oxidize its container and then oxidize you.... nasty, nasty stuff.
There are 10 types of people in this world, those who can count in binary and those who can't.
No doubt that these improved solid rockets would still be inferior to LH2/LOX liquids, but still a significant improvement to current solid rocket technology. Solids have the advantage of storability and simplicity of construction/low cost. They will continue to have wide application for the foreseeable future.
If you are interested in reading some stories about really exotic fuels/oxidizers, check out the book "Ignition!" by John D. Clark. Chlorine Trifluoride, anyone?
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