I was using a pad on that capture but yeah it’s set it up for the keyboard aswell using a combination of W,S,A,D for pitch and yaw, Q and E for rolling. Also mapped stuff to the numbpad so there’s a few combinations depending on what you fancy,works pretty much the same apart from you have to sort of quick tap the keyboard for small increments as the input from the keyboard is always 1. I grew up playing a specccy 48k so I don’t mind it, not sure how a newer generation would take to using the keyboard 
But yeah its not really easy to pitch, roll, yaw, manage the throttle and fire all at the same using they keyboard. Maybe get a wired xbox 360 pad on the cheap would be my advice
it would be best with a joystick but that’s another conversation
Not tried making character pawns fly. The old UDK method was to stick the state into ‘flying’ and then pretty much do what I’ve done in my screenshot.
On UE4 could you stick the character into simulate physics mode like you do when you go into a ragdoll then use my method above to control the movement? That would just make a flying ragdoll I suppose but it would look funny