Hello. This is my first post here, so I can only hope (having read the guidelines and physics FAQ), that my post is appropriate to go here. If not, and it is deleted, I'd much appreciate an explanation by PM and a suggestion as to where it would be appropriate to post. That said, the reason for my questions is that I am in the preliminary stages of try to write a science fiction novel. I'm 62 and have not written previously, although I have a lifelong interest in science, especially astronomy, cosmology, and particle physics, and I've read many hundreds of of SF (and other) novels. The idea of starting to write at my age (now that I'm retired) is probably quixotic, but I'd still appreciate answers to my questions for their own sake, even if I never write a paragraph. If anyone's still reading, my request is for the mathematical formulas to calculate how long it would take to travel a set distance (in ly or parsecs), both from the traveler's reference frame and from the reference frame of someone remaining at the point of origin of the trip. I would like the formulas to be able to handle not only constant acceleration (and deceleration), but also acceleration for part of the trip, then 'coasting', then deceleration for the final part of the trip. Of course, the formulas won't be of much help to me if they are too complex to calculate without powerful computer assistance, so it may be necessary to simplify the formulas so as to be practical to use and only give approximately accurate results. For example, it may not be feasible to include in the formulas the steadily changing mass of the vehicle as fuel is expended. It would also help to have access to some table of the energy per mass unit that different types of fuel can produce, such as chemical (lox, etc.), fusion materials, and fission materials. I guess anti-matter materials would be interesting as well, although I don't see that as a feasible fuel. And I guess such a chart should also show the maximum efficiency likely with each type of fuel (thrust-producing energy/total energy output). I have read a number of books that cover, in varying degrees, the topic of relativistic space travel, but none that I've come across are very specific in this particular area. Examples are books by Peebles, Thorne, Barrow and Tipler, Davies, Hawking, Maffei, Smoot and Davidson, Kaku, and Weinberg. Of course, if there is a book I haven't come across (of which there are definitely many) which covers the area of my interest in detail, I'm much appreciate knowing that. I've also tried looking online, but I've been able to find only two items that are at all useful. The lesser one is a page called 'Space Math' on the site cthreepo.com, which gives a java script for calculating time or distance or acceleration if two of the three variables are given. However, the basic formulas upon which the script is based are not given, nor does the calculation allow for 'coasting'. It assumes (constant) acceleration for half the journey, then (constant) deceleration for the other half. The more useful page is one by Philip Gibbs, updated by Don Koks, called 'The Relatavistic Rocket' (http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html [Broken]). This does in fact give a number of very useful formulas, but its shortcomings include the assumption of constant acceleration/deceleration (no coasting), and idealized fuel and efficiency. It doesn't allow one to calculate, for example, given a maximum feasible amount of fusionable fuel, how long it would take (by the traveler's and by Earth's clock) to travel, via acceleration, coasting, and deceleration, approximately 4ly (Alpha Centauri) or 12ly (Tau Ceti) or 20ly (82 Eridani). Now that I think about it, in the previous example, I guess there is also the question, if fuel is limited, how quickly (half of) it should be consumed to produce the minimum total trip time. In any case, I've rambled on far too long as it is. Any answers, recommended sources, or corrections to my questions would be much appreciated.