Chemical rockets: the short-range workhorse
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Chemical rockets: the short-range workhorse
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| Chemical Rockets - Data Panel
Summary: The oldest and most primitive type of rocket propulsion are chemical rockets, in which two or more chemicals are mixed together to produce a powerful chemical reaction. The reaction produces hot gases that are forced out a nozzle at high speed, creating thrust and propelling the rocket forward. There are two types, solid and liquid. Solid Fuel
Summary: the most primitive type of rocket. various uses. Lo tech. Basic Propulsion: Reaction Specific Impulse: usually no more than 150 to 280 Fuel: mono- or bipropellant solid fuel Minimum Technology Required: Iron age / Medieval Matter Manipulation: macroscale Controller required: none First Introduced: First rockets Iron Age Old Earth (Chinese fireworks) - Earth Orbit Atomic Age Old Earth Used by: mostly worlds off the main nexus, medium tech polities, outposts, backwaters, etc. Also, quite popular with some S<1 hobbyists Used in: close range ordinance (military); strap-on boosters for orbital launch; fireworks; lo tech hobbyists Construction Costs: Industrial Age: depends on size, not over-expensive; Autofac: very cheap; Hylonano: very cheap (assuming presence of component materials) Running cost: very cheap or n/a (once-only use) Advantages: Can be stored for months or years without any sort of maintenance, regulation, stasis, or inert gas, even in atmospheric conditions, and still will not degrade. Simplicity of structure means can easily be replicated or produced Disadvantages: Extremely low isp. Useless even for short-range interplanetary vessels. Once ignited cannot be shut off until it burns itself out. Normal Acceleration: >3G normal top/cruising speed <0.05 km/sec to >5 km/sec, depending on size, purpose, etc |
More sophisticated than the solid fuel rocket, the liquid fuel rocket engine uses liquid propellants that are mixed and ignited in a combustion chamber. They have a superior ISP than solid fuel rockets.
| Propellant | isp (normal) | isp (ideal) | Advantages | Disadvantages | ||
|---|---|---|---|---|---|---|
| Solid-fuel | 150 to 280 | Cheap, reliable, very simple and lo tech | Cannot be controlled once ignited | Many independent and low tech polities (booster rockets, short range ordinance, etc) | ||
| LOX/LH2 | 450 - 460 | 528 | Easily available fuel, simple components, high thrust to weight | Explosive, | Many independent and low tech polities (booster rockets) | |
| LO3/LH2
(hydrogen/ozone) |
580 | 607 | Easily available fuel, simple components, high thrust to weight | Highly explosive | Some independent and low tech polities (booster rockets) | |
| (F2/Li-H2
(hydrogen/fluorine) |
546 | 703 | high thrust to weight | exhaust product (hydrofluoric acid) is highly corrosive | Some independent polities (booster rockets) | |
| (F2/Li-H2
(beryllium/oxygen) |
705 | simple components, high thrust to weight | beryllium is toxic. | Some independent polities (booster rockets) | ||
| Free Radicals (H+H)->H2 | 2130 | high isp | very unstable, requires advanced tech | A few independent polities (boosters and interplanetary rockets) | ||
| Metastable Atoms (e.g.Helium) | 3150 | high isp | very unstable, requires advanced tech | A few independent polities (boosters and interplanetary rockets) | ||
An invention as old as the fossil fuel / industrial age, with iron age / medieval precursors (e.g. Old Earth Chinese circa 1000 c.e.), chemical fuel rockets have been used as missile weapons and as cheap and effective lo-tech near space transportation every since. Both solid- and liquid-propellant forms utilize a chemical reaction between a fuel and an oxidizer. Although chemical rockets can develop great thrust, they are not capable of long continuous operation, due to the very poor isp [specific impulse], which generally varies from 150 to 450, with the LOX-LH2 (Liquid Oxygen-Liquid Hydrogen) mix used on the early (late 20/early 21st century) space shuttle system giving 450 to 475, and the O-BeH bipropellant as the most energetic natural chemical propellant providing 705. Much later some nanofactured synthelements were to give specific impulses as high as 3000, but these were so unstable and expensive it was easier to use fusion propulsion.
The use of chemical rockets for space exploration really came into its own during the second half of the 21st and the early to mid 22nd centuries, when increasingly cheap nanofactured buckyfibre and diamondoid materials reduced structural weight sufficiently for the very poor isp to be viable at least for Earth orbital and near orbital flights. Rockets were of greater utility in low gravity worlds like Luna and Mars. In fact, their cheapness, robustness and (with the less exotic propellants) reliability made them very easy to manufacture by robot factory or autofab during the middle interplanetary age, and they remained the standard short range transport right up until the nanoswarm crisis, and again during the First Federation period. Even today many systems, especially in the outer volumes or on low tech worlds, use chemical rockets as a standard space propulsion, especially when lifting off from the surface of moons and planets. In these instances, small unmanned craft and single manned construction and mining ships used chemical rockets for movement between closely spaced orbital structures. Many asteroids and Selenese-class Moons are rich in aluminium and oxygen, candidates for chemical reactants, and hence can be very easily and cheaply nanogrown.
