There is precedent: SpaceShipOne was successfully launched from an airplane [1]. The great force downward is (mostly) irrelevant if there is nothing below. Jus

There is precedent: SpaceShipOne was successfully launched from an airplane [1]. The great force downward is (mostly) irrelevant if there is nothing below. Just hang the rocket between two towers over a void, with the atmosphere below. [1]: https://en.wikipedia.org/wiki/SpaceShipOne#Launch_aircraft https://en.wikipedia.org/wiki/SpaceShipOne#Launch_aircraft