well, right now they use hydrogen I think. i believe it is liquid, and that is why they have to constantly refill the engines, because the hydrogen atom is small enough to exit between the metal or plastic molecules. solid hydrogen is the best of the 3 states, but Im not sure what the best combination is. :m:
No hydrogen is a gas under "normal" conditions. I mean we're breathing trace amounts right now. It has to be cooled to -423.0°F at atmosphereic pressures to get it to condense to a liquid. They don't "refill" the tanks while on the launchpad. They actually do the opposite where they vent away liquid hydrogen because it boils, becomes a gas, and builds up pressure...pressure that needs to be bled away. The same goes for liquid oxygen (boiling point 1 atm: -297.4°F). I believe the combustion of oxygen and hydrogen is the most powerful combination. It's just a pain to mess with. That's why propellants like alcohol and kerosene are used with liquid oxygen. Also solid propellants/oxidizers are used. They may not give the best bang but they are better for the buck.
Hydrogen will not become solid at atmospheric pressure. To get really powerful, you want hyperbolics. Not oxidizer/fuel, but just two chemicals that release ALOT of energy when they combine. An example combination is used in the third Die Hard movie. These are really too powerful, they'd blow up the rocket, no pun intended.
It depends on what you mean by 'best'. Liquid hydrogen and oxygen are the most powerful combination of chemicals for rocket fuel; in terms of the amount of energy per weight of fuel, nothing can beat liquid H2 and O2. Unfortunately there are other considerations when determining the 'best' fuel. While liquid H2/O2 is the most energetic, the fuel tanks needed to store liquid hydrogen weigh more than most other propellants, so your energy advantage might be canceled out by your fuel weighing more. Liquid oxygen and kerosene are a popular choice for large rockets, because kerosene is much easier to store than hydrogen, and the engines are usually easier to make. The Saturn Five was powered mainly by liquid oxygen and kerosene, as are most of the current Russian rockets. There are all sorts of other possibilities...hydrogen peroxide can be used as a fuel all by itself, engines using it are extremely light and simple to make, and it doesn't produce and pollution. Then there are solid fuels and hybrid rockets...all sorts of possibilities.
I think you mean hypergolic propellants. They do require an oxidiser. They're not especially powerful -- they've been used in unmanned probes and also in Apollo spacecraft. They are also used in the current RCS thrusters and the orbital manoeuvring system for the Space Shuttle.
It's not really an oxidizer. Its just another chemical to react with. An oxidizer has one big requirement: oxygen. Not all of the combinations here include oxygen in the mix. Hydrazine and an oxidizer would be one example of a hyperbolic combination, but not the only one. I looked on google, and found hyperGolic and hyperBolic to be two different things. HyperBolic chemicals react on contact with each other, hyperGolic chemicals require external ignition. So far as I know, AD1, those would be fairly mild combinations used there. I've been told that some combinations rival nuclear weapons in energy density. I couldn't find anything to back that up, however, and it may well be exagerated.
potassium nitrate is pretty good, just try for a liquid form(mix it with alcohol) or gaps in the power will act as a combustion chamber and make your bottle rocket blow up(i assume thats what you are trying to do)
Vslayer, you bring up a good point. The most powerful fuel is not nessecarily the best. Refering to the title of the thread, the best propellant depends on the use. Small rockets require different materials than large ones.
They certainly are different things, hyperbolic means exaggerated or resembling a hyperbola. I would like to request a cite in an authoritative source that the term hyperbolic is applied to rocket propellants in the manner stated. Hypergolic propellants do not require external ignition, which is why they were used on the Apollo CSM and LM, because of the increased reliability. If the Aerozine-50 (fuel) and nitrogen-tetroxide (oxidizer) come into contact with one another, they combust. Could you give us an example of a "hyperbolic" propellant combination? Aerozine-50 and nitrogen-tetroxide is an example of hypergolic, so is UDMH and nitrogen tetroxide. http://dictionary.reference.com/search?q=hypergolic http://dictionary.reference.com/search?q=hyperbolic
Any chemical that accepts electrons in a chemical reaction is an oxidizer. We use the term 'oxidizer' to describe accepting elections because oxygen almost always plays that role in a reaction, but other (non-oxygen containing) chemicals are also able to function as oxidizers. Pretty much any time you have two chemicals violently combining like they do in a binary rocket fuel, you can bet that one of them is an oxidizer.
I'm humbled. While I couldn't locate specific examples, I can present the source for my last post, MSDS definitions: http://www.ilpi.com/msds/ref/hypergolic.html A hypergolic mixture ignites upon contact of the components without any external source of ignition (heat or flame). Hyperbolic---Describing rocket fuel or propellant that consists of combinations of fuels and oxidizers that ignite spontaneously on contact. It's somewhat confusing that I had to go to two different sites to find both definitions, I'd have thought that I could find them in the same place. I've heard it used before by a chemistry student. I'll stand down my claim as the msds definition is the only one I can find online.
The mention of hyperbolic in the second link seems to be a typo, either that, or the person who wrote the glossary has little idea of what they're talking about. That's hardly a substantial claim to authority. This chemistry student was more than likely simply mistaken.
Ahh, a chance for the good old mnemonic I learnt in school, years ago: OIL RIG oxidation is loss (of electrons) reduction is gain (of electrons)
I saw this thing on TV where they insist on using this solid fuel, it is black in colour. I'll try and find a link.
I just looked somewhere on the web that said flourine and hydrogen were the most powerful propellants, but too poisonous to use. Is this true?
Hydrogen is in use. Fluorine is probably not used I think because it would supposedly deplete the ozone layer(I think it's in that class of chemicals, I'm not sure).
But it seems plausible to use flourine in outer space, where there is probably no environmental concern. It is the most electronegative element, and one of the most reactive.
The best chemical propellant is probably a solid propellant like those used in the Space Shuttle SRBs. There are halogens released in the combustion of that fuel, but who cares? The chemicals that supposedly "deplete" the "ozone layer" are chloro-flouro carbons (CFCs).
