SpinLaunch: General Company and Development Updates and Discussions

[HMXHMX]

I can't find a short clip of the 16" naval rifle discharge from the movie "Under Siege", but it is worth checking out...

While looking at the that discharge, keep in mind the projectile will weigh twice as much and be fired three times as fast.

Matthew

It had not escaped my notice. 

[edzieba]

On the upside, the support infrastructure needed is far less than for even a small rocket. Sticking it on some near-equatorial island along with a generator isn't out of the question

[jongoff]

Their patent.

http://www.freepatentsonline.com/y2018/0194496.html

Deeply unimpressive document.

Genuinely pitiful.

Out of curiosity why do you find it so unimpressive and pitiful?

~Jon

[ringsider]

Their patent.

http://www.freepatentsonline.com/y2018/0194496.html

Deeply unimpressive document.

Genuinely pitiful.

Out of curiosity why do you find it so unimpressive and pitiful?

~Jon

It's just so unoriginal. I was really hoping (as you see above) that they had something clever, some new approach or insight.

But no. It is just a word-for-word re-hash of an old, old idea. Literally nothing in that patent is novel; I am amazed they wasted time writing it because if they had spent the same time on looking at literature they wouldn't have bothered.

Given their past aerospace companies I guess I should not be surprised.

[as58]

On the upside, the support infrastructure needed is far less than for even a small rocket. Sticking it on some near-equatorial island along with a generator isn't out of the question

Sure, if you don't count the whole 100-metre-vacuum chamber contraption as a part of support infrastructure...

[Bananas_on_Mars]

On the upside, the support infrastructure needed is far less than for even a small rocket. Sticking it on some near-equatorial island along with a generator isn't out of the question

Your comment and the reference to the 16 inch guns plus the "noise" discussion before made me think, why not put everything on a barge (=your own island) and pull it out to the middle of the ocean? The necessary structure seems like something a "normal" shipyard could build, and it might be cheaper than to build something that massive underground. No noise complaints from the neighbours, don't know how it would affect marine life though.
Also inclination changes are quite easy if everything floats...

[jongoff]

Their patent.

http://www.freepatentsonline.com/y2018/0194496.html

Deeply unimpressive document.

Genuinely pitiful.

Out of curiosity why do you find it so unimpressive and pitiful?

~Jon

It's just so unoriginal. I was really hoping (as you see above) that they had something clever, some new approach or insight.

But no. It is just a word-for-word re-hash of an old, old idea. Literally nothing in that patent is novel; I am amazed they wasted time writing it because if they had spent the same time on looking at literature they wouldn't have bothered.

Given their past aerospace companies I guess I should not be surprised.

That's fair--as Gary pointed out, there's very little novel in this particular patent. It doesn't reflect all of details I found interesting about their approach, but it at least allows us to narrow the conversation about what they're doing a bit.

~Jon

[jongoff]

On the upside, the support infrastructure needed is far less than for even a small rocket. Sticking it on some near-equatorial island along with a generator isn't out of the question

Your comment and the reference to the 16 inch guns plus the "noise" discussion before made me think, why not put everything on a barge (=your own island) and pull it out to the middle of the ocean? The necessary structure seems like something a "normal" shipyard could build, and it might be cheaper than to build something that massive underground. No noise complaints from the neighbours, don't know how it would affect marine life though.
Also inclination changes are quite easy if everything floats...

Interesting, I like that idea. Though it would be kind of wide (about the size of two of SpaceX's ASDS's side-by side, or about 30% wider than a container ship if they went with an 80m diameter system), that would let you go down to the equator, and as you say, just rotate the ship to hit different azimuths. Though there might be some fun dynamics with the change in angular momentum for a floating system. But barges can be pretty darned massive, so maybe it isn't a problem? It would solve a few problems (though might create others with the interaction between wave dynamics and God's own gyroscope...

~Jon

[HMXHMX]

On the upside, the support infrastructure needed is far less than for even a small rocket. Sticking it on some near-equatorial island along with a generator isn't out of the question

Your comment and the reference to the 16 inch guns plus the "noise" discussion before made me think, why not put everything on a barge (=your own island) and pull it out to the middle of the ocean? The necessary structure seems like something a "normal" shipyard could build, and it might be cheaper than to build something that massive underground. No noise complaints from the neighbours, don't know how it would affect marine life though.
Also inclination changes are quite easy if everything floats...

Interesting, I like that idea. Though it would be kind of wide (about the size of two of SpaceX's ASDS's side-by side, or about 30% wider than a container ship if they went with an 80m diameter system), that would let you go down to the equator, and as you say, just rotate the ship to hit different azimuths. Though there might be some fun dynamics with the change in angular momentum for a floating system. But barges can be pretty darned massive, so maybe it isn't a problem? It would solve a few problems (though might create others with the interaction between wave dynamics and God's own gyroscope...

~Jon

Jon, I've been doing a fair amount of barge launch work (can't say why, unfortunately) but I can say that the problems of motion are major, even with massive platforms.  Heave is the worst issue, at least for the work I'm doing.  I do think that ocean launch is the only viable option for an entity like Spinlaunch – even then, the EIS will be a nightmare.  I'd estimate the minimum platform cost to accommodate a notional centrifugal launcher would be on the order of $30-50m, and maybe quite a bit more, depending on who fabricates said platform.  Lots more difficult than SpaceX recovery barges...and way, way more expensive than a simple mobile launcher at a conventional range.  In fact, you could develop an air-launch system for much less.

[matthewkantar]

How about a large ship with the spin gizmo's axis across the beam?

[ChrisWilson68]

I'm having trouble seeing how putting on a ship or barge would be viable unless it's a Ford-class nuclear-powered aircraft carrier.  Where else are they going to get the large amount of power this would take?

[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.

[HMXHMX]

I'm having trouble seeing how putting on a ship or barge would be viable unless it's a Ford-class nuclear-powered aircraft carrier.  Where else are they going to get the large amount of power this would take?

LNG or Kerosene-fueled turbines driving electric generators. They’d power the Azipod-type main propulsion and also the electric motor(s) driving the rotor.  The system will take quite a while to spin up, on the order of tens of minutes to hours, so the instantaneous power needed isn’t all that great.

‘Diverting power from the engines to the weapons, Capt’n!...er, I mean, rotor!”

[HMXHMX]

I'm having trouble seeing how putting on a ship or barge would be viable unless it's a Ford-class nuclear-powered aircraft carrier.  Where else are they going to get the large amount of power this would take?

LNG or Kerosene-fueled turbines driving electric generators. They’d power the Azipod-type main propulsion and also the electric motor(s) driving the rotor.  The system will take quite a while to spin up, on the order of tens of minutes to hours, so the instantaneous power needed isn’t all that great.

‘Diverting power from the engines to the weapons, Capt’n!...er, I mean, rotor!”

So in essence you are saying, build a gigantic gas generator and carry loads of non-green propellants, then use them to power an electric motor driving the world's largest centrifuge (harder than a turbopump), that is also angled and on a moving container sized ship, to give a 2800 m/s boost to a conventional rocket, that has to withstand over 15k gees and a pretty sizeable amount of aeroheating. Cool.

I didn’t say I’d do this...only that Spinlaunch could, if they opt for ocean launch, as they probably must.  (BTW, LNG is usually considered “green.”)

Myself, I’d build a reusable rocket.

[jongoff]

I'm having trouble seeing how putting on a ship or barge would be viable unless it's a Ford-class nuclear-powered aircraft carrier.  Where else are they going to get the large amount of power this would take?

It doesn't take as much power as you'd think, since you can add it over the course of several hours (since the centrifuge is inside the vacuum chamber you're not fighting a lot of drag).

If I'm doing my math right, 2000kg at 2800m/s of velocity is ~7.8GJ of energy. Assume triple that to account for the counterweight and the sling tether (more mass, but not going as fast), so round up to ~25GJ. But if that's added over the course of say 6hrs, is only ~1.15MW. That's like 0.2% of the power level of a Ford class aircraft carrier. Even if you wanted to launch once per hour, you're still talking ~7MW, which is 7% of the power of one of the nuclear reactor turbines on the older Nimitz class ships.

No, I think the coupled dynamics of the wave motion and the gyro is the much bigger challenge than the power required.

This is getting a little crazy, but I wonder if you could stack two such sling launchers, one on top of the other, counterrotating to deal with some of the gryoscopic dynamics...

~Jon

[jongoff]

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

[jongoff]

Myself, I’d build a reusable rocket.

For earth launch I totally agree that I'd put my money on full RLVs being more likely to win economically. But I'd love to see them put the technology on the shelf for lunar launch. Get rid of the atmospheric effects, and now you have a perfectly feasible way to get lunar ISRU propellants off the surface without having to burn most of it on the way back to Earth. This is basically an update on Zubrin's work on sling tethers that we've discussed before here on NSF, and the old numbers suggested you could get a 1 tonne to orbit sling tether packed into a single XEUS landing.

So, while the terrestrial launch economic competitiveness is iffy, this work would retire almost all the technical risks associated with making a lunar version work, so I'm hopeful they make real progress.

~Jon

[Bananas_on_Mars]

I'm having trouble seeing how putting on a ship or barge would be viable unless it's a Ford-class nuclear-powered aircraft carrier.  Where else are they going to get the large amount of power this would take?

It doesn't take as much power as you'd think, since you can add it over the course of several hours (since the centrifuge is inside the vacuum chamber you're not fighting a lot of drag).

If I'm doing my math right, 2000kg at 2800m/s of velocity is ~7.8GJ of energy. Assume triple that to account for the counterweight and the sling tether (more mass, but not going as fast), so round up to ~25GJ. But if that's added over the course of say 6hrs, is only ~1.15MW. That's like 0.2% of the power level of a Ford class aircraft carrier. Even if you wanted to launch once per hour, you're still talking ~7MW, which is 7% of the power of one of the nuclear reactor turbines on the older Nimitz class ships.

No, I think the coupled dynamics of the wave motion and the gyro is the much bigger challenge than the power required.

This is getting a little crazy, but I wonder if you could stack two such sling launchers, one on top of the other, counterrotating to deal with some of the gryoscopic dynamics...

~Jon

I think you can get a diesel generator with ~10MW electric in a 40ft shipping container or something similar size.
I thought that making the centrifuge spin around a horizontal axis and having most of it submerged would get rid of most of the swell influences.

[ChrisWilson68]

I'm having trouble seeing how putting on a ship or barge would be viable unless it's a Ford-class nuclear-powered aircraft carrier.  Where else are they going to get the large amount of power this would take?

It doesn't take as much power as you'd think, since you can add it over the course of several hours (since the centrifuge is inside the vacuum chamber you're not fighting a lot of drag).

If I'm doing my math right, 2000kg at 2800m/s of velocity is ~7.8GJ of energy. Assume triple that to account for the counterweight and the sling tether (more mass, but not going as fast), so round up to ~25GJ. But if that's added over the course of say 6hrs, is only ~1.15MW. That's like 0.2% of the power level of a Ford class aircraft carrier. Even if you wanted to launch once per hour, you're still talking ~7MW, which is 7% of the power of one of the nuclear reactor turbines on the older Nimitz class ships.

No, I think the coupled dynamics of the wave motion and the gyro is the much bigger challenge than the power required.

This is getting a little crazy, but I wonder if you could stack two such sling launchers, one on top of the other, counterrotating to deal with some of the gryoscopic dynamics...

If they spin it up over a 6 hour period, I'd think the power requirement would be dominated by friction.  Sure, it's vacuum, but there's still a central hub or bearing it's rotating on, and then there's all the friction in the motor and gearing to drive the rotation.

The way I think of it is that if it's rotating at full speed ready for launch and you suddenly cut power, how long does it take to spin down?  That tells you how quickly friction is removing energy from your system.  If it would take 6 hours to spin down (including the electric motor, gearing, and everything), then friction is taking power out of your system at the same rate it would take to spin it up, so it's roughly doubling your power requirements to spin it up in the first place.  But if it would spin down on its own in an hour, it would take 6 times the power to fight friction that it would take to spin it up according to the friction-free analysis.

But, really, it's worse than that because friction increases with speed, and what we're concerned about is the peak power requirement.  That's what it takes to overcome friction and speed it up just a little bit when it's going nearly full speed.

We don't know enough to calculate actual numbers, unfortunately.

[edzieba]

Air-bearings are out due to the evacuated environment, but EM suspension is not so exotic for high load applications. Right up until payload release the spinup is a pretty benign process (about the only real variable load is the tether straightening as RPMs rise due to gravity being perpendicular to spin) and the addition of a replaceable 'slam sleeve' within the hub - along with the synchronised counterweight release - would avoid hub damage.

The patent may not be 'impressive' (they rarely are, all interesting implementation details will be absent), but like similar age-old concepts ("just land a rocket and re-use it") the exiting part is the implementation. SpinLaunch are getting a non-negligable amount of funding, which puts them ahead of most previous centrifugal launch concepts.
'Exiting' or 'new' overly-fancy designs made of unobtanium and 4-dimensional geometry are not required for the concept to work, it just requires someone to actually build one.