Anything over Expert will not let you outfly it and Expert only does some of the time.
NPCs all have a sweet spot range where they will try to open up distance before attempting to turn into you; if you can control range closely enough, most will never be able to get a shot off after you insert yourself behind them. This has been a persistent hole in NPC AI. You can see this in the Incursion video I posted.
Frequently I can sit behind NPC as agile as higher ranked (Master all the way through Elite) Vultures in a Corvette, and about the only NPC ships I can't stay continually out of the firing arc of in an Engineered Viper are mid and upper ranked FASes, some Chieftains, and the rare Clipper. Most other NPCs don't have either the pitch rate or the boost acceleration to break away and turn in time.
Example:
Source: https://www.youtube.com/watch?v=LIdOunjGr20
~500m is the sweet spot for most ships. If they can't get further away, they will just try to boost again to open up distance for another attempt, and most NPCs are too slow to do this, even against a Corvette (well an Engineered one), unless the pilot makes a mistake and overshoots (as I did at the end of that clip). Almost everything is too slow to break from an Engineered Viper, as it doesn't even need to boost to keep up with most boosting ships (but it can of course, and being able to interrup boost with the scoop means overshoots are rare, with some practice) and can simply trichord directly toward it's opponent at near full speed without even needing to turn.
It's been about a year since I tested this, but I haven't heard of any major NPC piloting overhaul in the interim and the basic pattern is as old as the game.
Can you show me how you do those 'deadly conda, two deadly cobras and six deadly eagles' Signal sources in massacre missions? Can't figure out how to do it in a viper myself. :/
Not with an unmodded Viper (doesn't have the staying power for such a group, at least not with me at the controls), but I could probably dust off my HOTAS, slap together an Engineered one, and record it. Could take a bit though as I've mostly been focused on surface stuff and my CMDRs ship assets are a mess.
In the meantime, I'd recommend trying to focus on the Anaconda first, as it should be fairly easy to get (and stay) close enough for you to block some incoming fire with it, or force the other hostile ships to shoot it, while staying out of the reach of it's weapons. After it goes down, the Eagles are the next priority as they should be considerably softer than the Cobras, but don't lag far behind in firepower; they also have a lowish boost speed and are easier to stay behind, despite their solid rotationals.
I would also recommend a hull-focused loadout (you can put ~1800 hull with good resists on a Viper III and still have a thermal resistant+low draw bi-weave and an MRP) as this will maximize both the offensive and defensive capabilities of the ship. Weapon wise, you'll want a feedback rail for countering Anaconda SCBs and coring out it's power plant, plus a corrosive weapon. Short-range weapons are very viable against NPCs.
