[4] In the end, no good economic case ever closed and Stratolaunch halted all work on their own family of air-launched rockets in January 2019.
[6] Funding would be provided by Vulcan, an investment company created and chaired by Microsoft co-founder Paul G.
[11] As development progressed, the scope of alterations to the Falcon 9, including significant structural modifications to the first stage for aerodynamic surfaces,[12] and the disruption to manufacturing processes these modifications would have required,[11] led Stratolaunch and SpaceX to part ways and cease development of the Falcon 9 Air.
[16] The first two stages of the Pegasus II were to have had the same outside diameter as the Space Shuttle Solid Rocket Booster, but intended to be constructed using much lighter carbon-composite cases and contain a more energetic propellant mix.
[1] GTO missions would have used a 4 m (13 ft) meter fairing and a single RL10 engine, with a payload capacity of approximately 2,000 kilograms (4,500 lb).
[17] In November of that year, Stratolaunch clarified that they had modified the design and that Pegasus II was to have been an all-solid vehicle.