NASA will test SpinLaunch's ability to fling satellites into orbit
newatlas.com
newatlas.com
The fact of the matter is that this concept, if it works, will only launch as much payload into orbit as an Electron rocket (a very small launch vehicle), and would require payloads specially designed for the g-forces which would make them heavier. This launch concept has exchanged fuel mass for heat shield mass to allow it to survive after it leaves the spin system.
Now, one actual use case for this type of technology is if they were to build it on the moon, especially for launching things like mined resources off the surface. The launch forces would be lower as the speed requirements are lower and it would allow launching material with little to no fuel consumption as long as there is electrical power (of which there is near infinite amounts of because of the semi-constant sunlight).
Unless you want to launch on the night side of the moon, then you have to wait up to 14 days. But yeah the moon with its lower atmosphere makes a lot of sense.
You'd still need to send spacecraft and larger cargo up the old fashioned way, but this would allow you to neatly work around the "your only fuel is what you carry to orbit with you" problem (as long as you carry enough fuel to rendezvous with one of the fuel pods to begin with).
I assume there are some reasons this isn't done, like the rocket equation persisting outside of Earth's atmosphere and gravity well, ie. you still have to accelerate the fuel mass if you intend on taking it with you, but taking it from launch obviates the needed complexity to rendezvous with an orbital gas station.
Just to clarify for you here, but this can't actually launch anything directly into LEO. It needs a rocket of some sort, or something in space to "catch" it and complete the orbit. This is why what they're launching in their slingshot isn't a payload, but a small rocket with plentiful heat shielding that will contain the payload to be released. That small rocket still needs to be built every time so it doesn't actually reduce costs that much until there is something in space to "catch" the payloads. Which I am skeptical of the ability to do for Earth orbit given the much larger speed differentials of catching things in LEO.
Also on the cost thing, you have the cost issue inverted and you're trying to solve the wrong problem. The most expensive part of space travel is the whole "throwing away the vehicle after one use" aspect, not the cost of the fuel. SpinLaunch makes the vehicle itself cheaper, but it's still throwing it away.
As here on Earth, it's probably one of the most valuable 'heavy things' we need up there. it's just bloody expensive to get up there. At least until we can start lassoing asteroids... .
You still need to build a rocket and waste it.
One Starship launch can reusably launch like 150tons of fuel.
Compare that to 1500 SpinLaunches.
There is no way for this to be even remotly economical.
Problem (for both lunar or in orbit idea) is getting the heavy motors off earth.
"Current Space Act Agreements": https://www.nasa.gov/partnerships/about.html
Still can't find a NASA site with a reference to this agreement. Do you know if one exists?
However, electronics have been subjected to such high G forces as far back as WWII but on a much smaller scale when the proximity fuze was introduced towards the end of the War (one of its first uses was at the Battle of the Bulge, Patton waxed lyrically about its high effectiveness): https://en.wikipedia.org/wiki/Proximity_fuze
When I first heard about VT Fuzes years ago I didn't really believe it because it didn't use solid state devices, transistors etc. but rather a 'ruggedized' vacuum tube (this was several years before the transistor was invented in 1947). At the time I couldn't see how glass vacuum tubes could withstand ≈20,000Gs when fired out of a gun barrel but somehow they did.
Therefore, I'd imagine that upgrading to solid state devices would allow an even higher scaling in the G department (i.e.: relative to the VT Fuze), so it seems highly possible (perhaps the SpinLaunch idea actually originated from VT type Fuzes, I'd not be surprised).
people, less so.
The more I read about US research developments during WWII the more I appreciate the tremendous effectiveness of the US's OSRD (Office of Scientific Research and Development)—the instigation of the Manhattan Project, the huge enhancement of RADAR by the MIT Rad Lab (https://en.wikipedia.org/wiki/MIT_Radiation_Laboratory), the proximity fuze and much other work (as here: https://www.loc.gov/rr/scitech/trs/trsosrd.html), owes a huge amount of success to its science administrator, Vannevar Bush. Whilst Bush is still known amongst technical cognoscenti, it seems to me he ought to be much better known amongst the broader public. Not only was he a top rate scientist and engineer but also a first-rate administrator who got things done. It's very rare that we get someone with such a wide understanding of physical phenomena and engineering expertise in addition to having excellent administrative skills and experience.
It seems to me historians ought to promote Bush up amongst the ranks of the key players who were responsible for the US/Allied victory in WWII. Of course, Bush had much help from other important notables such as Alfred Loomis, Fredrick Terman (father of Silicon Valley and author of one of my textbooks), Henry Stimson, (War Secretary) and many, many others. Nevertheless, there was something unique about this group of individuals which is pretty rare, just about everything they touched worked well and was on time to help the war effort (shame that team isn't around today).
We continue to see many documentaries about military action during the War but they almost never mention anything about the enormous 'backroom' effort made by many, many people and of the remarkable amount of coordination that was necessary between them—unfortunately, they are now mostly forgotten to history. We need to give much more credit to those who made this huge contribution to the War effort—those who not only developed reliable and effective prototypes of new weapons but also who ensured that these weapons were put into production quickly and manufactured in sufficient quantity to effect a successful outcome of the War. Seems to me that the broader historical record ought to be changed and updated to reflect these forgotten facts.
Back to proximity fuzes. I'm still amazed these devices worked as well as they did. To understand why I'm still trying to find out more about their design details. For instance, on the web there are any number of cutaway drawings of the Mark 53 VT fuze together with lots of general descriptions of its operation but I've not found a fully detailed drawing of its circuit (engineering drawings, etc.). Nor have I come across a detailed description of its theory of operation (only general outlines). Nor have I ever seen its detailed specifications.
From various reports of its development, many thousands of test firings were done so where are these test results now (it's hard to believe that they no longer exist)? For instance, what was the sensitivity of the device, that is, what is the nominal distance from an aircraft (of given size) for its thyratron to trigger? There has to be a nomogram of aircraft sizes (or types) versus trigger distances, as this information would have been a vital conclusion from the testing procedures (not to mention also being key operational parameters).
Similarly, there seems to be no detailed description of the dry battery (aka its energizer) which provides the 'delayed-start' power to the device (some published circuits show that it supplies 100 Volts needed to operate the vacuum tubes and this voltage is what we would expect for battery-powered tubes)—but there's nothing about the battery's chemistry or its actual physical construction). To achieve 100 Volts EMF, multiple cells would have had to be involved (joined in series), however this poses a problem and it's never explained. The breaking of a single ampule of electrolyte to start the battery needs more detailed explanation. After breaking, the ampule would have flooded the whole (single) battery compartment which contained the dry battery cells. However, individual cells can never reach more than a few volts each let alone 100 Volts using standard chemistry—electrode potentials forbid such high voltages: https://en.wikipedia.org/wiki/Standard_electrode_potential_(.... So with only one single battery compartment why didn't the electrolyte short out cells as the voltage tried to rise above the nominal voltage potential for a single-cell? (Clearly, the fact that the fuze worked meant that the battery also worked and supplied the high 100V, so some important information is still missing.)
Perhaps this information is readily available and it's just that I've somehow missed it. I can't see any reason for why parts of this information would be still classified after all these decades. Moreover, such info could no longer be classed as a security risk for the simple reason that there is no way that you could get the specialized components for, say, to manufacture a clandestine device (the ruggedized tubes alone were very special and are no longer made).
If anyone knows where this additional info can be found then I think many of us would be interested in seeing it.
__
FYI, here's an aside comment on the strength of normal commercial glass vacuum tubes and vacuum tube glass.
Years ago, I worked in a TV station and there was always ongoing banter and rivalry between the electronic staff (engineers and technicians) and the electrical staff (electricians). Electronics staff looked down on the electricians and considered them clowns, likewise they considered electronics people as overpaid professional wankers (the rivalry didn't descend into animosity, rather it was more like behavior seen between competing football teams). What exacerbated this rivalry was that the electricians had their own building some 20/30 meters from the main building, it not only housed their complete operations but also the station's emergency power source (an ex-WWII submarine diesel engine and a 3-ɸ alternator). In essence, as a group, the electricians were isolated from the rest of the staff which put them slightly apart.
Anyway, some of the more adventurous of the electronics staff (including yours truly) were always up to mischief and one of our inventions was our infamous Valve Gun (Tube Gun for you US-ers). Initially, its invention had nothing to do with the electricians but later we found it a devastatingly effective 'weapon' to use against them. It consisted of a CO2 fire extinguisher with a conical discharge nozzle, two lengths of plastic electrical conduit about 2m in length. One conduit had an internal diameter just sufficient to snugly (but not tightly) fit 7-pin vacuum tubes (6AU6, etc.), similarly the other was for 9-pin tubes (12AT7, etc.). To operate, place a vacuum tube into the conduit at the near (extinguisher) end with base/pins first, couple the conduit into the extinguisher's nozzle until it is a tight fit, aim and then pull the trigger. Not far from us was an old disused quarry that we used as a test firing range, tubes would leave the gun with such velocity that there was no way anyone could ever see them exit the conduit. They'd then immediately disappear many hundreds of meters off into the distance to eventually land somewhere at the bottom of the quarry.
The electricians' building's entrance was through a green wooden door that faced the electronics department and OB garage exit on the main building. Much to our amazement, tubes fired from the garage at the electrician's door would embed themselves in the wood up to the full length of their pins but they would rarely break (after this tortuous ordeal their glass envelopes remained intact and their getter deposits were still a shiny silvery colour which meant their vacuums were still OK). Their internal electrodes, however, would often collapse downward towards the tube's base (to the glass seal area where the pins exit). Surprisingly, the collapse of the internal structure was often limited to only the support wiring that connected the pins in the glass base to the electrodes, that is, top and bottom mica separators, cathode, grids and anode structures often remained intact without any noticeable damage or obvious physical distortion.
This turned out to be more than just stupid antics on our part in that we all were amazed at the G forces that these glass tubes could take before their glass envelopes would break. Unfortunately, we had no simple way of measuring the exit velocity of the tubes but I'd confidently say it was such that if one of those tubes hit one in a vulnerable part of one's body then one could easily have been killed. At that time I was unaware of the history of VT fuzes. If I'd known about them back then, then I'd have taken more interest in the tubes' exit velocity. (In hindsight, we had access to 931A photomultipliers and oscilloscopes, so with a little effort we could have timed the tubes' velocity over a known distance). Perhaps in some minor way our 'gun-tube' experiments add a modicum of weight to the accuracy of the VT fuze story (even if at the time we were oblivious of the fact).
Oh, the electricians: they were only day workers, so we carried out our nefarious work on evening shifts. Suffice to say, they were not amused when they'd arrive in the morning to find a dozen or two vacuum tubes embedded in their front door. They couldn't retaliate either, whilst they could have easily built the gun only we had carefully guarded access to the tube ammo. Incidentally, removing the tubes from the door turned out to be very difficult. They were embedded in the wood so very tightly that they could not be removed by just pulling on them by hand. To remove them we forced screwdrivers under their bases and this was difficult (there being no space between the glass and the door surface). When glass envelopes were broken it mainly happened at this time.
Electronics and such are pretty light, the regular rockets we have are fine for that. This is more for raw material, for example the structural components of a space station.
Global annual CO2 emissions = 30 billion tons.
If all the fuel became CO2, that's 0.01% of the global emission rate, so worthy sacrifice for a Mars colony, I think.
Methane combustion produces 2.75kg of CO2 for each kg of fuel.
However, I think I used the wrong value anyway, for Starship instead of its booster, so x4 or so. Doesn't affect the conclusion.
Or 1000+ SpinLaunches?
Though if NASA have chosen to enter into a contract them that gives a big credibility boost. It'll be very interesting to see how it goes.
"Spinlaunch: BUSTED!": https://youtu.be/9ziGI0i9VbE
The article describes it like they are throwing satellites into orbit. In reality even the far fetched plan, is to throw a small rocket into high altitude to save money on the first stage. Then the rocket is what will put the satellite in orbit.
I can't find a single reference to this agreement (yet) in any NASA official site. Not saying it's not real, just that I can't find an official NASA reference yet. It's not yet listed here under the current available ongoing agreements:
"Current Space Act Agreements"
"Spinlaunch Feasibility Analysis":
https://colab.research.google.com/gist/jeff-hemingway/a3d322...
Edit: The HARP project is also mentioned in the analysis as a comparison.
The real question is what kind of mass fraction is sacrificed to build something to survive being spun up.
As to why not use a gun, barrel damage is probably a deal killer for Quicklaunch and other such designs. Quickly spinning something in a vacuum and letting go should allow for launches roughly as fast as you can pull vacuum. Supporting something like a Starlink constellation seems possible with their design which could be incredibly profitable.
As for barrel wear...it's possible that that would be higher than for a normal gun, but I'm pretty sure that the rather famous author of that design took that into consideration. (It doesn't seem like SpinLaunch's design is immune to firing wear either, considering the sudden rush of air into a space with hypersonic machinery in motion.)
Starlink’s shape is optimized for it’s launch system, while I doubt spaceX is going to use a competitor anytime soon they would seriously consider sufficient cost savings.
I don't think Quicklaunch would have to suffer significant barrel damage, maybe some fouling that can be cleaned off. The pressures and temperatures required are pretty low, and the required chemistries are pretty tame; it's just the velocities that are high.
“This test accelerator is 108 ft (33 m) in diameter, which makes it a one-third scale of the operational system that is being designed.”
Perhaps though there's a big push to invest in private space and they're not looking too closely at lower value/more speculative prospects.
His phosphine "debunking" video was high on "hot takes" but low on actual intellectual honesty
There are ways of criticizing and going about that don't involve patronizing and shallow dismissals
Just watched this video. His argument for why Spinlaunch won't work is basically:
1) in the video of their first test chamber (12m diameter) there's some dirt and rust, therefore they don't know anything about vacuums
2) in their first ever test fire of a projectile leaving their 33m chamber, the projectile is wobbling, therefore they don't know anything
3) in a mock up video they made of a future launch system the headquarters is close to the launcher, which might explode if there's a misfire, therefore they don't know anything
4) the founder has an uninspiring resume when you look online
'Add these up and there's no chance they'll succeed. What they've done isn't as impressive as 50+ year old gunships.'
Give me a break. Their rate of progress is exceptional. They've already overcome so many challenges. These are weak arguments. Doesn't mean they'll be successful. But these arguments are weak. Some quick counter-arguments
1-) the 12m test chamber was a demo chamber. they were constantly spinning it up and letting people go inside. doing tours. stress testing new materials and arms. blowing stuff up. if anything the fact that it was so reliable even with the imperfections is a positive
2-) when someone is learning to throw a football there's tons of wobble. spinlaunch needs to figure out a perfect spiral. these videos were from their first couple attempts ever out of a chamber. what they're showing is very hard. this team has shown an ability to innovate and improve. those were images of their first few attempts to "throw the football"
3-) give the team some credit. these videos are designed for the general public. what they built already has an incredible amount of kinetic energy. they stress tested many tethers (past their limits) before going to this scale. when you're picking on things as small as "they're going to kill themselves by sitting right next to the system" you clearly don't have much left to nitpick
4-) jonathan is an absolute genius. just because he has a spartan online bio and unorthodox background doesn't mean he's not an absolute force of nature. thunderf00t is a very smart dude. but i'd bet anything that in a debate -- on basically any topic -- jonathan would absolutely decimate thunderf00t
cheers to the builders
I just saw one of his videos on why Falcon 9 will never be economically viable so I would strongly disagree with this assessment.
https://nitter.net/thunderf00t/status/961312911393218560?lan...
About the claim if he is smart or not, you might want to watch this then reevaluate your opinion:
Taking ten years to come up with some simple experiments to debunk someone who is reasonably frequently publicly wrong and then labouring the point and being really condescending isn't a sign of someone being especially smart (although it's hardly stupidity either).
Combine that with serving on the Anti-Musl wave and you have surefire way to be reddit famous.
SpinLaunch is a rather out there. I've actually had this idea and I'm sure many others have as well. I happen to think it can work but I was still skeptical when I first heard of them. You can only infer so much from the outside.
Thanks for the additional info blackholesRhot and for throwing money into this, the sort of bets we should be making. Godspeed. :)
However, that doesn't seem possible because the centrifuge is not in a decent vacuum (as Thunderf00t points out in his second video) due to the whooshing sound of the centrifuge 'blade', and the speed can be estimated as just less than the speed of sound. If they have the ability to do hypersonic tests already, why would they not show it in their promotional video?
The fact that they intentionally blurred the data on the screens during the demo is also odd.
---
Regarding your final point, it's much easier to pretend to be a genius than to actually be one; Elon Musk is a master at it. Additionally, debating skill is a very misleading measure of intelligence.
The mass isn't rotating as it exits the launcher.
Edit: Here's a link to an illustration, as your link provides zero information in that regard.
https://www.youtube.com/watch?v=TGO4LtCctTk&t=141s&ab_channe...
I clearly see their rocket rotate around its center of gravity, with the same angular velocity as the arm it's sitting on, while the center of gravity is moving on a circular path.
So, again, how is it not spinning? Where does the angular momentum go?
The launcher does not spin the payload around the long axis.
It is indeed exactly like a bucket. And the bucket changes its orientation throughout you spinning it, that's the whole thing, that's why the water stays inside. The top side of the bucket is always facing you. For that to happen, it has to rotate around its COG with the same rate it's rotating around.
A different example: the moon is tidally locked to the earth (like the bucket to you, or the rocket to the spin launcher) - very obviously, it needs to spin around its axis to achieve that, and it does so at exactly the same rate as it is rotating around the earth.
That momentum doesn't just disappear.
https://en.wikipedia.org/wiki/Richard_van_der_Riet_Woolley#V...
He should improve his video making skill beyond 2003 and stop making insulting people a core part of his message.
I have no interested in addressing his arguments, whatever they are on SpinLaunch. And I don't want to defend SpinLaunch anyway as it is terrible idea.
He is primarily producing entertainment, and there is no harm in that. But he does it with a correct scientific background and some humorist tones not everybody appreciates. It's not a purely scientific channel, sometimes he get's some things wrongs, mostly on his opinions about the economics of projects.
The only thing I found too many, easily dismissing in this thread, is that when he makes one these busted videos he is also daring to make a statement and they are not random ramblings.
For example his first video of SpinLaunch, if you ignore the tone is a much better analysis than the one from Scott Manley, even if Scott Manley is a much better source for anything else related to Space.
Can you point me one of those egregious errors he made? Because I looked at this whole thread out of curiosity, and every single commentator criticizing him, did not provide a single concrete example.
It's a new genre...Scientific Entertainment ( bit still scientific) Not sure everything in this short life of ours, needs to be taken so seriously:-)
He employs a large number dishonest lines of arguments. Drawing large conclusions for limited unrepresentative data. Not actually fairly representing the things he is arguing about. What he does is build narratives to lead viewers to the conclusion he want them to reach.
> Can you point me one of those egregious errors he made? Because I looked at this whole thread out of curiosity, and every single commentator criticizing him, did not provide a single concrete example.
I have not one of his videos in a long time. I remember watching his videos on Falcon 0 and struck by him clearly have no understanding of the issues with his driving goal seeming to be to gather all possible evidence and building a 'Busted' narrative while ignoring any evidence that points into another direction.
In general, looking at his videos he seems to have made a career out of calling Musk an idiot. To be fair their are a lot of low equally low quality channels that made a career out of calling Musk a genius but those are equally stupid.
He even attacks some of those channels in his own videos, but its very telling that those are the kinds of channels he interacts with. Because that the level he is playing at.
> It's a new genre...Scientific Entertainment ( bit still scientific) Not sure everything in this short life of ours, needs to be taken so seriously:-)
You don't have to be serious but I very much get the vibe that he thinks he is very serious and his fans think he is very serious as well. A also think he is deeply unfunny and his videos are pure cringe to watch. Somehow he is a genius who knows everything about everything and yet his videos production quality is worse then a 8 year old on Instagram.
His channel is the kind of channel that is designed around making online interactions worse for any topic, not better.
This is the kind of video that I find actually helpful:
I have no doubt that useful payloads could be designed to withstand the spinning as well as later rocket thrusts. (source: a couple of years on a satellite design project in university)
Lots of things "bounce" in funny ways when you put them under very large loads, then release that load suddenly.
Edit: this is, btw- fixable. Like other commenters mentioned, a trebuchet/sling like release mechanism would slow that radial unloading and reduce stress on the spinning arm too. It’s a lot more complicated to achieve though (as if this prototype/trial weren’t complicated enough!)
Then it hits the atmosphere and is subjected to significant drag, but that onset is reasonably slow (by some metric) compared with the release mentioned above, but it's along a different axis. What's more, the projectile has spin along its long axis ... I don't know how that's imparted.
Yeah, there are some huge forces that change rapidly in lots of directions.
Edit: the video in question: https://www.youtube.com/watch?v=8Phy3n_S3ng
and a more honest and detailed look at the company, again from Scott: https://www.youtube.com/watch?v=JAczd3mt3X0
However, there's a benefit in this case: heat shield probably scales with area (often something like mass^(2/3)), making it progressively less significant compared to fuel mass (which is roughly a constant fraction, i.e. it scales like mass^(1)). I think a high altitude launch site could make a significant difference as well (although that creates other logistic inconveniences). Atmospheric pressure approximately halves every 5km, and air resistance is roughly proportional to pressure.
It would be more efficient, if they could use a whip effect to (match impedance) capture much more of the rotational energy they put into the spin, more like a trebuchet.
Helium-3 is the obvious one, but that is also betting on fusion reactors becoming viable in the near future.
Some "rare earth" minerals might also be economically viable.
Silicon could be useful in orbit for building solar panels.
But beyond that, the moon will no doubt export large amounts of volatiles from the permanently shadowed craters in the poles, and structural building materials for construction in Earth orbit or elsewhere in cis-lunar space, or the fueling of expeditions to the rest of the solar system. You'd just have to tilt the spin launcher to a different angle and adjust the throw velocity to send payloads on other trajectories through cis-lunar space.
What's cheaper, mining infrastructure on moon, with a launch system on the moon to transport it back to Earth?
Considering you need potentially 100 launches from the moon to match one Starship launch. And the capital cost for the moonining and launch is absurdly high. And the only way we will ever even be able to build such a system will require a Starship type vehicle anyway.
The actual cost for Starship is unlikely to be the crazy low numbers space nerds like us are hoping for. No space launch system (including Falcon) has ever reached its theoretical minimum cost. It will be transformative, but not too cheap to meter.
We will never build an industrial base on the moon unless we have a full reusable launch system and if we have such a system mining things on earth is just far, far, far, far, far, far cheaper.
The only reason you would mine on the moon is to build things ON THE MOON.
The actual energetic cost of going from the moon to an Earth-capture orbit is only about 1 kwh/kg. Or about $150 per metric ton. Obviously real costs will be higher than physical limits, but you still might want to check your intuitions about just how costly mining the Moon really could be.
Ultimately we need to move our heavy industry off-earth to save our planet's biosphere. In a hundred years when there is a vibrant interplanetary economy, its possible we could eliminate toxic heavy industry on Earth entirely.
The problem is that to do mining you need a huge industrial base. Mining starts with prospecting. Then you need to develop the resource. You need to refine the resource at least a little. Then you need to mine that resources. Then you need to transport those resources to wherever your cheap launch option is. And then you need to launch it.
Building up such an industrial base on moon is incredibly difficult and would for sure require a massive Starship like rocket at the very minimum.
> Ultimately we need to move our heavy industry off-earth to save our planet's biosphere. In a hundred years when there is a vibrant interplanetary economy, its possible we could eliminate toxic heavy industry on Earth entirely.
Ok, in 100 years, but predicting that far ahead is pretty much useless. My point is that for any foreseeable future launching resource from earth is far more practical.
And from a money perspective it might never make sense, specially from the moon.
If its about the environment, then maybe but then you might capture asteroids instead.
NASA also funded experiments into the microwave engine thing [1], and that turned out to be bunk [2].
The point is, these are just tests. They give them a fair shake and see what happens. I highly suspect there are simply too many problems with flinging stuff into space for it to be practical.
[1] https://www.nationalgeographic.com/science/article/nasa-impo...
[2] https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster
How can this device fling a functioning rocket motor into space?
http://www.scielo.org.mx/img/revistas/rmaa/v52n2/0185-1101-r...
If you apply thrust at A then you have the solid line: an elliptical orbit.
If you just throw something hard all you have is the dashed line: go up then come back down again.
(In this diagram, substitute “initial circular orbit” for “surface of Earth” :)
But if you throw something hard enough from the Earth's surface, it absolutely does not have to return to that position. You would just need to throw it hard enough that it was at escape velocity. Due to air friction, the actual speed you would need to throw the object would be flat out absurd if on Earth at sea level. But on a body like the moon with no atmosphere it isn't that bad at all. The bonus to this is the direction doesn't matter at all really. Anything other than straight down is fine.
Now, where this does become problematic is when the velocity you would need to achieve is higher than the speed of light. At that point you're basically on a neutron star or some supermassive planet.
Isn’t this sort of a definition of a black hole? My non-physicist intuition tells me a neutron star can’t have an escape velocity higher than the speed of light, otherwise the light wouldn’t escape
The practical problems make me skeptical, but the potential advantages make me hopeful. To all the skeptics out there : remember that people were also skeptical when SpaceX said they wanted to land their rockets, yet here we are.
“People who say it cannot be done, should not interrupt those who are doing it.” - George Bernard Shaw
Any fuel you want to use on a spin launched craft still needs to be accelerated with the craft if you intend on using it to power that craft.
You still end up with a non-reusable small launcher that cant put most payloads into orbit.
And making it much bigger is not that practical.
I don’t know why but I’m excited about this idea.
They cannot fling things to orbit, they can fling things very fast but a (smaller) rocket is still needed to finish getting to orbit.
and G Forces are extreme so this is only suitable for payloads that don't mind extreme G forces.
On reentry from orbit vehicles are going mach ~25.
The drag and resulting heat production at sea level would not be as easy to deal with if you were zipping along at Mach 25 right after launch. Even supersonic aircraft don't run full speed (for a whole host of reasons) at sea level.
Anyway, the earliest patent I could find was a steam centripetal launcher in 1918. It never went anywhere and it has been followed by a number of improbable reinventions that all faded away.
NASA and the US Army tried again in 1982 and thought they could put a 60g projectile down range at 3 km/s. Mach 8. Guns and rockets could perform as well or better with simpler systems and the idea was shelved.
https://patents.google.com/patent/US1332992 https://ui.adsabs.harvard.edu/abs/1982ITM....18..209F/abstra...
https://www.youtube.com/watch?v=JAczd3mt3X0
He...encourages caution. It's one thing to call a technology "debunked", another to say it's very difficult or that it has a low probability of success.
The founder has little demonstrable understanding of physics, and their demonstration video was misleading.
If SpinLaunch's idea was practical, it would've been in use for decades already. The company seems unaware of this... for now.
I look forward to watching SpinLaunch's progress.
About what? Most of his recent content is clickbait debunking videos about stupid ideas that no serious person has ever taken seriously.
"Solar Roadways Debunked" Yeah no fucking shit.
And here we are talking about spinlaunch.....
Obviously scientists are not perfect, but you seem to imply that most of his videos are incorrect. I can't see any evidence to support that, but I'm happy to be contradicted.
There are many mentally deranged people who have published papers and are "scientists".
That's true, but it could be interpreted as a distraction from the fact that you haven't provided any evidence to support your claim.
In my experience, few mentally deranged people have a good understanding of physics. Even fewer have published in 'Nature'.
Whatever rotating mechanism (call it flywheel) they have needs to be charged up with rotational energy to launch. The amount of energy remaining in it after the projectile gets launched is the fraction M/(M+m) where M is the flywheel mass and m is the mass of the projectile.
Now you see the problem (if you have any physics instinct)
If you dont want a sudden shift in the center of rotation (going off balance) then you need the flywheel mass to be high. But the higher the flywheel mass, the more amount of energy left "wasted" as it spins to a halt in the de-evacuated atmosphere.
Bearings can handle some amount of jerking and some amount of imbalance in most applications. But here there is massive centrifugal pull of the imbalanced flywheel, the instantaneous jerk as the rotational center shifts after launch, shock wave of the instantaneous rushing in of air into the vacuum (speed of sound), the massive heating up of the whole structure, the precession that may be induced by turbulence etc.
This will most likely destroy the whole shebang in seconds, if not make it completely unusable a second time.
Slingshots work only because the sling has negligible mass compared to the stones that are launched.
This comic book idea dreamed by by some non-engineer is just going to eat up investor money and lots of precision machined equipment
I guess that's not too bad, but still wonder how difficult it is to reliably achieve a precise launch angle?
Or are sensors so fast these days that this is easy? Maybe this is just a misplaced instinct from my subconscious fear of stuff hitting me in the head when kids inevitably start playing with centripetal motion using heavy objects.
I don't think the launch angle needs to be precise; if it's off by 10 degrees (175 milliradians) they lose 1.6% of their altitude to cosine error. That would be an error of plus or minus 8 milliseconds, which seems about two orders of magnitude on the easy side of achievable.
There are no materials that are stiff enough at that size - not even carbon fiber.
The biggest ships engine shafts are literally like pasta and only work because they are mounted on dozens of bearings at regularly spaced intervals.
This is the next step in my genius idea with 0 flaws or potential disasters
>potential disasters
unless that's the intention
8000km/hour is 2200m/s. Reaching 2200m/s at only 10000 gees takes 23 milliseconds, which is only 25 meters if you're traveling in a straight line. So you might be able to do this with, say, a 2-meter-diameter by 25-meter-long supergun, with a total volume of 79 cubic meters, which you might want to dig into the ground to reduce the risk of explosion. Accelerating a 200 kg launch vehicle at 10000 gees takes 20 meganewtons; over a 2-meter-diameter area that's about 6 megapascals of gas pressure, which is only 900 psi, eminently achievable with a light gas like hydrogen (the SHARP gun reached 3km/s). Then it's just a matter of timing the gas release through different ports as the launch vehicle moves through the barrel, a problem that's enormously easier now than in the 01960s with HARP or in 01918 when the Germans solved it for the Paris Gun.
The vehicle itself doesn't have to be 2 meters in diameter, and shouldn't be; an APDS-like approach with a lightweight sabot that fragments upon exit from the barrel gives your launch vehicle better power to penetrate the atmosphere.
Contrast that with a centrifugal launcher like the SpinLaunch design. For the centripetal acceleration to be only 10000 gees at 2200 m/s, the radius of the spinning arm needs to be 49 meters, which means its diameter is 98 meters, four times the length of the supergun. It's a building the size of a city block! But turned up on its side, vertically, so it's 40 stories tall. Its total cross-sectional area is 7700 square meters. You probably have to evacuate the interior so air resistance doesn't melt your rotor, since its outer edge is spinning at Mach 6.7. (This is the "300-foot diameter steel vacuum chamber" mentioned in the article). Even if you can make it only 100 mm thick over most of its area, it's 770 cubic meters, about an order of magnitude more volume than the supergun, and that entire huge area has to be leakproof, which makes it expensive (though admittedly it only has to withstand one atmosphere of pressure, not 60 like the supergun barrel).
From appearances their test launch facility is only about 7 stories tall, so only about 20 m, and they say they're only doing launches at about 450 m/s, which would work out to about 2000 gees by the same math. But it also looks like it's about 3 m thick, 30 times more volume (per unit area) than I described above: 20000 cubic meters at full scale.
The usual problem with centrifugal weapon systems doesn't apply here, though: you don't need to aim your launch vehicle precisely at a target to milliradian precision, you just need to hit the exit port instead of the solid launch-chamber wall. (The enormously larger radius also means you're spinning at many fewer radians per second.) And the free breaking length of carbon fiber is 400 km at one gee, and thus 40 m at 10,000 gees, and the outer part of the rotor can be thinner than the inner part, which is also under proportionally lower acceleration, and there are another half dozen materials with free breaking lengths over 150 km, so a 49 m rotor that spins at this speed is straightforwardly achievable. So I think the SpinLaunch approach will work if they spend enough money on it. I'm not a SneerClubber, I'm not here to sneer.
(Realistically the most likely way for centrifugal space launch to happen is that NASA will cut their funding before they can do their first launch, and ten years later China will build a working centrifugal launcher, because building new things is not really a thing people do in the US anymore.)
But if you're willing to evacuate 20000 cubic meters to launch your vehicle at 2200 m/s, you could drill your supergun barrel down through 6 km of rock, dropping the necessary acceleration to only 42 gees. That would enormously simplify the design of the launch vehicle, though it still wouldn't allow crewed spaceflight.
I don’t follow material science stuff super closely but as far as I’m aware the investment is orders of magnitude less than propulsion and other tech.
Then again these things just take time unfortunately
[1] Technically, escape velocity is also a possibility. But it's not a useful one, as the payload is still lost.
Another out-there idea would be to shoot things at a space station that had a giant catcher's mitt or something. Would it be possible to design a decelerator that would work? And to hit it precisely with a dumb projectile from the ground?
A third possibility would be to recover and reuse the rocket engines en masse. Not sure how it could be done in a way that was cost effective though.
[1] https://en.wikipedia.org/wiki/Proximity_fuze#Improvement_in_...
In this particular configuration, the rotational kinetic energy for a 200kg load would be massive and the current materials would not be able to withstand it and another issue would be the release timing through the opening, as seen on the video the margin of error would be so narrow that is likely not possible with the current technology. I hope I am proven wrong in my armchair assessment though.
Got any numbers or facts to back this assertion up?
I haven't investigated the mechanics behind spin launch, so I'm eager to see something concrete.
From the article, they've only achieved 8,047 km/h or 2.23 km/s.
Also, flinging waste from your home into the air and hoping it won't come back down sounds like a really bad idea.
It's honestly a smaller number than I expected it to be. So I suspect that those inefficiencies add up pretty fast.
Where did we put the energy dense radioactive stuff again? We could use it... Sorry boss we yeeted it into space.
Although of course that fast of a throw from within the atmosphere is probably not practical.
https://en.wikipedia.org/wiki/Mass_driver
That way you can also launch people without having to subject them to thousands of G.