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Catapult to Orbit - SpinLaunch


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12 hours ago, magnemoe said:

Think the kinetc energies here is larger than the chemical ones.

You have to be traveling significantly faster than exhaust velocity of your rocket for that to be true, so for kerlox with ISP of 300s+ you know it has to be well above 3km/s. More rigorously, chemical energy of kerlox is about 9.6MJ/kg when you account for oxidizer mass, and that's almost 4.4km/s. All of the articles are talking about SpinLaunch targeting something in the 1km/s neighborhood, maybe a little faster. Certainly nowhere near comparing to chemical energy of the fuel. Besides, if they ever were to actually attempt this, anything light enough that you could hope to make the rest of the way to orbital would burst from acceleration load way before you get to these speeds.

But fair point, it's still a lot of energy, and the only reason I'm thinking explosion breaks the air seal and not the ram impact of the propellant and rocket debris smashing into the wall, is that I'm picturing this at least partially buried, reinforcing the wall, and leaving the ceiling as a weak point. But that's just because that would be a smart thing to do, and given the rest of the plan, might not actually be in the design.

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5 hours ago, sevenperforce said:

No possible way that air-dropping is more expensive than this setup.

For initial capital dollar per dollar probably not, but if these guys find paying customers and can actually meet their five launches per day target, then the economies of scale should make it worth it.

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Five launches a day seems like a long shot. Leaving aside the question of demand for launches at this rate, there's a lot more going into each mission than a rocket launch. Small satellites are going to need less pre-launch processing, but a launcher that needs to endure 10 000G will certainly need some additional accommodations. The only way such high rate could be achieved is multiple launch campaigns in parallel, which is a tall order, to say the least.

This is an interesting experiment, maybe it'll even work, but ultimately, I don't think there's enough activity in the space sector to truly make it work.

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5 launches per day is still only ~500 kg. It would take them half a year to match one Starship launch, so there might be market out there, but can they match the price?

Tater, to ease your mind, you didn't recursify the thread. It's all Gargamel's fault.

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Except Starship can carry a rather larger payload than 100kg. This comparison is meaningless, because Starship won't be flying with payloads of this class. Besides Starlink, just how many uses are there for 100kg satellites? Cubesats that don't care about the exact orbit can hitch a ride on anything, and there aren't that many of them being made, anyway. There's only so much you can do in LEO with 100kg of instrumentation, even most other smallsat launchers can do better than that.

I have my doubts about there being a demand for flying the Starship at max rate (assuming it works), too, but that's another matter.

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59 minutes ago, sevenperforce said:

That appears to be their plan.

I mean I could see it being launched from much higher plateaus - the Andes is already where most planes fly at, at least for regional flights and approach phase and stuff.

Though that's what I thought until I read about it being done mechanically...

idk but I don't think humans have ever made such a huge machine before, even if it only spins at a constant rate around a small radius of gyration. I'd rather waste propellant than making such a huge machine from scratch. We should try make a working miniature first... Then fiddle with the ways of how to reach really high speeds, then how to make a rocket that somehow survives all that and finally what can you really launch from it.

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2 hours ago, YNM said:

I mean I could see it being launched from much higher plateaus - the Andes is already where most planes fly at, at least for regional flights and approach phase and stuff.

Though that's what I thought until I read about it being done mechanically...

idk but I don't think humans have ever made such a huge machine before, even if it only spins at a constant rate around a small radius of gyration. I'd rather waste propellant than making such a huge machine from scratch. We should try make a working miniature first... Then fiddle with the ways of how to reach really high speeds, then how to make a rocket that somehow survives all that and finally what can you really launch from it.

As far as I know, the plans are to build the miniature first.  I think they claim to be building it now, but I suspect that "building" includes some very preliminary design...

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One possible use may be to launch bulk material into orbit, a sort of poor-man's mass driver for an atmospheric body. Water ice, aluminum, steel etc. for an infantile orbital manufacturing industry, until asteroid mining or lunar export becomes practical.

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  • 7 months later...

Inside SpinLaunch, the Space Industry’s Best Kept Secret | WIRED

Well this is very interesting. Spinlaunch wants to use a massive football field sized centrifuge inside a vacuum to launch a small rocket to 5,000 MPH to put 200 pounds into orbit.  Owner says it will reduce prices of small satellites by a factor of 20, with up to 5 launches a day, under 500k a launch. They have built a smaller version for testing and ran it a few hundred times. Even though the G-Forces are in the thousands, the parts they tested could handle it and still work.

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Reality check:

5000mph = 2200 m/s

Using a 50m radius, I get 10k g-forces.  Good luck building a rocket that can take that  (especially laterally).

Next, they want to push it through the atmosphere at over Mach 6 (might be mach 7 depending on where they build it, but I'd suggest Leadville, CO as it is "two miles high").

Smallsat launchers have issues with aerodynamic drag, and this only makes things much, much worse.  If you could possibly make this work, I'd expect to be bought out by Spacex to scale it up again and fling propellant into LEO.

Successful smallsat launchers so far (success means achieved orbit, not financial success):

Orbital:  air launched
Spacex (Falcon 1): ground launched
Rocket Labs: ground launched
Virgin Orbital: air launched

So far, it looks like half the companies have gone to extreme measures to minimize air resistance.  Orbital used 3 stages, so I doubt that they were as concerned with matching nozzel size to atmospheric pressure.  No idea about Virgin Orbit.  But even so, I think the real issue is that 10k g-force.

Edited by wumpus
trying to singlespace
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This is an excuse to spend other people’s money while having a good time. One of the job listings on their website is “Sous Chef”.

If you’re going to subject your rocket and payload to 10000 gs, a cannon would be much easier to build. 

https://en.m.wikipedia.org/wiki/Project_HARP

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On 1/31/2021 at 1:22 AM, wumpus said:

Reality check:

5000mph = 2200 m/s

Using a 50m radius, I get 10k g-forces.  Good luck building a rocket that can take that  (especially laterally).

Next, they want to push it through the atmosphere at over Mach 6 (might be mach 7 depending on where they build it, but I'd suggest Leadville, CO as it is "two miles high").

Smallsat launchers have issues with aerodynamic drag, and this only makes things much, much worse.  If you could possibly make this work, I'd expect to be bought out by Spacex to scale it up again and fling propellant into LEO.

Successful smallsat launchers so far (success means achieved orbit, not financial success):

Orbital:  air launched
Spacex (Falcon 1): ground launched
Rocket Labs: ground launched
Virgin Orbital: air launched

So far, it looks like half the companies have gone to extreme measures to minimize air resistance.  Orbital used 3 stages, so I doubt that they were as concerned with matching nozzel size to atmospheric pressure.  No idea about Virgin Orbit.  But even so, I think the real issue is that 10k g-force.

This, the 10 K g laterally will eat up all your benefits I think the rocket has to be build very solid to survive this. Worse the payload will also has to survive it. 
Yes you have smart artillery shells who are pretty complex  and can survive these forces but they are specifically build for this  and the first versions was very expensive. 
You can not launch cubesats with this to say it simple. 

Now on an place like the moon a scaled up version of this might work.

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3 hours ago, kerbiloid said:

A SpinLaunch Orion drive

  Hide contents

Hits the pusher plate with centrifugally accelerated balls.

baseliner-1-sm.1513924979.jpg

 

You can presumably make a "reverse spin-launch" by using a cyclotron as an ion-propulsion unit (*not* a launch, more likely an interstellar probe engine).  Less energy efficient, but arbitrarily high Isp (via relativistic exhaust speeds).  No idea if you can keep the efficiency lower than an LED (infinite Isp*) or not.

* you could argue that all that energy needed for LED propulsion reduces your mass (well momentum, but the rocket equation is all about momentum anyway).

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On 6/12/2020 at 7:22 PM, K^2 said:

You have to be traveling significantly faster than exhaust velocity of your rocket for that to be true, so for kerlox with ISP of 300s+ you know it has to be well above 3km/s. More rigorously, chemical energy of kerlox is about 9.6MJ/kg when you account for oxidizer mass, and that's almost 4.4km/s. All of the articles are talking about SpinLaunch targeting something in the 1km/s neighborhood, maybe a little faster. Certainly nowhere near comparing to chemical energy of the fuel. Besides, if they ever were to actually attempt this, anything light enough that you could hope to make the rest of the way to orbital would burst from acceleration load way before you get to these speeds.

But fair point, it's still a lot of energy, and the only reason I'm thinking explosion breaks the air seal and not the ram impact of the propellant and rocket debris smashing into the wall, is that I'm picturing this at least partially buried, reinforcing the wall, and leaving the ceiling as a weak point. But that's just because that would be a smart thing to do, and given the rest of the plan, might not actually be in the design.

US navy looked into optional trajectory for smart artillery shells with good control and found that it was smartest to aim almost straight up. This would be mach 2 at the muzzle. Benefits was very easy reloading and easy to absorb the recoil, allowing you to go up in gun size if you wanted. Downside was that it would only work with smart shells with good control, nothing else so you would still need standard guns for their many missions also planes and missiles could to the vertical gun jobs cheaper. 
 

 

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I only recently learned that there was a steam-powered centrifugal cannon deployed during the Civil War. 

1280px-Replica_Winans_Steam_Gun.jpg

A steam engine was used to spin a barrel assembly which was fed ball bearing rounds from a hopper. A spring-loaded door was used as a trigger to release rounds from the end of the barrel.

It did not work particularly well. It boasted a much higher potential rate of fire than any other projectile weapon of the time -- up to 200 rounds per minute -- but its muzzle velocity was substantially lower than the cannons and rifles of the day and the shots were not particularly likely to go in the direction intended by the operator.

During World War One, diesel-powered centrifugal guns were developed which claimed rates of fire in excess of 2,000 rounds per minute and muzzle velocities as high as Mach 1 but they were heavy and unreliable.

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On 2/3/2021 at 1:38 AM, magnemoe said:

US navy looked into optional trajectory for smart artillery shells with good control and found that it was smartest to aim almost straight up. This would be mach 2 at the muzzle. Benefits was very easy reloading and easy to absorb the recoil, allowing you to go up in gun size if you wanted. Downside was that it would only work with smart shells with good control, nothing else so you would still need standard guns for their many missions also planes and missiles could to the vertical gun jobs cheaper. 
 

 

They weren't the only ones. At least some Soviets argued for a 406 mm gun/missile launcher on the Sovremennyi destroyers.

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