Watch out, Boeing. Hybrid Air Vehicles is coming for you with the Airlander 10, the world's largest aircraft.

The blimp-plane hybrid is just over 300 feet long and is 143 feet wide. When it's ready for takeoff, it's filled with 1.3 million cubic feet of helium. (Yes, helium, that gas that gives you a squeaky voice if you inhale it.) According to Hybrid Air's website, the Airlander 10 can stay up in the air for five days manned and up to two weeks unmanned. The company believes the very conspicuous aircraft — its front end resembles a derrière, hence its nickname "The Flying Bum" — has a role to play in military and commercial projects, including surveillance and cargo transportation.

As is pointed out in the video, by filling the Airlander 10 with helium, Hybrid Air can avoid the fate of other massive aircraft filled with gases (i.e., the Hindenburg), since helium and fire don't interact in explosive ways. Hybrid Air also touts the Airlander 10's lower carbon footprint compared to more conventional aircraft. While it's true the Airlander 10 doesn't rely as much on fossil fuels, the craft does use a good deal of helium, and helium is a precious, dwindling commodity on Earth.

Watch helium-filled 'Flying Bum' take flight
The Airlander 10 is a helium-filled airship intended for surveillance, communications and aid deliveries.