You can build something like this, but <i>much bigger</i>, and with no external casing, on the Moon or anywhere with little or no atmosphere.<p>Professor James Longuski and his students at Purdue University have done quite a bit of research on this idea over the years. They call it a tether sling. To keep the tip acceleration (v^2)/r low, you want a large r. Some papers:<p><a href="https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=longuski+tether+sling&btnG=" rel="nofollow">https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=long...</a><p>Note 1: Professor Longuski was my PhD advisor, but I never did any research on tether slings myself.<p>Note 2: Others have also researched tether slings. The papers linked above give many citations to related research.
This is clearly a military oriented startup.<p>For sending civilian payloads into space, it has a very low chance to reach a price point that is competitive with reusable rockets. You either need an absolutely gargantuan centrifuge -> high capital costs - or you need to subject your payload to thousands of Gs. "The payload" is in this scenario must include 1 ton liquid fuel rocket for every 200Kg you want to put into space, or 1 ton solid for every 100Kg.<p>You have to ensure this "second stage" will never explode inside your centrifuge despite being subjected to orders of magnitude higher loads than the typical rocket. This is possible but very expensive, you will need huge structural mass to hold what would appear to be thousands of tons of propelant at 1G. So the mass fraction goes down, the costs of the rocket and centrifuge "spin" out of control, and you provide a paltry orbital capacity of a few tens of Kg and only for specifically engineered satellites that no existing manufacturer knows how to build. A commercial dead end.<p>For military applications on the other hand, it's close to perfect. You don't need orbital insertion, you can accelerate your payload silently without allowing for detection in the early phase of the attack, your projectile starts at essentially cruise speed and can only be detected by infrared emissions due to atmospheric heating for a few seconds until the launch ablative heatshields are ejected. It's a fantastic first strike weapon.
Lot of red flags for Spinlaunch.<p>> The test projectile "goes as fast as the orbital system needs, which is many thousands of miles an hour," Yaney told CNBC<p>This is an evasive statement. The test projectile is nowhere near as fast as their planned orbital system. The challenges scale poorly. Acceleration (and resulting loads during the spin) scales with v^2. Then once you hit the atmosphere, drag and thermal flux increases with speed even faster.<p>--<p>Here's John Carmack (who ran his own rocket company once, Armadillo Aerospace) on Spinlaunch.<p><a href="https://twitter.com/ID_AA_Carmack/status/1458870561606615046" rel="nofollow">https://twitter.com/ID_AA_Carmack/status/1458870561606615046</a>
Scott Manley has made a video about it <a href="https://youtu.be/JAczd3mt3X0" rel="nofollow">https://youtu.be/JAczd3mt3X0</a>
This is either total scam or the founder didn't do school physiscs. Most of the info is quoted as "founder said to CNBC", hence I see no material proof.<p>A school-level physics calculation is enough to debunk it in a minute.<p>Earth orbital velocity is roughly 8000 m/s. To achieve even a small fraction of it by spinning, the projectile and the device must withstand centrifugal acceleration:<p>a = V ^ 2 / r<p>Let's assume we obtain 1/8th of the orbital velocity, which will give a significant fuel reduction, thanks to fuel is exponential to delta V.<p>r of the full-scale should be 136 m (small-scale diameter is 91 m as in the article, scaled by 3 as said there too, divided by 2)<p>1000 ^ 2 / 136 = 7352 m/s^2 = 750 g.<p>I leave to the others to calculate how many RPMs should the device make. There's no material that can withstand such forces for extention. Many projects of energy conservation with flywheel were cancelled because sighnificantly heavy and large flywheels (couple of tons and just about 1 meter in radius) tear themselves apart at 2-3K RPM.<p>I've not heard of any devices handling 100g over any significantly long periods of time.
Makes me wonder about the military uses of such tech. Remember Gerald Bull and his quest to launch a satellite with an artillery piece? He later was embroiled in a project for Iraq to create a supergun that could potentially provide ICBM tech to a country without rocket tech.<p><a href="https://en.wikipedia.org/wiki/Supergun_affair" rel="nofollow">https://en.wikipedia.org/wiki/Supergun_affair</a>
I don't think the advantages outweigh the disadvantages.<p>G-loading. Rockets are normally rated for force in one direction (down) the same as gravity and launch acceleration. They can only handle a few small percentages of G laterally. This rocket would need that, plus at least a few G of lateral acceleration for spinup and a massive negative G capability for the impact with the lower atmosphere immediately after launch.<p>Was there a G-meter on this rocket/dart? What did it feel like to go from thousands of mph in a vacuum to suddenly thousands of mph at sea level? 50g? It would be like slamming through concrete. Larger rockets would no doubt feel less of this impact but they would still need structures akin to fighter jets. Those structures would be heavy and likely nullify any fuel savings.
I couldn't resist mashing these two together<p><a href="http://www.youtubemultiplier.com/618f3abec89ec-you-spin-me-right-round-baby.php" rel="nofollow">http://www.youtubemultiplier.com/618f3abec89ec-you-spin-me-r...</a>
This is probably a silly question, but for the test run, did they launch the rocket straight up? From my limited understanding of gravity, I’d expect it to come straight down if anything went wrong, and it looked like there were quite a few things for it to come down on.<p>Edit: looking at the video closer, it looks like there is a slight angle to the launch, tilting away from the building next to it, which makes sense.
This is the scale model. The orbital version has to be several times larger.<p>The idea is, I think, to use this as a first stage. The second stage is a rocket that takes the projectile to orbit.
Cool to see some new ideas here. Saturn V burned nearly 200 tons of propellant by the time it cleared the launch tower. Tsiolkovsky got us to the moon but he won't get us to the stars.
People here seem very interested in questions about payload G-forces and basic functioning, but to me, non of those matter. Even if you assume 100% of this works, it has no place in the market.<p>A Starship can launch 150 tons to Orbit, fully reusable.<p>Now ask yourself, if SpinLaunch even if you assume the largest possible ground station can not launch more then a few 100kg to Orbit and still requires a Upper Stage rocket that has to be thrown away. How could it possibly be cheaper?<p>So lets assume an absurdly large SpinLaunch system that can get 500kg to Orbit. You still need 300 launches to match what Starship can do in a single afternoon. In a more practical situation its more like 800 launches to match a single Starship.<p>Now try to think a gigantic stack of 300 SpinLaunch upper stage rockets that would be thrown away including 300 rocket engines, 300 avonics systems and so on. Compared to a Starship that simply lands and is fully reusable.<p>Not to mention that a chemical rocket is far more flexible in regards to orbit and far more versatile in possible payloads.<p>At best it can compete for a very small part of the small rocket launch business. But even then, a lot of the time dedicated launches are used for non-standard orbit and SpinLaunch has far less flexibility then a normal rocket.<p>I really see no way this makes much sense.
Neat concept but don't see how they're going to get around the g forces.<p>Think about it...even a playground wheel can generate enough centrifugal/petal force to make a human feel a little unwell.<p>Non-trivial fundamental problem that you can't disappear by just inventing a new material/technique or something.
I wonder how big it would have to be to even consider putting people on it, albeit sleeping ones. A younger me would look up the required velocity and do the math. A slightly older me is going to sleep soon and will dream that one day he gets to get into the space flinger.<p>Edit: and not come out as human paste
Perhaps this can also be used to send a continuous stream of supplies, such that we could have a true, inhabitable space station, where all the components required for space travel are manufactured and assembled in orbit.
This concept has been pretty thoroughly rubbished by Thunderf00t (video):<p>Part 1: <a href="https://yewtu.be/watch?v=9ziGI0i9VbE" rel="nofollow">https://yewtu.be/watch?v=9ziGI0i9VbE</a><p>Part 2: <a href="https://yewtu.be/watch?v=ibSJ_yy96iE" rel="nofollow">https://yewtu.be/watch?v=ibSJ_yy96iE</a><p>TL;DW:<p>- Vacuums are hard.<p>- Rotation is hard.<p>- Mach 7 is hard.<p>- Lower-atmospheric thermal ablation is hard.<p>- Promotional videos long on drama, simulation, confetti, and inspriring soundrack, short on actual data and performance shots.<p>- Leadership expertise and experience is profoundly lacking.
is this really more efficient than just launching the rocket normally with chemicals?<p>the article doesn't really go into detail but alludes to the answer to my question being "yes".<p>I guess the idea is:<p>you can spin a smaller rocket which requires energy EnergySml. Alternatively you could have a larger rocket which requires EnergyLrg to get out of the atmosphere.<p>So EnergySml + Fuel in rocket to leave atmosphere << EnergyLrg (which is launch + leave atmosphere)?<p>---<p>other questions I had were:<p>- wouldn't the rocket being spun have to be heavier than the equivalently sized chemical rocket because it has to be able to survive being flung around in a centrifuge?
Neil Stephenson was just talking about this concept on Lex Friedman’s podcast.<p><a href="https://www.youtube.com/watch?v=xAfdSak2fs8" rel="nofollow">https://www.youtube.com/watch?v=xAfdSak2fs8</a>
This is getting pretty close to science fiction. I wonder how much crazier future science fiction writers can get. They're running out of imaginary ideas that hasn't turn out to be real.
So you will only be able to send payloads that can handle such immense G-force pressures, I imagine? Humans can be ruled out then unless you want hominoid scrambled eggs in space
This is quite interesting, recently I watched video explaining similar rail-gun/cannon concept, end explanation what would it take to work for human payload.<p><a href="https://www.youtube.com/watch?v=Rb6sxy3f7VE" rel="nofollow">https://www.youtube.com/watch?v=Rb6sxy3f7VE</a><p>Well train human can survive:<p>38G for 0.5s<p>9G for 2min<p>7.5G for 5min<p><a href="https://www.youtube.com/watch?v=-4lVfrTcr0c" rel="nofollow">https://www.youtube.com/watch?v=-4lVfrTcr0c</a>
I somehow expected this to be some kind of [Skyhook](<a href="https://en.wikipedia.org/wiki/Skyhook_%28structure%29?wprov=sfla1" rel="nofollow">https://en.wikipedia.org/wiki/Skyhook_%28structure%29?wprov=...</a>).<p>Thinking about that, would it be possible to "fling" an object trebuchet-style by flying some crazy maneuver with a "hook-plane" instead of a satellite?
That giant sling somehow looks more suited to deliver small packages directly into a backyard than Amazon's attempts at drone delivery.<p>The military have probably already tried something like that to send ballistic missiles I guess, and in that case you don't even have to accurately aim as the missile can guide itself to the target. Why isn't this a thing already?
In the video of the launch we see the rocket punch through a membrane to go from vacuum pressure to atmosphere, what kind of forces does this involve ? Intuitively it seems like hitting a wall, but thinking more about it, inside the rocket this is just a change of acceleration (jerk) so maybe it's not so bad ? Would a human survive it ?
What if they built a giant multiple mile long electromagnetic rail gun that accelerated the payload to a few thousand miles and hour and fired it off into orbit? It would solve the same problem as this spinny thing but would subject the rocket to lower g forces during its launch?
I wonder if this could be used in a rifle type design, where the "spinner" would carry an impactor that would push against the space-bound rocket/projectile, to avoid (some) of the high g-forces?
How much force is exerted on the rocket / payload when it is released from the vacuum chamber — traveling at full operating speed for an orbital mission — and smacks into the atmosphere?
What’s the reason they have decided to couple this with a two stage chemical rocket? - Would the physics/g-forces reason be too much to go all the way or some other reason?
Here is Carmack's take on it: <a href="https://twitter.com/ID_AA_Carmack/status/1458870561606615046" rel="nofollow">https://twitter.com/ID_AA_Carmack/status/1458870561606615046</a>
TLDR Useless, but fun to work on.
This video is really weird because usually a launch video that has all the theatrics of a Hollywood production (all white launch room with dramatic lighting and shallow depth of field cinematography) would usually be done by trust-fund startup LARPers, but they actually built this shit and launched it which is not characteristic of a LARPer.
We changed the URL from <a href="https://jalopnik.com/a-startup-just-launched-a-rocket-by-spinning-it-really-1848040339" rel="nofollow">https://jalopnik.com/a-startup-just-launched-a-rocket-by-spi...</a>, which points to this. We changed its hideously baity title as well.