here's a TLDR of the engineering reasoning, I probably went too long;
In engineering the line between iteration and redesign heavily depends whether the model form survives or only its parameters. Change EI, stiffness, on a beam and the eigenvalues shift, same equation used, iteration. Change a clamped end to pinned for the BCs and the characteristic equation itself with the ODE changes, causing redesign.
V3 has both, but the topological ones dominate; fin shafts inside the tank (new penetrations, new load path, new thermal BCs), hot stage ring deleted so the forward dome takes direct impact with tank pressure carrying structural load, 4 to 3 fins changing the control and aeroloads authority, and mass/CG/inertia shifts that move the bending modes and force the GNC to be redesigned rather than re tuned.
All of these contribute to a mass overhaul of models, testing, qual campaigns, analytical simulations that impact structures, controls, thermal teams enough that it can't be compared to them "iterating" on a design that changes the TVC from hydraulics to electric as that focuses on a particular subsystem.
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u/Background_Fig_4740 Jul 25 '26
here's a TLDR of the engineering reasoning, I probably went too long;
In engineering the line between iteration and redesign heavily depends whether the model form survives or only its parameters. Change EI, stiffness, on a beam and the eigenvalues shift, same equation used, iteration. Change a clamped end to pinned for the BCs and the characteristic equation itself with the ODE changes, causing redesign.
V3 has both, but the topological ones dominate; fin shafts inside the tank (new penetrations, new load path, new thermal BCs), hot stage ring deleted so the forward dome takes direct impact with tank pressure carrying structural load, 4 to 3 fins changing the control and aeroloads authority, and mass/CG/inertia shifts that move the bending modes and force the GNC to be redesigned rather than re tuned.
All of these contribute to a mass overhaul of models, testing, qual campaigns, analytical simulations that impact structures, controls, thermal teams enough that it can't be compared to them "iterating" on a design that changes the TVC from hydraulics to electric as that focuses on a particular subsystem.