[Aerkuld]

The V1 had a pulse jet with a series of flap valves on the inlet that hinged inwards. The inlet was much shorter and the flap valves were closed by combustion pressure and reopened by the air pressure generated by forward motion of the device. If I recall correctly, fuel was introduced when the flap valves were opened. When the mixture ignited the flap valves shut, forcing all the hot gas out the rear of the engine as thrust. This moved the device forward, which opened the flap valves, etc. The one above appears to have a tuned inlet length and no moving parts, so works on a somwhat different, but similar effect probably more like a put-put boat engine (I need to read the article don't I...)