Zygmunt Fonberg, was designer ramjets. There is information at the Nasm with reference Fot. (BF-599900-20).

From Appendix 6: Zygmunt Fonberg designed propulsion ducts to be installed on the ends of light helicopter rotors.

“Fonberg, the taller one with his engine” (PiP=ps)

-Clearly a ramjet, that we see below starting and in operation.

"Two photos of a running Fonberg ramjet"

-With regard to its application we see its assembly on the main rotor of a helicopter and at the blade tips of an airplane propeller.

“Two examples of Fonberg applications” (PiP)