> DARPA confirmed plans on Aug. 26 to launch development of a High-Mach Gas Turbine (HMGT) engine, seeking to create the low-speed propulsion module for a planned hypersonic Next Generation Responsive Strike (NextRS) demonstrator aircraft.https://aviationweek.com/defense/aircraft-propulsion/high-mach-turbine-moves-forward-darpa-hypersonic-plane
Is this the variable cycle engine?
>>64188758Different thing. The variable cycle engine for Air Force NGAD is focused on allowing efficient cruise and better cooling while being able to shift into a high performance mode with similar or better thrust to current engines when the situation demands. Also better power generation I think. From what I read GE is pitching two different engine concepts for this project that are different ways to achieve the goal of allowing an aircraft to go hypersonic without needing a separate rocket to boost it to ramjet speeds first. It’s a bit high concept for me but one of them basically has a regular turbine engine that somehow gets it to that speed and starts up a ramjet, while the other is more exotic. Not the best explanation I know but that’s the just of what they’re doing as far as I understand it.
>>64188758Nah, it's a jet engine with very high turbine inlet temp, probably also a fully supersonic turbine, which dumps efficiency but it's the only way you can get around the heat issue. Previously these engines were generally designed to milk everything they can out of their components as they were intended for munitions, so they could get away with the turbine destroying itself, but I guess DARPA wants more and wants an engine with an actual service life measured in hours. Best guess is they're betting on some kind of giga fancy SiC-SiC turbine with complex internal geometry to make it possible.
>>64188905I'm pretty sure the HMGTs aren't supposed to be the classical bypass type turboramjets, but like proper turbine engines that can function in that regime
>>64188931I’m not a subscriber so I can only read the intro blurb but they put up another article describing it as a TBCC engine, which as best I can tell functions how I described it. Could always be wrong though, it’s a bit out of my wheelhouse. https://aviationweek.com/defense/aircraft-propulsion/ge-executive-names-designations-new-tbcc-propulsion-systems
>>64189052The TBCC is the entire propulsion system, the HMGT is a subcomponent of the propulsion system, not the entire system, the ramjet is its own thing.
>>64189078Ah gotcha, so the articles are about the component engines to be combined to create the whole system then?
>>64189082yes, the whole all-in-one concept has generally fallen out of favor, it's not really all that much different volumetrically speaking to wrap the ramjet around the engine vs. having separate flowpaths
>>64188910You don't use a turbo engine for hypersonic speed. Above Mach 3 the intake compression is higher than any current gas turbine, including prototypes. All +M3.0 aircraft relied on a combined gas turbine + turbineless engine like ramjets/or supersonic ramjets.
>>64189110I'm not saying they're gonna solely use the HMGT engine for cruise you numbnuts, they want a turbine engine that can reach ramjet starting speeds with margin to spare and won't burn itself down while doing it
>>64188905GE really makes everything huh
>>64189138There's only two engine companies state side (that matter), GE and Pratt, of course they basically do everything.
>>64189138Except when there’s a contract for a new military jet. Pratt always seems to win those even when GE seems to have the better offer looking from the outside
>>64189250The GE designs are generally more technologically advanced but seen as less mature and more risky options. That being said the F404/414 and F110 families are still going strong on the military side
