The following submission statement was provided by /u/lughnasadh:

Submission Statement

Stratolaunch has been around for a while. Way back in 2011, they were a contender with SpaceX to launch the earliest iterations of the Falcon rockets. While this aircraft was initially developed to launch rockets into space. Presumably, that hasn't worked out, but they see another opportunity - hypersonic research. China seems to have taken a lead in that, which must be funneling US DoD money in that direction.

I wonder will anyone ever crack the nut that is a successful horizontal space launch from aircraft? Virgin Galactic tried in recent weeks and failed. Using this approach for small payloads of 500 kg or so seems most likely to succeed. Among the many problems this approach has, is that building rockets (that are mainly fuel containers for their small payloads) that can take both horizontal and vertical stresses is hard.

Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/10cmgjj/the_stratolaunch_roc_the_largest_aircraft_ever/j4gei3t/