{
  "export": {
    "source": "https://urth.darkrealm.vip/thread/whorl/1472",
    "note": "Exported from an unofficial mirror of a public mailing list. Copyright in each message remains with the person who wrote it.  Email addresses are obscured as `user at host`, the form the original archive published. This file was rebuilt from parsed fields rather than retained headers, so it is faithful in content but not byte-exact.",
    "addresses": "obscured as 'user at host'"
  },
  "archive": "whorl",
  "thread": {
    "id": 1472,
    "subject": "Voyage of the Whorl: Calculations of Thrust, Distance",
    "messages": 1,
    "voices": 1,
    "first": "2001-09-04T09:15:08+00:00",
    "last": "2001-09-04T09:15:08+00:00"
  },
  "messages": [
    {
      "message_id": "<whorl-v0012-0916@digest.urth.net>",
      "from": {
        "name": "Michael Andre-Driussi",
        "address": "mantis at siriusfiction.com"
      },
      "date": "2001-09-04T09:15:08+00:00",
      "subject": "Re: (whorl) Voyage of the Whorl: Calculations of Thrust, Distance",
      "in_reply_to": null,
      "reply_link": null,
      "blocks": [
        {
          "kind": "text",
          "depth": 0,
          "text": "Travel back through time--Today!"
        },
        {
          "kind": "quote",
          "depth": 1,
          "text": "From \"Welcome Wombat\" 7 Sep 97, I wrote:\nRe: Whorl flight time.  It appears to have been 332 years subjective\ntime (III,173) and 1000 years objective time (III,242); which in turn\nsuggests an average speed of around .95 c (95% of light speed).  (Time\ncompression, doncha know.)"
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "Note that the compression is based on average speed, not peak speed.  This\nimplies, I think, a flight profile Boost/Glide/Boost.\n\nI compared a number of stardrives in \"Stardrive\" 3 Nov 98.  (I'd paste it\nin right here, but I'm too lazy to strip out the html coding.)\n\n(I also talked about the Whorl calendar somewhere, I think.)"
        },
        {
          "kind": "quote",
          "depth": 1,
          "text": "Talarican wrote:\nAssuming a \"Bussard ramjet-style\" 1/2 continuous acceleration, 1/2\ncontinuous deceleration flight profile, to calculate the necessary\nacceleration/deceleration and actual distance covered, the elapsed times\nwere divided in half, as the acceleration and deceleration phases are (ah,\nso Wolfean!) symmetrical."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "Your flight profile is Boost/Boost (acceleration/deceleration).\n\n[equations cut]"
        },
        {
          "kind": "quote",
          "depth": 1,
          "text": "{a'} was found to be equal to about 0.02026 gee, which gets you within about\na fortnight of exact. And if _that's_ not close enough, there's no more\nhelp, hope, or comfort _I_ can offer you. (especially since {t} and {t'}\naren't known to the nearest year anyway).\n\nTherefore, {d}= 2*{x} was 9.54 * 10^18 meters, or 309 parsecs, or 1008\nlight-years (as we'd expect);\nand {v[peak]} at turnover was 2.99 * 10^8 m/s, or 0.996 c.\n\nby way of comparison, using 2*{t} = 1000yr,\n{a'} ~ .0194 gee, {d} = 277 psc, {v[peak]} = 0.995c."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "Hmmm.  My guestimate is that with .02 gees constant acceleration it would\ntake about 50 years to reach NAFAL (nearly as fast as light); and the\ndistance covered in this time would be 25 light years.\n\nIf there is no Glide phase, therefore, the next boost will bring the ship\ndown to a rest . . . 25 light years further, and 50 years later.  Thus the\naverage speed is .5 c, and the total distance is 50 light years in 100\nyears.  The time comression at .5 c is too small for our purposes.\n\nSince you want the objective time to equal 1100 years, we can add a glide\nperiod of 1000 years.\n\n        Objective\nBoost     50 years\nGlide   1000 years\nBoost     50 years\nTOTAL   1100 years"
        },
        {
          "kind": "quote",
          "depth": 1,
          "text": "Talarican wrote:\nThe Bussard Ramjet, unfortunately, has one glaring limitation, provided you\ngrant that they and their vast \"ramscoops\" are even possible. A Bussard\nramjet's terminal velocity is said to limited by the resistance of the\ninterstellar gas against the ramscoop to about 0.90 c."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "The figures I read in THE STARFLIGHT HANDBOOK (one of my favorite books)\ngive 0.2c as being the top speed for an interstellar ion ramjet (I think\nI'll call 'em \"bramjets,\" myself).  Best models for the Whorl are (still)\nHainish drives ala Le Guin, Quantum/Vacuum jets (aka zero point) ala Clarke\nand Sheffield, possibly wormhole photon output, or maybe even tachyon drive\n(for that super exhaust velocity!).  These systems either \"live off the\nland\" or are otherwise magical (Hainish drives having no explanation given,\nother than being photon).\n\n=mantis=\n\n\nSirius Fiction\nHas Moved To\nhttp://www.siriusfiction.com/\n\n\n\n*This is WHORL, for discussion of Gene Wolfe's Book of the Long Sun."
        }
      ]
    }
  ]
}