Re: Not new
" The problem of directing the thrust thus produced, and avoiding also combusting the payload, has however proven hard to solve."
This rocket has a relatively conventional combustion chamber with convergent (and, in practice -divergent) nozzle to direct the thrust in the usual way. Steering also needs adding, as it does for any rocket, and is a mature technology. A non-combustible stub between the payload and the fuel rod should protect the former from combustion.
But sending a plastic spear through an oxygen-rich atmosphere at high Mach number may prove less practicable.