A disclaimer: I'm trying to limit myself to asking questions on Physics Forums, partly because I feel I've gone way past my quota. Still, there is one question that simply won't go away, and it concerns the relative efficiencies between two forms of motion. The first involves continuous acceleration/deceleration; the second a far shorter, brisker spell of acceleration/deceleration linked by a period of inertial motion. Three assumptions must hold true: (1) distance (2) flight-time and (3) fuel use remain precisely the same in both modes of travel. There's quite a lot of info about this subject on the net, but somehow I keep getting left behind. Also, there's a marked tendency to bring in Special Relativity, which adds a layer of complexity which I really can do without right now. Newton's Laws of Motion are plenty enough to be getting on with, at least for me. I've chosen space travel just to keep things as simple as possible. I've also tried working this out on the calculator pad - so much so that I don't understand anything at all now. (Again) Many thanks.