Torchships are a type of exceedingly powerful rocket that has engine output in the near terawatt to multi terawatt range. They combine high thrust with high efficiency. The engine output is so high (equivalent to a tactical or even strategic nuclear bomb every second) they require special shielding, cooling and so on. Any unprotected thing on the outside of the hull would be vaporised. They cannot be used anywhere around habitats, or other vessels, so they usually employ chemical rockets as an auxiliary means of propulsion, or even a lower output (low gigawatt) nuclear rocket as a middle gear.
They are popular with groups and ideologies that don’t have access to exotic matter and don’t want to deal with Tyrusian or other alien races that supply transingularitan-based tech. In the military and among the megacorps however they have long been superseded by exotic matter, reactionless drives .
Torchship isp allows them to travel up to a couple of hundred or even thousands of kilometers per second. Relativistic travel is usually impractical due to the astronomical energy requirements, although advanced torchships (conversion drive) can attain low relativistic velocity.
Types of Torchships
Saltwater nuclear fission