>>11717184>>11717267also, it does nothing to help with slowing and protecting the rocket when reentering the atmosphere. The engines are just as vital for the reentry burn as for as for the landing burn. Remember, in the early days SpaceX tried to forgo the reentry burn and just add more insulation. They lost several stages before they figured out that was a dead end.
The whole rocket-power strategy is a way to reuse the hardware they already had for those two hard problems (reentry and landing) and adding as little extra hardware as possible (grid fins, attitude thrusters, and legs). Spaceplanes solve that problem a different way: more shielding for reentry, wings with aerilons for control, and retractable landing gear for a runway landing. But nobody has tried a space-plane first-stage booster yet.
