New Molecule Could Lead To Better Rocket Fuel 121
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."
Premature Celebration (Score:5, Informative)
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.
20-30% more efficient solid rocket fuel (Score:5, Informative)
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...
Re:Hydrochloric acid? (Score:4, Informative)
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)
Redeeculous (Score:5, Informative)
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.
Comment removed (Score:5, Informative)
Re:Solid rockets (Score:4, Informative)
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.
Re:Hydrochloric acid? (Score:5, Informative)
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.
Re:20-30% more efficient solid rocket fuel (Score:4, Informative)
They are also notoriously simple and inexpensive.
The LOX/LH2 in the shuttle's external tank costs far less than the two SRBs on the side. It's the liquid-fuelled engines that are expensive, if you throw them away after each flight.
Re:No hydrogen = poor exhaust velocity (Score:5, Informative)
The solid/liquid decision and the choice of fuel is a complex engineering process involving much more than picking the one with the highest ISP.
BTW lithium-flourine-hydrogen tripropellent has an ISP of 542, versus 455 for hydrogen-oxygen. By your reasoning everyone should be using it, but in fact it has never been used.
Nitrogycerin mixed with nitrocellulose was used in the past, but theoretical ISP is not the only consideration. Which is my point.
Re:Redeeculous (Score:4, Informative)
Ignition!: An informal history of liquid rocket propellants
John D Clark, Rutgers University Press, 1972, ISBN-10: 0813507251
If your dad worked in oxidizers, he likely knows of this book.
http://www.amazon.com/Ignition-informal-history-liquid-propellants/dp/0813507251
Amazing book, some of the funniest science stories I have seen published (destroyer parts and bats!, boron!, etc...) - Any scientist would appreciate this.
Sadly, it is out of print, and copies run up to $200. I got it from my university library and scanned the whole thing.
You can order reprints from online sources.
Re:Hydrochloric acid? (Score:4, Informative)
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.
Re:Redeeculous (Score:4, Informative)
FWIW
http://thepiratebay.org/torrent/4822749/Ignition__An_informal_history_of_liquid_rocket_propellants [thepiratebay.org]
Re:Redeeculous (Score:5, Informative)
Agreed. If you want really high specific impulse fuel, then mono-atomic hydrogen, or possibly metallic hydrogen have fantastic theoretical performance. Atomic hydrogen can be easily produced (as a very low density gas), the "only" problem is stabilising it as a liquid or solid.
In reality the problem with launching to orbit is cost, and that cost is NOT dominated by fuel. As a rough estimate a saturn V used 1 million gallons of kerosine ($5M), to put 200K pounds in orbit. That is ~$25/pound. Whatever is the driving cost in space travel, it is not the cost of the fuel.
---Joe Frisch