If you made a '2nd stage to orbit and return' vehicle capable of sitting atop the reusable Falcon Heavy 1st stage, how heavy could it be, and to what height and speed could the 1st stage push it in a trajectory directly upwards1?
Elon Musk is quoted in the article linked above:
Falcon 9 will do satellites up to roughly 3.5 tonnes, with full reusability of the boost stage, and Falcon Heavy will do satellites up to 7 tonnes with full reusability of the all three boost stages …
That suggests the mass it can push in fully reusable mode is '7 tonnes + the mass of the 2nd stage'. Unfortunately I can't locate a mass for the 2nd stage! As to the figures for altitude & velocity at time of separation, I'm not having any luck.
- Originally I was after a trajectory that would give the greatest time between separating from the first stage and the payload hitting a high before falling back to the atmosphere (with its associated drag) in order to allow the '2nd stage' enough time to reach orbital velocity (presuming it has a relatively low acceleration rate). But I'm thinking those figures are simply not available. So.. I'd happily accept the numbers for an actual mission profile instead.