When the spacecraft's fusion efficiency is 0.01%, the spacecraft's fusion fuel is 1t, and the total mass of the spacecraft is 1.2t, the friend bet the final speed of the spacecraft is 80% of the speed of light. The state of the fuel at nuclear fusion is assumed to be D + T and 0.01% of the maximum energy of the fusion of the fuel, although the fusion method has not yet been firmly determined. I am curious about the answer of the final speed of this space ship.