3 ms·

I may be wrong but I think a ramjet doesn't need Mach 5 to ignite, Mach 3 to 6 is just where it is most efficient at high altitudes. E.g. early German experime

• belviewreview 5mo ago
  Ok, but the question still remains, how is it going to get up to the required speed? And in a way that is practical for a passenger plane?
  • flohofwoe 5mo ago
    I'm no aircraft engineer, but I guess it would use traditional jet engines to get up to some low Mach 1+ speed until the ramjet gets enough air to bite on. My bet is that this hasn't been done yet simply because it wouldn't be economical (the technology itself is a century old and has been tried over and over again), and that the 'civilian ramjet aircraft' is just a feel good story for what will end up as purely military usage, and most likely not in an airplane, but in missiles (there are a couple ramjet engine missiles in use already, like the European Meteor).
• trhway 5mo ago
  >https://en.wikipedia.org/wiki/Kronach_Lorin https://en.wikipedia.org/wiki/Kronach_Lorin coal burning ramjet! "It was initially proposed that a wire-mesh basket holding coal be mounted behind a nose air intake, protruding slightly into the airflow and ignited by a gas burner. [...] The air passing through the ramjet would take the gases from the burning coal ..."
  • flohofwoe 5mo ago
    Yes, not because it would be any better than the alternatives, but because this was one of countless "last ditch" efforts.