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Some context for non-hockey fans: "A good hockey player plays where the puck is. A great hockey player plays where the puck is going to be." - Wayne Gretzky

InclinedPlane 14y ago
Let's continue this digression. Fun fact I learned recently about guided missiles (I have diverse interests), modern ones don't adjust to aim directly at the target, they adjust to keep the target at the same relative angle (the same position on the imager). This has the effect of leading the target and flying an intercept course instead of a following course, which is more efficient and effective.
- mpyne 14y ago
  Interestingly, the fun fact is something any mariner could have told a missile designer. We call it CBDR; Constant [relative] Bearing, Decreasing Range. Stay in CBDR for long enough and you're pretty much guaranteed a collision.
  - kevinconroy 14y ago
    I heart comment chains like these. Thanks for the wonderful side trip of interesting but unrelated facts!
  - marklabedz 14y ago
    Dogs catching frisbees employ a similar methodology: http://digitalunion.osu.edu/r2/summer06/maynor/journal_articles/Dogs%20Catching%20Frisbees.pdf http://digitalunion.osu.edu/r2/summer06/maynor/journal_artic...
- arethuza 14y ago
  This video of the Sprint ABM missile (0 to Mach 10 in 5 seconds!) shows it intercepting a ICBM RV in a test - given the speed of the RV it does look like the missile is aiming where the RV is going to be rather than where it is - and this is from the 1970s: http://www.youtube.com/watch?v=msXtgTVMcuA http://www.youtube.com/watch?v=msXtgTVMcuA
  - InclinedPlane 14y ago
    Another fun fact, the Sprint's first stage only fired for 1.2 seconds.
- dubya 14y ago
  To get back to sports, this is also how outfielders (in baseball) catch fly balls: http://psychology.clas.asu.edu/files/2002_JEP-HPP%28UncatchableBalls%29.pdf http://psychology.clas.asu.edu/files/2002_JEP-HPP%28Uncatcha...
- Gravityloss 14y ago
  Umm, "modern ones"? Meaning practically the first one, Sidewinder: http://en.wikipedia.org/wiki/AIM-9_Sidewinder#History http://en.wikipedia.org/wiki/AIM-9_Sidewinder#History "The Sidewinder also included a dramatically improved guidance algorithm. The Enzian attempted to fly directly at its target, feeding the direction of the telescope into the control system as it if were a joystick. This meant the missile always flew directly at its target, and under most conditions would end up behind it, "chasing" it down. This meant that the missile had to have enough of a speed advantage over its target that it did not run out of fuel during the interception. The Sidewinder is not guided on the actual position recorded by the detector, but on the change in position since the last sighting. "
  - InclinedPlane 14y ago
    By "modern" I mean a subset of systems which excludes first generation systems as well as some second and other generation systems, it's generally just simpler to say "modern" than be more specific. If I said "modern computers use integrated circuits" the timeline of modernity would be clear, I don't mean state of the art, just not archaic.
    - badgar 14y ago
      > By "modern" I mean a subset of systems which excludes first generation systems as well as some second and other generation systems The word you're looking for is "mature."
      - InclinedPlane 14y ago
        Maturity of a technological system to me implies a plateau of design, but that's not the case in missile guidance. Current generation systems are significantly more advanced and more capable than previous generation systems.
        Gravityloss 14y ago
        Yes, sorry for nitpicking but I just think that the word choice was perhaps not good. I'd think modern missiles means something much more recent easily, when this is talking about something practically existent for the whole development time of missiles. Sidewinder development was started in 1946.
ams6110 14y ago
Actually a good hockey player plays his position, so he is where he needs to be when his teammate gets the puck.
FigBug 14y ago
Except Walter said it, not Wayne. And it was advice for junior players, not pros.
johncoltrane 14y ago
Not strictly a Hockey thing. Try playing Space Invaders "where the invader is"…

InclinedPlane 14y ago

Let's continue this digression. Fun fact I learned recently about guided missiles (I have diverse interests), modern ones don't adjust to aim directly at the target, they adjust to keep the target at the same relative angle (the same position on the imager). This has the effect of leading the target and flying an intercept course instead of a following course, which is more efficient and effective.

mpyne 14y ago
Interestingly, the fun fact is something any mariner could have told a missile designer. We call it CBDR; Constant [relative] Bearing, Decreasing Range. Stay in CBDR for long enough and you're pretty much guaranteed a collision.
- kevinconroy 14y ago
  I heart comment chains like these. Thanks for the wonderful side trip of interesting but unrelated facts!
- marklabedz 14y ago
  Dogs catching frisbees employ a similar methodology: http://digitalunion.osu.edu/r2/summer06/maynor/journal_articles/Dogs%20Catching%20Frisbees.pdf http://digitalunion.osu.edu/r2/summer06/maynor/journal_artic...
arethuza 14y ago
This video of the Sprint ABM missile (0 to Mach 10 in 5 seconds!) shows it intercepting a ICBM RV in a test - given the speed of the RV it does look like the missile is aiming where the RV is going to be rather than where it is - and this is from the 1970s: http://www.youtube.com/watch?v=msXtgTVMcuA http://www.youtube.com/watch?v=msXtgTVMcuA
- InclinedPlane 14y ago
  Another fun fact, the Sprint's first stage only fired for 1.2 seconds.
dubya 14y ago
To get back to sports, this is also how outfielders (in baseball) catch fly balls: http://psychology.clas.asu.edu/files/2002_JEP-HPP%28UncatchableBalls%29.pdf http://psychology.clas.asu.edu/files/2002_JEP-HPP%28Uncatcha...
Gravityloss 14y ago
Umm, "modern ones"? Meaning practically the first one, Sidewinder: http://en.wikipedia.org/wiki/AIM-9_Sidewinder#History http://en.wikipedia.org/wiki/AIM-9_Sidewinder#History "The Sidewinder also included a dramatically improved guidance algorithm. The Enzian attempted to fly directly at its target, feeding the direction of the telescope into the control system as it if were a joystick. This meant the missile always flew directly at its target, and under most conditions would end up behind it, "chasing" it down. This meant that the missile had to have enough of a speed advantage over its target that it did not run out of fuel during the interception. The Sidewinder is not guided on the actual position recorded by the detector, but on the change in position since the last sighting. "
- InclinedPlane 14y ago
  By "modern" I mean a subset of systems which excludes first generation systems as well as some second and other generation systems, it's generally just simpler to say "modern" than be more specific. If I said "modern computers use integrated circuits" the timeline of modernity would be clear, I don't mean state of the art, just not archaic.
  - badgar 14y ago
    > By "modern" I mean a subset of systems which excludes first generation systems as well as some second and other generation systems The word you're looking for is "mature."
    - InclinedPlane 14y ago
      Maturity of a technological system to me implies a plateau of design, but that's not the case in missile guidance. Current generation systems are significantly more advanced and more capable than previous generation systems.
      - Gravityloss 14y ago
        Yes, sorry for nitpicking but I just think that the word choice was perhaps not good. I'd think modern missiles means something much more recent easily, when this is talking about something practically existent for the whole development time of missiles. Sidewinder development was started in 1946.

ams6110 14y ago

Actually a good hockey player plays his position, so he is where he needs to be when his teammate gets the puck.

FigBug 14y ago

Except Walter said it, not Wayne. And it was advice for junior players, not pros.

johncoltrane 14y ago

Not strictly a Hockey thing. Try playing Space Invaders "where the invader is"…