THERE is no reason, Mr. Fedden predicts, why single-sleeve-valve aero engines should not eventually supplant completely existing types equipped with poppet valves with their inherent fundamental problems, especially for military and commercial craft.
The single sleeve valve has now passed from the experimental to the production stage with hundreds flowing through the Bristol factory, and the author sees ahead a vast field of research yet to be explored.
Among the nineteen inherent advantages claimed for the sleeve-valve engine over the poppet-valve type by Mr. Fedden are quieter operation, higher compression ratio with its attendant benefits, absence of maintenance except for plugs and magneto servicing, and complete enclosure of all working parts. Data comparing the two types are given in detail.
The paper starts by giving a historical background of the sleeve-valve internal combustion engine from 1905 when Charles Y. Knight first began work; then carries on with the development by different groups until the Bristol Co. entered the field.
Then follows a résumé of Bristol single-cylinder research, and subsequent main-engine development, giving particulars of type tests together with flight-testing of the Bristol sleeve-valve engines. The author announces that more than 10,000 hr. of main-engine running and flying have been attained on the Bristol sleeve-valve types to date.