Press control-e first and hear the low double beep before typing codes in:

battlecheats = enable in-flight cheats (see below)
canttouchthis = invincibility in battle
fillerup = unlimited fighter flight range
knowitall = complete all research
quickbase = finishes all BASES currently under construction - not modules
payday = money, and lots of it!!!!

Enabled battlecheats have been found by Mark Berger :

In-flight cheats : ALT + ~ = To destroy current target & ALT + 2 to render the targeted craft disabled.
I have found if you use high range number keys like 7, 8 or 0, you will do the same for X-COM - not advisable to disable your craft!!!!