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M-Drives at TL-7

Hi reading through the design sequences in the T20 rule book it seems that starship/spacecraft drives become available at tl-7, surely this must be late tech level 8 ot perhaps early tech level 9, as the drives described only require energy points and do not consume fuel. Can anyone clarify this for me, or does the tech level simply represent the earliest that these drives could be made at with the correct knowledge as opposed to the earliest they could be developed through scientific discovery (as i've always assumed the tech level charts indicate) It's just its hard to imagine a tl-7 society being able to create a reactionless drive without outside help let alone them becoming common place at that tech level.

Many Thanks
The proper answer to this involves reading back through the Traveller history. The T20 ship design sequence is a slightly updated version of the High Guard ship design system. Neither mentions that the "Maneuver drive" is reactionless, though it is a common assumption given the drive consumes power but not fuel. The first edition of High Guard stated that you could use the "Maneuver drive" like a plasma gun at close range.
However, the T20 power plant consumes, for a fusion reactor, a inordinate amount of fuel. As Chris Thrash pointed out on the JTAS boards, the Beltstrike module for CT has a table where the power plant fuel requirements go down by a factor of 5 (4 weeks to 20 weeks) if the maneuver drives are not used. So, you can't claim the the M-Drive must be reactionless, it just the best answer.

Alternalty, the Grav modules used to drive the air/raft are invented at TL8. If anything becomes a reactionless thruster, the manipulation of gravity would fit the bill. And I wouldn't be surprized if a TL7 society, once they learned the tricks of gravity manipulation, could build reactionless M-Drives.
Great Answer, I this makes sense when I think of the Heplar thrusters described in TNE, not to mention the incredibly efficient fusion reactors used in the TNE system.

Many Thanks, this is definately a rational I will use in my games