The BAe Sea harrier is Britain’s VTOL naval aircraft. This one’s simple enough to fly. I and K control the nozzles and throttle down to about 2/3 from full power for a nice hover thrust. RCS toggles the VTOL controls which makes the aircraft controllable in vertical flight - it’s not recommended to use this in flight.
H and N control the flaps, bring them all the way down and toggle brakes for VTOL. It’s highly recommended to use the horizontal and vertical speed indicators on the kerbal engineer redux HUD.