This invention relates to apparatus for use in effecting the combustion of a mixture of a liquid fuel and a liquid oxidizing agent. The invention further relates to the provision of combustion apparatus of very light weight, which is thereby adapted for use in self-propelled rockets and in other aircraft in which unnecessary weight must be eliminated. More specifically, my invention relates to that type of combustion apparatus in which one of both of the liquids which supports combustion are utilized as cooling agents for the combustion chamber walls. One form of such apparatus is shown in my prior Patent No. 2016921, issued October 8, 1935. It is the general object of my invention to improve the construction shown in my prior patent, to th...