Thrust generation of a laser pulsejet with a conical nozzle has been studied. An impulse imparted by a laser‐induced blast wave to the conical nozzle was measured experimentally, and the computational analyses were performed to clarify the relationship between the nozzle configuration and the fluid motion. As a result, it was found that the optimum nozzle length was predictable for given blast wave energy conversion efficiency. The impulse was quite sensitive to the divergence angle of the nozzle. This sharp decrease is mainly due to the fluid motion during the refilling stage of the engine cycle. © 2004 American Institute of Physics