On 9 May 2020, at 01:32, Thomas Jones-Low <xxxxxx@gmail.com> wrote:
>
>     Which ruleset are you thinking of building your ship?
>
>    - TNE (FF&S) and GURPS reverse the formula (install thrust quantity and calculate thrust from the mass of the ship).
>
>    - Most of the ship design sequences like HG use a formula which would make it easy and obvious how to calculate a fractional drive system. T5 and MGT both use a table, but reversing that into the formula isn't hard.

Fractional drives are possible on all versions, except High Guard in LBB.

The Drive Potential table in LBB Book 2 has all the fractional Gs rounded down, so you could reverse engineer that into fractional G.

With book 5 you choose the manoeuvre drive as a number 1-6 (0 in none). However the cost and displacement percentages are only given for integer values.

Strictly, the only system that does not do fractional drives is the USP.

Personally I’m of the opinion that UPP/USP/UWP in fact all of the U?P are the worst blight Traveller inflicted on out imaginations.

As a randomly generated starting point for development, ok.
As something to use in a game - useless.

The book 5 USP is the worst offender - you have to reverse engineer it from a couple of pages of calculations, it is too long and still needs several lines of additional info and then another paragraph to explain it.

Phil Kitching