It would be the world's largest airplane. It's being built by a billionaire. And it's getting ready to fly.
https://www.washingtonpost.com/news/the-switch/wp/2018/04/16/it-would-be-the-worlds-largest-airplane-its-being-built-by-a-billionaire-and-its-getting-ready-to-fly/
Paul Allen, the Microsoft co-founder, is building an airplane that could “air launch” as many as three rockets and perhaps even a space shuttle.