I am writing a story on a civilization that has the ability to make constant accelerating drives. The ships will accelerate with 8g's (heavy worlders) for half of the trip and then de-accelerate for the remaining half. Thus the need for artificial gravity is no longer necessary. I know however for large distances time dilation will become an issue and I don't know how to deal with it for an accelerating drive.
I recently found this app which calculates the time dilation due to constantly accelerating drives but I am not quite sure if I should trust it.
The calculation methods have a lot of sinh functions for the time dilation and I've only ever seen time dilation with square roots. I can't get the book the app references so I was wondering if anyone here has worked with constant acceleration drives and knows of any good references on the time dilation which results? If there are numerical examples which I can check against the app, I would appreciate that as well.