The US Defense Advanced Research Projects Agency (DARPA) is seeking to develop a new aircraft propulsion system that could operate at hypersonic speeds.
The Advanced Full Range Engine (AFRE) programme aims to develop the propulsion system based on a turbine-based combined cycle (TBCC) engine concept.
Combining a turbine engine for low-speed operations and a dual-mode ramjet will offer the potential for military operations from longer ranges with shorter response times and enhanced effectiveness compared to current military systems.
The new system could bridge the gap between the Mach 2.5 top speed of a turbine engine and the Mach 3-3.5 minimum speed for a ramjet engine.
DARPA programme manager Christopher Clay said: "Instead of designing an entirely new kind of engine, we're envisioning an inventive hybrid system that would combine and improve upon the best of off-the-shelf turbine and ramjet / scramjet technologies.
"This won't be the first time that ambitious engineers will attempt to combine turbine and ramjet technologies.
"But with recent advances in manufacturing methods, modelling, and other disciplines, we believe this potentially groundbreaking achievement may finally be within reach."
The AFRE will develop critical technologies and conduct ground-based testing of a full-scale, integrated technology demonstration system.
Upon successful completion of the testing, the AFRE technology would undergo flight testing in a potential follow-on demonstration programme.
DARPA will call for tenders from potential bidders for the programme on 13 and 14 July this year.