Get a First Look at the World's Largest Airplane…

Elon Musk and Jeff Bezos aren’t the only tech billionaires with their eyes set on space.

Microsoft co-founder and Seattle Seahawks owner Paul Allen has been hush-hush about the massive aircraft he’s been constructing, but now it’s finally ready for testing.

Allen’s “Stratolaunch” is the world’s largest aircraft, with a 385-foot wingspan and a height of 50 feet. The airplane features six engines — the same used on Boeing 747 aircrafts — and can carry up to 250,000 pounds of fuel. Without fuel, the plane weighs 500,000 pounds. With fuel, it can reach a whopping 1.3 million pounds. It features 28 wheels to get all that mass moving.

Related: What Will It Be Like to Fly in a Blue Origin Spaceship?

The aircraft has been in the works for years in an area of California’s Mojave Desert. The company’s goal is to have a launch demonstration by 2019, shared Stratolaunch’s CEO Jean Floyd. “Over the coming weeks and months, we’ll be actively conducting ground and flight line testing at the Mojave Air and Space Port,” Floyd said in a statement.

This plane isn’t going to fly you to your next vacation destination. Instead, it will be used to launch rockets. Partnered with Orbital ATK, Allen’s Stratolaunch company has plans to “air launch” the Pegasus XL rocket, which delivers small satellites into orbit.

So how exactly does that work? With the rockets attached to the bottom of the aircraft, the Stratolaunch will reach a flying altitude of about 35,000 feet — similar to that of commercial airplanes. “As the launch vehicle rockets into orbit, Stratolaunch will fly back to a runway landing for reloading, refueling and reuse,” Allen said in a blog post last year.

Related: 8 Inspirational Quotes From Space Pioneer John Glenn

Like other tech entrepreneurs dipping into the aerospace industry, the primary goal of Allen’s Stratolaunch is to reduce costs and create a more efficient way to get small satellites to space.

“When such access to space is routine, innovation will accelerate in ways beyond what we can currently imagine,” Allen said. “That’s the thing about new platforms: When they become easily available, convenient and affordable, they attract and enable other visionaries and entrepreneurs to realize more new concepts.”