You cannot build a full-scale rocket and "see if it breaks" during the design phase. This is where come in.
While the full textbook is a copyrighted publication, several academic and technical papers by the authors provide similar foundational data: Dynamics and Simulation of Flexible Rockets | ScienceDirect dynamics and simulation of flexible rockets pdf
If you’ve ever seen a high-speed video of a large launch vehicle during ascent, you’ll notice the vehicle isn't perfectly straight. Those deflections—caused by thrust oscillations, wind shear, and control surface movements—can couple disastrously with the guidance and control system if not modeled correctly. You cannot build a full-scale rocket and "see
That’s where come in.
The most dangerous consequence of flexibility is CSI. The flight control system (FCS) uses gyroscopes and accelerometers to measure body rates. If a structural bending mode has a frequency close to the rigid-body control bandwidth, the FCS may interpret the bending as an attitude error and command the engines to correct it. This creates a positive feedback loop, leading to rapid structural divergence and vehicle breakup. Classic examples include early Titan II and Atlas-Centaur flights, which suffered from severe bending mode coupling. The flight control system (FCS) uses gyroscopes and