What are the main elements that compose rocket fuel?

Question

Rocket fuel that spaceships use

Answer 1

Thus, the Apollo-Saturn V first stage used kerosene-liquid oxygen rather than the liquid hydrogen-liquid oxygen used on the upper stages (hydrogen is highly energetic per kilogram, but not per cubic metre). Similarly, the Space Shuttle uses high-thrust, high-density SRBs for its lift-off with the liquid hydrogen-liquid oxygen SSMEs used partly for lift-off but primarily for orbital insertion.

There are three main types of propellants: solid, liquid, and hybrid.


Solid propellants
Main article: Solid rocket
The earliest rockets were created hundreds of years ago by the Chinese, and were used primarily for fireworks displays and as weapons. They were fueled with black powder, a type of gunpowder consisting of a mixture of charcoal, sulfur and potassium nitrate (saltpeter). Rocket propellant technology did not advance until the end of the 19th century, by which time smokeless powder had been developed, originally for use in firearms and artillery pieces. Smokeless powders and related compounds have seen use as double-base propellants.

Solid fuels (and almost all rocket fuels) consist of an oxidizer and a fuel. In the case of gunpowder, the fuel is charcoal, the catalyst is sulfur (Note: sulfur is not a true catalyst in gunpowder as it is consumed to a great extent into a variety of reaction products such as K2S) and the oxidizer is the potassium nitrate. During the 1950s and 60s researchers in the United States developed what is now the standard high-energy solid rocket fuel. The mixture is primarily ammonium perchlorate powder (an oxidizer), combined with fine aluminium powder (a fuel), held together in a base of PBAN or HTPB (rubber-like fuels). The mixture is formed as a liquid, and then cast into the correct shape and cured into a rubbery solid.

Solid fueled rockets are much easier to store and handle than liquid fueled rockets, which makes them ideal for military applications. In the 1970s and 1980s the U.S. switched entirely to solid-fuelled ICBMs: the LGM-30 Minuteman and LG-118A Peacekeeper (MX). In the 1980s and 1990s, the USSR/Russia also deployed solid-fuelled ICBMs (RT-23, RT-2PM, and RT-2UTTH), but retains two liquid-fuelled ICBMs (R-36 and UR-100N). All solid-fuelled ICBMs on both sides have three initial solid stages and a precision maneuverable liquid-fuelled bus used to fine tune the trajectory of the reentry vehicle.

Their simplicity also makes solid rockets a good choice whenever large amounts of thrust are needed and cost is an issue. The Space Shuttle and many other orbital launch vehicles use solid fuelled rockets in their first stages (solid rocket boosters) for this reason.

However, solid rockets have lower specific impulse than liquid fueled rockets. It is also difficult to build a large mass ratio solid rocket because almost the entire rocket is the combustion chamber, and must be built to withstand the high combustion pressures. If a solid rocket is used to go all the way to orbit, the payload fraction is very small. (For example, the Orbital Sciences Pegasus rocket is an air-launched three-stage solid rocket orbital booster. Launch mass is 23,130 kg, low earth orbit payload is 443 kg, for a payload fraction of 1.9%. Compare to a Delta IV Medium, 249,500 kg, payload 8600 kg, payload fraction 3.4% without air-launch assistance.)

Solid rockets are difficult to throttle or shut down before they run out of fuel. Essentially, the burning grain must be vented to lower the chamber pressure. Venting generally involves destroying the rocket, and is usually only done by a Range Safety Officer if the rocket goes awry. The third stages of the Minuteman and MX rockets have precision shutdown ports which, when opened, reduce the chamber pressure so abruptly that the interior flame is blown out. This allows a more precise trajectory which improves targeting accuracy.

Finally, casting very large single-grain rocket motors has proved to be a very tricky business. Defects in the grain can cause explosions during the burn, and these explosions can increase the burning propellant surface enough to cause a runaway pressure increase, until the case fails.


Liquid propellants
Main article: Liquid rocket propellants

Liquid fueled rockets have better specific impulse than solid rockets and are capable of being throttled, shut down, and restarted. Only the combustion chamber of a liquid fueled rocket needs to withstand combustion pressures and temperatures. On vehicles employing turbopumps, the fuel tanks can be built with less material, permitting a larger mass fraction. For these reasons, most orbital launch vehicles and all first- and second-generation ICBMs use liquid fuels for most of their velocity gain.

The primary performance advantage of liquid propellants is the oxidizer. Several practical liquid oxidizers (liquid oxygen, nitrogen tetroxide, and hydrogen peroxide) are available which have much better specific impulse than ammonium perchlorate when paired with comparable fuels.

Most liquid propellants are also cheaper than solid propellants. For orbital launchers, the cost savings do not, and historically have not mattered; the cost of fuel is a very small portion of the overall cost of the rocket, even in the case of solid fuel.

The main difficulties with liquid propellants are also with the oxidizers. These are generally difficult to store and handle, either due to extreme toxicity (nitric acids), extreme cold (liquid oxygen), or both (liquid fluorine is a perennial favorite of wild-eyed enthusiasts). Several exotic oxidizers have been proposed: liquid ozone (O3), ClF3, and ClF5, all of which are unstable, energetic, and toxic.

Liquid fuelled rockets also require troublesome and highly stressed pressurization systems, plumbing and combustion chambers, which greatly increase the cost of the rocket. Many employ turbopumps which raise the cost still more.

Though all the early rocket theorists proposed liquid hydrogen and liquid oxygen as propellants, the first liquid-fuelled rocket, launched by Robert Goddard on March 16, 1926, used gasoline and liquid oxygen. Liquid hydrogen was first used by the Lockheed CL-400 Suntan reconnaissance aircraft in the mid-1950s. In the mid-1960s, the Centaur and Saturn upper stages were both using liquid hydrogen and liquid oxygen.

The highest specific impulse chemistry ever test-fired in a rocket engine was lithium and fluorine, with hydrogen added to improve the exhaust thermodynamics (making this a tripropellant). The combination delivered 542 seconds (5.32 kN·s/kg, 5320 m/s) specific impulse in a vacuum. The impracticality of this chemistry highlights why exotic propellants are not actually used: to make all three components liquids, the hydrogen must be kept below -252 °C (just 21 K) and the lithium must be kept above 180 °C (453 K). Lithium and fluorine are both extremely corrosive, lithium ignites on contact with air, fluorine ignites on contact with most fuels, and hydrogen, while not hypergolic, is an explosive hazard. Fluorine and the hydrogen fluoride (HF) in the exhaust are very toxic, which trashes the environment, makes work around the launch pad difficult, and makes getting a launch license that much more difficult. The rocket exhaust is also ionized, which would interfere with radio communication with the rocket.

The common liquid propellant combinations in use today are:

LOX and kerosene (RP-1). Used for the lower stages of most Russian and Chinese boosters, and the first stage of the Saturn 5. Very similar to Robert Goddard's first rocket. This combination is widely regarded as the most practical for civilian orbital launchers.
LOX and liquid hydrogen, used in the Space Shuttle, the Centaur upper stage, the newer Delta IV rocket, and most stages of the European Ariane rockets.
Nitrogen tetroxide (N2O4) and hydrazine (N2H4), MMH, or UDMH. Used in military, orbital and deep space rockets, because both liquids are storable for long periods at reasonable temperatures and pressures. This combination is hypergolic, making for attractively simple ignition sequences. The major inconvenience is that these propellants are highly toxic, hence they require careful handling. Hydrazine decomposes energetically to nitrogen and hydrogen, making it a fairly good monopropellant all by itself.

Hybrid propellants
A hybrid rocket usually has a solid fuel and a liquid or gas oxidizer. The fluid oxidizer can make it possible to throttle and restart the motor just like a liquid fuelled rocket. Hybrid rockets are also cleaner than solid rockets because practical high-performance solid-phase oxidizers all contain chlorine, versus the more benign liquid oxygen or nitrous oxide used in hybrids. Because just one propellant is a fluid, hybrids are simpler than liquid rockets.

Hybrid motors suffer two major drawbacks. The first, shared with solid rocket motors, is that the casing around the fuel grain must be built to withstand full combustion pressure and often extreme temperatures as well. Modern composite structures handle this problem well.

The primary remaining difficulty with hybrids is with mixing the propellants before burning. In solid propellants, the oxidizer and fuel are mixed in a factory in carefully controlled conditions (and even then it is tricky). Liquid propellants are generally mixed by the injector at the top of the combustion chamber, which directs many small fast-moving streams of fuel and oxidizer into one another. Liquid fuelled rocket injector design has been studied at great length and still resists reliable performance prediction. In a hybrid motor, the mixing happens at the surface of the melting or evaporating surface of the fuel. The mixing is not a well controlled process and generally quite a lot of propellant is left unburned, which limits the efficiency and thus the exhaust velocity of the motor.

There has been much less development of hybrid motors than solid and liquid motors. For military use, ease of handling and maintenance have driven the use of solid rockets. For orbital work, liquid fuels are enough better than hybrids that most development has concentrated there. There has recently been an increase in hybrid motor development for nonmilitary suborbital work:

The Reaction Research Society (RRS), although known primarily for their work with liquid rocket propulsion, has a long history of research and development with hybrid rocket propulsion.
Several universities have recently experimented with hybrid rockets. Brigham Young University, the University of Utah and Utah State University launched a student-designed rocket called Unity IV in 1995 which burned the solid fuel Hydroxy-terminated polybutadiene (HTPB) with an oxidizer of gaseous oxygen, and in 2003 launched a larger version which burned HTPB with nitrous oxide.
Portland State University also launched several hybrid rockets in the early 2000's.
Scaled Composites SpaceShipOne, the first private manned spacecraft, is powered by a hybrid rocket burning HTPB with nitrous oxide. The hybrid rocket engine was manufactured by SpaceDev. SpaceDev partially based its motors on experimental data collected from the testing of AMROC's (American Rocket Company) motors at NASA's Stennis Space Center's E1 test stand. Motors ranging from as small as 1000 lbf (4.4 kN) to as large as 250,000 lbf (1.1 MN) thrust were successfully tested. SpaceDev purchased AMROCs assets after the company was shut down for lack of funding.

Answer 2

Rocket fuel can be almost anything. The whole point is to throw mass out of the rear at high velocity and anything that accomplishes this will work. The Saturn 5 rocket that took us to the moon used kerosine and liquid oxygen in the bottom stage, and liquid hydrogen and liquid oxygen in the upper stages. The Space Shuttle uses solid rocket boosters that are composed of a rubbery polymer that burns at high velocity, and the shuttle main engines use liquid oxygen and liquid hydrogen. The new Ares rockets that NASA is planning for Moon and Mars exploration will use liquid methane and liquid oxygen for the more forward applications, but rely on liquid hydrogen and liquid oxygen for liftoff from Earth. Hydrazine has been used in various combinations on many space probes. Ion drive spacecraft use Xenon gas that is ionized and then expelled electrically. I have even heard of using atomic bombs, exploding several per second to achieve thrust. If you are interested, I highly recommend the book "Entering Space" by Dr Robert Zubrin, PhD available on Amazon and in many local bookstores.

Answer 3

Primarily, the components are some form of combustible substance and an oxidizing substance. Most often today those are Hydrazine and Liquid Oxygen.
Some of the older military ICBMs were liquid propelled weapons and used some highly volatile compounds called Unsymmetricaldimethylhidrazine and Nitrogentetroxide. (say that 5 times fast) It was some nasty stuff that would dissolve human flesh so the workers had to use space suits.

Answer 4

Rocket fuels are referred to as propellants. There are basically 2 types, viz. Solid propellants & Liquid propellants.
Liquid propellants are considered to provide better impluse and are more popular.

Some examples are
solid (were used in ancient times)
Charcoal, sulfur, potssium nitrate, ammonium perchlorate
Liquid
Liquid oxygen, nitrogen tetroxide, hydrogen peroxide, LITHIUM & fluorine etc.

Answer 5

Nitrogen

Answer 6

Liquid oxygen and liquid hydrogen

Answer 7

oxygen, nitrogen, hydrogen and some other components, but these one are almost alsways used.

Answer 8

Carbon and hydrogen...

Same as any other fossil fuel.

Answer 9

It is called TENNANTS SUPER LAGER