4 ms·

That's insane. A 3d matrix of ferrite rings suspended by wire would seem (to me) somewhat sensitive to vibrations or gforces. Military gonna military I guess.

by Phlarp 7y ago

anyfoo 7y ago
The same technology was very successfully used to fly to the moon. Cores aren’t so much suspended when they are wholly embedded in epoxy.
- jackfraser 7y ago
  Stupid question, but the cores don't physically flip, do they? It's a purely electrical thing?
  - muzika 7y ago
    Yes
  - gattilorenz 7y ago
    It's the magnetic field that flips, the ferrite cores remain in place
  - m463 7y ago
    I think it's just clockwise vs counterclockwise.
dvdkhlng 7y ago
But on the other hand core memory is very resilient against EMP and hard radiation :)
alex_hitchins 7y ago
I seem to recall something along the lines of large bombers running valves as they were less prone to effects of EMP around nuclear blasts. Not sure if this perhaps something similar?
- jabl 7y ago
  In one of the documentaries about the Vulcan raid on the Falklands (1982), one of the pilots interviewed remarked that somebody flying Avro Lancasters in WWII would have felt right at home in the cockpit of the Avro Vulcan. E.g. the navigator used mechanical clocks to keep track of when to turn, and so on. Not sure if this was a conscious decision wrt EMP, or was it just that they were in a hurry to develop a jet bomber for delivering nukes and they reused existing stuff as much as possible.
  - NeedMoreTea 7y ago
    Not in the least surprising. The Vulcan prototype, the 707, first flew in 1949. They even had a mount for the old Lancaster bomb sight - though that was mostly used for a camera. Flight engineer and radar operator in the seats behind would have got the fancy new (for the early 50s) electronic things.
    - mhh__ 7y ago
      The Lancaster was loaded with the technology of the time by the end up the war e.g. they had radar navigation, radio navigation, (when it worked) a 'lock' detector for German night fighter radar
  - johncalvinyoung 7y ago
    Which documentary was this? I read Vulcan 607 about ten years ago and loved it.
    - jabl 7y ago
      I'm quite sure it's this one: https://www.youtube.com/watch?v=PBJ99bIhAVk https://www.youtube.com/watch?v=PBJ99bIhAVk
- rangibaby 7y ago
  From wiki for the MiG-25: The majority of the on-board avionics were based on vacuum-tube technology, not solid-state electronics. Although they represented aging technology, vacuum tubes were more tolerant of temperature extremes, thereby removing the need for environmental controls in the avionics bays. With the use of vacuum tubes, the MiG-25P's original Smerch-A (Tornado, NATO reporting name "Foxfire") radar had enormous power – about 600 kilowatts. As with most Soviet aircraft, the MiG-25 was designed to be as robust as possible. The use of vacuum tubes also made the aircraft's systems resistant to an electromagnetic pulse, for example after a nuclear blast
tirpen 7y ago
For airplanes flying at high altitudes with modern computers, random bit flips from comsmic radiation is actually a very real threat that has to be considered. IIRC there's about a factor of about 300x more radiation at 30000 ft and 900x at 60000 ft. Core memory is a lot less sensitive to this than most memory types, so it makes some sense to store the most flight critical data in such a memory.
- adrianN 7y ago
  The sensible way to deal with bit flips is a gratuitous amount of ECC.
  - akiselev 7y ago
    ECC doesn't help when you have an EMP caused by an atmospheric nuclear detonation. Those are the kinds of things the design has to consider.
    - devonkim 7y ago
      Makes me why we don’t count NASA under DoD similar to DARPA to help with their funding.
      - mikeash 7y ago
        NASA exists to be the civilian side of the US’s aerospace ventures. The military side is the Air Force.
        wolfgke 7y ago
        > NASA exists to be the civilian side of the US’s aerospace ventures. The military side is the Air Force. Not the Space Force? > https://www.buzzfeednews.com/article/briannasacks/trump-space-force https://www.buzzfeednews.com/article/briannasacks/trump-spac... ;-)
      - Kadin 7y ago

That's insane. A 3d matrix of ferrite rings suspended by wire would seem (to me) somewhat sensitive to vibrations or gforces. Military gonna military I guess.

by Phlarp 7y ago

That's insane. A 3d matrix of ferrite rings suspended by wire would seem (to me) somewhat sensitive to vibrations or gforces. Military gonna military I guess.

anyfoo 7y ago

The same technology was very successfully used to fly to the moon. Cores aren’t so much suspended when they are wholly embedded in epoxy.

jackfraser 7y ago
Stupid question, but the cores don't physically flip, do they? It's a purely electrical thing?
- muzika 7y ago
  Yes
- gattilorenz 7y ago
  It's the magnetic field that flips, the ferrite cores remain in place
- m463 7y ago
  I think it's just clockwise vs counterclockwise.

dvdkhlng 7y ago

But on the other hand core memory is very resilient against EMP and hard radiation :)

alex_hitchins 7y ago

I seem to recall something along the lines of large bombers running valves as they were less prone to effects of EMP around nuclear blasts. Not sure if this perhaps something similar?

jabl 7y ago
In one of the documentaries about the Vulcan raid on the Falklands (1982), one of the pilots interviewed remarked that somebody flying Avro Lancasters in WWII would have felt right at home in the cockpit of the Avro Vulcan. E.g. the navigator used mechanical clocks to keep track of when to turn, and so on. Not sure if this was a conscious decision wrt EMP, or was it just that they were in a hurry to develop a jet bomber for delivering nukes and they reused existing stuff as much as possible.
- NeedMoreTea 7y ago
  Not in the least surprising. The Vulcan prototype, the 707, first flew in 1949. They even had a mount for the old Lancaster bomb sight - though that was mostly used for a camera. Flight engineer and radar operator in the seats behind would have got the fancy new (for the early 50s) electronic things.
  - mhh__ 7y ago
    The Lancaster was loaded with the technology of the time by the end up the war e.g. they had radar navigation, radio navigation, (when it worked) a 'lock' detector for German night fighter radar
- johncalvinyoung 7y ago
  Which documentary was this? I read Vulcan 607 about ten years ago and loved it.
  - jabl 7y ago
    I'm quite sure it's this one: https://www.youtube.com/watch?v=PBJ99bIhAVk https://www.youtube.com/watch?v=PBJ99bIhAVk
rangibaby 7y ago
From wiki for the MiG-25: The majority of the on-board avionics were based on vacuum-tube technology, not solid-state electronics. Although they represented aging technology, vacuum tubes were more tolerant of temperature extremes, thereby removing the need for environmental controls in the avionics bays. With the use of vacuum tubes, the MiG-25P's original Smerch-A (Tornado, NATO reporting name "Foxfire") radar had enormous power – about 600 kilowatts. As with most Soviet aircraft, the MiG-25 was designed to be as robust as possible. The use of vacuum tubes also made the aircraft's systems resistant to an electromagnetic pulse, for example after a nuclear blast

tirpen 7y ago

For airplanes flying at high altitudes with modern computers, random bit flips from comsmic radiation is actually a very real threat that has to be considered. IIRC there's about a factor of about 300x more radiation at 30000 ft and 900x at 60000 ft. Core memory is a lot less sensitive to this than most memory types, so it makes some sense to store the most flight critical data in such a memory.

adrianN 7y ago
The sensible way to deal with bit flips is a gratuitous amount of ECC.
- akiselev 7y ago
  ECC doesn't help when you have an EMP caused by an atmospheric nuclear detonation. Those are the kinds of things the design has to consider.
  - devonkim 7y ago
    Makes me why we don’t count NASA under DoD similar to DARPA to help with their funding.
    - mikeash 7y ago
      NASA exists to be the civilian side of the US’s aerospace ventures. The military side is the Air Force.
      - wolfgke 7y ago
        > NASA exists to be the civilian side of the US’s aerospace ventures. The military side is the Air Force. Not the Space Force? > https://www.buzzfeednews.com/article/briannasacks/trump-space-force https://www.buzzfeednews.com/article/briannasacks/trump-spac... ;-)
    - Kadin 7y ago