- These technologies are often used by cultures that do not have access to the gravity drive technology.
- Many cultures use rockets on aircraft, spaceplanes, and even dedicated spacecraft or system craft.
- They are known as R-Drives or Reaction Drives to some.
Library Data Referral Tree
- Speed of Travel
- Spacecraft Drives (Interplanetary Drives or Impulse Drives)
- Starship Drives (Interstellar Drives)
Rockets use a reaction mass, and basic physics of action-reaction, to produce changes in velocity and position. Because Rockets produce thrust based on mass (rather than volume), fuel consumption details are complex, and constantly changing.
Rocket performance is measured by two items:
- Thrust (Newtons) determines how much of a change in velocity is given by activating the drive.
- Specific Impulse (Isp) determines how much fuel is required to produce a specific change in velocity.
These two values are frequently combined along with the specifics of the ships mass and fuel tank size to calculate the overall performance of the ship in G-Hours, the ability to accelerate at 1-G for one hour.
Chemical rockets combine chemicals in an exothermic reaction in a combustion chamber to produce thrust. Rockets are high volume fuel users.
- Electrothermal Augmented Plasma Combustion (EAPlaC)
- AZHRAE Rocket
- Hybrid Fuel Rocket
- Hypergolic Fuel Rocket
- Liquid Fuel Rocket
- Solid Fuel Rocket
Electric rocket use an external power source to add energy to the fuel to produce thrust.
- Ion Drive
- Magneto-plasma Dynamic Drive (MPD Rocket)
- Mass Driver
- Pulsed Plasma Thruster or Plasma Jet (PPT)
- Variable Specific Impulse Magnetoplasma Rocket (VASIMR)
Nuclear rockets use either a nuclear power plant (fusion or fission) to heat fuel, or directly use the fission or fusion process as a reaction to produce thrust.
- Bussard Hydrogen Ram
- Fusion Drive (Fusion Torch Rocket)
- Nuclear Pulse Drive (NPD)
- Nuclear Thermal Rocket (NTR) or (NERVA)
Selected Rocket Drive Types
Types of Rockets: The following sections detail the different types of rocket technology
|Name||Earliest TL||Propulsion Type||Propulsion Mechanism||Fuel||Remarks|
|AZHRAE Rocket||TL-9||Rocket Engine||Chemical Rocket||Liquid Fuel||The Advanced Zero speed to Hypersonic Regime Air breathing Engines (AZHRAE) includes a wide variety of exotic engine types designed, unlike turbine engines and ramjets, to function at low speeds for takeoff and landing, where they function as turbojets, hypersonic speeds for high-altitude operations, where they function as ramjets, and in suborbital or orbital insertion profiles, where they close off their intakes and function as rockets, As a group these are referred to as "ducted rockets," and are the preferred engines for trans-atmospheric craft.|
|Bussard Ramjet||TL-9||Rocket Engine, Electromagnetic Engine||Nuclear Rocket||Hydrogen, Interstellar||TL–9 The Bussard hydrogen ramscoop drive uses a magnetic projector to generate a wide magnetic field. The hydrogen gathered The scoop is used to gather the trace hydrogen atoms in deep space as fuel for a fusion drive. One limitation of the ramscoop is its minimum velocity. To be able to scoop enough [[hydrogen][ to power the fusion drive, the ship has to be moving at least 1% the speed of light. |
|Daedalus Drive||TL-9||Nuclear Engine||Nuclear Rocket||Fissionables||TL–9 The Daedalus thermonuclear pulse drive is a refinement of the Orion drive system. Hydrogen fuel, in the form of formed 1.5 gram pellets, is fed into the ignition chamber and super-heated by lasers or high-energy electron beams. The resulting thermonuclear explosion pushes the ship forward. The ignition chamber and supporting electronics (electron guns and magnetic fields which protect the ship as well as directing thrust) give the engines a lower thrust-to-mass ratio than a conventional fusion rocket, but provide fuel efficiency about one order of magnitude higher. |
|EAPlaC Rocket||TL-6||Rocket Engine, Electromagnetic Engine||Chemical Rocket||Solid Fuel||Electrothermal Augmented Plasma Combustion: EAPlaC is a TL–9 enhancement to the Solid fuel rockets. Uses a electrically charged grid (similar to an Ion Drive) to further accelerate the solid fuel combustion products. This produces an huge increase in thrust. |
|Fusion Rocket AKA
||TL-10||Nuclear Engine, Rocket Engine||Nuclear Rocket||Hydrogen||TL–10 A Fusion Drive is not much more than than a fusion reactor with a steady stream of hydrogen going in and a hole in one end. Super-heated helium plasma expelled at tremendous velocities forms the reaction mass. Because of the nature of the drive, the exhaust is extremely dangerous. |
|HEPlaR Drive||TL-10||Nuclear Engine||Nuclear Rocket||Fuel||It consists of an heat exchanger recombustion chamber added to a fusion power plant. Hydrogen is injected into the recombustion chamber and the power generated by the engine heats the hydrogen to a plasma state. The plasma is them released as a high velocity stream of reaction mass, providing thrust. Because the engine is used to heat the plasma, this effectively drains the engine heat, reducing the power output of the engine in proportion to the thrust of the drive.|
|Hybrid Fuel Rocket||TL-6||Rocket Engine||Chemical Rocket||Hybrid Fuel||TL–6 One drawback to solid fuel rockets is inherent in their nature: Once you ignite the propellant, the rocket burns until it's all gone. The Hybrid fuel rocket is an attempt to overcome this; One component, usually the propellant, is solid and cast identically to a solid fuel rocket. The other component, usually the oxidizer, is a liquid and fed into the solid propellant core to allow combustion. By controlling the amount of oxidizer the duration and thrust of the rocket can be changed. |
|Hypergolic Fuel Rocket||TL-6||Rocket Engine||Chemical Rocket||Hypergolic Fuel||TL–6 Hypergolic Fuels are another type of liquid fuel rocket. Hypergolics are fuels that react spontaneously to each other and ignite (often explosively) without need for outside ignition methods. This simplicity is offset by the fact the fuels are chemically unstable, very reactive, and highly toxic. |
|Ion Drive||TL-7||Electromagnetic Engine||Electric Rocket||Fuel (Ionizates)||TL–7 The thrust in the Ion Drive is created by electrically reducing the fuel to a stream of charged particles (ions) which creates a very low thrust. The primary advantage of this system is its endurance, low power requirements and reliability. However, the low acceleration generally relegate vessels of this type to short range runs taking weeks or even months. 
The fuels used for this are known as "ionizates." This term includes cesium, mercury, and a variety of liquefied noble gases (argon, neon, krypton, etc).
|Liquid Fuel Rocket||TL-5||Rocket Engine||Chemical Rocket||Liquid Propellant & Fuel||TL–5 A liquid fuel rocket carries its propellant and fuel as two separate liquids, which are combined in a thrust chamber to produce thrust.  Liquid Fuel rockets are the standard rocket drives.
The basic start-up technology most civilizations use to get off their planet and into space. The high power of these engines makes them good bootstraps, but also makes them voracious fuel eaters. The rockets most frequently encountered in known space (98% of the time) are cryogenically fueled (liquid hydrogen and liquid oxygen). Others use hydrocarbons, although the costs and environmental disadvantages of using that fuel type generally outweigh any conceivable advantages. One type which works well is the propelyne/hydrogen peroxide engine system, using a hydrocarbon fuel and H2O2 oxidizer fuel
|Mass Driver||TL-8||Launch-assist Mechanism||Electric Rocket||Raw Mass||TL–8 Mass Drivers: Use electromagnetic repulsion (the principle used by Mass Driver weapons) to generate thrust. Just as firing a gun will impart acceleration to the firer in Zero-G, so will the electronic firing of rocks, which in this case are propelled in (and discharged from) an endless treadmill of steel containers. The primary drawback to such systems is that they require tremendous amount of raw mass as propellant. Poor prospectors find this vice to be a virtue, as they can put a pressure dome on a small asteroid (very small), place one or two mass drivers and a power source, and begin firing pieces of the rock for propulsion. Another major use of this system is to propel promising asteroids out of a belt and toward mining vessels which can then reduce the asteroids to usable ores. Also note that anything that can fire pebbles at sufficient acceleration to be useful as a propulsion system is also sufficiently robust to be interesting as a weapon system- and unlike plasma, pebbles don't spread out or cool off as they travel further away from the launcher, a fact not lost on Navy minds.|
|MPD Rocket AKA
||TL-9||Rocket Engine||Electric Rocket||Hydrogen||Magneto-plasma dynamic (MPD) drive: Utilize hydrogen plasma to create thrust. This is, in effect, a crude, very low temperature plasma gun. Similar in operation to an ion drive but with more thrust, and consequently increased fuel consumption.|
|Nuclear Thermal Rocket||TL-7||Rocket Engine||Nuclear Rocket||Liquid Propellant||TL–7 Nuclear thermal rockets (NTR) pass a liquid propellant - usually liquid hydrogen - through a fission reactor core, heating the propellant to a superheated state and using that for thrust. These are very simple and remarkably clean drives, as long as the reactor core is in good shape. An NTR can use just about any chemically inert fluid as a working medium without major problems or even a redesign. |
|Orion Drive||TL-7||Nuclear Engine||Nuclear Rocket||Fissionables||TL–7 The ultimate in brute force nuclear drive systems. The Orion Drive detonates nuclear (fission, fusion, or anti-matter) devices externally behind a massive protective plate to produce powerful thrust. Regardless of technology (fusion, fission, or AM), Orion detonators are self-contained exploders with a programmable yield based on the needs of the system (typically 0.2 kilotons; dialable from 0.01 to 1.0). Each is a cylinder 8 cm in diameter and 20 cm long (about 1 liter), and designed for use with an automated feed system. The devices typically have a variety of fail-safe interlocks and codes, remote tracking and identifications, and other non-pubic protections. |
|Resistojet Rocket AKA
||TL-4||Rocket Engine||Electric Rocket||Inert Fluid||TL–4 The earliest and simplest form of propulsion for space vehicles. They heat an inert fluid (usually water) into a high pressure vapor which is released to create thrust. Simple and inexpensive, they are not very efficient. Miniature resistojets are often used for station keeping and attitude change by much more advanced craft.|
|Solid Fuel Rocket||TL-2||Rocket Engine||Chemical Rocket||Solid mixture of propellant and an oxidizer||Developed staring at TL–2, Solid fuel rockets consist of a solid mixture of propellant and an oxidizer, with some form of hollow core where the rocket is ignited. Properly shaping this core controls how the rocket burns. 
Usually associated with the propulsion of unmanned missiles. Solid rockets play an important role in the early stages of spaceflight. They can be dangerous to use since, once ignited, they cannot be turned off. As a result, any failures within solid rocket systems have a high probability of catastrophic results. However, the solid rocket retains the advantage of a very high power-to-weight ratio.
One partial solution was the segmented solid engine, with layers cast in the shell, isolating buffer layers of inert material, and individual ignition systems. These allowed the segmented engine to burn one or more portions on command.
Rockets are most often the breakthrough technology that nascent sophont societies employ to first achieve spaceflight around TL:4-6. Through technological development, rockets maintain a leading position for spacecraft even into the contemporary interstellar period of TL:10-18. It is estimated that gravitic spaceflight and the G-drive may eventually completely supplant this technology.
Escape Velocity vs. Efficient Interplanetary Propulsion
Broadly speaking, spacecraft beginning planetside have two different demands:
- Use brute force to overcome the stresses of gravity and achieve low planetary orbit (...a high fuel flow/high thrust/low efficiency drive)
- Fight the vast distances of interplanetary and interstellar flight which greedily eat of reaction mass or fuel supplies (...a low fuel flow/low thrust/high efficiency drive)
The demands of these two mission profiles are generally in opposition with one another. Earlier societies tend to solve the differing problems with multiple stages, each specialized for a different flight envelope. The advent and later development of gravity control drives and reactionless thrusters makes the task much easier.
Early Spaceflight Strategies
Expected Technological Progression of Spacecraft Development
- Rocket → Aircraft → Shuttle → Spaceplane → G-Carrier → Advanced G-Carrier → Interstellar Spacecraft → Starcraft
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