Those big sentinel ships can be a real pain when they start launching fighters at you but ive found some tricks that make them way more manageable. First off, you'll want to keep moving, those guys love to swarm you and staying still is basically asking for trouble. I usually focus on taking out the smaller ships first cause they're super annoying when youre trying to deal with the big one, and the photon cannon works great for picking them off.

Something that's helped me a lot is carrying plenty of shield batteries and resources, cause these fights can drag on sometimes. The positron ejector absolutely shreds when you get in close to the capital ship, and if you've got a rocket launcher that's pretty solid for breaking their shields down too. One neat trick i've discovered is attacking from behind, those big ships have trouble hitting you there and it's saved my ship more than once.

You might want to upgrade your ship systems before picking these fights, especially the shields and weapons, makes a huge difference when you're in the thick of it. And if things get really hairy don't feel bad about boosting away to recharge, i do it all the time. Just remember to stock up on sodium and tritium before you start the fight, running out mid battle is not fun trust me!