Which UFO flight computers will I recover?

Solution 1:

This is an alien Flight Computer:

This appears to be a scout-class UFO, and I believe the model used for them is slightly truncated due to the overall size of the UFO, so the thing in the middle of your image is the flight computer. The two on the sides with the square-ish screens are just decoration as far as salvageable parts go.

The second flight computer on this model of UFO is seen here at the far left of the screen (opposite the one in the center) - it doesn't have the holographic display above it because it's been damaged, either in the crash or as a result of combat. So, you should end up with 1 damaged and 1 functional, assuming nothing damages the functional one before the end of the mission.

In general, the number of flight computers you stand to salvage is based on the type of UFO, and should always be the same amount. You'll get X flight computers in total, either damaged or intact, depending on how many survived the crash and/or combat.