spinlaunch but in LEO

[cAsE-sEnSlTivE]

I've taken the Spinlaunch concept and put it in LEO which gave it several advantages:

- no friction
- solar powered electric motor can be weak and take its time spinning up the payload
- payload can be connected by carbon fiber tether instead of rigid rod
- payload doesn't have to fly through atmosphere
- because the tether can be very long the g-force acting on the payload is low even at high tangential velocities
-velocity of 1 km/s with a 1 km long tether results in only 1000 g-force acting on the payload  (comparable to the g-force experienced by a smartphone hitting the ground)

[rakaydos]

https://en.wikipedia.org/wiki/Skyhook_(structure)

[TrevorMonty]

I've taken the Spinlaunch concept and put it in LEO which gave it several advantages:

- no friction
- solar powered electric motor can be weak and take its time spinning up the payload
- payload can be connected by carbon fiber tether instead of rigid rod
- payload doesn't have to fly through atmosphere
- because the tether can be very long the g-force acting on the payload is low even at high tangential velocities
-velocity of 1 km/s with a 1 km long tether results in only 1000 g-force acting on the payload  (comparable to the g-force experienced by a smartphone hitting the ground)

How are you going spin it up without core being anchored to something that won't move.

[DanClemmensen]

I've taken the Spinlaunch concept and put it in LEO which gave it several advantages:

Please read
   https://en.wikipedia.org/wiki/Angular_momentum#Conservation_of_angular_momentum

[cAsE-sEnSlTivE]

I've taken the Spinlaunch concept and put it in LEO which gave it several advantages:

Please read
   https://en.wikipedia.org/wiki/Angular_momentum#Conservation_of_angular_momentum

Looks like the motor "stator" would spin up quickly

[Nomadd]

How are you going spin it up without core being anchored to something that won't move.

Use two counter rotating systems on the same axis.
 Not that it helps with other issues that would keep it from being practical.

[TrevorMonty]

How are you going spin it up without core being anchored to something that won't move.

Use two counter rotating systems on the same axis.
 Not that it helps with other issues that would keep it from being practical.

Makes more sense. Oneil cylinders were to be built in pairs and joined in parallel then rotated counter clockwise. Which explains physics.

A video would be useful.

[octavo]

I've taken the Spinlaunch concept and put it in LEO which gave it several advantages:

- no friction
- solar powered electric motor can be weak and take its time spinning up the payload
- payload can be connected by carbon fiber tether instead of rigid rod
- payload doesn't have to fly through atmosphere
- because the tether can be very long the g-force acting on the payload is low even at high tangential velocities
-velocity of 1 km/s with a 1 km long tether results in only 1000 g-force acting on the payload  (comparable to the g-force experienced by a smartphone hitting the ground)

I tried this in KSP and all that happens is your very light motor spins very rapidly and your heavy arms hardly move at all.

Nomad's suggestion of contra-rotating arms might make it worth trying again...

[edzieba]

If you're putting two tether systems in orbit, instead of tying them together and having one just act as an inert mass, use them as staggered Bolos so both are doing useful work. Or a Bolo and a Rotavator to catch payloads from suborbital trajectories (an in-orbit 'spinlaunch' needs your payload to have already been launched into orbit anyway).

[InterestedEngineer]

I've taken the Spinlaunch concept and put it in LEO which gave it several advantages:

- no friction
- solar powered electric motor can be weak and take its time spinning up the payload
- payload can be connected by carbon fiber tether instead of rigid rod
- payload doesn't have to fly through atmosphere
- because the tether can be very long the g-force acting on the payload is low even at high tangential velocities
-velocity of 1 km/s with a 1 km long tether results in only 1000 g-force acting on the payload  (comparable to the g-force experienced by a smartphone hitting the ground)

I tried this in KSP and all that happens is your very light motor spins very rapidly and your heavy arms hardly move at all.

Nomad's suggestion of contra-rotating arms might make it worth trying again...

Rotational momentum wants to be conserved.

[InterestedEngineer]

Serious question about all spinlaunch systems:

Has anyone simulated with e.g. FEM the whiplash effect of letting go of an object that is under load?

Or maybe even a closed-form first order solution?

I have yet to see such an analysis in the literature, but maybe I just missed it.

I do know that such moves are a bad idea on e.g. cranes.  No large system under serious strain wants to suddenly have the strain let go, it results in unstable behavior.

[Zed_Noir]

Serious question about all spinlaunch systems:

Has anyone simulated with e.g. FEM the whiplash effect of letting go of an object that is under load?

Or maybe even a closed-form first order solution?

I have yet to see such an analysis in the literature, but maybe I just missed it.

I do know that such moves are a bad idea on e.g. cranes.  No large system under serious strain wants to suddenly have the strain let go, it results in unstable behavior.

Not that much difference from extremely large artillery pieces like railroad guns and the various german mobile seige artillery units in WWII.

[edzieba]

Serious question about all spinlaunch systems:

Has anyone simulated with e.g. FEM the whiplash effect of letting go of an object that is under load?

Or maybe even a closed-form first order solution?

I have yet to see such an analysis in the literature, but maybe I just missed it.

I do know that such moves are a bad idea on e.g. cranes.  No large system under serious strain wants to suddenly have the strain let go, it results in unstable behavior.

The whiplash effect for large (non-bridge or gantry) cranes is due to the bending of the boom or arm, and is a hazard due to these cranes being balanced over a pivot (such that a recoil will often lead to toppling). A rotary accelerator is a pure tensile load, so at most you have recoil from any energy stored in the tether's stretch which will be in line with the pivot and unable to overbalance the system. In addition, tether material of a high Young's Modulus minimises this, and helpfully materials with a high tensile strength generally also have a high Young's modulus.

[cAsE-sEnSlTivE]

An alternative but similar concept would be to have two spacecraft with solar electric propulsion connected between themselves with a long tether, and a big xenon depot at the center of the tether (at the center of rotation) to supply the spacecraft with propellant.

[InterestedEngineer]

Serious question about all spinlaunch systems:

Has anyone simulated with e.g. FEM the whiplash effect of letting go of an object that is under load?

Or maybe even a closed-form first order solution?

I have yet to see such an analysis in the literature, but maybe I just missed it.

I do know that such moves are a bad idea on e.g. cranes.  No large system under serious strain wants to suddenly have the strain let go, it results in unstable behavior.

The whiplash effect for large (non-bridge or gantry) cranes is due to the bending of the boom or arm, and is a hazard due to these cranes being balanced over a pivot (such that a recoil will often lead to toppling). A rotary accelerator is a pure tensile load, so at most you have recoil from any energy stored in the tether's stretch which will be in line with the pivot and unable to overbalance the system. In addition, tether material of a high Young's Modulus minimises this, and helpfully materials with a high tensile strength generally also have a high Young's modulus.

Fair enough about the cranes, but if I take a stretchy piece of tubing I use for PT and stretch it and let it go and film it at high speed, it shows oscillations as it contracts.

I'm sure there's a parameter in the differential equations that decides whether a system oscillates or not, but does the high Young's modulus move that parameter enough?   The other parameters will be the load, the length, etc.

That's the paper I'm looking for.

[Robotbeat]

Doing it in a natural vacuum does make the idea a heck of a lot more viable.

[jee_c2]

Or on the Moon (also vacuum).
I love the idea of seroius kinetic energy transfer applications in space. Not easy, but very rewarding, imo.

[colbourne]

It might be worth capturing an asteroid to use as the core. It would otherwise be possible to have two contra rotating arms, but the danger of collision at high speed may make this idea unpopular.

This is basically the Bolo launch method and would work well on the Moon where you would have an orbiting rotating tether and from the Moons surface you could catch the tip of the moving arm (at less than orbital speed )and launch objects into space at greater than orbital speed. All this could be solar powered.

[pk67]

Spin capture in LEO would be easier and way more usefull than spinlaunch in LEO i bet. But spinlaunch would also exist in this case as a secondary feature. Refueling or stage exchange in LEO would also help to gain extra performance (delta v) or lower launch mass.