3 ms·

Andrew Cote gives the missing details here: https://twitter.com/Andercot/status/1763063321857757210 https://twitter.com/Andercot/status/1763063321857757210

by marze 3y ago

JumpCrisscross 3y ago
If it can truly "act as the first stage of a rocket," that's impressive--the most powerful jet engine ever built. If, instead, it will power a plane that will carry a rocket, that's a well-trodden path whose engineering problem is not particularly related to the carrier's efficiency. [1] https://en.wikipedia.org/wiki/Geared_turbofan https://en.wikipedia.org/wiki/Geared_turbofan
- deleted 3y ago
  [deleted]
- carabiner 3y ago
  GTF is exactly what it is. The fact that Andrew Cote missed this is a testament to his lack of familiarity with anything in aerospace.
  - modeless 3y ago
    Don't geared turbofans typically have a fixed gear ratio? This is more like a continuously variable transmission for a turbofan. Seems novel at least.
    - JumpCrisscross 3y ago
      > Don't geared turbofans typically have a fixed gear ratio? This is more like a continuously variable transmission for a turbofan Yes and no. An electric compressor doesn't mean the turbine doesn't drive the fan. (It might make pre-cooling easier.)
      - modeless 3y ago
        I just saw an interview with more detail and it sounded to me like they were going to have the turbine drive a generator powering an electric motor to drive the fan. Like a diesel electric locomotive. And this is supposed to allow it to transition from turbofan to turbojet to reach mach 2.7 to allow starting up a ramjet which launches the second stage to mach 5 before lighting its rocket engine. Not sure why none of that detail was mentioned here. https://youtu.be/Detvd2EqWWU https://youtu.be/Detvd2EqWWU
        JumpCrisscross 3y ago
        > the turbine drive a generator powering an electric motor to drive the fan Maybe the transmission losses aren't relevant if you're thrusting for a short interval? > transition from turbofan to turbojet to reach mach 2.7 to allow starting up a ramjet Oh. Cool. Sounds like an air turboramjet [1]. Plus a fan? Not sure how you ditch the fan, nor why they'd describe an electric motor driving the fan as an electric compressor. Granted, I skimmed the video. [1] https://en.wikipedia.org/wiki/Air_turborocket https://en.wikipedia.org/wiki/Air_turborocket
        modeless 3y ago
        The ramjet is on the second stage, separate from the turbofan/jet on the first stage. The loss in the electrical system should be pretty small, and they claim that they gain a lot of efficiency from being able to optimize the engine over the whole range from 0 to mach 2.7.

Andrew Cote gives the missing details here: https://twitter.com/Andercot/status/1763063321857757210 https://twitter.com/Andercot/status/1763063321857757210

by marze 3y ago

Andrew Cote gives the missing details here: https://twitter.com/Andercot/status/1763063321857757210 https://twitter.com/Andercot/status/1763063321857757210

JumpCrisscross 3y ago

If it can truly "act as the first stage of a rocket," that's impressive--the most powerful jet engine ever built. If, instead, it will power a plane that will carry a rocket, that's a well-trodden path whose engineering problem is not particularly related to the carrier's efficiency. [1] https://en.wikipedia.org/wiki/Geared_turbofan https://en.wikipedia.org/wiki/Geared_turbofan

deleted 3y ago
[deleted]
carabiner 3y ago
GTF is exactly what it is. The fact that Andrew Cote missed this is a testament to his lack of familiarity with anything in aerospace.
- modeless 3y ago
  Don't geared turbofans typically have a fixed gear ratio? This is more like a continuously variable transmission for a turbofan. Seems novel at least.
  - JumpCrisscross 3y ago
    > Don't geared turbofans typically have a fixed gear ratio? This is more like a continuously variable transmission for a turbofan Yes and no. An electric compressor doesn't mean the turbine doesn't drive the fan. (It might make pre-cooling easier.)
    - modeless 3y ago
      I just saw an interview with more detail and it sounded to me like they were going to have the turbine drive a generator powering an electric motor to drive the fan. Like a diesel electric locomotive. And this is supposed to allow it to transition from turbofan to turbojet to reach mach 2.7 to allow starting up a ramjet which launches the second stage to mach 5 before lighting its rocket engine. Not sure why none of that detail was mentioned here. https://youtu.be/Detvd2EqWWU https://youtu.be/Detvd2EqWWU
      - JumpCrisscross 3y ago
        > the turbine drive a generator powering an electric motor to drive the fan Maybe the transmission losses aren't relevant if you're thrusting for a short interval? > transition from turbofan to turbojet to reach mach 2.7 to allow starting up a ramjet Oh. Cool. Sounds like an air turboramjet [1]. Plus a fan? Not sure how you ditch the fan, nor why they'd describe an electric motor driving the fan as an electric compressor. Granted, I skimmed the video. [1] https://en.wikipedia.org/wiki/Air_turborocket https://en.wikipedia.org/wiki/Air_turborocket
        modeless 3y ago
        The ramjet is on the second stage, separate from the turbofan/jet on the first stage. The loss in the electrical system should be pretty small, and they claim that they gain a lot of efficiency from being able to optimize the engine over the whole range from 0 to mach 2.7.