GE Aerospace Successfully Develops and Tests New Hypersonic Dual-Mode Ramjet

Original Article ↗ Hacker News Discussion ↗

GE Aerospace’s successful test of a hypersonic dual‑mode ramjet engine prompts debate over its likely military applications, such as missiles, drones, and potential SR‑72‑type reconnaissance platforms, rather than any role in civilian aviation. Commenters explain how dual‑mode ramjets bridge supersonic and hypersonic flight regimes, why hypersonic speeds pose extreme thermal and control challenges, and how such systems differ from traditional ballistic missiles. The conversation also situates the technology in a broader geopolitical and industrial context, contrasting US, Russian, and Chinese progress on hypersonic weapons and noting the immense barriers to entry in commercial aircraft and engine development.

Civil aviation, fuel efficiency, and industrial base

  • Several comments argue that fuel efficiency dominates commercial aviation decisions; inefficient jets are hard to sell given thin airline margins.
  • Others counter that airframe makers don’t build engines and mostly depend on a tiny set of engine OEMs; competitiveness is constrained more by industrial scale, safety reputation, and integration than by fuel-burn know‑how alone.
  • Discussion notes the difficulty new entrants face (Japan’s canceled Mitsubishi SpaceJet, Ukraine’s lost Antonov/Motor Sich capacity). Embraer is seen as technically capable but financially constrained, with Bombardier’s C‑Series saga cited as a warning.

Russia/China airliners and economies

  • Russia’s SSJ‑100, MS‑21, Tu‑204/214 programs are described as reliant on Western parts, now being “russified” with older, less efficient domestic tech. Reliability and crash history of SSJ‑100 are criticized.
  • China’s COMAC C919 is flying domestically and seeking EASA certification; engine technology is still catching up, with a domestic CJ‑1000A program mentioned.
  • There is debate over Russia’s economic strength: PPP GDP and low debt vs heavy war spending, sanctions, inflation, and constrained borrowing. Several commenters argue current growth is war‑driven and not durable.

Supersonic vs hypersonic flight

  • Supersonic civil flight is considered effectively dead due to sonic boom regulations, limited viable routes, and economics rather than pure technology. Concorde/Tu‑144 are used as historical examples.
  • Hypersonic (≈Mach 5+) is differentiated from supersonic by extreme heating, different aerodynamics, and the need for specialized propulsion (ramjets/scramjets).

Hypersonic weapons and defenses

  • One view: Russia is ahead with operational hypersonic missiles (e.g., Kinzhal); hypersonics are hard to intercept and enable maneuvering at very high speed.
  • Counter‑view: many “hypersonic” systems are just fast ballistic or quasi‑ballistic missiles; speed alone isn’t new, maneuverability is limited by materials, and Ukraine has intercepted many with existing air defenses.
  • Some assert the US has long-running hypersonic R&D and downplays its capabilities.

GE dual‑mode ramjet and rotating detonation

  • The dual‑mode ramjet is seen as mainly relevant to missiles, drones, or a speculative SR‑72‑type platform; manned hypersonic aircraft are viewed as impractical.
  • Commenters are impressed by the claimed 11‑month development but suspect it built on prior work at an acquired specialist firm and years of internal RDE research.
  • Dual‑mode is explained as operating across supersonic and hypersonic regimes, though it still requires another system to accelerate to initial supersonic speed.