Sack New Venus is a long mission, but not difficult if you can handle the tachyonic fighter well. Demand tribute from the planet, and use your speed to outmanuver the fighters and other reasonably fast ships that come your way. New Venus will also send out gun platforms, but don't worry about those yet. Keep destroying the ships coming at you (mind that you dodge those missiles, the tach fighter is fast for a reason!). When (if) its all gun platforms facing you, move in toward them and circle them QUICKLY (so you can keep ahead of their fire), firing your lasers. If this is difficult for you to do, approach from an angle and hold down the auto-pilot key so you circle with little effort. The platforms won't last long if you keep up a sustained assault.
Mind you, if you take some hits, BACK OFF and let your shields recharge (it doesn't take long with the tach fighter), then attack again. The fighter can regenerate shielding much faster than most ships you will encounter in FH, take advantage of that when you need to.
Fight a smart battle, and the mission is a cinch.
UEC
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