[Spaceships] Designing Hyperspace / FTL for space opera (and implications)

[vicky_molokh]

An FTL variant I haven't considered yet, found in the later Spaceships books - the 'Lightspeed' drive, which bumps the ship's virtual velocity to c, but shuts down when the ship enters an 'interesting' area (primarily a gravity well of an important power). This is one of the best variants for in-system travel, IMO, with the following notes on how it works:

• Being a certain distance from a significant mass, or another craft using the same drive type with a different vector pushes both craft to normal speed.
• The above condition also prevents starting the drive.
• Mid-flight course corrections are allowed - the crew doesn't experience time dilation!
• Optionally: instead of c, the drive provides a speed of (c*x)/(1+x), where x is the number of normal-sized drives per ship (the usual 5% mass of the ship per drive). This results in speeds of c/2, c*2/3, c*3/4 and so on, with each upgrade being faster than the other - important in chase scenes! - but never sufficient to start worrying about outrunning light.

This kind of setup allows preserving causality within a star system, which might be used to preserve causality throughout the galaxy if the other 'FTL' travel method is a weird spacetime geometry (i.e. certain variants of wormholes).