Improvements in gas turbine engines

743,493. Gas turbine plant; jet propulsion plant. SOC NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION. March 10, 1953 [March 11, 1952], No. 6641/53. Addition to 728,451. Drawings to Specification. Class 110(3) A gas turbine engine as claimed in the parent Specification has combustion chambers of the short intermittently operating type as defined in Specification 743,492. These combustion chambers comprise a combustion chamber connected on one side to a valve or other non-return device for the admission of fresh air and communicating at the other side with an ejection tube which has insufficient length to provide self-filling of the chamber by pulsation of the ejected gases, the filling of the chamber being effected by a scavenging device which maintains, during normal operation of the unit, a total air pressure at the entry to the chamber which is always greater than the static obtaining at the outlet of the ejection tube. The particular embodiment described is similar to that described in the parent Specification except that means are provided to obtain a scavenging pressure drop across the combustion chambers. Means may also be provided to vary the frequency of operation of the combustion chambers.