> No. Overture will fly without the use of afterburners, meeting the same strict regulatory noise levels as the latest subsonic airplanes. The airliner will be powered by the Symphony propulsion system. Symphony will be a medium-bypass turbofan engine designed and optimized for environmentally and economically sustainable supersonic flight.
> ... meeting the same strict regulatory noise levels as the latest subsonic airplanes
Extremely dishonest: as far as I can tell (CFR title 14, B36.5) there are no specific noise level regulations for subsonic cruise flight (i.e. not take-off and landing) because you can't hear subsonic aircraft at cruise altitude. On the other hand, however, you will be able to hear sonic booms.
It's intentionally misleading, they are technically saying they will meet the takeoff and landing requirements (which they are required to meet by law) but implying that the plane is going to be quiet at cruise (which they want to perform over the continental United States, not just over the ocean).
Moreover, their statement falsely suggests that Concorde does not "[meet] the same strict regulatory noise levels as the latest subsonic airplanes" but 36.301 says that Concorde also has to meet the same standards as subsonic planes (standards which exclude operation at cruise which didn't matter for Concorde because it was over the Atlantic).
The SR-71 engine is a weird beast operating like both a ramjet and turbojet due shaping the flow and injecting fuel in the air stream.
A ramjet [1] stays efficient at high speeds even though it on the outside kind of looks like an afterburner.
It was a conventional afterburning turbojet for take-off and acceleration to Mach 2 and then used permanent compressor bleed to the afterburner above Mach 2. The way the engine worked at cruise led it to be described as "acting like a turboramjet".
The afterburner on the SR-71's engine is being fed super-compressed bypass air from the intake. It can ignite the exhaust with comparatively minuscule amounts of fuel when compared to a regular turbojet.
At speeds beyond Mach 3, you don't even need fuel to ignite the oxygen. The simple friction and drag of the airframe is enough to ignite the oxygen around it and surround the aircraft with superheated plasma.
