Paul Allen has been tirelessly working on a once-secret project that just showed its wings to the world. The Stratolaunch is the world's largest airplane and it finally saw the sunlight of the California desert, where it was built. 

Watch as the huge airplane leaves the hangar for fuel testing in the video below:

It is called Stratolaunch because of it's purpose; not carrying passengers but launching things into the stratosphere. It has a wingspan of 385 feet and a height of 50 feet. Dry, it weighs 500,000 pounds and it can carry 250,000 pounds of fuel. Counting the fuel, load, staff and possibly the rockets it will carry; it can reach 1.3 million pounds. MILLION. This airplane is so big that the country had to issue special construction permits for the scaffolding. 

The Stratolaunch is powered by six 747 jet engines and it has 28 wheels due to the wide structure. It has been built after the partnership with ORbital ATK to launch the Pegasus XL, a rocket that delivers small satellites to orbit. The empty belly of the airplane would be filled to the brim with rockets. Then after the plane reaches an altitude of around 35,000 feet, the rockets are dropped into space. According to Paul Allen, "air launching" rockets is a mor efficient way to get satellites into space. This removes the need to build complex vertical takeoff systems. 

Stratolaunch will begin ground and flight testing at the Mojave Air and Space Port. For the first time, an aircraft like this will undergo intensive testing to ensure the safety of the pilots and crew. Expect to see the first launch demonstration sometime in the near 2019. Allen hopes to create a revolution in space travel, developing technologies that use LEO (Low Earth Orbit) travel to essentially drop off satellites and rockets into orbit without the expenses of vertical takeoff.