Author Topic: SpinLaunch: General Company and Development Updates and Discussions  (Read 142480 times)

Offline ringsider

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Or 10km at 20g. But i'm sure they have some special tricks up their sleeve. You don't get that kind of investment for crazy ideas, and they already have a lot of hardware in that only picture i have seen.
I'm definitely looking forward to seeing more of their tech.

That picture:



is a rendering.
Mea maxima culpa...

It's a very good render...

If you look behind the foreground missile, where the tracks lead, there is a tunnel. That tunnel has an autoclave-like door, implying that it is a low pressure / vacuum tunnel. That gives you some idea of the concept.

Plus, the image on this blog by the brother of Jonathan Yaney, Maximus, tells you a little more:

http://maximusyaney.com/creating-spinlaunch/

I got a hold of Alexander Bolonkin’s book: Non-Rocket Space Launch and Flight, a 488-page behemoth which we consumed cover to cover. Bolonkin had numerous fascinating centripetal schemes and out of those was born our idea of a ground-based launcher. I came up with the name SpinLaunch and we were off to the races.

This is the Bolonkin book:

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.649.6590&rep=rep1&type=pdf

Offline gosnold

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OK so assuming this has to launch fairly conventional payloads and does not provide a lot of speed, it must be a kind of fairing that you put around a small rocket to get it out of the atmosphere and enjoy an Isp boost due to the higher expansion ratio. So for an apogee at 50km with a 45° launch angle, they need an initial speed of 1400m/s (neglecting atmospheric drag). That's only Mach 5.

The main issue I see is the deceleration when crossing the atmosphere. The centrifugal acceleration can be kept relatively low if the centrifuge has a large diameter. If you attach the large end of the "fairing" to the centrifuge, and put the payload inside with its base towards the tip of the fairing, then the acceleration during spin up and the deceleration due to the atmosphere are in the same direction.

The remaining question is what is the drag force at sea level on that thing. If it's too high it will need dedicated payloads and that would kill its business case.

Offline uranium

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@John Smith 19
How does that solve the centripetal acceleration problem? Unless I misunderstand you, you pack all the turning acceleration into a jerk at each corner instead of having it distributed around the whole curve. That seems much worse.
« Last Edit: 06/17/2018 02:20 pm by uranium »

Offline intrepidpursuit

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The centrifugal acceleration can be kept relatively low if the centrifuge has a large diameter.

If they launch at 1400 m/s, if the centrifuge is 1 km across then there will be 400g of centrifugal force. Those are impossible numbers and improving one makes others worse.

That's the problem with a centrifuge is that any momentum gained is constantly restrained into a circle, so you compress all the acceleration stresses into the centrifugal force until you release it. You just can't bend the physics unless there is some big configuration change.
« Last Edit: 06/17/2018 06:28 pm by intrepidpursuit »

Offline intrepidpursuit

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I have to be careful about what I say, since the details were shared confidentially, but yes they know that they have to deal with centrifugal forces, yes, they've done a significant amount of analysis and testing, and no, it's not an insurmountable problem. Artillery shells regularly see 2-3x the acceleration this vehicle would see, and many modern shells have electronics and mechanisms. It is totally possible to harden structures for those kind of loads, especially when they're well known in advance.
There is (theoretically) a way to side step the centripetal acceleration problem.

Implement the accelerator ring as an N-sided polygon of linear accelerators. At the corners the the vehicle is moving in a straight line, only subject to gravity.  It can then be reorientated with relatively low stress ready for entry into the next segment. It also means that the exit could be at several different directions to the Equator, rather than a single fixed direction.

The attraction is the acceleration can be relatively sedate. 10g's could get you to orbital velocity (at ground level) within 90 secs. The problems would be formidable. Heavy duty power electronics, fast acting control systems and some fairly large scale tunneling (or at least trench cutting, followed by covering over).   You'd want an exit ramp to put it on a fairly steep climbing trajectory and some fast acting foil shutters to retain vacuum.
Then there's the LV.
It'll need some serious TPS.
OTOH liquid fuel is not as difficult as you might think.  The Germans in WWII developed an artillery shell with a a 300Km+ range using the spin to inject liquid fuel into a circular duct (essentially a ramjet wrapped round an artillery shell). However this used the phenomenally dangerous Carbon Disulphide as the fuel. I'd guess they'd want something more benign today. Gerald Bull (who I like to think of as "The last of the long range gunmen"  :)  ) reckoned solid propellant charges were adequate for circularizing to orbit, probably fired by a time delay or some kind of burnout trigger.
Using rotation to pressurize propellant was also the plan of Rotary Rocket.

The question with these concepts is not  "Can it be done?"

It is "Will commercial customers be prepared to swallow the costs inherent in making their payloads more rugged to survive this launch method than others" ?

GPS guided artillery shells are in use and are effective  but the electronics package was designed to do that as part of the customers requirements.

What happens when the launch price is very low but the payload has to be re-engineered from the ground up use the launch method?

If the momentum is constrained into a circle then there will be centrifugal forces. If you have linear accelerators then they will have to point mostly inward to keep it from flying out to oblivion. I don't see how this is a solution to anything.

I think it is a given that no one will custom design 400g capable payloads for such a launch system unless it was radically cheaper, and given that the centrifuge is only accounting for a quarter of the acceleration needed for orbit there is no way this will be a massive improvement over Electron or SpaceX.
« Last Edit: 06/17/2018 06:53 pm by intrepidpursuit »

Offline intrepidpursuit

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Is there some piece we are missing here that would make this thing possible? Have they addressed the seemingly insurmountable issues of the centripetal forces at launch and the drag through the low atmosphere?

I have to be careful about what I say, since the details were shared confidentially, but yes they know that they have to deal with centrifugal forces, yes, they've done a significant amount of analysis and testing, and no, it's not an insurmountable problem. Artillery shells regularly see 2-3x the acceleration this vehicle would see, and many modern shells have electronics and mechanisms. It is totally possible to harden structures for those kind of loads, especially when they're well known in advance.

As for drag going through the atmosphere, once again, yes they will slow down, but the square-cube law means that its easier to get a high ballistic coefficient (which means you decelerate less from drag) with a large vehicle than a small round.

That doesn't mean that their system is bound to obsolete all existing rockets, just that they've put more thought and effort into this than you can easily tell from the existing public articles.

~Jon

If they are okay with massive acceleration forces akin to an artillery round, then why not just fire these apparently hardened optics and antennas like artillery and not reinvent a wheel? (the pun is unintended but noticed, sorry)

Artillery electronics are rated for ~15000g, so doing the math backward says that perhaps they are planning on an 80m centrifuge, which would accelerate a projectile to 1400m/s with 5000g of force. That structure is probably possible. Now we just need an upper stage capable of providing the remaining 6500m/s of delta V and along with navigation and a payload that can survive 5000g.

So what customers are interested in the capability?

Offline john smith 19

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@John Smith 19
How does that solve the centripetal acceleration problem? Unless I misunderstand you, you pack all the turning acceleration into a jerk at each corner instead of having it distributed around the whole curve. That seems much worse.
It would depend on the size of the circle and the number of segments. It also depends on the size of the joint between those segments. I'm picturing a turning couple as one end of the vehicle turns out and the other end turns in to align with the next segment.

With 4 segments (a square) they change in angle is 90 degs, but at 8 it's 45. At high number it's a small angular change. At 360 it's 1 deg per segment and the turning forces rise with as the payload is accelerated.
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Offline Rabidpanda

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@John Smith 19
How does that solve the centripetal acceleration problem? Unless I misunderstand you, you pack all the turning acceleration into a jerk at each corner instead of having it distributed around the whole curve. That seems much worse.
It would depend on the size of the circle and the number of segments. It also depends on the size of the joint between those segments. I'm picturing a turning couple as one end of the vehicle turns out and the other end turns in to align with the next segment.

With 4 segments (a square) they change in angle is 90 degs, but at 8 it's 45. At high number it's a small angular change. At 360 it's 1 deg per segment and the turning forces rise with as the payload is accelerated.

The max acceleration at each corner will be larger than the equivalent acceleration if it is just a circle... Each corner requires an abrupt change in momentum vector, which requires a large acceleration.

You said it yourself, as you add segments to the polygon the acceleration required to change direction at each corner gets smaller. A circle is just a polygon with infinite segments.

Offline meekGee

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@John Smith 19
How does that solve the centripetal acceleration problem? Unless I misunderstand you, you pack all the turning acceleration into a jerk at each corner instead of having it distributed around the whole curve. That seems much worse.
It would depend on the size of the circle and the number of segments. It also depends on the size of the joint between those segments. I'm picturing a turning couple as one end of the vehicle turns out and the other end turns in to align with the next segment.

With 4 segments (a square) they change in angle is 90 degs, but at 8 it's 45. At high number it's a small angular change. At 360 it's 1 deg per segment and the turning forces rise with as the payload is accelerated.

Yeah you can't do better than a circle.  Any polygon will have a combination of zero centripetal acceleration, and then a sudden jolt, much larger than the circular case, as you round the corner.  This is because the local radius at the joint is much smaller, and the speed remains the same.  (v2/r)

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Offline edzieba

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Centrifugal launchers/rotary mass drivers aren't exactly a new idea. No real technical barriers to construction of both the accelerator and the projectile (as mentioned before, SMT electronics have crazy high acceleration tolerance even without any potting), and plenty of designs for the accelerator from basic bar-centrifuges with detaching counterweights and opposing decel-sumps, to rim-linear-motor designs with trapdoors or 'over the lip' detachment, to spiral accelerator tracks, etc.
Their main stumbling block to gaining funding (beyond all the normal issues of funding space startups) is that the launcher is not compatible with current payloads. You either need to convince satellite manufacturers to design and assembly kilogee-tolerant satellites just for your launcher, or find something else to launch. If ULA make good on their offer to pay $3k/kg for water in LEO that's about the only market I can think of that this launcher would serve, beyond a handful of cubesats potted in epoxy. That of course means launch prices need to be below $3k/kg.

Offline ringsider

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Their main stumbling block to gaining funding (beyond all the normal issues of funding space startups) is that the launcher is not compatible with current payloads. You either need to convince satellite manufacturers to design and assembly kilogee-tolerant satellites just for your launcher, or find something else to launch.

I wonder if the plan is to build up the velocity very gently, using a very long acceleration time on a long track, such that the payload experiences "normal" G loads? If you accelerate at 10-15G for a long time you can get to a large velocity without damaging anything...

Vf = Vi + at

If you set Vf large, say 60,000 kph (orbital velocity being about half that), Vi =0, a = 20G i.e., 200 m/s2, what t do you need to get to that Vf? Answer = 1111 seconds i.e. 14 minutes.

Offline hkultala

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Their main stumbling block to gaining funding (beyond all the normal issues of funding space startups) is that the launcher is not compatible with current payloads. You either need to convince satellite manufacturers to design and assembly kilogee-tolerant satellites just for your launcher, or find something else to launch.

I wonder if the plan is to build up the velocity very gently, using a very long acceleration time on a long track, such that the payload experiences "normal" G loads? If you accelerate at 10-15G for a long time you can get to a large velocity without damaging anything...

Vf = Vi + at

If you set Vf large, say 60,000 kph (orbital velocity being about half that), Vi =0, a = 20G i.e., 200 m/s2, what t do you need to get to that Vf? Answer = 1111 seconds i.e. 14 minutes.

You are talking about linear physics, for a direct track thousands of kilometes long.

Spinlaunch talks about SPINNING. There are centrifugial forces which you ignore, and no matter how slow you accelerate, with spinnign system you will eventually have very high centrifugial forces.



Offline Bananas_on_Mars

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Their main stumbling block to gaining funding (beyond all the normal issues of funding space startups) is that the launcher is not compatible with current payloads. You either need to convince satellite manufacturers to design and assembly kilogee-tolerant satellites just for your launcher, or find something else to launch.

I wonder if the plan is to build up the velocity very gently, using a very long acceleration time on a long track, such that the payload experiences "normal" G loads? If you accelerate at 10-15G for a long time you can get to a large velocity without damaging anything...

Vf = Vi + at

If you set Vf large, say 60,000 kph (orbital velocity being about half that), Vi =0, a = 20G i.e., 200 m/s2, what t do you need to get to that Vf? Answer = 1111 seconds i.e. 14 minutes.
I think you miscalculated, i'm getting about 83 seconds. Even with that, i'm getting a linear track that's almost 700 kilometres long for your 60000 kph.

For LEO orbital velocity, at 20g linear acceleration, that's a track 155 km long.

Offline ringsider

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Well what ever they are doing it requires vacuum: they are buying big vacuum pumps:-

USA Import Data Shipment Reports

Arrival Date    
23-03-2016

Manufacturer / Shipper    
BENAD GMBH & CO
KG IM FUNKWERK 9 KOELLEDA 99625 DE

Consignee Name    
SPINLAUCH
181 COMMERCIAL ST SUNNYVALE CA 94086 US

Weight(KG)    
3239

Quantity    
2

Quantity Unit    
CAS

Country    
GERMANY

Product Details    
VACUUM PUMP BOC EDWARDS IF30K INT460
VACUUM PUMP NRC-322-000

PO 23045 INVOICE 2016-00499 HS 845690 SCAC SSLL AMS-REF OAK205584

Place of Receipt    
HAMBURG

Loading Port    
BREMERHAVEN

Unloading Port    
OAKLAND CA

Container_Id    
BSIU9231224

Container Size    
4000*906*800

Bill of Lading    
SSLLOAK205584

Master Bill of Lading    
HDMUBMWB1203148

Vessel Name    
SINGAPORE EXPRESS

Voyage    
6858

HTS Code    
845690
« Last Edit: 06/18/2018 07:06 pm by ringsider »

Offline A_M_Swallow

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Their main stumbling block to gaining funding (beyond all the normal issues of funding space startups) is that the launcher is not compatible with current payloads. You either need to convince satellite manufacturers to design and assembly kilogee-tolerant satellites just for your launcher, or find something else to launch.

I wonder if the plan is to build up the velocity very gently, using a very long acceleration time on a long track, such that the payload experiences "normal" G loads? If you accelerate at 10-15G for a long time you can get to a large velocity without damaging anything...

Vf = Vi + at

If you set Vf large, say 60,000 kph (orbital velocity being about half that), Vi =0, a = 20G i.e., 200 m/s2, what t do you need to get to that Vf? Answer = 1111 seconds i.e. 14 minutes.
I think you miscalculated, i'm getting about 83 seconds. Even with that, i'm getting a linear track that's almost 700 kilometres long for your 60000 kph.

For LEO orbital velocity, at 20g linear acceleration, that's a track 155 km long.

There are  equivalent equations for circular motion.
https://en.wikipedia.org/wiki/Circular_motion

The connect equations are
v = (2πr)/T
a =v2/r

Where V = velocity, r= radius of launcher, T = time for one rotation and a = acceleration

In real life the acceleration will not be constant but the energy supplied per second may be.

Offline jongoff

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Centrifugal launchers/rotary mass drivers aren't exactly a new idea. No real technical barriers to construction of both the accelerator and the projectile (as mentioned before, SMT electronics have crazy high acceleration tolerance even without any potting), and plenty of designs for the accelerator from basic bar-centrifuges with detaching counterweights and opposing decel-sumps, to rim-linear-motor designs with trapdoors or 'over the lip' detachment, to spiral accelerator tracks, etc.
Their main stumbling block to gaining funding (beyond all the normal issues of funding space startups) is that the launcher is not compatible with current payloads. You either need to convince satellite manufacturers to design and assembly kilogee-tolerant satellites just for your launcher, or find something else to launch. If ULA make good on their offer to pay $3k/kg for water in LEO that's about the only market I can think of that this launcher would serve, beyond a handful of cubesats potted in epoxy. That of course means launch prices need to be below $3k/kg.

Yeah, while I think what they're doing is technically feasible, I agree that market desirability is more of a question, even if they can hit the price-points they're claiming. They are going after smallsat launch as a market (which I agree would require hardened satellites), but I also think they could be pretty interesting for bulk materials launch such as propellants, materials for on-orbit construction, supplies for a space facility, etc. If they can make this thing work and hit their price point, I wouldn't be surprised if they earned some market share, but I'm skeptical they're going to outright replace rockets for earth-to-orbit launch.

The application I'm most interested in though would be using this same technology for propellantless launch from the lunar surface. That's an area where these systems could totally shine. But that's a bit far off, so I'm keeping my fingers crossed that they'll be successful enough to stay in business and put this technology "on the shelf".

~Jon


Offline John-H

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This system has the same issues as the gun launch scheme that was proposed many years ago. I think the conclusion was that it may be possible, but it wasn't worth the effort.

----------------------

Gerald Bull must be "spinning" in his grave...........  Sorry, I just couldn't resist.

John.

Offline Asteroza

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The application I'm most interested in though would be using this same technology for propellantless launch from the lunar surface. That's an area where these systems could totally shine. But that's a bit far off, so I'm keeping my fingers crossed that they'll be successful enough to stay in business and put this technology "on the shelf".

Would it be appropriate to differentiate between some types of bulk payload lunar surface launch such as water or liquefied gases, and solid sintered regolith mass slugs? I ask, because some rotorvator architectures could vastly benefit from increased counterweight mass, preferably sourced from higher orbits. Not to mention infrastructure support via standardized regolith blocks (rad shielding).

More importantly, how viable would it be to have the whole slingatron on a rotating turntable to change azimuth, hardware-wise and from an infrastructure perspective? It would need to be compared to the tipping points between simple tether slings and a large conventional linear mass driver for instance...

Too bad sintered regolith tensile strength isn't very high, otherwise you could simplify to regolith balls/cylinders spun out on a ramp DREAD-style...

Offline ringsider

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You would have to assume to attract those investors that the concept is simple and easily proven, and doesn't need the entire satellite customer base to change they way they work to handle extreme loads.

I wonder if SpinLaunch has hit upon something interesting using a very large moment of inertia?

The press release talks about use of rotational kenetic energy: "We are very intrigued by SpinLaunch’s innovative use of rotational kinetic energy".

Rotational KE is defined as half of the moment of inertia x the rotational velocity squared. So what if they increase the moment of inertia massively, instead of rotational velocity, creating a kind of massive, broad flywheel, that can create a large amount of KE without inherent high speeds and centripetal forces?

The logo is  kind of hint that the projectile is part of the circle before leaving the circle and flying off i.e. it is not a spiral. So it has to either go very fast, or somehow be heavy enough and be able to impart that energy to the vehicle upon release.
« Last Edit: 07/02/2018 06:32 pm by ringsider »

Offline chipguy

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You would have to assume to attract those investors that the concept is simple and easily proven, and doesn't need the entire satellite customer base to change they way they work to handle extreme loads.

I don't think that assumption is at all warranted. At best the concept doesn't blatantly
violate basic fundamental physical laws (perpetual motion, faster than light etc). When
there is significant venture capital sloshing around global financial markets in search of
long shot bets that is often good enough, especially in fashionable fields like new space
is right now.

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