2020 Work In Progress

The launch loop design is evolving, and the 2020 COVID year has kept me inside and at work. Like all engineering work, every problem solved unveils two more. Problems will keep accumulating for centuries after launch loops have connected the solar system, but by then there will be millions of engineeers solving new problems soon after they appear.

I hope those problems include healing the Earth, spreading adapted life to the edge of the solar system, cataloging the rest of the galaxy with vast arrays of orbiting instruments, and preparing for the slow but inevitable overheating of the Sun. In 2020, my focus is on making those problems easier to solve, not harder, by minimizing unwanted side effects.

One big problem will be rocket exhaust plumes - those should either reenter the Earth's atmosphere, or escape into the solar wind. Persistent plumes will tarnish optics, cause ram drag and erosion on space objects, and ionize and trap in the Earth's magnetic field. Trapped charges are diamagnetic, and can weaken the field and reduce its cosmic ray shielding effect.

The rotor and track will follow a curve from the 40 km west station, "over the top" near 80 km for vehicle release, then curving back down to a 40 km altitude east station. Lower stations means shorter elevators and less cable mass to support. Picture coming soon.

I am considering adding a pair of lower speed (3000 m/s ?) "helper loops" to support each station. That adds more pieces to fail, but the station no longer needs a deflection magnet on the main rotor itself, allowing the rotor/track to pass through at a steeper incline while reducing the incline "launch angle" at the surface. Since the height of the incline vertical deflection magnets is proportional to 1-cos(angle), which is proportional to angle squared for small deflections, reducing the angle saves a lot of vertical structure height near the surface.

The "evolutionary ancestor" of the helper loops will be the first suborbital loop, see DebrisIntercept .

Instead of using a suborbital loop supporting a big chemical rocket, it can instead use a velocity transformer track (as below) to magnetically launch many small (20 kg?) 25 gee vehicles into suborbital retrograde ballistic trajectories. 20 gees and 40 km is 3840 m/s + 430 m/s drag loss (WAG); if the exit is at a 60 degree angle, that is 3320 m/s vertical velocity, an apogee of 900 km, and a retrograde velocity of 1.28 km/s.

After launch, adjust the velocity with laser ablation thrust, from a laser platform suspended under the loop.

What's that good for? Launching a canister of expanding foam precisely in front of a derelict space object, slowing it down and deorbiting it after enough impacts. All earth-orbiting objects cross the equator twice per orbit; if one of those crossings

The Velocity Transformer Track replaces the wasteful, difficult "induction heat" track with magnet array motors on the vehicle sled that couple with very low slip to the iron rotor. That webpage is old, many changes and improvements in the works:

The sled will be longer and the sled magnets will be more spread out lengthwise, less flux wasted between neighboring magnets.

The loop pattern shown doesn't work efficiently, instead, each single sled-facing winding will be positioned with the same pitch as the wider-spaced sled magnets, but couple to only one longer winding facing the rotor, the width proportional to the ratio of rotor to vehicle speed.

The vehicle magnets will consist of a short section of "exciter magnets" and a long section of "motor magnets". The exciter magnets will "imprint" a synchronous magnetic field pattern onto the rotor, and the motor magnets will thrust against that imprinted field pattern. Keep in mind that the spatial frequency of the track must to match time frequency with the vehicle, and the time frequency of the vehicle will increase as it accelerates towards exit velocity.

The rotor will be divided into shorter copper-coil-wrapped sections. Each coil will have an optically triggered triac to short the coil and lock in the flux.

The vehicle sled has evolved, I haven't posted the new picture yet, but it looks more like a tobaggan, with a nose cone on the front. That nose cone could endure a LOT of stagnation point heating from the high altitude airstream. The sled gets the heavy nosecone, the vehicle nosecone is protected until release, at which point its supra-orbital-velocity radial acceleration ("centrifugal force" or "high radius Kepler orbit ellipse") sends it out into high vacuum in less than a minute.

I considered adding a

2020WIP (last edited 2020-11-13 04:20:52 by KeithLofstrom)