10 ms·

Space catapult startup SpinLaunch comes out of stealth

88 points by stingrae 9y ago

kuon 9y ago
Realistically, what is the feasibility of a space catapult? I mean, the speed at ground level to be able to reach orbit must be insanely high, no? This high speed in a thick atmosphere would cause all kind of heating problem on the catapult itself and the "rocket". I wonder what would be the actual numbers.
- rmcpherson 9y ago
  Not to mention the acceleration needed to achieve orbital velocity with a catapult. Seems like insanely high forces on the payload. I’d love to see how they solve this.
  - pesmhey 9y ago
    It’s a centrifuge, so the acceleration could be low enough to not cause damage to the payload.
    - JoeAltmaier 9y ago
      Simply spinning is acceleration. Every been on a fast playground merry-go-round?
      - pesmhey 9y ago
        Yeah, you’re right! Wonder how they handle it then.
        JoeAltmaier 9y ago
        You could embed the electronics in a resin - acceleration of a solid block would have fewer shear stresses inside the block.
        simooooo 9y ago
        Sounds heavy
        deleted 9y ago
        [deleted]
    - ecpottinger 9y ago
      No it is not. Calculate the outward force of a centrifuge with 300 foot radius with a speed of 3000 MPH at the edge and you get a force of 2000G! Check your own numbers at: http://www.calctool.org/CALC/phys/newtonian/centrifugal http://www.calctool.org/CALC/phys/newtonian/centrifugal
      - maxxxxx 9y ago
        At around 50km radius you get 3g. That would be a pretty big centrifuge! Humans will probably never use this but maybe some types of satellites can handle the load.
      - mhandley 9y ago
        Yes, the centripetal acceleration only starts to get reasonable (ie less than 10g) with a 20km radius centrifuge. The only practical way to do that would be an evacuated circular tunnel equipped with a maglev. Maybe that's their solution?
        oh_sigh 9y ago
        That's starting to sound like a hyperloop now
        TipVFL 9y ago
        It would be pretty cool if Musk was using Hyperloop as a proving ground for technologies to build Hyperlaunch.
        abakker 9y ago
        Please let him be playing the long game. Hyperloop, magnets, battery arrays, solar, boring company, etc sounds pretty cool.
        justinpombrio 9y ago
        > Yes, the centripetal acceleration only starts to get reasonable (ie less than 10g) That's reasonable _for humans_. No one's going to launch a human by this thing, though, I hope.
- JoeAltmaier 9y ago
  Launch from near the equator, high in the mountains? Chimborazo, Ecuador? At 6000 feet, its half the air pressure of sea level, and 1/4 the atmosphere to travel through. And accessible. A good start? https://www.google.com/maps/place/Chimborazo/@-1.4685873,-79.014542,11.22z/data=!4m5!3m4!1s0x91d372d7706a480b:0x69d5c66d2e629dff!8m2!3d-1.4693018!4d-78.8169396?hl=en https://www.google.com/maps/place/Chimborazo/@-1.4685873,-79...
  - jsmthrowaway 9y ago
    Going to space is not entirely about being high. It's about going sideways, fast. And if, at 6,000 feet, air pressure were half that of sea level, nobody would live in Denver and most Tibetans would be dead. Half is more like 6,000 meters.
    - ceejayoz 9y ago
      Getting high quickly is important, which is why launch vehicles go up first, then do a gravity turn in thinner air, reducing drag and aerodynamic pressures on the vehicle. It's hard to go horizontally fast when you're fighting thick atmosphere. Air density at the top of Everest is 1/3 of sea level, and because of the Earth's shape, Chimborazo's 20,000 feet (6,000 meters) is actually further from the Earth's center than Everest, so half pressure sounds pretty reasonable: https://www.npr.org/templates/story/story.php?storyId=9428163 https://www.npr.org/templates/story/story.php?storyId=942816...
      - 205guy 9y ago
        What you're forgetting is that the same mechanics that make Chimborazo the furthest from the earth's center (the oblate spheroid shape due to spin) also applies to the atmosphere (though probably to a different degree). So over Chimborazo, the atmosphere is also thicker, I'd imagine (could be more, could be less). I haven't looked at the actual measurements, but you might want to before you compare different latitudes. Also, see my other comment for non-engineering difficulties.
        9y ago
- tensor_rank_0 9y ago
  if we assume our desired orbit to be at an altitude of 320 kilometers and our orbital velocity to be 7 kilometers per second; and we assume that air resistance decreases as a proportion of the cube of velocity inside the troposphere, proportional to the square of velocity inside the stratosphere, proportional to velocity inside the mesosphere, and discount air resistance above the mesosphere, we can begin to set up a differential equation to solve the problem. I'll be back, if anyone wants to follow along at home, post your answers when you are ready.
- ridgeguy 9y ago
  Actual numbers, haven't tried to calculate. But the heat load due to atmospheric friction would be immense and immediate. The US built an antiballistic missile system that included a missile called Sprint [1]. It accelerated at 100G and developed temperatures of over 3000°C less than 5 seconds after launch. A video here [2]. It's a formidible engineering challenge to make a vehicle and payload that will survive such a difficult flight regime with commercially attractive economics. At this point, I don't understand SpinLaunch's advantage over earlier projectile systems (Gerald Bull) or current launchers like SpaceX. This will be interesting to follow. [1] https://en.wikipedia.org/wiki/Sprint_(missile) https://en.wikipedia.org/wiki/Sprint_(missile) [2] https://www.youtube.com/watch?v=msXtgTVMcuA https://www.youtube.com/watch?v=msXtgTVMcuA
  - olliej 9y ago
    Worst case scenario the missile blows up on launch leveling the surroundings before the enemy missiles arrive, thus stealing the sense of achievement from them ;)
ralphington 9y ago
They mention in the article of being able to launch objects at 3,000 MPH. That's a tad short of the typical 17,500 MPH used for low earth orbit, and that's not counting the extra Delta-V required to resist atmospheric drag. I'm very glad that this company exists, but this article doesn't help its case very much other than "Hey look, they got a load of funding".
- pesmhey 9y ago
  Just a wild guess here, maybe they’re using a variant of a ramjet, skipping the inefficient speeds, and then propelling it to LEO speed once it’s launched.
  - jcims 9y ago
    Ramjet would still require atmosphere. If you look at the Japanese SS-520 or the RocketLab's Electron, you don't need a giant rocket to get a small payload to orbit from a standing start. If you give your payload a Mach 5 kick you can eliminate a lot of the propellant mass and get by with smaller rocket motors optimized for high altitude operation. Elon Musk wants to put 12,000 satellites into orbit. It would be very strange to me if he doesn't have someone looking into the feasibility of a giant subterranean launch tube to do something similar. Get the payload up to Mach 10 on terrestrial power and complete the orbit with a small single stage.
    - bboreham 9y ago
      > Elon Musk ... giant subterranean launch tube Hyperloop?
      - manigandham 9y ago
        The Hyperloop is a rehashed vacuum-train idea originally from the 1800s (reduce air and rolling resistance as the primary forces counteracting speed). [1] A launch tube would be very different, if for no other reason then the fact that you need to actually jettison the payload at one end at high speed. 1. https://en.wikipedia.org/wiki/Vactrain https://en.wikipedia.org/wiki/Vactrain
aventrix 9y ago
The physics of this makes no sense...
Pica_soO 9y ago
So the projectiles are spun, to generate a sort of carvatation effect in atmosphere? Rather brilliant.
p0wn 9y ago
I'm picturing a daredevil getting shot out of a cannon. Where is super dave when you need him? Could be the spokesperson.
soared 9y ago
> SEC documents show that Yaney raised $1 million in equity in 2014, the year SpinLaunch was founded, $2.9 million in equity in 2015, $2.2 million in debt in mid-2017 and another $2 million in debt in late 2017. Now Yaney confirms SpinLaunch has raised a total of $10 million to date, and that he’s personally an investor... “The current status of our Series A raise is that we are still taking meetings with potential investors and have not yet received an executed offer.” Do I not understand how series of funding works?
wrnu 9y ago
This reminds me of the "Supergun" that Gerald Bull [2] was trying to build with Saddam Hussein [1]. One of my professors, that worked with Bull at the University of Toronto, told me all about his arms dealing/designing escapades. Bull was ultimately assassinated outside his home in Brussels. [1] https://en.wikipedia.org/wiki/Project_Babylon https://en.wikipedia.org/wiki/Project_Babylon [2] https://en.wikipedia.org/wiki/Gerald_Bull https://en.wikipedia.org/wiki/Gerald_Bull
- philsnow 9y ago
  I heard about Bull in the book Soonish [0], which has a whole chapter on cheap access to space. Readers of this thread might be interested in it. [0] https://smbc-comics.com/soonish/ https://smbc-comics.com/soonish/
- toomanybeersies 9y ago
  Before he was working with Iraq, he worked on Project HARP, which was funded by the USA and Canada. They did managed to get a projectile to space. They had plans to try and get one to orbit, using a rocket as a second stage, but the project was cancelled before that came to fruition.
zurp 9y ago
> Two sources say physicists who’ve looked into the company said a potential challenge could be air resistance on the cargo when the catapult fires. Earth’s atmosphere is so dense that it could be like the cargo was hitting a brick wall upon ejection. Reminds me of the calculation that shows Santa Claus and his reindeer, if they ever existed would have vaporized instantly at the beginning of first Christmas delivery: ...353,000 tons traveling at 650 miles per second creates enormous air resistance — this will heat the reindeer up in the same fashion as spacecraft reentering Earth’s atmosphere. The lead pair of reindeer will absorb 14.3 QUINTILLION joules of energy. Per second. Each. In short, they will burst into flame almost instantaneously, exposing the reindeer behind them, and create deafening sonic booms in their wake. The entire reindeer team will be vaporized within 4.26 thousandths of a second. Santa, meanwhile, will be subjected to centrifugal forces 17,500 times greater than gravity. A 250-pound Santa (which seems ludicrously slim) would be pinned to the back of his sleigh by 4,315,015 pounds of force. In conclusion — If Santa ever DID deliver presents on Christmas Eve, he’s dead now.
- danbruc 9y ago
  Even ignoring air resistance, if your hypothetical spacecraft centrifuge had a radius of one mile, then the spacecraft would still experience 114 g at 3000 miles per hour. If you more realistically spun up Apple's new headquarter with a diameter of 461 meters [1] to one revolution per second, that makes 3240 miles per hour, the spacecraft and the outer wall of your centrifuge would experience a centripetal acceleration of 928 g. Not going to happen. And 3000 miles per hour is also pretty slow, about half the speed in a geostationary orbit, for a low earth orbit you need about 17,500 miles per hour [2] which is almost 6 times faster and would increase the forces 36 times. [1] https://en.wikipedia.org/wiki/Apple_Park https://en.wikipedia.org/wiki/Apple_Park [2] https://en.wikipedia.org/wiki/Orbital_speed https://en.wikipedia.org/wiki/Orbital_speed
  - throwaway99OO 9y ago
    What's wrong with 928 g? A lot of jet turbines can go over 10,000 g at the blade tips. https://en.wikipedia.org/wiki/Turbofan https://en.wikipedia.org/wiki/Turbofan I don't think they are targeting 17,500mph. Guessing they are trying to do something sub Mach 10 for aero reasons to reduce fuel and increase structural margins that are held tight by the rocket equation. Reduced delta v = improved margins. https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation#/media/File:Tsiolkovsky_rocket_equation.svg https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation#/m...
WilliamSt 9y ago
Which startups are trying to build a launch loop or space towers? I'd love to keep track of those startups.
- Ftuuky 9y ago
  Are you referring to the space tower hypothesized by Thoth Technologies? http://thothx.com http://thothx.com https://en.wikipedia.org/wiki/ThothX_Tower https://en.wikipedia.org/wiki/ThothX_Tower
robkop 9y ago
I wonder how they plan to reduce the costs of fairings when spaceX fairings cost most than their entire launch cost.
deleted 9y ago
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brett40324 9y ago
Is there a calculation to determine a max spin speed of an object? Can an object spin infinitely faster and faster if it had unlimited energy and force spinning it? Is there a name for where centrifugal force is so high that an object rips itself apart? Picturing hand tossing pizza dough as a simple example, but what about massive structures?
- andbberger 9y ago
  > Can an object spin infinitely faster and faster if it had unlimited energy and force spinning it? Nope. Eventually the centrifugal force exceeds inter-molecular forces. Not quite what you were asking, but related https://www.wikiwand.com/en/Roche_limit https://www.wikiwand.com/en/Roche_limit
SteveGerencser 9y ago
I think that this is cool, but I recall reading papers for rail launched vehicles, mostly from the moon, back in the early 80s.
- alex_duf 9y ago
  from the Moon I can see how it makes sense. From Earth I still have trouble to believe it would work. That being said I had trouble believing you could land two rocket boosters simultaneously so at worst I'm not surprised, at best it works
Pica_soO 9y ago
Could you lift the whole catapult setup to a higher altitude with a greatly reduced atmosphere before firing? Or create a tunnel ahead of the projectile? You could use a laser to facilitate a artificial lightning strike- and fire the projectile up the thunder-tunnel of the lightning.
nathannecro 9y ago
The idea of launching objects into space using a catapult interests me if only because my physics profs in high school and university all have at one point or another shot down the idea of space catapults. Since I don't remember exactly what their beef with space catapults was about, I figured I'd have a go and see if I could get an estimation of feasibility myself. I am also not an aeronautical engineer (or even close to being one), but I do have some free time and I have a notepad. According to Wiki[1], ∆V to LEO is ~8km/s plus 1.5km/s to account for drag (so a total of 9.5km/s total). The article claims that the craft exits the launch device at ~1.3km/s which leaves 8.2km/s to be accounted for. For the purposes of our math, let us assume that the craft has an alternate way to get up to speed. We'll note that SpinLaunch is not throwing their spacecraft into space at all; in fact, they're barely getting their spacecraft off the ground (relative to LEO). Even with the significantly reduced launch speed, getting the craft spun up to speed is no small task. The equation for relating linear speed to angular speed is: [Linear Speed] = [Rotational Speed]*[Radius] Since we have a linear speed in mind, we can make assumptions for rotational speed or for the radius of the launching arm and solve for the other. I think revolutions per second is easier to imagine, so we'll just Fermi this out. If your maximum angular speed is one revolution per second (~6.3rad/s), then your launching arm will need to be ~213m long. To put that in perspective, the centrifuge would need to be about four football fields in diameter. Not only that, but it would be hurling a spacecraft around the circumference once every second! Because the relationship is linear, if you want to halve the angular speed, then you'd have to double the radius. Just building a structure that can not only support the weight of a spacecraft at the tip, have a diameter of 450m, and complete full revolution every second seems like a challenge already. Additionally, unlike a regular centrifuge, this launch structure would likely not be parallel to the ground either; you want to launch your craft into space after all. Which means that you'll have to deal with unequal forces and accelerations as you spin. To really put things into perspective, the largest centrifuge in the world is the TsF-18 in Russia and it has a radius of 18m and can only manage 0.65 rotations per second at maximum speed[2]. But hey, I'm no mechanical engineer either, so maybe that's no big deal. Maybe introducing a vacuum in the launch structure makes such a huge difference that getting up to speed is easy enough. How does one exactly create such a big vacuum chamber though? Even if the height of the chamber is only 5m tall, the total volume is ~710,000m3. The largest vacuum chamber is the Space Power Center and it has a maximum volume of 22,653 m3[3]. You'll need to build something that outspins the largest centrifuge in the world (by more than an order of magnitude) and outsucks the largest vacuum in the world (by more than an order of magnitude). If somehow SpinLaunch can build the most spinniest and suckiest structure ever built, you're still only 13% of the way into space. Really puts into perspective how outrageous SpinLaunch's claims are. 1: https://en.wikipedia.org/wiki/Delta-v_budget https://en.wikipedia.org/wiki/Delta-v_budget 2: http://www.rusadventures.com/tour35.shtml http://www.rusadventures.com/tour35.shtml 3: https://www1.grc.nasa.gov/facilities/spf/ https://www1.grc.nasa.gov/facilities/spf/
newnewpdro 9y ago
Isn't this obviously impossible? What sort of launch vehicle or payload is going to tolerate the Gs of being spun at such a high rate. How on earth does this even raise a dollar of funding? It has crossed my mind in the past why we don't use something like a linear electric motor to help get rockets going off the pad, even just a hundred yards or so of acceleration assist might save a good chunk of fuel. But the rockets aren't exactly designed to have acceleration applied anywhere other than at the engine, so maybe you end up having to add the weight you'd save in fuel back in structure for the ancillary acceleration source.
- gameswithgo 9y ago
  Would a very large radius reduce the Gs for a given speed?
- throwaway99OO 9y ago
  At its face it does sound pretty crazy but I found some analogs of previous and ongoing projects that provide some reason to suspend disbelief. Here's what I can find on high G launch vehicle's and payloads: Breakthrough Starshot: Backed by physicist and VC Yuri Milner and lead by former director of NASA Ames, Peter Worden. 10,000 G's. Project Ongoing. [1] Hiller Hornet: US Army helicopter, powered by jet turbines located at the tips of the helicopter blades. The turbines operated under 14,000 Gs. Project Completed [2] HARP Project: Joint US Army & Canadian effort. Successfully launched electronics (radios, control systems, etc) and solid fueled rockets. 10,000+ Shock G's. Project Completed. [3] A variety of documents come up while researching g-hardening electronics. The US Army Research Lab a a few papers. Linked one of them. 30,000 + Shock G's. Various Projects Completed and Ongoing[4] The Hiller Hornet is likely the most applicable given it is a propulsion system operating at over 10,000 G's. I wonder how they designed the Hornet's turbine given Finite Element Analysis wasn't really a thing in 1950. [1] https://en.wikipedia.org/wiki/Breakthrough_Starshot https://en.wikipedia.org/wiki/Breakthrough_Starshot [2] http://www.aviastar.org/helicopters_eng/hiller_hoe-1.php http://www.aviastar.org/helicopters_eng/hiller_hoe-1.php [3] http://www.astronautix.com/a/abriefhistoheharpproject.html http://www.astronautix.com/a/abriefhistoheharpproject.html [4] http://www.arl.army.mil/arlreports/2006/ARL-TR-3705.pdf http://www.arl.army.mil/arlreports/2006/ARL-TR-3705.pdf
ChuckMcM 9y ago
The fact that this seems demonstrably impossible on its face, and yet he is raising money, always makes me curious. During the 'Star Wars' period in the US when the military was going to buy up thousands and thousands of launches to low earth orbit there were probably 1/2 dozen companies pursuing a single stage to orbit (SSTO) type solution. Gary Hudson, the CEO of Rotary Rocket (one of the SSTO companies at the time), gave a great example that showed that because the atmosphere was thick at ground level and thin at altitude you wanted a velocity that proportional to altitude. As he explained it, everything you do to a rocket to reinforce it adds weight, and every pound you add is another 90lbs of fuel (or what ever your mass fraction is). In that way your rocket could be as delicate as a feather if you went very slowly down near the ground and hypersonic near the edge of the atmosphere. But systems that attempt to impart enough kinetic energy at altitude zero to allow the rocket to coast to orbit require a rocket that is structurally extremely rigid because it withstands both the force of acceleration and the atmospheric drag at its worst. That is astonishingly hard to pull off. I a serious challenge, first you have to actually start at higher than orbital velocity because you're going to exchange a lot of energy with the air around the air frame. Volcanoes are currently the champions at throwing things up into the air, Mt St. Helens through ash over 100,000 feet up. But if you start your orbit going straight up you won't be able to miss hitting the planet post apogee. The more angled you make your initial shot, the more air you have to go through before you are in space, the more energy you're going to dump in the atmosphere, and the faster you'll have to start. And all of that makes me really wonder about an engineering solution that fits within all those constraints. What ever it is, it will be super amazing.
- anvandare 9y ago
  The "Lazy Kerbal" approach: go straight up to get out of the atmosphere as soon as possible (stupid drag) and turn right once you pass the Kármán... Err, Kerman Line (at 70km). Start burning near apoapsis until your periapsis is >=70km as well. If your initial apoapsis was high enough, you'll make it to orbit before re-entry. If not, revert to launch. Efficient? Not at all, but certainly effective and simple.
- pitaj 9y ago
  > it withstands both the force of acceleration and the atmospheric drag at its worst Not to mention that the payload must also be able to survive these high accelerations.
blackrock 9y ago
Since we're talking about space, I am wondering when some nation can build a rotating space station. Null-gravity is nice to play in, and some null-g research is necessary. But to work, and operate normally, null-g sucks. Especially if you need to handle fluids. And if you need to do an emergency surgery in space, then dealing with floating blood is disgusting and biologically hazardous. As well as dealing with used surgical tools that can float around. I would rather live in a centrifuge space station, and go to the null-g zone to conduct my work research. It's interesting how in all scifi movies, all the spacecraft have an artificial gravity. It's too bad China's proposed space station, will not break new ground, and have a rotating space station. They would need to spend much more money on designing and building it, than what they are willing to spend.
- sschueller 9y ago
  I think the main issue is the size required to do this in order not to spin something at a ridiculous speed.
- dmurray 9y ago
  > It's interesting how in all scifi movies, all the spacecraft have an artificial gravity. Possibly related to the fact that all film studios are subject to gravity.
  - blackrock 9y ago
    You know.. I never actually considered that possibility..
- maccam94 9y ago
  I've actually been posting about this a bit recently on various threads. I think a permanent rotating space station with 1G artificial gravity in low earth orbit could be the next stepping stone to opening access into outer space. Facilities with gravity would enable permanent habitation without bone and muscle loss, and manufacturing could be done with existing processes. As to why we haven't built one already, the main reason is because early research indicated that such structures would have to be prohibitively large to avoid nausea (300+ meter diameter) and require thousands of tons of shielding. The Space Shuttle's lift capacity was also limited (only 25T of payload) and expensive ($450M/launch). This paper suggests that humans are more tolerant of a rotating environment than early studies led us to believe, and that shielding is unnecessary for some low-Earth orbits: http://www.nss.org/settlement/space/GlobusRotationPaper.pdf http://www.nss.org/settlement/space/GlobusRotationPaper.pdf (In particular, see pages 19-23) The figures it suggests are ~600 tons of mass, 25m to 60m radius for the station. Falcon Heavy can launch 63T for $95M, and the BFR is aiming for 150T for $7M.
Ftuuky 9y ago
Would it help to catapult the cargo at high altitude where the air is rarefied? That way you have to deal with less atmosphere and the initial energy required for the catapult is smaller. Idk where, maybe the Andes?
skookumchuck 9y ago
What has happened with all the studies about launching to orbit after being dropped from a jet at high altitude?
mywacaday 9y ago
The child/mythbuster in me wonders what would have if you spun a large disc at this speed and tried to skim it across an ocean
- alex_duf 9y ago
  probably a lot of smoke and noise, I'd watch it though
zaarn 9y ago
I played enough KSP to know that this sort of thing is somewhere halfway up on the list of "things that you might think go to space but don't". Hitting the atmosphere after accelerating will probably cause most materials outside of reentry heatshield to immediately melt, ignite and explode without particular order of these events. After turning into a molten blob of lava or a spent heatshield, it would still be nowhere close to orbital velocity and would have to fire an engine that somehow survived A) the heat and B) the intense G-forces involved. I'll probably file this under "solar freaking roadways" and hope they don't try to fire a human in this.
- Cthulhu_ 9y ago
  And yet, also in KSP, if you can find a cheap and efficient way to cross the first hundred meter upwards, you've already saved a load of fuel. I had a setup once where my first booster was a lot of plane engines; seemed to work all right.
  - zaarn 9y ago
    The last half of the atmosphere is an easy flight; drag is reduced to the point that it barely matters and most of the bigger engines have reached almost peak efficiency. Due to lack of drag you will also barely loose any velocity anymore. The first half is hard because drag is so high but if you can sustain atleast 150m/s (or Mach 0.5) until you reach about 15km altitude and then sustain atleast 1.5G until 35km you can make it easily into space. If necessary you can try to gain some vertical velocity and abuse body-lift to drag you up higher despite not having sufficient lifting power in your boosters (if you have between 1.02 and 1.1 TWR) Most rockets burn 80% of their fuel to get out of the atmosphere, the remaining 20% are usually good enough to get into orbit, insert into any transfer orbit you like and fly off into empty space.
- phire 9y ago
  Eh, I'm going to give them the benefit of the doubt, mostly because they appear to be able to attract large amounts of VC funding. When it comes to orbital mechanics, the idea works. You just need to make your starting velocity high enough after it has decelerated though our atmosphere slows down to orbital velocity. Then you just design your ascent capsule to "deal" with the extreme declaration and heating, which isn't a huge problem: Heat shields exist, and so do g-force hardened electronics. Nobody should be under the impression that this will be used to launched anything other than small specially designed g-force hardened satellites. It's not like "solar freaking roadways" which has blearlying obvious economic and efficiency flaws, the designs for catapult based launchers have been well studied and there is nothing physically stopping them. It's more of a engineering problem. Honestly, I'm more concerned about the engineering practicalities of building an extremely large centrifuge spinning at some absurdly high RPM (presumably at the top of a mountain, so it bypasses some of our atmosphere)
jlebrech 9y ago
you could have a covered (hyperloop) train go round and round in the antarctic (against the earth's spin) until in reached escape velocity and segment of the loop would detach and point the train up the space. A second idea would be to create a bridge from the closest points of africa and south america, use it as a standard bridge between launches, the launches would only have to do 2g to get to escape velocity.
KaiserPro 9y ago
I assume they are using a cyclotron accelerator. Basically its a large disk with a spiral track on the inside. The disk is then oscillated in along its flat plane, like this: https://www.youtube.com/watch?v=OPLzsRojo_A https://www.youtube.com/watch?v=OPLzsRojo_A There was a video of a marble cyclotron, that basically had a spiral like the above, but instead of tilting, the whole disk moved along the z axis (as we look at it, x up, y left and right) it was about 1 meter wide, and was oscillating at about 2hz, that was capable of ejecting marble sized objects at about 500 mph or something similar. So I can see the method, but I doubt how payloads will survive that level of G. edit This idea: https://www.youtube.com/watch?v=UnZWu1FXxd4 https://www.youtube.com/watch?v=UnZWu1FXxd4
anotheryou 9y ago
It's a flywheel, some really good clutch mechanism and a straight track for linear acceleration, right?
deleted 9y ago
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tony_rusi 9y ago
Dana Andrews used this Spinlaunch idea in his University of Washington Undergraduate Astronautics Capstone Engineering Class to launch Lunar Mining Ores from the moon cheaply. Maybe they intend to use it on the Lunar Poles?

88 points by stingrae 9y ago

kuon 9y ago

Realistically, what is the feasibility of a space catapult? I mean, the speed at ground level to be able to reach orbit must be insanely high, no? This high speed in a thick atmosphere would cause all kind of heating problem on the catapult itself and the "rocket". I wonder what would be the actual numbers.

rmcpherson 9y ago
Not to mention the acceleration needed to achieve orbital velocity with a catapult. Seems like insanely high forces on the payload. I’d love to see how they solve this.
- pesmhey 9y ago
  It’s a centrifuge, so the acceleration could be low enough to not cause damage to the payload.
  - JoeAltmaier 9y ago
    Simply spinning is acceleration. Every been on a fast playground merry-go-round?
    - pesmhey 9y ago
      Yeah, you’re right! Wonder how they handle it then.
      - JoeAltmaier 9y ago
        You could embed the electronics in a resin - acceleration of a solid block would have fewer shear stresses inside the block.
        simooooo 9y ago
        Sounds heavy
      - deleted 9y ago
        [deleted]
  - ecpottinger 9y ago
    No it is not. Calculate the outward force of a centrifuge with 300 foot radius with a speed of 3000 MPH at the edge and you get a force of 2000G! Check your own numbers at: http://www.calctool.org/CALC/phys/newtonian/centrifugal http://www.calctool.org/CALC/phys/newtonian/centrifugal
    - maxxxxx 9y ago
      At around 50km radius you get 3g. That would be a pretty big centrifuge! Humans will probably never use this but maybe some types of satellites can handle the load.
    - mhandley 9y ago
      Yes, the centripetal acceleration only starts to get reasonable (ie less than 10g) with a 20km radius centrifuge. The only practical way to do that would be an evacuated circular tunnel equipped with a maglev. Maybe that's their solution?
      - oh_sigh 9y ago
        That's starting to sound like a hyperloop now
        TipVFL 9y ago
        It would be pretty cool if Musk was using Hyperloop as a proving ground for technologies to build Hyperlaunch.
        abakker 9y ago
        Please let him be playing the long game. Hyperloop, magnets, battery arrays, solar, boring company, etc sounds pretty cool.
      - justinpombrio 9y ago
        > Yes, the centripetal acceleration only starts to get reasonable (ie less than 10g) That's reasonable _for humans_. No one's going to launch a human by this thing, though, I hope.
JoeAltmaier 9y ago
Launch from near the equator, high in the mountains? Chimborazo, Ecuador? At 6000 feet, its half the air pressure of sea level, and 1/4 the atmosphere to travel through. And accessible. A good start? https://www.google.com/maps/place/Chimborazo/@-1.4685873,-79.014542,11.22z/data=!4m5!3m4!1s0x91d372d7706a480b:0x69d5c66d2e629dff!8m2!3d-1.4693018!4d-78.8169396?hl=en https://www.google.com/maps/place/Chimborazo/@-1.4685873,-79...
- jsmthrowaway 9y ago
  Going to space is not entirely about being high. It's about going sideways, fast. And if, at 6,000 feet, air pressure were half that of sea level, nobody would live in Denver and most Tibetans would be dead. Half is more like 6,000 meters.
  - ceejayoz 9y ago
    Getting high quickly is important, which is why launch vehicles go up first, then do a gravity turn in thinner air, reducing drag and aerodynamic pressures on the vehicle. It's hard to go horizontally fast when you're fighting thick atmosphere. Air density at the top of Everest is 1/3 of sea level, and because of the Earth's shape, Chimborazo's 20,000 feet (6,000 meters) is actually further from the Earth's center than Everest, so half pressure sounds pretty reasonable: https://www.npr.org/templates/story/story.php?storyId=9428163 https://www.npr.org/templates/story/story.php?storyId=942816...
    - 205guy 9y ago
      What you're forgetting is that the same mechanics that make Chimborazo the furthest from the earth's center (the oblate spheroid shape due to spin) also applies to the atmosphere (though probably to a different degree). So over Chimborazo, the atmosphere is also thicker, I'd imagine (could be more, could be less). I haven't looked at the actual measurements, but you might want to before you compare different latitudes. Also, see my other comment for non-engineering difficulties.
      - 9y ago
tensor_rank_0 9y ago
if we assume our desired orbit to be at an altitude of 320 kilometers and our orbital velocity to be 7 kilometers per second; and we assume that air resistance decreases as a proportion of the cube of velocity inside the troposphere, proportional to the square of velocity inside the stratosphere, proportional to velocity inside the mesosphere, and discount air resistance above the mesosphere, we can begin to set up a differential equation to solve the problem. I'll be back, if anyone wants to follow along at home, post your answers when you are ready.
ridgeguy 9y ago
Actual numbers, haven't tried to calculate. But the heat load due to atmospheric friction would be immense and immediate. The US built an antiballistic missile system that included a missile called Sprint [1]. It accelerated at 100G and developed temperatures of over 3000°C less than 5 seconds after launch. A video here [2]. It's a formidible engineering challenge to make a vehicle and payload that will survive such a difficult flight regime with commercially attractive economics. At this point, I don't understand SpinLaunch's advantage over earlier projectile systems (Gerald Bull) or current launchers like SpaceX. This will be interesting to follow. [1] https://en.wikipedia.org/wiki/Sprint_(missile) https://en.wikipedia.org/wiki/Sprint_(missile) [2] https://www.youtube.com/watch?v=msXtgTVMcuA https://www.youtube.com/watch?v=msXtgTVMcuA
- olliej 9y ago
  Worst case scenario the missile blows up on launch leveling the surroundings before the enemy missiles arrive, thus stealing the sense of achievement from them ;)

ralphington 9y ago

They mention in the article of being able to launch objects at 3,000 MPH. That's a tad short of the typical 17,500 MPH used for low earth orbit, and that's not counting the extra Delta-V required to resist atmospheric drag. I'm very glad that this company exists, but this article doesn't help its case very much other than "Hey look, they got a load of funding".

pesmhey 9y ago
Just a wild guess here, maybe they’re using a variant of a ramjet, skipping the inefficient speeds, and then propelling it to LEO speed once it’s launched.
- jcims 9y ago
  Ramjet would still require atmosphere. If you look at the Japanese SS-520 or the RocketLab's Electron, you don't need a giant rocket to get a small payload to orbit from a standing start. If you give your payload a Mach 5 kick you can eliminate a lot of the propellant mass and get by with smaller rocket motors optimized for high altitude operation. Elon Musk wants to put 12,000 satellites into orbit. It would be very strange to me if he doesn't have someone looking into the feasibility of a giant subterranean launch tube to do something similar. Get the payload up to Mach 10 on terrestrial power and complete the orbit with a small single stage.
  - bboreham 9y ago
    > Elon Musk ... giant subterranean launch tube Hyperloop?
    - manigandham 9y ago
      The Hyperloop is a rehashed vacuum-train idea originally from the 1800s (reduce air and rolling resistance as the primary forces counteracting speed). [1] A launch tube would be very different, if for no other reason then the fact that you need to actually jettison the payload at one end at high speed. 1. https://en.wikipedia.org/wiki/Vactrain https://en.wikipedia.org/wiki/Vactrain

aventrix 9y ago

The physics of this makes no sense...

Pica_soO 9y ago

So the projectiles are spun, to generate a sort of carvatation effect in atmosphere? Rather brilliant.

p0wn 9y ago

I'm picturing a daredevil getting shot out of a cannon. Where is super dave when you need him? Could be the spokesperson.

soared 9y ago

> SEC documents show that Yaney raised $1 million in equity in 2014, the year SpinLaunch was founded, $2.9 million in equity in 2015, $2.2 million in debt in mid-2017 and another $2 million in debt in late 2017. Now Yaney confirms SpinLaunch has raised a total of $10 million to date, and that he’s personally an investor... “The current status of our Series A raise is that we are still taking meetings with potential investors and have not yet received an executed offer.” Do I not understand how series of funding works?

wrnu 9y ago

This reminds me of the "Supergun" that Gerald Bull [2] was trying to build with Saddam Hussein [1]. One of my professors, that worked with Bull at the University of Toronto, told me all about his arms dealing/designing escapades. Bull was ultimately assassinated outside his home in Brussels. [1] https://en.wikipedia.org/wiki/Project_Babylon https://en.wikipedia.org/wiki/Project_Babylon [2] https://en.wikipedia.org/wiki/Gerald_Bull https://en.wikipedia.org/wiki/Gerald_Bull

philsnow 9y ago
I heard about Bull in the book Soonish [0], which has a whole chapter on cheap access to space. Readers of this thread might be interested in it. [0] https://smbc-comics.com/soonish/ https://smbc-comics.com/soonish/
toomanybeersies 9y ago
Before he was working with Iraq, he worked on Project HARP, which was funded by the USA and Canada. They did managed to get a projectile to space. They had plans to try and get one to orbit, using a rocket as a second stage, but the project was cancelled before that came to fruition.

zurp 9y ago

> Two sources say physicists who’ve looked into the company said a potential challenge could be air resistance on the cargo when the catapult fires. Earth’s atmosphere is so dense that it could be like the cargo was hitting a brick wall upon ejection. Reminds me of the calculation that shows Santa Claus and his reindeer, if they ever existed would have vaporized instantly at the beginning of first Christmas delivery: ...353,000 tons traveling at 650 miles per second creates enormous air resistance — this will heat the reindeer up in the same fashion as spacecraft reentering Earth’s atmosphere. The lead pair of reindeer will absorb 14.3 QUINTILLION joules of energy. Per second. Each. In short, they will burst into flame almost instantaneously, exposing the reindeer behind them, and create deafening sonic booms in their wake. The entire reindeer team will be vaporized within 4.26 thousandths of a second. Santa, meanwhile, will be subjected to centrifugal forces 17,500 times greater than gravity. A 250-pound Santa (which seems ludicrously slim) would be pinned to the back of his sleigh by 4,315,015 pounds of force. In conclusion — If Santa ever DID deliver presents on Christmas Eve, he’s dead now.

danbruc 9y ago
Even ignoring air resistance, if your hypothetical spacecraft centrifuge had a radius of one mile, then the spacecraft would still experience 114 g at 3000 miles per hour. If you more realistically spun up Apple's new headquarter with a diameter of 461 meters [1] to one revolution per second, that makes 3240 miles per hour, the spacecraft and the outer wall of your centrifuge would experience a centripetal acceleration of 928 g. Not going to happen. And 3000 miles per hour is also pretty slow, about half the speed in a geostationary orbit, for a low earth orbit you need about 17,500 miles per hour [2] which is almost 6 times faster and would increase the forces 36 times. [1] https://en.wikipedia.org/wiki/Apple_Park https://en.wikipedia.org/wiki/Apple_Park [2] https://en.wikipedia.org/wiki/Orbital_speed https://en.wikipedia.org/wiki/Orbital_speed
- throwaway99OO 9y ago
  What's wrong with 928 g? A lot of jet turbines can go over 10,000 g at the blade tips. https://en.wikipedia.org/wiki/Turbofan https://en.wikipedia.org/wiki/Turbofan I don't think they are targeting 17,500mph. Guessing they are trying to do something sub Mach 10 for aero reasons to reduce fuel and increase structural margins that are held tight by the rocket equation. Reduced delta v = improved margins. https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation#/media/File:Tsiolkovsky_rocket_equation.svg https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation#/m...

WilliamSt 9y ago

Which startups are trying to build a launch loop or space towers? I'd love to keep track of those startups.

Ftuuky 9y ago
Are you referring to the space tower hypothesized by Thoth Technologies? http://thothx.com http://thothx.com https://en.wikipedia.org/wiki/ThothX_Tower https://en.wikipedia.org/wiki/ThothX_Tower

robkop 9y ago

I wonder how they plan to reduce the costs of fairings when spaceX fairings cost most than their entire launch cost.

deleted 9y ago

[deleted]

brett40324 9y ago

Is there a calculation to determine a max spin speed of an object? Can an object spin infinitely faster and faster if it had unlimited energy and force spinning it? Is there a name for where centrifugal force is so high that an object rips itself apart? Picturing hand tossing pizza dough as a simple example, but what about massive structures?

andbberger 9y ago
> Can an object spin infinitely faster and faster if it had unlimited energy and force spinning it? Nope. Eventually the centrifugal force exceeds inter-molecular forces. Not quite what you were asking, but related https://www.wikiwand.com/en/Roche_limit https://www.wikiwand.com/en/Roche_limit

SteveGerencser 9y ago

I think that this is cool, but I recall reading papers for rail launched vehicles, mostly from the moon, back in the early 80s.

alex_duf 9y ago
from the Moon I can see how it makes sense. From Earth I still have trouble to believe it would work. That being said I had trouble believing you could land two rocket boosters simultaneously so at worst I'm not surprised, at best it works

Pica_soO 9y ago

Could you lift the whole catapult setup to a higher altitude with a greatly reduced atmosphere before firing? Or create a tunnel ahead of the projectile? You could use a laser to facilitate a artificial lightning strike- and fire the projectile up the thunder-tunnel of the lightning.

nathannecro 9y ago

The idea of launching objects into space using a catapult interests me if only because my physics profs in high school and university all have at one point or another shot down the idea of space catapults. Since I don't remember exactly what their beef with space catapults was about, I figured I'd have a go and see if I could get an estimation of feasibility myself. I am also not an aeronautical engineer (or even close to being one), but I do have some free time and I have a notepad. According to Wiki[1], ∆V to LEO is ~8km/s plus 1.5km/s to account for drag (so a total of 9.5km/s total). The article claims that the craft exits the launch device at ~1.3km/s which leaves 8.2km/s to be accounted for. For the purposes of our math, let us assume that the craft has an alternate way to get up to speed. We'll note that SpinLaunch is not throwing their spacecraft into space at all; in fact, they're barely getting their spacecraft off the ground (relative to LEO). Even with the significantly reduced launch speed, getting the craft spun up to speed is no small task. The equation for relating linear speed to angular speed is: [Linear Speed] = [Rotational Speed]*[Radius] Since we have a linear speed in mind, we can make assumptions for rotational speed or for the radius of the launching arm and solve for the other. I think revolutions per second is easier to imagine, so we'll just Fermi this out. If your maximum angular speed is one revolution per second (~6.3rad/s), then your launching arm will need to be ~213m long. To put that in perspective, the centrifuge would need to be about four football fields in diameter. Not only that, but it would be hurling a spacecraft around the circumference once every second! Because the relationship is linear, if you want to halve the angular speed, then you'd have to double the radius. Just building a structure that can not only support the weight of a spacecraft at the tip, have a diameter of 450m, and complete full revolution every second seems like a challenge already. Additionally, unlike a regular centrifuge, this launch structure would likely not be parallel to the ground either; you want to launch your craft into space after all. Which means that you'll have to deal with unequal forces and accelerations as you spin. To really put things into perspective, the largest centrifuge in the world is the TsF-18 in Russia and it has a radius of 18m and can only manage 0.65 rotations per second at maximum speed[2]. But hey, I'm no mechanical engineer either, so maybe that's no big deal. Maybe introducing a vacuum in the launch structure makes such a huge difference that getting up to speed is easy enough. How does one exactly create such a big vacuum chamber though? Even if the height of the chamber is only 5m tall, the total volume is ~710,000m3. The largest vacuum chamber is the Space Power Center and it has a maximum volume of 22,653 m3[3]. You'll need to build something that outspins the largest centrifuge in the world (by more than an order of magnitude) and outsucks the largest vacuum in the world (by more than an order of magnitude). If somehow SpinLaunch can build the most spinniest and suckiest structure ever built, you're still only 13% of the way into space. Really puts into perspective how outrageous SpinLaunch's claims are. 1: https://en.wikipedia.org/wiki/Delta-v_budget https://en.wikipedia.org/wiki/Delta-v_budget 2: http://www.rusadventures.com/tour35.shtml http://www.rusadventures.com/tour35.shtml 3: https://www1.grc.nasa.gov/facilities/spf/ https://www1.grc.nasa.gov/facilities/spf/

newnewpdro 9y ago

Isn't this obviously impossible? What sort of launch vehicle or payload is going to tolerate the Gs of being spun at such a high rate. How on earth does this even raise a dollar of funding? It has crossed my mind in the past why we don't use something like a linear electric motor to help get rockets going off the pad, even just a hundred yards or so of acceleration assist might save a good chunk of fuel. But the rockets aren't exactly designed to have acceleration applied anywhere other than at the engine, so maybe you end up having to add the weight you'd save in fuel back in structure for the ancillary acceleration source.

gameswithgo 9y ago
Would a very large radius reduce the Gs for a given speed?
throwaway99OO 9y ago
At its face it does sound pretty crazy but I found some analogs of previous and ongoing projects that provide some reason to suspend disbelief. Here's what I can find on high G launch vehicle's and payloads: Breakthrough Starshot: Backed by physicist and VC Yuri Milner and lead by former director of NASA Ames, Peter Worden. 10,000 G's. Project Ongoing. [1] Hiller Hornet: US Army helicopter, powered by jet turbines located at the tips of the helicopter blades. The turbines operated under 14,000 Gs. Project Completed [2] HARP Project: Joint US Army & Canadian effort. Successfully launched electronics (radios, control systems, etc) and solid fueled rockets. 10,000+ Shock G's. Project Completed. [3] A variety of documents come up while researching g-hardening electronics. The US Army Research Lab a a few papers. Linked one of them. 30,000 + Shock G's. Various Projects Completed and Ongoing[4] The Hiller Hornet is likely the most applicable given it is a propulsion system operating at over 10,000 G's. I wonder how they designed the Hornet's turbine given Finite Element Analysis wasn't really a thing in 1950. [1] https://en.wikipedia.org/wiki/Breakthrough_Starshot https://en.wikipedia.org/wiki/Breakthrough_Starshot [2] http://www.aviastar.org/helicopters_eng/hiller_hoe-1.php http://www.aviastar.org/helicopters_eng/hiller_hoe-1.php [3] http://www.astronautix.com/a/abriefhistoheharpproject.html http://www.astronautix.com/a/abriefhistoheharpproject.html [4] http://www.arl.army.mil/arlreports/2006/ARL-TR-3705.pdf http://www.arl.army.mil/arlreports/2006/ARL-TR-3705.pdf

ChuckMcM 9y ago

The fact that this seems demonstrably impossible on its face, and yet he is raising money, always makes me curious. During the 'Star Wars' period in the US when the military was going to buy up thousands and thousands of launches to low earth orbit there were probably 1/2 dozen companies pursuing a single stage to orbit (SSTO) type solution. Gary Hudson, the CEO of Rotary Rocket (one of the SSTO companies at the time), gave a great example that showed that because the atmosphere was thick at ground level and thin at altitude you wanted a velocity that proportional to altitude. As he explained it, everything you do to a rocket to reinforce it adds weight, and every pound you add is another 90lbs of fuel (or what ever your mass fraction is). In that way your rocket could be as delicate as a feather if you went very slowly down near the ground and hypersonic near the edge of the atmosphere. But systems that attempt to impart enough kinetic energy at altitude zero to allow the rocket to coast to orbit require a rocket that is structurally extremely rigid because it withstands both the force of acceleration and the atmospheric drag at its worst. That is astonishingly hard to pull off. I a serious challenge, first you have to actually start at higher than orbital velocity because you're going to exchange a lot of energy with the air around the air frame. Volcanoes are currently the champions at throwing things up into the air, Mt St. Helens through ash over 100,000 feet up. But if you start your orbit going straight up you won't be able to miss hitting the planet post apogee. The more angled you make your initial shot, the more air you have to go through before you are in space, the more energy you're going to dump in the atmosphere, and the faster you'll have to start. And all of that makes me really wonder about an engineering solution that fits within all those constraints. What ever it is, it will be super amazing.

anvandare 9y ago
The "Lazy Kerbal" approach: go straight up to get out of the atmosphere as soon as possible (stupid drag) and turn right once you pass the Kármán... Err, Kerman Line (at 70km). Start burning near apoapsis until your periapsis is >=70km as well. If your initial apoapsis was high enough, you'll make it to orbit before re-entry. If not, revert to launch. Efficient? Not at all, but certainly effective and simple.
pitaj 9y ago
> it withstands both the force of acceleration and the atmospheric drag at its worst Not to mention that the payload must also be able to survive these high accelerations.

blackrock 9y ago

Since we're talking about space, I am wondering when some nation can build a rotating space station. Null-gravity is nice to play in, and some null-g research is necessary. But to work, and operate normally, null-g sucks. Especially if you need to handle fluids. And if you need to do an emergency surgery in space, then dealing with floating blood is disgusting and biologically hazardous. As well as dealing with used surgical tools that can float around. I would rather live in a centrifuge space station, and go to the null-g zone to conduct my work research. It's interesting how in all scifi movies, all the spacecraft have an artificial gravity. It's too bad China's proposed space station, will not break new ground, and have a rotating space station. They would need to spend much more money on designing and building it, than what they are willing to spend.

sschueller 9y ago
I think the main issue is the size required to do this in order not to spin something at a ridiculous speed.
dmurray 9y ago
> It's interesting how in all scifi movies, all the spacecraft have an artificial gravity. Possibly related to the fact that all film studios are subject to gravity.
- blackrock 9y ago
  You know.. I never actually considered that possibility..
maccam94 9y ago
I've actually been posting about this a bit recently on various threads. I think a permanent rotating space station with 1G artificial gravity in low earth orbit could be the next stepping stone to opening access into outer space. Facilities with gravity would enable permanent habitation without bone and muscle loss, and manufacturing could be done with existing processes. As to why we haven't built one already, the main reason is because early research indicated that such structures would have to be prohibitively large to avoid nausea (300+ meter diameter) and require thousands of tons of shielding. The Space Shuttle's lift capacity was also limited (only 25T of payload) and expensive ($450M/launch). This paper suggests that humans are more tolerant of a rotating environment than early studies led us to believe, and that shielding is unnecessary for some low-Earth orbits: http://www.nss.org/settlement/space/GlobusRotationPaper.pdf http://www.nss.org/settlement/space/GlobusRotationPaper.pdf (In particular, see pages 19-23) The figures it suggests are ~600 tons of mass, 25m to 60m radius for the station. Falcon Heavy can launch 63T for $95M, and the BFR is aiming for 150T for $7M.

Ftuuky 9y ago

Would it help to catapult the cargo at high altitude where the air is rarefied? That way you have to deal with less atmosphere and the initial energy required for the catapult is smaller. Idk where, maybe the Andes?

skookumchuck 9y ago

What has happened with all the studies about launching to orbit after being dropped from a jet at high altitude?

mywacaday 9y ago

The child/mythbuster in me wonders what would have if you spun a large disc at this speed and tried to skim it across an ocean

alex_duf 9y ago
probably a lot of smoke and noise, I'd watch it though

zaarn 9y ago

I played enough KSP to know that this sort of thing is somewhere halfway up on the list of "things that you might think go to space but don't". Hitting the atmosphere after accelerating will probably cause most materials outside of reentry heatshield to immediately melt, ignite and explode without particular order of these events. After turning into a molten blob of lava or a spent heatshield, it would still be nowhere close to orbital velocity and would have to fire an engine that somehow survived A) the heat and B) the intense G-forces involved. I'll probably file this under "solar freaking roadways" and hope they don't try to fire a human in this.

Cthulhu_ 9y ago
And yet, also in KSP, if you can find a cheap and efficient way to cross the first hundred meter upwards, you've already saved a load of fuel. I had a setup once where my first booster was a lot of plane engines; seemed to work all right.
- zaarn 9y ago
  The last half of the atmosphere is an easy flight; drag is reduced to the point that it barely matters and most of the bigger engines have reached almost peak efficiency. Due to lack of drag you will also barely loose any velocity anymore. The first half is hard because drag is so high but if you can sustain atleast 150m/s (or Mach 0.5) until you reach about 15km altitude and then sustain atleast 1.5G until 35km you can make it easily into space. If necessary you can try to gain some vertical velocity and abuse body-lift to drag you up higher despite not having sufficient lifting power in your boosters (if you have between 1.02 and 1.1 TWR) Most rockets burn 80% of their fuel to get out of the atmosphere, the remaining 20% are usually good enough to get into orbit, insert into any transfer orbit you like and fly off into empty space.
phire 9y ago
Eh, I'm going to give them the benefit of the doubt, mostly because they appear to be able to attract large amounts of VC funding. When it comes to orbital mechanics, the idea works. You just need to make your starting velocity high enough after it has decelerated though our atmosphere slows down to orbital velocity. Then you just design your ascent capsule to "deal" with the extreme declaration and heating, which isn't a huge problem: Heat shields exist, and so do g-force hardened electronics. Nobody should be under the impression that this will be used to launched anything other than small specially designed g-force hardened satellites. It's not like "solar freaking roadways" which has blearlying obvious economic and efficiency flaws, the designs for catapult based launchers have been well studied and there is nothing physically stopping them. It's more of a engineering problem. Honestly, I'm more concerned about the engineering practicalities of building an extremely large centrifuge spinning at some absurdly high RPM (presumably at the top of a mountain, so it bypasses some of our atmosphere)

jlebrech 9y ago

you could have a covered (hyperloop) train go round and round in the antarctic (against the earth's spin) until in reached escape velocity and segment of the loop would detach and point the train up the space. A second idea would be to create a bridge from the closest points of africa and south america, use it as a standard bridge between launches, the launches would only have to do 2g to get to escape velocity.

KaiserPro 9y ago

I assume they are using a cyclotron accelerator. Basically its a large disk with a spiral track on the inside. The disk is then oscillated in along its flat plane, like this: https://www.youtube.com/watch?v=OPLzsRojo_A https://www.youtube.com/watch?v=OPLzsRojo_A There was a video of a marble cyclotron, that basically had a spiral like the above, but instead of tilting, the whole disk moved along the z axis (as we look at it, x up, y left and right) it was about 1 meter wide, and was oscillating at about 2hz, that was capable of ejecting marble sized objects at about 500 mph or something similar. So I can see the method, but I doubt how payloads will survive that level of G. edit This idea: https://www.youtube.com/watch?v=UnZWu1FXxd4 https://www.youtube.com/watch?v=UnZWu1FXxd4

anotheryou 9y ago

It's a flywheel, some really good clutch mechanism and a straight track for linear acceleration, right?

deleted 9y ago

[deleted]

tony_rusi 9y ago

Dana Andrews used this Spinlaunch idea in his University of Washington Undergraduate Astronautics Capstone Engineering Class to launch Lunar Mining Ores from the moon cheaply. Maybe they intend to use it on the Lunar Poles?