SpinLaunch: General Company and Development Updates and Discussions

[TrevorMonty]

Have my doubts about spinlaunch for earth  launches but agree with Jon that it would ideal for moon.

Payload could be iron (lunar iron) missile containing water or other payloads, would need radio beacon and maybe small gas thrusters to stabilise it for capture in orbit.

You wouldn't need the iron missile part on the moon, since there's no atmosphere you have to fight through. Just reusable Kevlar bags with the water frozen cryogenically as ice. You would need thrusters to stabilize the orbit (or tugs nimble enough to rendezvous with them suborbitally and do the circularization burn).

~Jon

I was thinking of using iron for in space construction and its easiest lunar metal to extract.

[Asteroza]

Barge launch strikes me as difficult because the system is predicated on a fixed mount for transferring forces. Once barge movement (heave, yaws/rolls) gets involved the forces on the rotation bearing will be very non-trivial, compared to a land anchored rig with pilings under each bearing/motor complex.

[Lars-J]

This project ... sigh ... makes a space elevator look practical. Yes there is nothing in the laws of physics that may prevent either SpinLaunch or a space elevator, but c'mon - neither approach is anywhere near being practical on Earth. That they have attracted any funding for this just blows my mind.

[QuantumG]

This project ... sigh ... makes a space elevator look practical. Yes there is nothing in the laws of physics that may prevent either SpinLaunch or a space elevator, but c'mon - neither approach is anywhere near being practical on Earth. That they have attracted any funding for this just blows my mind.

Perhaps you could enlighten the rest of us as to why this isn't practical on Earth?

I'm not disagreeing with you, but this seems like a lazy argument.

[ChrisWilson68]

This project ... sigh ... makes a space elevator look practical. Yes there is nothing in the laws of physics that may prevent either SpinLaunch or a space elevator, but c'mon - neither approach is anywhere near being practical on Earth. That they have attracted any funding for this just blows my mind.

Perhaps you could enlighten the rest of us as to why this isn't practical on Earth?

I'm not disagreeing with you, but this seems like a lazy argument.

To me, the arguments that it isn't practical were made some ways upthread.  It basically boils down to this: either:

    1. The spin launch part of it isn't doing most of the work of getting to orbit, and instead it's just launching at a steep angle and low fraction of orbital speed, in which case they need a very hefty second stage, which will have to be so over-engineered to survive the huge g forces when spinning that it will be more expensive than just a normal two-stage rocket; or

    2. The spin launch part really is doing most of the work of getting to orbit, in which case the upper stage will exit the spinner at more than Mach 20 and nearly horizontal, and will have to go through hundreds of miles of thick atmosphere at Mach 20 without losing much speed, which seems implausible.

[john smith 19]

Barge launch strikes me as difficult because the system is predicated on a fixed mount for transferring forces. Once barge movement (heave, yaws/rolls) gets involved the forces on the rotation bearing will be very non-trivial, compared to a land anchored rig with pilings under each bearing/motor complex.

Putting it on water certainly sounds a pretty clever idea. One set of chamber exit hardware would be very much simpler.

On the downside that trades fewer exits for the problem of compensating for the varying suspension loads between the arm and the base. Obviously how serious that problem is depends on the height and frequency of the waves it has to deal with.

That sounds pretty tricky, given the high rotation speeds, large masses and (relatively) unpredictable waves.

[Mardlamock]

This project ... sigh ... makes a space elevator look practical. Yes there is nothing in the laws of physics that may prevent either SpinLaunch or a space elevator, but c'mon - neither approach is anywhere near being practical on Earth. That they have attracted any funding for this just blows my mind.

Perhaps you could enlighten the rest of us as to why this isn't practical on Earth?

I'm not disagreeing with you, but this seems like a lazy argument.

To me, the arguments that it isn't practical were made some ways upthread.  It basically boils down to this: either:

    1. The spin launch part of it isn't doing most of the work of getting to orbit, and instead it's just launching at a steep angle and low fraction of orbital speed, in which case they need a very hefty second stage, which will have to be so over-engineered to survive the huge g forces when spinning that it will be more expensive than just a normal two-stage rocket; or

    2. The spin launch part really is doing most of the work of getting to orbit, in which case the upper stage will exit the spinner at more than Mach 20 and nearly horizontal, and will have to go through hundreds of miles of thick atmosphere at Mach 20 without losing much speed, which seems implausible.

Getting to orbit is an exponential affair, those few km/s they save through catapult launch equate to more than a first stage. Comparing it to a ground launched rocket in the same payload class, you're looking at around a 10x reduction or further in vehicle size.

The problem isn't whether catapult launch is possible or not, because it actually seems to be within the realm of the spec sheets of other engineering projects (in power, rotor size, gees, etc.), but rather if that 10x or more reduction in vehicle size is enough to justify the fairly high development costs of the catapult, especially if you consider that it could only be used to launch heavily modified payloads, or bulk fuel/cargo launches that aren't in high demand.

Sure, those 250+ million in startup costs fade away if you are launching say 1000 times per year, but you still need to:

a) Build and maintain lines to produce and launch 1000 rockets per year.
b) Get satellite manufacturers to heavily modify their designs (which would make them bound to your success or failure).
c) Hope your first launch facilities don't kick the bucket in early RUDs.

It does seem to be within the realm of what developing a same payload class reusable rocket rocket would cost, and if they were to make it work here on earth, it could do amazing stuff for the Moon; but it is obvious that it carries far higher execution and technical risks than conventional launch methodologies, and is built around launch frequencies and payloads that just don't exist.

[Lars-J]

This project ... sigh ... makes a space elevator look practical. Yes there is nothing in the laws of physics that may prevent either SpinLaunch or a space elevator, but c'mon - neither approach is anywhere near being practical on Earth. That they have attracted any funding for this just blows my mind.

Perhaps you could enlighten the rest of us as to why this isn't practical on Earth?

I'm not disagreeing with you, but this seems like a lazy argument.

Three factors, each by themselves ought to be  show-stoppers for any project:

1. Thousands(?) of Gs during the spin.
2. Instant entry from vacuum into sea level atmosphere at several thousand km/s.
3. Surviving the sustained sea level flight at multiple km/s.
4. If not ejected at orbital speed, building a reasonable upper stage that can survive factors 1-3 above.

Any point above is theoretically possible (laws of physics aren’t being broken) - BUT each point would be ridiculous to attempt for even an organization with NASA level resources, let alone a startup. Now add several of these.

[edzieba]

The technical challenges are not in any way insurmountable (SMD electronics can handle those G loads with minimal hassle, barring MEMS devices). Contemporary guided rockets that can survive high-G shock loads are almost-CotS parts (plenty of guided rocket-assisted artillery projectiles).


The real challenges are economic:
(1) Startup costs to build the accelerator (i.e. convincing investors the project is viable).
(2) Legal costs to convince those along the flightpath(s) you are not building a hypersonic bombardment weapon.
(3) Chicken-and-egg situation of needing a large number of small hardened payloads to sustain operation, and payload makers needing an existing launcher for it to be worth building small hardened payloads.

(3) is the big kicker. The current crop of dedicated smallsat launchers are only just starting to be viable after nearly two decades of Cubesats because the market was able to grow by 'tagging along' on larger launchers, and then transition without form-factor change to dedicated launchers.

[ellindsey]

One thing I have not seen addressed at all is that the projectile is going to still be rotating as it comes out of the launcher.  If the centrifuge is spinning at 535 RPM per the patent, the payload will also be rotating end-over-end at 535 RPM.  The payload will move in a straight line when released, but it will still carry that rotation as it moves.  In a vacuum, this wouldn't be much of a problem, although you'd still need to despin it before making any course changes.  In air, that spin is going to cause some very undesirable aerodynamic interactions.  They've given their projectile fins, but I'm not convinced those will instantly cancel the rotation, especially as the projectile may have rotated sideways by the time it reaches the exit shutter.

[edzieba]

Releasing the projectile with a 'kick' (e.g. releasing the front a fraction of a second before the rear) would be sufficient to minimise the spin to the point where aerodynamic forces can be used to align the projectile without destruction.

[envy887]

One thing I have not seen addressed at all is that the projectile is going to still be rotating as it comes out of the launcher.  If the centrifuge is spinning at 535 RPM per the patent, the payload will also be rotating end-over-end at 535 RPM.  The payload will move in a straight line when released, but it will still carry that rotation as it moves.  In a vacuum, this wouldn't be much of a problem, although you'd still need to despin it before making any course changes.  In air, that spin is going to cause some very undesirable aerodynamic interactions.  They've given their projectile fins, but I'm not convinced those will instantly cancel the rotation, especially as the projectile may have rotated sideways by the time it reaches the exit shutter.

The method of release from the arm can cancel this rotation. E.g. if the projectile is held by 2 points, one forward and one rearward of its center of mass, and one of the hold points is released before the other, the centripetal force acting through the center of mass will apply a torque about the other hold point. That torque can despin the projectile if the release timing is tightly controlled.

[ellindsey]

Releasing the projectile with a 'kick' (e.g. releasing the front a fraction of a second before the rear) would be sufficient to minimise the spin to the point where aerodynamic forces can be used to align the projectile without destruction.

That is still a complex operation and additional stress on the projectile, as you're essentially having to de-spin the projectile from the full rotation rate to nearly zero in a very short period of time.  It also means that your tether can't be a simple cable as described in the patent, but has to be at the very least two tethers, if not some kind of truss or A-frame, to be able to impart rotation to the payload in the moment before full release.

[Davidthefat]

This just reminds me of Punkin Chunkin competitions.

It seems that the pneumatic cannons beat out the centrifugal throwers, due to the limitations on the size of the rig and the energy density.

[Asteroza]

This just reminds me of Punkin Chunkin competitions.

It seems that the pneumatic cannons beat out the centrifugal throwers, due to the limitations on the size of the rig and the energy density.

Like the old Quicklaunch concept, using a neutrally buoyant long pipe floating in the sea to house a light gas gun?

Of note, a recent Sandia news release mentioned a new high wear resistance palladium/gold alloy that somehow also magically turns surrounding carbon matter into a diamond-like thin film to additionally lubricate for wear resistance (bonus points for making the diamond-like amorphous thin film at room temp rather than the usually expensive vacuum plasma furnace).

https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.201802026

https://www.sciencedirect.com/science/article/pii/S0008622318305621



Oh lord, bad idea of the week, using the spin launcher as a zero-stage to feed into a light gas gun somehow since you only need a sphere for the driver piston...

[edzieba]

Releasing the projectile with a 'kick' (e.g. releasing the front a fraction of a second before the rear) would be sufficient to minimise the spin to the point where aerodynamic forces can be used to align the projectile without destruction.

That is still a complex operation and additional stress on the projectile, as you're essentially having to de-spin the projectile from the full rotation rate to nearly zero in a very short period of time.  It also means that your tether can't be a simple cable as described in the patent, but has to be at the very least two tethers, if not some kind of truss or A-frame, to be able to impart rotation to the payload in the moment before full release.

It's is an extremely simple release mechanism (literally a preset time delay between two releases). It does not require multiple tethers either: a single tether to a mount point, and a mount attached to the mount point with the two projectile latching mounts. Replicate this on the counterweight release side to ensure tension on the tether remains balanced.

[ChrisWilson68]

To me, the arguments that it isn't practical were made some ways upthread.  It basically boils down to this: either:

    1. The spin launch part of it isn't doing most of the work of getting to orbit, and instead it's just launching at a steep angle and low fraction of orbital speed, in which case they need a very hefty second stage, which will have to be so over-engineered to survive the huge g forces when spinning that it will be more expensive than just a normal two-stage rocket; or

    2. The spin launch part really is doing most of the work of getting to orbit, in which case the upper stage will exit the spinner at more than Mach 20 and nearly horizontal, and will have to go through hundreds of miles of thick atmosphere at Mach 20 without losing much speed, which seems implausible.

Getting to orbit is an exponential affair, those few km/s they save through catapult launch equate to more than a first stage.

You think a standard first stage doesn't give a few km/s???

No, a few km/s doesn't equate to more than a first stage.  That's exactly what a first stage does.

[Lars-J]

Releasing the projectile with a 'kick' (e.g. releasing the front a fraction of a second before the rear) would be sufficient to minimise the spin to the point where aerodynamic forces can be used to align the projectile without destruction.

That is still a complex operation and additional stress on the projectile, as you're essentially having to de-spin the projectile from the full rotation rate to nearly zero in a very short period of time.  It also means that your tether can't be a simple cable as described in the patent, but has to be at the very least two tethers, if not some kind of truss or A-frame, to be able to impart rotation to the payload in the moment before full release.

It's is an extremely simple release mechanism (literally a preset time delay between two releases). It does not require multiple tethers either: a single tether to a mount point, and a mount attached to the mount point with the two projectile latching mounts. Replicate this on the counterweight release side to ensure tension on the tether remains balanced.

I feel that using the phrase "extremely simple" is not appropriate for this thread. 

[edzieba]

Ballistic launch is more of a materials and economics problem than a systems one. Releasing one latch a set time after another is not going to be the hurdle that prevents your system from working.

[Markstark]

https://twitter.com/spaceport_nm/status/1084900275163287552