Differences between revisions 11 and 12
Revision 11 as of 2019-01-15 07:05:59
Size: 7470
Comment:
Revision 12 as of 2019-01-15 07:06:37
Size: 7522
Comment:
Deletions are marked like this. Additions are marked like this.
Line 104: Line 104:
 * Not directly associated with launchloop ... yet

Short Intro

MoreLater, work in progress, links will be added

  • Launch loops are assembled over and float the ocean for safety and security

    • A good place is 8 degrees south, 120 degrees west, west of Ecuador and south of San Diego
      • The "most boring weather in the world" according to one meteorologist
  • Launch vehicles will travel on a magnetically levitated and coupled sled

    • Aerodynamically shaped launch vehicles are 5000 kg, and ride above a 2000 kg magnet sled
    • Magnet sleds (perhaps 50 meters long) couple to the rotor through a velocity transformer track

    • Magnet sleds will use a lot of expensive Neodymium magnets
      • Nanostructured iron nitride may be a cheap, earth-abundant replacement someday; theoretical for now
    • After payload release, sleds are decelerated, retested, repaired, and reused
  • Launch loops must be very long

    • at 30 m/s² (≈ 3 gees) payload acceleration to 11.1 km/s exit velocity:
      • 370 seconds of acceleration, and a 2053 km launch path.
    • at 150 m/s² (≈ 15 gees), the empty sled stops in 74 seconds over 411 km
    • A 2500 km launch path means a 6000 km total rotor length
  • The launch loop rotor masses 3 kg/m, with a 4 cm hexagonal cross section

    • Each hexagonal is a row of iron-faced bolts, each perhaps 10 meters long.

  • Loop failure

    • The entire rotor stores almost 2e15 joules
      • A "1 megaton" bomb releases 4.2e15 joules instantly
    • The rotor circulates in 430 seconds
    • The rotor "power rate" is 4100 GW
      • A failing launch loop releases some rotor at the point of failure
      • most will be deflected and fanned into the ocean at two places, boiling a LOT of seawater fast

    • some material may be thrown into Earth escape orbit
    • a very small amount of material will re-enter
    • the bolts should be designed to disintegrate into small fragments during re-entry or ocean penetration
  • The launch loop track and stabilization cables mass 6.5 kg/m

    • the track contains velocity transformer coils, which couple sled magnets to the rotor
  • Stabilization cables to the surface transmit N/S and radial forces

    • cables must be aluminum-sheathed to carry lightning strokes
      • perhaps they can be actively charged to "cloud neutrality", but this seems unlikely
  • Launch loop launch altitude is 80 km

    • Post-release payload drag and blunt nose heating will be significant but not extreme
    • The tenuous atmosphere above 80 km will de-orbit smaller (and hard to track) space debris
      • Larger debris objects must be dodged or intercepted.
  • Launch loop inclines descend from the tracks to turnaround ambits at the ends

    • an upwards curve supports "west station" at 30 km altitude
    • the inclines enter upward deflector structures at the ocean surface at a 20 degree angle

    • presuming a 6 km turn radius, and a 100 meter superstructure:
      • the deflector structures will descend 300 meters below the ocean surface
      • they will deflect the rotor back up to 50 meters below the surface and wave agitation
      • they will be able to release a failing rotor into the ocean floor
  • The return track will also be at altitude

    • the return track will support most of the stabilization cable mass
    • the return track can provide backup power (through optical fiber) to the track above
    • the return track can be an additional reference platform for stability
    • it will help support west station:
  • West station will be on the upward eastward incline at 30 km altitude

    • This is above lighting and most of the wind loading
    • multiple vibration-powered elevator cables will carry vehicles up to west station

    • vehicles will be loaded onto magnet sleds and accelerated on a 5 km coilgun catapult to 500 m/s at west station
      • Power levels of 100 MW will be needed at the end of the catapult, 2MW per meter for 100 milliseconds
      • Power will be transferred from the rotor "somehow"
    • vehicles+sleds will undergo some brief "shake tests" to verify the sled release is working right
  • Launch loop ambits will deflect six "tracks" of separated bolts

    • turn radius estimated 6000 meters
    • The ambits will have GW power plants and 10 km long linear motors
    • The ambits will be associated with "spare bolt racetracks"
      • These will also store burst power
    • High speed inspection stations will photograph each bolt at speed, to micrometer resolution
    • Bolt measurements will be "synopsized" by large parallel computers, and compared to previous measurements
      • Significant changes will cause a bolt to be diverted into a "used bolt racetrack
    • The ambits and deflection magnets will resemble a low-tech version of the Large Hadron Collider

      • Loop design will shamelessly steal technologies and best practices from LHC
      • If no particles are discovered after the Higgs, thousands of brilliant technicians may be available
  • Launch loops require Server Sky constellations overhead

    • Providing redundant and precision interferometric positioning to the loop controllers
    • Providing redundant whole system control in case of failure
    • Capturing diagnostic information for modelling and optimization
    • Tracking vehicles and managing orbital traffic
    • Tracking incoming debris objects and planning mitigations

Power Storage

  • At realistic launch market growth rates, it will be decades before launch loops are profitable

    • Space solar power has been just around the corner for half a century

    • Missions to Mars will be robotic, and humans can't compete economically
    • Mars will never be a practical "second Earth" (the asteroids might).
    • Deep space missions to deflect asteroids are way too expensive
    • Asteroid mining missions are proposed only by non-geologists and non-miners
    • We will do all of these things someday, but advocates must first start talking economic sense.
  • Grid scale energy storage is an urgent need

    • Grid demand varies hourly and seasonally
    • Wind and solar is intermittent and unpredictable
    • Nuclear is steady but not "peakable"
    • Carbon fuel stinks
  • Loop technology can store huge amounts of power

    • The fast loop described above stores 500 GW-hours
    • A slower, heavier loop running at 7900 m/s will "orbit" in its tunnel without vertical deflection forces
      • A kilogram of 7.9 km/s rotor stores 17 kWh.
      • Cycled 200 times per year, buying power at \$3/MWh and selling at \$10/MWh, a kilogram earns \$24 per year
      • purchase and automated forming cost might be \2 per kg ... ≫≫profit!≪≪

    • Most of the system losses are in the ambits; a longer "straightaway" adds storage with little loss
      • power storage loops can span the Pacific Ocean, time-shifting power across 10 time zones.
    • Much heavier rotors can store more energy
    • Power storage rotors can be simpler and safer than launch rotors
  • Lessons learned from power storage will speed the design of launch loops

  • Manufacturing lines for power storage can be used to build launch loops

Small experimental power storage loops are being built in Finland in 2018

  • Not directly associated with launchloop ... yet

ShortIntro (last edited 2019-01-15 07:39:38 by KeithLofstrom)