This plane has four propellers and five engines. The fifth one is a small turboshaft of about 1,364 hp that never turns a propeller. It runs a compressor that blows air over the flaps, a trick called boundary layer control. It keeps the airflow stuck to the wing at flap angles where an ordinary wing would stall, so a big amphibian can fly as slowly as about 90 km/h. That slow speed is the whole point. Waves don't flatten out for you, and the slower you touch down, the gentler the hit. ShinMaywa says the US-2 can land in waves up to 3 meters. Then there's the spray. Watch the clip the hull has a spray suppressor that pushes water down and spray strips that throw it sideways, so it stays out of the engines. A flying boat has to solve the water as well as the air. Video by Cpl. Madison Sharpe