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What I am suggesting is a rocket fuel with a very low carbon foot print.
The oxidizer to go with this fuel will be hydrogen peroxide.
and the fuel would be, centrifuged, used cooking oil.
I assume that we have all seen the fire safety video warning against poring water onto a chip pan fire, or
something similar. water thrown into a container of burning cooking oil. Now imagine it with hydrogen peroxide instead.
Before launch all of the fuel in the fuel tank is heated to about its spontaneous ignition temperature. The energy used to heat that cooking oil as no weight but will be released as thrust, when the fuel is burned in a rocket motor.
A Kg of very hot oil as a lot more energy to release then the same oil would when it is cold.
Black Arrow
http://en.wikipedia.org/wiki/Black_Arrow
...the United Kingdom is the only country to have successfully developed and then abandoned a satellite launch capability. [Loris, Feb 12 2014]
Ignition! - book review
http://www.fourmila...dices/book_852.html
Chlorine trifluoride...also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water—with which it reacts explosively. ... [Loris, Feb 12 2014]
A biofuel-powered rocket
http://www.flometri...iofuel-rocket.shtml
It is what it says on the tin. [Alterother, Feb 12 2014]
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Annotation:
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// rocket fuel with a very low carbon foot print.// |
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How about hydrogen? Zero carbon, unless you
include the energy used to produce it, but that
can be hydroelectric. |
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//A Kg of very hot oil as a lot more energy to
release then the same oil would when it is cold.// |
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Nope. A Kg of hot oil has very, very slightly more
energy to release than the same oil would when it
is cold. Go check the numbers. |
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Too slow. I did the numbers: |
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Specific heat capacity of vegetable oil: ~2kJ/kg/K |
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Therefore, additional energy per kg of hot (300°C)
oil, compared to ambient ~500kJ/kg. |
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Energy of combustion of vegetable oil: ~40MJ/kg. |
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Therefore, additional energy available from hot oil
as opposed to cold = 0.5/40, or about 1.2%. |
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Very Baked. Hydrogen peroxide and hydrogen; H2/LOX;
UDMH/nitrogen tetroxide. Various solid state pyrotechnic propellants. |
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[Suggested-for-deletion], Baked and Widely Known To Exist. |
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Even smokeless powder reverts to a handful of
harmless elements and simple compounds when burned. It's
mostly carbon to begin with. |
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... apart, that is, from the supersonic metallic projectile(s),
MUHWHAHAHAHA !!!! |
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specific heat capacity vegetable oil 1.67 J g.-1. K.-1.
specific heat combustion animal/vegetable fat 37 MJ Kg-1.
smoke point vegetable oil (sunflower), semi-refined: 232°C |
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Let us assume an increase in temperature of 200°C. |
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so let's see... 1.67 * 1000grams * 200degrees=334000 J = 0.334 MJ.
fraction=0.334/37=0.0098 ~=0.01. Or about 1% |
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...oh, max did it already. Different ball-park numbers, similar result. |
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1% is actually not bad as a marginal gain.
I'm reminded of Black Arrow, which used kerosene/HT peroxide and was awesome. |
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Horrible carnage and destruction, yes. Long-lasting harm to
the environment (from rockets and bombs), no. |
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Environmental impact reports on the space shuttle flights
are publicly available. Mostly they produced water vapor
and
a little free carbon. Gasoline, on the other hand, produces
water vapor and the far more deadly CO, plus traces of
sulfur di-something-ide and really-nasty-shit-ium.
Somebody who enjoys math can do the figures for me, but
burning one ounce of gasoline is far more toxic than
burning one ounce of rocket fuel (any type currently in
use), and the ratio of gasoline to rocket fuel used every day
is ridiculously lopsided. |
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Are you kidding? Many rocket fuels are just hilariously dangerous. |
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Quite dangerous in their unused state. There's a reason why
old ICBMs are disposed of by strapping them down in a
three-walled bunker and touching them off, and it's not
because it's easy or safe. It's because the cleanest and most
complete
way to get rid of rocket fuel is burning it. Otherwise the
rocket must be carefully dismantled and the fuel broken
down into its crude components, which is dangerous,
messy,
sometimes impossible, and requires substantial
infrastructure. |
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The one thing go-greeners always seem to disregard is the
carbon footprint of the establishment and operation of the
infrastructure that supports most green tech. |
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Oh, and another thing: the reason oil is heated for fuel
purposes (like in big ship engines) is not to release more
energy but to change its liquid properties and ensure a
more complete burn. You may be confusing increased
power with increased efficiency. |
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I have an aftermarket device that
heats the deisel in my M35 to 85-95 degrees F, and the roar
produced as the engine fires on hot fuel definitely gives the
impression of more power. Along with a bucket warmer
wrapped around the oil pan and an electric blanket over
the header, it comes in handy for
waking the beast on a
cold Winter's morn, but it doesn't noticably increase
performance. I'm not too proud to admit that I got
the idea from watching Ice Road Truckers. |
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This is a good'ish idea in general: heating up fuel decreases the amount of energy required to break apart the molecules. But why stop at "boiling" ? heat that sucker up to supercritical; as much energy as the containing apparatus can stand. It's only a few percent (I imagine), but with rockets these things tend to snowball, more potent fuel = less fuel needed = less weight = less fuel needed. The extra pressure also means less work for the turbopumps to do. |
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Many of your species' primitive reaction engines use fuel pumped
round the combustion chamber and venturi nozzles to both cool the
structure and heat the fuel, so that also is Baked (or rather, boiled ...) |
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Don't worry 8/7, we'll still have the liquid oxygen to cool the engine. |
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I had not realized that the numbers would be so bad.
But still a bio-fueled rocket |
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//I had not realized that the numbers would be so bad. // |
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// But still a bio-fueled rocket // |
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//I had not realized that the numbers would be so
bad. // |
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If you don't have the relevant intuition, it's at least
advisable to do some elementary maths. |
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Has this ever been mentioned to the Federal Reserve ? |
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Is it time to point out the glaring spelling mistake in the title yet, or is
his humiliation to go on a while longer ? |
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No, let it be. I presume he meant some sort of
chimney to carry the smoke away. |
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Fine, fine. The tar is hot, and we have two large sacks of feathers to
hand. Just off now to oil the hinges on the ducking stool and re-
varnish the pillory. |
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Well that titled kept intriguing me, but I just couldn't
fit a rocket in my chimney. |
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That's because you're just not trying hard enough. |
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Put the biggest rocket that will just fit into the fireplace, then pile up
sandbags. Light the fuse, et viola ! The chimney will be more than big
enough for any projectile you care to launch. |
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There is some Bad Science in the main text. A
"carbon footprint" is associated with the amount
of carbon in a fuel, that eventually becomes
carbon dioxide. The Saturn V rocket used
kerosene as the fuel in its first-stage booster (and
liquid hydrogen in the upper stages). |
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There is a basic sequence of hydrocarbon
compounds called the "alkane series". The first
members of the series, in order, are methane,
ethane, propane, butane, pentane, hexane,
heptane, and octane. One molecule of each
contains, respectively, 1, 2, 3, 4, 5, 6, 7, and 8
carbon atoms. They also contain, respectively, 4,
6, 8, 10, 12, 14, 16, and 18 hydrogen atoms. There
is a simple formula: H = (Cx2) + 2, that relates the
number of hydrogen to carbon atoms, in the
alkane series. |
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Now, the "greener" the fuel, the more hydrogen it
must contain, RELATIVE to the amount of carbon
it contains. Obviously methane is the "greenest",
since hydrogens outnumber carbons 4-to-1 in that
substance. The higher-number alkanes merely
have just a bit more than twice as many hydrogens
than carbons. |
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So, what about kerosene? Kerosene contains a
mixture of Hydrocarbon liquids ranging from
C12H26 to C15H32 --these are members of the
alkane series, from 12 to 15 carbon atoms. Not
very "green", compared to octane/gasoline! |
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Now, what about cooking oil? The molecules are
generally not members of the alkane series,
although many have a "backbone" structure that is
basically an alkane. It is not unusual for that
backbone to have 16 carbons in it --which means
that cooking oils are generally not as "green" even
as kerosene. |
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//with a very low carbon foot print. |
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Simply align all the carbon atoms vertically and the footprint area will be tiny |
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If it was switched to lard, then I'd bun..then next time Sandra Bullock is stuck out there she can have a decent fry-up. |
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There are far worse things than carbon dioxide to put into the atmosphere. Many exotic rocket fuel combinations, especially the hypogolic ones, end up producing such things as HCl (which soon ends up as hydrochloric acid), toxic and/or corrosive oxides of nitrogen, exotic metal oxides (mostly catalysts and catalyst biproducts), and halogen compounds. That said, the most ideal reaction gas is hydrogen, and so a lot of rocket fuels are designed to produce as much H2 in the exhaust stream as possible, sometimes just by being far too "rich". |
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There are some interesting alternatives. One of the ones being trialled right now is the reaction of Aluminium and water (or in this case, ice). This produces Aluminium oxide and hydroxides (which rapidly settle out of the exhaust stream) and hydrogen gas. It's really quite neat, although not really as storable as other solid fuels. Still it's easier than having a gigantic dewar vessel as your fuel tank. |
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I see [Loris] has recommended the book "Ignition" - I would heartily second that, if you can get a copy (it's out of print). |
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//hypogolic// - I don't think that's the word you
meant, although I'm tempted to apply it to a
potassium permanganate / glycerine mixture... |
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This whole discussion just led me to discover
"triethylborane"; that's enough to send me to bed
happy. |
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Goddamned prefixes. Yes, HypERgolic. I stand corrected. |
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But it was used to restart SR-71 engines, it must be safe.... |
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If you like Triethylborane, you'll love ClF3 or FOOF. |
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From the wonderful book "Ignition!" I refer you to the
authors comments re: Chlorine Trifluoride. |
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"It is, of course, extremely toxic, but that's the least of
the problem. It is hypergolic with every known fuel, and
so rapidly hypergolic that no ignition delay has ever been
measured. It is also hypergolic with such things as cloth,
wood, and test engineers, not to mention asbestos, sand,
and water — with which it reacts explosively. It can be
kept in some of the ordinary structural metals — steel,
copper, aluminum, etc. — because of the formation of a
thin film of insoluble metal fluoride which protects the
bulk of the metal, just as the invisible coat of oxide on
aluminum keeps it from burning up in the atmosphere. If,
however, this coat is melted or scrubbed off, and has no
chance to reform, the operator is confronted with the
problem of coping with a metal-fluorine fire. For dealing
with this situation, I have always recommended a good
pair of running shoes." |
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Actually, looking back at the numbers that [MaxwellBuchanan] ran...
it looks like he did the right math on the wrong numbers. Although
the total heat capacity does rise slightly, the effect is
overwhelmed by the fact that the density of hot oil will drop by more
than 10%. (That is, the fuel tank that would hold X kg of oil at
ambient temperature will hold less than .9X kg of hot oil.) Hard
numbers seem difficult to come by - oddly enough, I have only been
able to find tables up to 110°C, which would be quite inadequate for
cooking a doughnut; and cooking a doughnut would seem a fairly
agreeable excuse for collecting a little lab data. |
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Anyway, the tank expansion will offset that somewhat, but 10%
volumetric thermal expansion is not commensurate with a
structurally un-oopsified rocket. |
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(One may note that Mr. Musk's Magnificent Rocket Rodeo &
Renovation Squad chills their hydrocarbons & oxidizers so they can
squeeze more into the tube. So, no, I di'i'nt thunk it up first) |
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From the title, I assumed this was some kind of vast
chimney to assist rocket launches. |
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Thankfully, Team Duck includes both genders, so not only are there still ducks a-plenty, but there have been numerous tasty roast dinners in the interim. |
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