Incredible space questions ?

The answer to your question would involve only simple arithmetic.

Find out what is the speed of light. Multiply that by fifty. The product will be the speed at which you want your imaginary spacecraft to travel.

Divided the distance to Ross 128 b by the speed you have calculated. The quotient is the time it would take.

Fact is that "spacecrafts" cannot go faster than light. And what's more the bigger they are the more energy (vastly more energy) it would take to make them go anywhere near the speed of light. So you see the idea is impossible on both theoretical and practical grounds.

And what's with Ross 128b? A planet tidally locked to a red dwarf star in a probably unstable and elliptical orbit? Interesting in itself, but hardly worth the sweaty exertion and costly hardware needed to go there. I suppose the planet could be a super Venus, which would be interesting, but seeing we already have a Venus right here in our own solar system that we know little about, making a journey of a hundred trillion miles just to see another seems rather pointless.