Copyright (c) 1995 by Onno Meyer <Onno.Meyer@arbi.informatik.uni-oldenburg.de>

I use space performance in analogy to air performance and include
all noteworthy data: 

- Acceleration: the thrust/mass ratio, complicated by the fact that 
  the fuel mass drops over time. 
- Delta-V: the maximum velocity change (accel * time for constant 
  acceleration). If the flighttime is long compared to the actual
  engine use (e.g. for a chemical-fuel marsflight), this is much
  more important than mere acceleration. With fusion plants and 
  reactionless engines, it becomes virtually infinite, but with
  e.g. a fusion rocket the navigator has to watch the fuel.
  A spacecraft with 100 km/s delta-V could accelerate to 25 km/s,
  brake, accelerate to 25 km/s for the return trip and brake 
  again (this calculation ignores the various gravity fields in
  a system, planets can be obstacles or help).
- Warpspeed if applicable: straight from Space.
- Hyperspeed or jumpspeed if not constant in your universe.
- Hyperdrive/jumpdrive power cell recharge time: minimum time 
  between FTL-trips.