Differences between revisions 17 and 18
 ⇤ ← Revision 17 as of 2022-01-24 17:12:42 → Size: 7802 Editor: KeithLofstrom Comment: ← Revision 18 as of 2022-01-24 17:13:50 → ⇥ Size: 7817 Editor: KeithLofstrom Comment: Deletions are marked like this. Additions are marked like this. Line 51: Line 51: * Be aware that lateral stability is described by eight coupled, fourth order, nonlinear partial differential equations. Without proper control, involving whole system measurement and optimization, these equations are unstable and diverge rapidly. I am still working on that. * Be aware that '''lateral stability''' is described by eight coupled, fourth order, nonlinear partial differential equations. Without proper control, involving whole system measurement and optimization, '''these equations can be unstable and diverge rapidly'''. I am still working on that.

# Short Intro

• 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
• Be aware that lateral stability is described by eight coupled, fourth order, nonlinear partial differential equations. Without proper control, involving whole system measurement and optimization, these equations can be unstable and diverge rapidly. I am still working on that.

• 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

### Destinations

• Launch rates for this "small" loop can be 400 tonnes per hour
• up to 3.5 million tonnes per year
• Stations in 23h56m geosync ConstructionOrbits can gather and assemble large missions, 100 tonnes per sidereal day

• 3 years is 110,000 tonnes per construction orbit, perhaps a fueled 60,000 tonne Aldrin Cycler
• A Stanford Torus for 10,000 inhabitants is projected to weigh 10 million tonnes

• Not any time soon; industrial infrastructure isn't easy
• ask the North Koreans, they have air, food, ores, and millions of people
• Space Solar Power Satellite Assembly

### 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 2022-01-24 17:28:20 by KeithLofstrom)