Abstract: For the flying-panelin double parallel ERAs, the interaction between jet and doubleparallel ERAs can be devided into two phases. Before the collision with the middlepanel, the jet can be considered to interact with two single ERAs. But aftercollision, the jet is considered to interact with a single ERA. Based on themovement of the flying-panel, the collision time of the middle panelcan be obtained. Results of the simulation and experiment are in goodagreement.