Falcon 1: second flight fails from second-stage oscillation

On 21 March 2007 the Falcon 1 flew for the second time from Omelek, carrying the DemoSat payload for DARPA and NASA. The first stage performed normally, but during separation the interstage fairing bumped the second-stage engine nozzle, triggering a roll oscillation worsened by propellant slosh in the LOX tank. The thrust vector control system could not damp it, the Kestrel engine shut down prematurely, and the vehicle was lost before reaching orbit.