Stratolaunch Systems, the private space company founded by Microsoft co-founder Paul Allen, says that it is discontinuing development of a new group of rockets and is reported to be laying off “more than 50 people” following Allen’s death last October.

The company told GeekWire that it is “ending the development of their family of launch vehicles and rocket engine,” in order to focus on its flagship aircraft, which is expected to take its first flight this year. That’s a turnaround from the company, which announced plans for the rockets last summer.

Allen co-founded the company in 2011 to develop a massive aircraft that would haul a rocket to an altitude of 35,000 feet, where it would then launch into orbit. Stratolaunch unveiled its aircraft in 2017, and with a 385-foot wingspan, it is the largest airplane in the world. The vehicle has been in testing since then, with its first flight expected to take place sometime this year. The company has already lined up a customer for its services: Orbital ATK signed a deal to launch its Pegasus XL rocket from the aircraft.

That plane was clearly the first step in an ambitious roadmap for the company. It had begun development of its “Medium Launch Vehicle,” which it planned to fly in 2022, with a bigger version and a reusable space plane called “Black Ice” to follow. But with Allen’s death in October, it seems that the company is reining in those plans to focus on getting its aircraft off the ground this year. We’ve reached out to Stratolaunch Systems for further comment, and will update this post if we hear back.