Checked out Proton Torpedoes vs Orion. I brought 16 BBs with Augs, Bscanner, Bpods and Heavy Armor. As I had traded for Megafluxers, I crammed in 5 Proton Torpedoes in each, level 2 refinement (all the way to Interphase Drive), Enveloping, ECCM, Overloaded.
I also had Weapon and Ordnance officers.
With only Neutron Scanners, I had an abysmal miss rate. On one test, 11 BBs firing killed the Orion; on two more, round 1 didn't do it and I had to wait out the torpedo recharge and finish with surviving ships.
After researching Sensors, 5 ships did the job (not counting 2 which died because I hadn't researched for initiative).
Without the officers, pre-Sensors the 16 ships weren't enough, afterwards around 8 would do the job.
Savegame - is 2 turns or so before researching Sensors, so you can easily compare before and after.
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To be sure, the only way to lower enemy Missile Defense is the ECCM mod and researching Tachyon Scanners/Neutron Scanners/Sensors? Computers or other tech don't help?
Also, these different scanners don't stack, do they? If I research Sensors, I don't get anything more for having earlier techs?