Proxima Centauri is 4.24 light years away – a bit over 268,000 AU or 40 trillion kilometres. To fly there at 1 gee takes just under 6 years or about 3.5 years onboard. However the present day systems are unlikely to be up to the challenge of 1 gee acceleration. The required constant acceleration – to speed up, then slow down in equal amounts – is four times the average velocity divided by the trip-time i.e. 4.V/t
Thus if you’re contemplating the 0.02c average speed of Dana Andrews’ Near-Term starship, then the delta-vee is 0.08c which is divided by the 212 year trip-time. That’s just 3.6E-3 m/s2, which is less than the Sun’s gravitational acceleration experienced by the Earth (5.93E-3 m/s2.) Thus the starship would speed some time spiraling out from the Sun before speeding off into interstellar space.
While that sounds *slow* it’s a blistering 12,000 km/s top-speed, some 400 times quicker than the Earth’s 0.0001c around the Sun. Far faster than any vehicle we’ve managed to launch so far.
Dana’s starship masses 4,000 tons. The force required for the interstellar trip is 14,340 newtons, which would require a hefty EM-Drive bank if they’re limited to a newton per kilowatt performance levels. A ~15 MW power supply (more like ~30 MW when inefficiencies are accounted for) is nothing to sneeze at and must be maintained for 212 years. Very efficient and low maintenance nuclear reactors can be assumed, not unlike Dana’s assumed design.
The alternative is if the EM-Drive proves to give even higher thrust levels as higher microwave cavity Q-factors are achieved. Then high acceleration, at 1 gee levels, become reasonable. But can we adequately shield against the proton barrage of the Interstellar Medium as we approach the speed of light? Magnetic fields may afford some protection, but we’ll need massive shielding to absorb any x-rays produced by the medium as it is violently thrust aside via our fields. Interstellar dust will pack a punch, thus precursor shields that smash the dust into ions will be needed and will need constant replacing. Is smashing around close to lightspeed worth it?