SpinLaunch

publiusr

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Mass drivers for the Moon. Now, could this also serve as a gyro-reaction wheel on a nickle iron asteroid? I could see metal mass slung out as cabling for starwisps or to Tarzan itself around in some wise. Easier to drag a wire than lift ingots.
 

Grey Havoc

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Archibald

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View: https://www.youtube.com/watch?v=PGNiXGX2nLU

You spin me right 'round, baby, right 'round
Like a record, baby, right 'round, 'round, 'round
You spin me right 'round, baby, right 'round
Like a record, baby, right 'round, 'round, 'round

Drats, not being a native english speaker, and being a rocket nerd, I thought the lyrics were
"Like a rocket, baby..." ROTFL I swear I really heard "Dead or alive" saying "rocket" instead of "record"... how about that.
 

TomcatViP

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IMOHO, it's not working as many think: the momentum gained during the rotation is simply converted to the launching system via a clutch to a gear system (pinion and rack).

Add a simple shock absorbing system beyond the clutch and off you go as smooth as you wish it.
 

antigravite

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Thx. Pretty cool stuff. They've been partly funded by Airbus Ventures since 2018. For the record, French engineers André Mas and Emile Drouet proposed this visionary idea back in the early 1910s. A technical article was published in L'Avion (15/01/1913) to unveil this concept, soon to be expanded as a popular novel solely authored by André Mas, "Les Allemands sur Venus" ("Germans on Venus"). Nikolai Alekseevich Rynin presented this concept in Mezhplanetnye Soobschniya (Interplanetary Communications), a nine-volume encyclopedia of space travel which in turn came to be popularized in France in L'Astronautique, the eponymous encyclopaedia written by Alexandre Ananoff published after WWII (Ananoff was a friend of Sänger and founder of the International Astronautical Federation). Then I loose track of the concept though I remember a flurry of mass drivers ideas for moon launchers… Anyway, as it seems, it seems to take a little more than a century to be able to turn a very simple idea — "fronde spatiale" (space sling) — into a potential reality. Let's see what happens next.
A
 

sferrin

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IMOHO, it's not working as many think: the momentum gained during the rotation is simply converted to the launching system via a clutch to a gear system (pinion and rack).

Add a simple shock absorbing system beyond the clutch and off you go as smooth as you wish it.
Not including the 10,000 lateral Gs anyway.
 

publiusr

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Now the release is critical. To slow the arm-as soon as the sabot is freed-can you suddenly turn the disk into a generator to power a slightly longer track as a railgun? I can imagine this on an Orion Starship. Maybe a directed energy beam in the sabots path to plow the atmospheric field before it? A cyclotron, a tokamak and spinlaunch have about the same lay-out, right? A three-fer? Maybe multiple beams converge just in front of and behind the sabot...a plasma esophagus via Myrabo.
 
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Archibald

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IMOHO, it's not working as many think: the momentum gained during the rotation is simply converted to the launching system via a clutch to a gear system (pinion and rack).

Add a simple shock absorbing system beyond the clutch and off you go as smooth as you wish it.
Not including the 10,000 lateral Gs anyway.

Gerald Bull's super-guns had similar acceleration levels. Seems avionics and plumbing and rocket engines can be "hardened" against such tremendous G-forces... but don't try that with human beings.
 

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Meh. Frankly I think the 1 and 1.5 generation startram makes more sense. Maglev assisted rocket. It would certainly cost more but it has so many benefits over what I can gather from their ideas of the full blown spinlaunch system.
 

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Gerald Bull's super-guns had similar acceleration levels.

In a different direction, though. Cannon shells and rockets have the "gravity vector" pointing aft throughout the launch. This system has the "gravity vector" pointing *sideways* while it's spinning up, then pointing *forwards* after release while it's being drag-braked , then pointing *aft* when the rocket eventually fires. Cannon shells also have that fore-aft gravity vector flip.
 
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Orionblamblam

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Note when the projectile punches through the membrane, it doesn't do it straight, but slides through kinda sideways a bit. They haven;t dialed in the release.

Thing I wonder about: why this isn't double-sided. One tunnel on the left pointing skywards, one on the right pointing down. At each end of the arm is a projectile with the same mass; release them simultaneously and the forces on the arm remain balanced. One projectile flies skywards, one punches down into sand or water or styrofoam peanuts or anti-nuclear activists, whatever, just something soft and expendable.
 

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Note when the projectile punches through the membrane, it doesn't do it straight, but slides through kinda sideways a bit. They haven;t dialed in the release.
Seems like a tricky situation. The round/projectile/vehicle can use aerodynamics for stability after it leaves the launcher, but between release and that membrane it's all Isaac Newton. Nasty bit of balance to keep it perfect .

Wonder if they could use magnetic fields in the "barrel" to nudge things into alignment between release and punch-through.
 

taildragger

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Note when the projectile punches through the membrane, it doesn't do it straight, but slides through kinda sideways a bit. They haven;t dialed in the release.

Thing I wonder about: why this isn't double-sided. One tunnel on the left pointing skywards, one on the right pointing down. At each end of the arm is a projectile with the same mass; release them simultaneously and the forces on the arm remain balanced. One projectile flies skywards, one punches down into sand or water or styrofoam peanuts or anti-nuclear activists, whatever, just something soft and expendable.
I'd guess that the big challenge with a balanced release would be achieving the necessary precision in timing. Balanced release would allow the whole device to be substantially lighter but even a very slight time gap between the 2 releases would then cause a rapid unplanned disassembly. With a balanced release system, it would probably be prudent to design the structure to handle the asymmetric loads created by a timing gap so you might as well just accept them and keep it simple but heavy.
Also, the mechanism necessary to catch and contain the ballast, without misaligning, the launcher would be another another complication.
 

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Also, the mechanism necessary to catch and contain the ballast, without misaligning, the launcher would be another another complication.


Build the launcher over a "This Is SPARTA" style hole a few hundred feet deep, halfway filled with water or the corpses of those foolish enough to defy me. Let the counterweights slam in and sink to the bottom; every six months or so when the launcher spends a few days down for maintenance, scoop out the bottom of the pit and recover the counterweights or bits thereof. Since the counterweights only need to have roughly the same shape and exactly the same weight, they can be made from cast cement or resin or something, dirt cheap and expendable.
 

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The whole concept is basically to shift the price of atmosphere friction and initial inertia losses from the rocket to the launcher. I.e. to pay in cheap electric power instead of complex rocket capability. The advantages:

+ The rocket itself does not need to carry that part of propellant that went to the compensation of air friction - i.e. rocket could be made smaller and cheaper.
+ The atmospheric fairing is external detachable part, which is ditched before the rocket ignite its own engine - more economy on propellant.
+ The rocket could use vacuum nozzles on the first stage - because its engine started to work already high enough to atmosphere pressure being greatly reduced.

Downsides:

- The rocket must survive extreme acceleration - which means that its structure must be made sturdy and therefore more massive.
- The shock from penetrating dense atmosphere on supersonic speed would be significant.
- Only a specific payload could be used - capable of surviving acceleration.
 

taildragger

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Also, the mechanism necessary to catch and contain the ballast, without misaligning, the launcher would be another another complication.


Build the launcher over a "This Is SPARTA" style hole a few hundred feet deep, halfway filled with water or the corpses of those foolish enough to defy me. Let the counterweights slam in and sink to the bottom; every six months or so when the launcher spends a few days down for maintenance, scoop out the bottom of the pit and recover the counterweights or bits thereof. Since the counterweights only need to have roughly the same shape and exactly the same weight, they can be made from cast cement or resin or something, dirt cheap and expendable.
Yeah, something like that could be developed but however you absorb it, it's a lot of energy to deal with immediately below the launcher. The counterweights would hit the water or dissidents with greater than orbital velocity (the projectile's velocity + speed lost during ascent). That's going to produce a concussion wave, not a gradual deacceleration. It might be similar to depth charging the launcher and the launcher would have to be built accordingly.
The hole might have to be quite deep or use some mechanism to slow the counterweights over the few hundred foot depth, not immediately on impact with the surface. I don't think there's a single material that could do that - you'd probably need a stack of materials or dissidents of increasing densities or maybe a tapering pipe. Anyway, they're complications that Spinlaunch probably figured that they didn't need when developing a machine that is already pretty novel.
 

publiusr

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This is why I suggested a disk sabot. We have seen them in submunitions…and I remember a Parabolic Arc story about disk sats. Yes the frontal surface area would be greater…again, could you stack this between a fusion reactor and a cyclotron to break down the air ahead of the disk?

A straight rocket could be more troublesome.
 

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The counterweights would hit the water or dissidents with greater than orbital velocity

I gotta doubt that this thing will get anywhere near orbital velocity. If it did, the sonic blammo at launch would be rather sporty, never mind all the other mechanical difficulties in getting a velocity like that.
 

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Close examination of the launch footage shows that the projectile doesn't just leave the "muzzle" crooked, it's actively tumbling and continues to do so throughout flight. Take a look at the video at about 0.47. Set the playback speed at 0.25; you can see the blurry projectile tumbling end over end. And it makes sense that it does so: while attached to the rotating arm, the projectile is rotating at about three revolutions per second. Once released, it will retain that angular momentum; since it’s not touching anything – it’s not riding rails, or sliding down a barrel, nor are its fins reacting against air since it’s in a vacuum – there is nothing to arrest that rotation. So it leaves the “barrel” tumbling. This would be *disastrous.* Even if the fins could stabilize the projectile in flight, a massive amount of launch energy would be wasted in the process, the trajectory would be virtually randomized, accelerations would be massive and all over the place.

View: https://youtu.be/Z6esOcWrrEE?t=47
 

publiusr

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That's why I suggested a disk-though that would be a difficult build. Now, let's say they convert the existing spin launcher into a disk shooter...any novel use for that beyond a kinetic art exhibit at Burning Man?
 

Orionblamblam

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That's why I suggested a disk-though that would be a difficult build.
It would also not be helpful. A disk has greater drag than a "dart," (and supersonic drag of a disk is immense IIRC) and you still need to stop the rotation before you can fire up a rocket stage.

As for alternate uses: use it to fling criminals. Other than that it seems pretty useless.
 

publiusr

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I remember wheel shaped fireworks...no telling where it would end up. Oh well.
 

taildragger

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Close examination of the launch footage shows that the projectile doesn't just leave the "muzzle" crooked, it's actively tumbling and continues to do so throughout flight. Take a look at the video at about 0.47. Set the playback speed at 0.25; you can see the blurry projectile tumbling end over end. And it makes sense that it does so: while attached to the rotating arm, the projectile is rotating at about three revolutions per second. Once released, it will retain that angular momentum; since it’s not touching anything – it’s not riding rails, or sliding down a barrel, nor are its fins reacting against air since it’s in a vacuum – there is nothing to arrest that rotation. So it leaves the “barrel” tumbling. This would be *disastrous.* Even if the fins could stabilize the projectile in flight, a massive amount of launch energy would be wasted in the process, the trajectory would be virtually randomized, accelerations would be massive and all over the place.

View: https://youtu.be/Z6esOcWrrEE?t=47
The wobble is probably due to the projectile's length, if it had zero length and were attached at the point where the arm is normal to the launch path there should be no wobble. The wobble should be predictable and I'd think it would be possible to stop it proactively with some sort of thruster at release.
 

Orionblamblam

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The wobble is probably due to the projectile's length, if it had zero length and were attached at the point where the arm is normal to the launch path there should be no wobble. The wobble should be predictable and I'd think it would be possible to stop it proactively with some sort of thruster at release.

The tumble is due to basic physics... as it is being spun about, the projectile is rotating. When it's released it retains that angular momentum until something acts on it.

It tumbled through at least one full rotation by the time it passed out of view of the drone that filmed it... perhaps a hundred, two hundred feet. You'd need a massively powerful thruster, and a precise one, to arrest that rotation rate in the short launch tube. That's yet more weight cost and complexity.

A simple cannon looks better and better.
 

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