3 ms·

The reason that dead reckoning was inaccurate was because of clock and vector inaccuracies. Looking at the advances in clockpieces and gyroscopes (both of these

The reason that dead reckoning was inaccurate was because of clock and vector inaccuracies. Looking at the advances in clockpieces and gyroscopes (both of these has benefitted over the optical revolution) over the years, I am not shocked that dead reckoning is back in vogue.

cameldrv 2y ago
Dead reckoning is also inaccurate due to unknown winds. Even if you take off with the best available forecast, it’s often wrong by 5mph+. After three hours your position is off by 15 miles. That’s not remotely good enough for most aviation purposes.
- t0mas88 2y ago
  Dead reckoning based on heading and time alone, but if you have a good INS it's not affected by wind only by accuracy of the gyroscopes/sensors. Current systems drift by about 0.5 miles per hour. And that's normal commercial grade systems, I'm sure the military has an option for better systems if they need them.
- deleted 2y ago
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- zinekeller 2y ago
  As t0mas88 said, you don't rely on the measured speed of the aircraft/ship, you rely on gyroscopes (which are much more resistant to external factors), and both clocks and gyroscopes have improved signifcantly (clocks are now better than cesium atoms - read about atomic clocks) and so are gyroscopes (again, optical gyroscopes that are miles better than mechanical ones).
  - fanf2 2y ago
    Portable clocks are not better than static caesium clocks, and optical clocks which are better than caesium clocks are not portable.
    - zinekeller 2y ago
      Eh, not smartphone-like portable, sure, but publicly (https://english.kyodonews.net/news/2025/03/c0945eb14bb6-japans-shimadzu-launches-worlds-1st-commercial-optical-lattice-clock.html https://english.kyodonews.net/news/2025/03/c0945eb14bb6-japa...) it can now be fitted on a ship or submarine (and I won't be surprised if there is classified miniturization out there).

cameldrv 2y ago

Dead reckoning is also inaccurate due to unknown winds. Even if you take off with the best available forecast, it’s often wrong by 5mph+. After three hours your position is off by 15 miles. That’s not remotely good enough for most aviation purposes.

t0mas88 2y ago
Dead reckoning based on heading and time alone, but if you have a good INS it's not affected by wind only by accuracy of the gyroscopes/sensors. Current systems drift by about 0.5 miles per hour. And that's normal commercial grade systems, I'm sure the military has an option for better systems if they need them.
deleted 2y ago
[deleted]
zinekeller 2y ago
As t0mas88 said, you don't rely on the measured speed of the aircraft/ship, you rely on gyroscopes (which are much more resistant to external factors), and both clocks and gyroscopes have improved signifcantly (clocks are now better than cesium atoms - read about atomic clocks) and so are gyroscopes (again, optical gyroscopes that are miles better than mechanical ones).
- fanf2 2y ago
  Portable clocks are not better than static caesium clocks, and optical clocks which are better than caesium clocks are not portable.
  - zinekeller 2y ago
    Eh, not smartphone-like portable, sure, but publicly (https://english.kyodonews.net/news/2025/03/c0945eb14bb6-japans-shimadzu-launches-worlds-1st-commercial-optical-lattice-clock.html https://english.kyodonews.net/news/2025/03/c0945eb14bb6-japa...) it can now be fitted on a ship or submarine (and I won't be surprised if there is classified miniturization out there).