Normal jet engines can reach Mach 2.5
Hypersonic scram jets can start working at Mach 3.5
DARPA will make a hybrid engine. It will have a dual mode ramjet combined with a regular jet engine.
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, modeling, and other disciplines, DARPA believes this potentially groundbreaking achievement may finally be within reach
“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,” said Christopher Clay, DARPA program manager. “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, modeling, and other disciplines, we believe this potentially groundbreaking achievement may finally be within reach.”
AFRE aims to explore a turbine-based combined cycle (TBCC) engine concept, which would use a turbine engine for low-speed operations and a dual-mode ramjet—which would work efficiently whether the air flowing through it is subsonic (as in a ramjet) or supersonic (as in a scramjet)—for high-speed operations. The two components of the hybrid engine would share a common forward-facing air intake and rear-facing exhaust nozzle to release thrust.
AFRE aims to develop critical technologies and culminate in ground-based testing of a full-scale, integrated technology demonstration system. If that testing is successful, further development of the AFRE technology would require flight testing in a potential follow-on demonstration program.
Systems that operate at hypersonic speeds offer the potential for military operations from longer ranges with shorter response times and enhanced effectiveness compared to current military systems. Such systems could provide significant payoff for future U.S. operations, particularly as adversaries’ capabilities advance.
The AFRE program will be conducted in two phases.
Phase I will include AFRE system design and subscale and large scale component development and ground demonstration.
Phase II is anticipated to conduct a large-scale, integrated test series or freejet test of the integrated low speed and high speed flowpaths.
To familiarize potential participants with the technical objectives of AFRE, DARPA has scheduled a Proposers Day in advance of a planned Broad Agency Announcement (BAA). The Proposers Day will be held on Wednesday and Thursday, July 13 and 14, 2016 at the DARPA Conference Center in Arlington, Va. The event will run from 1:00 PM to 5:00 PM Eastern on July 13 and from 9:00 AM to 12:00 PM Eastern on July 14.
SOURCES - DARPA