SpinLaunch: General Company and Development Updates and Discussions

[edzieba]

Ships are likely ruled out on practicality grounds: as the ship rolls and pitches, the rotor will try and precess. That's a lot of extra torsion load the rotor hub now needs to deal with, along with tip flexion from that torsion force displacing the projectile when it comes time for release. *

With the long spinup times, difficult in pointing (at all, let alone rapidly to track anything moving faster than your average two-story house), high power requirements, extremely low repetition rate, and overall comically unsubtle nature ("please stay still for a few hours whilst the conspicuous large building we brought with us powers up for a few hours"), there is little to recommend a rotary launcher over existing hypervelocity projectile launchers like light gas guns or EM accelerators. The only reason Spinlaunch makes sense for its particular use-case is the capability for high projectile masses beyond feasible linear accelerators: for large projectiles you start having to posit light gas guns kilometres long and suspended submerged from floating ocean platforms, which is somewhat cumbersome.

There is really no reason to replace existing ballistic/rocket artillery with a rotary accelerator.


* As an aside: assuming their suborbital launcher, with a 1000RPM spin rate, a 50m diameter rotor, and total rotor + projectile mass of 1 tonne the torque force just from the rotation of the Earth is ~9Nm applied to the hub.

[TrevorMonty]

Rampant speculation ahead.

I think there's plenty of potential for using SpinLaunch's tech as electrically powered long-range artillery; sort of a simpler, cheaper, quicker to develop railgun. Pair it with guided artillery shells and it becomes potentially interesting, if your willing to spend the money.

The Navy would be the obvious choice, but I think it's probably a bit too high risk for them. If the spinning arm snaps on land, it's bad, but it's probably only the launcher that's destroyed. If that happens on a ship, you likely sink the ship. Then again, it may not be any more of a risk than having a bunch of explosive on board. You'd have to do a risk assessment.

The Army had a program for a 1000 mi gun that was cancelled just earlier this year, back in May. Whether that was due to the traditional gun design having problems, or because they just didn't care about the capability that much, isn't clear to me. If it was the former, maybe they'd be interested in using this as a weapon system in the longer term.

Personally, I don't see how you could follow the events in the Ukraine war and not be dumping as much money into long range, precision artillery as possible. Think about everything that's been hit with HIMARS. Now imagine that those attacks could be made on a cheaper per shot basis, from Warsaw. So I predict a lot of DoD investment in technologies like this, and in more standard missiles/guided-rocket artillery, in the aftermath of the Ukraine War.

I can just someone requesting fire support.
Reply would be "can you hold on for 3 hours while spin up the gun".

[Robotbeat]

Seems to me that using Spinlaunch for artillery suffers from the fact that it’s very not-mobile.

And it scales poorly. Assuming you’re limited by some peak acceleration “a” to achieve some speed “v”, the distance needed to  accelerate to that velocity is: d=v^2/(2*a).

In a circle, your centrifugal acceleration is equal to radius times angular (radians) velocity squared, so your radius is: r=v^2/a. And your diameter is twice the radius, so diameter:
d = 2*v^2/a.

So spinning requires a diameter equal to four times a cannon barrel length. Cannon barrel also has much smaller volume than the big round pressure vessel. Volume for that pressure vessel scales actually by the diameter to the third power, whereas a cannon barrel volume scales merely linearly with length, and that length starts out a factor of 4 smaller than the diameter for the spinny artillery.

So it’s pretty bad for replacing artillery. A light gas gun of some sort makes a lot more sense.

But spinning is a good option in space, where your vacuum chamber is provided by nature.

[DanClemmensen]

Seems to me that using Spinlaunch for artillery suffers from the fact that it’s very not-mobile.

It's probably a bad idea, but not completely infeasible for naval artillery. Mounted to launch vertically like the never-implemented "VGAS", it launches a smart munition straight up to 80,000 feet or higher. No need to aim. The munition extends its control surfaces and guides itself to targets 100 miles or more from the launcher and lands at terminal velocity, like naval artillery shell, high-altitude bomb, or missile. The launching ship uses electricity instead of gunpowder, which simplifies a lot of things. The main drawback is firing rate. The (horrible) AGS on the Zumwalt-class destroyers has a nominal rate of 6 rounds a minute. The big question: does naval artillery has a place in today's world?

[TrevorMonty]

Seems to me that using Spinlaunch for artillery suffers from the fact that it’s very not-mobile.

It's probably a bad idea, but not completely infeasible for naval artillery. Mounted to launch vertically like the never-implemented "VGAS", it launches a smart munition straight up to 80,000 feet or higher. No need to aim. The munition extends its control surfaces and guides itself to targets 100 miles or more from the launcher and lands at terminal velocity, like naval artillery shell, high-altitude bomb, or missile. The launching ship uses electricity instead of gunpowder, which simplifies a lot of things. The main drawback is firing rate. The (horrible) AGS on the Zumwalt-class destroyers has a nominal rate of 6 rounds a minute. The big question: does naval artillery has a place in today's world?

Alternatively you just spend spin launcher build money on 100s of cruise or ballistic missiles that can be launched from various ships and planes.

[JEF_300]

I can just someone requesting fire support.
Reply would be "can you hold on for 3 hours while spin up the gun".

This would NOT be for fire support. It would be for strategic, precision destruction. It would go after the sorts of targets the Ukrainians are firing HIMARS at (bridges, ammo depots, command centers, etc.), and those don't move. So rate of fire isn't really a concern for this sort of weapon.

[JEF_300]

Seems to me that using Spinlaunch for artillery suffers from the fact that it’s very not-mobile.

It's probably a bad idea, but not completely infeasible for naval artillery. Mounted to launch vertically like the never-implemented "VGAS", it launches a smart munition straight up to 80,000 feet or higher. No need to aim. The munition extends its control surfaces and guides itself to targets 100 miles or more from the launcher and lands at terminal velocity, like naval artillery shell, high-altitude bomb, or missile. The launching ship uses electricity instead of gunpowder, which simplifies a lot of things. The main drawback is firing rate. The (horrible) AGS on the Zumwalt-class destroyers has a nominal rate of 6 rounds a minute. The big question: does naval artillery has a place in today's world?

Alternatively you just spend spin launcher build money on 100s of cruise or ballistic missiles that can be launched from various ships and planes.

The thing is, once you actually have the spin launcher developed and on ships, they will be vastly cheaper per shot. Smaller, cheaper shells/missiles means more ammo on board at any time, more practice during peacetime, and large stockpiles for wartime. That last one is key; just look at the Ukraine War or, if that's too far flung for you, the First Gulf War. There's a good argument to be made for more sustainable options.

[DanClemmensen]

Seems to me that using Spinlaunch for artillery suffers from the fact that it’s very not-mobile.

It's probably a bad idea, but not completely infeasible for naval artillery. Mounted to launch vertically like the never-implemented "VGAS", it launches a smart munition straight up to 80,000 feet or higher. No need to aim. The munition extends its control surfaces and guides itself to targets 100 miles or more from the launcher and lands at terminal velocity, like naval artillery shell, high-altitude bomb, or missile. The launching ship uses electricity instead of gunpowder, which simplifies a lot of things. The main drawback is firing rate. The (horrible) AGS on the Zumwalt-class destroyers has a nominal rate of 6 rounds a minute. The big question: does naval artillery has a place in today's world?

Alternatively you just spend spin launcher build money on 100s of cruise or ballistic missiles that can be launched from various ships and planes.

As of now, a cruise missile costs at least $1 million. The ships with the largest missile magazines are the four converted Ohio-class submarines that now carry 150 cruise missiles each. The Navy wants a system that can carry large quantities of munitions and that is cheaper per munition. The AGS on the Zumwalts failed miserably on munition cost. Spinlaunch would likely be technically far superior. I still don't understand why naval artillery makes any sense, but that's a separate issue.

[JEF_300]

Ships are likely ruled out on practicality grounds: as the ship rolls and pitches, the rotor will try and precess. That's a lot of extra torsion load the rotor hub now needs to deal with, along with tip flexion from that torsion force displacing the projectile when it comes time for release. *

* As an aside: assuming their suborbital launcher, with a 1000RPM spin rate, a 50m diameter rotor, and total rotor + projectile mass of 1 tonne the torque force just from the rotation of the Earth is ~9Nm applied to the hub.

That is a very fair point.

[DanClemmensen]

I can just someone requesting fire support.
Reply would be "can you hold on for 3 hours while spin up the gun".

This would NOT be for fire support. It would be for strategic, precision destruction. It would go after the sorts of targets the Ukrainians are firing HIMARS at (bridges, ammo depots, command centers, etc.), and those don't move. So rate of fire isn't really a concern for this sort of weapon.

If you are on a fire support mission, you are already spun up. But there must be some way to fire to 80,000 feet at a rate of six a minute or thereabouts.

[DanClemmensen]

Ships are likely ruled out on practicality grounds: as the ship rolls and pitches, the rotor will try and precess. That's a lot of extra torsion load the rotor hub now needs to deal with, along with tip flexion from that torsion force displacing the projectile when it comes time for release. *

* As an aside: assuming their suborbital launcher, with a 1000RPM spin rate, a 50m diameter rotor, and total rotor + projectile mass of 1 tonne the torque force just from the rotation of the Earth is ~9Nm applied to the hub.

Put it on a REALLY BIG gimbal mount. It needs to point straight up in any event. You end up designing the ship around the weapons system.

That is a very fair point.

[Asteroza]

I can just someone requesting fire support.
Reply would be "can you hold on for 3 hours while spin up the gun".

This would NOT be for fire support. It would be for strategic, precision destruction. It would go after the sorts of targets the Ukrainians are firing HIMARS at (bridges, ammo depots, command centers, etc.), and those don't move. So rate of fire isn't really a concern for this sort of weapon.

If you are on a fire support mission, you are already spun up. But there must be some way to fire to 80,000 feet at a rate of six a minute or thereabouts.

Which is where the idea of a converted container ship with one or two in each container cell (so 6+) works out sorta well. Slot in like an oversized module filling most of the container cell, fill the remaining TEU/FEU container slots with batteries and containerized gas turbine generators. Maybe Musk can get you a deal on Powerwall Megapack containers. It's arsenal ship done cheap-ish. But the PGM shell cost is a problem (magazine cost isn't all that different from just filling with VLS, on a shot basis), and makes the ship a one hit kill bomb/AShM magnet forcing it to stay at standoff ranges.

Plus that has to be contrasted against proposed UAV taxi rank style systems that can deliver CAS/missiles on call. With initiatives to migrate to more distributed lethality, this setup (arsenal ship style) is concentrating a lot of eggs in one basket (but much easier to implement). If large USV's become a thing though, then putting one spinlaunch device on such a ship and having a fleet of them to get the collective fire rate up might work, much like concepts for an auxiliary fleet of nearly barge like USV's carrying a small VLS pack accompanying a force, with all the expensive targeting sensors offboard on something fancy like an AEGIS destroyer.


But this is straying farrrr off-topic, and probably better off over at the SecretProjects forum...

[john smith 19]

As of now, a cruise missile costs at least $1 million. The ships with the largest missile magazines are the four converted Ohio-class submarines that now carry 150 cruise missiles each. The Navy wants a system that can carry large quantities of munitions and that is cheaper per munition.

I did not know this. I knew submarines carried cruise missiles, but I thought they were like torpedoes, maybe a dozen or so at a time. 

The AGS on the Zumwalts failed miserably on munition cost. Spinlaunch would likely be technically far superior.

There's a reason the contractor is known in some circles as "Billions Above Estimate" 
[EDIT BTW in WWII the Germans developed ramjet assisted artillery rounds with a (claimed) tested range of 300Km at about M5. No on board computing. No GPS. They used the shells spin to drive the liquid fuel into the combustion chamber. Unfortunately they use carbon disulphide as the fuel, which is pretty toxic. That would be difficult (but I don't think impossible) to duplicate with safer fuels today  ]

I still don't understand why naval artillery makes any sense, but that's a separate issue.

Well 70% of this planet is covered with water so a lot of places (of interest for various military reasons) are quite near to a shore line.

Aircraft carriers are harder to justify. I think you have to consider total systems costs. Not just the aircraft themselves. If you don't have them you need multiple airbases in foreign countries to deliver global military coverage. I think when you run the number 1 carrier = X number of overseas, permanently staffed airbases to support those plane in-country.

Aircraft carriers might be  the cheap option. 

[JEF_300]

And for the record, just like how when talking about orbital launch we have to compare SpinLaunch to reusable rockets, I think that comparison should also be made when looking at strategic strike. A ruggedized reusable first stage (lets assume it's VTVL & RTLS) might very well be able to throw an artillery shell downrange even cheaper or more reliably than SpinLaunch could. I just thought the possibility of using SpinLaunch as a weapon system was worth throwing out there, since the military applications were brought up.

[jstrotha0975]

And for the record, just like how when talking about orbital launch we have to compare SpinLaunch to reusable rockets, I think that comparison should also be made when looking at strategic strike. A ruggedized reusable first stage (lets assume it's VTVL & RTLS) might very well be able to throw an artillery shell downrange even cheaper or more reliably than SpinLaunch could. I just thought the possibility of using SpinLaunch as a weapon system was worth throwing out there, since the military applications were brought up.

Being able to chuck a cheap shell to the other side of the world is worth something to the military. Artillery strikes launched from US soil.

[Robotbeat]

And for the record, just like how when talking about orbital launch we have to compare SpinLaunch to reusable rockets, I think that comparison should also be made when looking at strategic strike. A ruggedized reusable first stage (lets assume it's VTVL & RTLS) might very well be able to throw an artillery shell downrange even cheaper or more reliably than SpinLaunch could. I just thought the possibility of using SpinLaunch as a weapon system was worth throwing out there, since the military applications were brought up.

Being able to chuck a cheap shell to the other side of the world is worth something to the military. Artillery strikes launched from US soil.

Youd be better off with a light gas gun.

[tankat0208]

It’s been a while since I heard anything about this. Any updates?

[gongora]

Removed the last couple posts.  Consider the "repurpose SpinLaunch as an artillery company" discussion to be over.  Let's focus on their launch business.

[matthewkantar]

SpinLaunch very quiet for nearly a year, anybody have any insight?

[Eric Hedman]

SpinLaunch very quiet for nearly a year, anybody have any insight?

The last news article on their website is from October of last year.  Not  good sign.