"Best kept secret" was a phrase used about Theranos, too. They also received money from Kleiner Perkins and the DOD despite their process being easily evaluated as impossible by anyone with any experience in blood chemistry or its measurement. For conversation's sake, here's a dowsing rod used to detect bombs that is still killing people. Experts fall down sometimes. Often when they aren't asked. Or when they're asked one question and the charlatans say they answered a different one. Let's look at some basic numbers. We'll use the ones on their own Wikipedia page which is 4800 km/h or 1333 m/s. They're trying for a "catapult" (centrifuge) three times the size of their proto, so 120ft in diameter. Newtonian physics says that our 200lb payload is experiencing 1,000 tons of force and approximately 10,000g. Separating blood into plasma, for comparison, takes 5 minutes at 3000g and we're gonna take an hour to spin this sucker up. 362 ksi turns the lead in your pencil to diamond. Build the proper anvil for this thing and you won't need to send anything into space to turn a profit. That doesn't get us into orbit, though. That gets us spit out the end of the centrifuge where we go from vacuum to atmosphere and 10,000g to one (do you like how there's no deceleration there? No accommodation for that transition? 'cuz I do). We now need to boost our rocket to get us from 1333 m/s to 7500m/s. We're going to burn for a minute: v(f) = v(i) plus (a)(t) so (a) is 103 m/s^2. Never mind the fuckin' centrifuge we're going to burn at 10 1/2 g for a minute. A Sprint missile will do that (it'll do the shit out of that) but out here in the land of normal? A Falcon 9 is good for about 12m/s^2 (or 2 once you cook off gravity). If our rocket weighs nothing but rocket fuel and we're trying to get a 200 kilo payload to LEO, we're now talking about 1400 kilos of solid rocket fuel, assuming the most efficient rocket fuel imaginable (thanks, omnicalculator). Our payload has been through some shit. So has our catapult. By our design we're ditching our counterweight at the same time as our payload; we've got 1600 kilos experiencing 10,000g. It's gonna cut loose at 1333 m/s. KE = 1/2 (m)(v)^2 so about 1400 megajoules. We aren't in kiloton yield range but just letting the fucking thing go is gonna let go of as much energy as blowing up a 600lb stack of TNT. You're going to have to do something with that. Water column, pressure canister, dunno. Meanwhile our spinny arm is experiencing 311,000 kN of force. We'll build it out of kevlar because tensile strength is where we're at. Never mind any forces other than lateral; 898Mpa/m3 means we need a third of a meter square of kevlar fibers (pulling straight! not in a mat!) to make this work. Talkin' a lab-grown stalk of aramid 60cm in diameter and 120 feet long. Or, the equivalent structure, which is gonna be sumpin' else. Let's take a step back. Suppose we skip the catapult entirely. We're going to boost at 10g because fuck you, that's why. Let's start from zero rather than 1300m/s. Tsiolkovsky equation says we're now looking at a 7500kg rocket; we're basically trading 10,000g of pain for 6 tons of first stage. Now. Push that "centrifuge" out to, oh, 200 miles and suddenly you're at escape velocity having experienced a mere 18g.
But the rocket is going to feel weightless in those 22 beautiful milliseconds coasting down the exit tube, every single resonant mode ringing out loudly after dropping that 70,000,000 pound [lateral load] tether before gracefully slipping [axial load if you ain't sideways] into beautiful New Mexico air at MACH-SIX-AND-A-HALF. I don't have the reference materials or the will to estimate supersonic drag, but I know they gotta kill off all rotation with the release mechanism because 3000 to 5000 mph on a 100m centrifuge is 250 to 425 rpm, and a 425 rpm speed flat spin at Mach 6 ends exactly how everyone expects it to. Also "Actuation accuracy <1 millisecond" sounds like a design requirement, not something they found out how to do yet. 1ms off at 425rpm is 2.5° of travel. Much more and you miss the exit.That gets us spit out the end of the centrifuge where we go from vacuum to atmosphere and 10,000g to one (do you like how there's no deceleration there? No accommodation for that transition? 'cuz I do)
What's even funnier is that they'll need to have the entire facility held at vacuum. You can't have the lever arm of your centrifuge going around at some fraction of 2 km/s with air in the way. Having a volume so large held at vacuum? Laughable. Absolutely laughable. Especially with so many moving parts inside. So then, when the payload comes out and hits air, your picture happens, essentially an explosion, which is then sucked back into your launch system, since it's sitting at a lower pressure. I wish them the best of luck with a design that inevitably leads to a series of valves, which, unless everything always goes absolutely perfectly, leads to complete destruction of the entire facility.
You know, just for fun. Moment of inertia is (mass1)(mass2)/(mass1 plus mass2)(distance)^2 is (1600)(1600)/3200 times (37m)^2 is 1.1e6 kg m^2 (presuming our 120 feet of kevlar has no mass). kinetic energy is 1/2 I omega^2 is (0.5)(1.1e6)(74 rad/sec)^2 is 3.01 gigajoules. Presume it's perfect. Presume it's frictionless. Presume sunshine and rainbows. You just pumped 833 kW/h into this thing and you're letting it go in a millisecond. That's 1400lbs of TNT, which is troublesome, because the linear energy is 1200lbs of TNT, which means ThurberMingus' entirely-expected flat spin has some real power behind it.
What this project needs is a high school physics teacher with a sense of humor and duty who walks his class through all the stuff they can see as a problem and then makes them do it on a chalkboard for Youtube. Now'd be about the time. In the US, the first semester of high school physics is all Newton. Second semester becomes E&M. In between you do a little rotational stuff. It's pretty much the season to remind the class of everything they've learned so far and let them get investigative on it. I would love to see a bunch of 11th graders schooling Kleiner Perkins on Newton's Laws. You don't even need to get into the more advanced shit ("If a 60cm^2 stalk of pure aramid fiber is necessary to support the centrifugal load of the launch vehicle, what will you make the release mechanism out of?"), just let 'em show off what they learned before Christmas.
I sent an email to some of the teachers I met through my outreach series with old uni. Now it's a waiting game, but if I were to bet, the most difficult part would be getting OKd for recording. Syllabus-wise, I think we're going Newton, thermo, E&M, mechanical waves and the senior year was optics + modern physics. Dunno if it's still the case, our board of education likes to look busy.
Oh god, you're right. Even if we'd assume it's just a cylinder with radius 100m and height 5m, it's still more than ten times the total volume of vacuum piping at the LHC.Having a volume so large held at vacuum? Laughable. Absolutely laughable.
So... When I initially skimmed the article, I glanced right over the schematic showing the design, thinking it was an advertisement (correct, I guess?), hence some "reinventing the centrifuge" on my behalf in this thread. Anyway, in the schematic, it does say "medium vacuum". The LHC is kept at "super duper vacuum", around 1E-9 Torr, to minimize collisions and keep the beam collimated. Let's say "medium" goes down to only about 1E-1 Torr. The delta between 760 Torr and 1E-9 vs. 1E-1 doesn't really matter, because from a structural consideration, you have a delta of just about 1 atmosphere in both cases. OK, so I know my little 1 meter diameter by 2 meters long cylindrical vacuum chamber (at ~1E-7 Torr, but irrelevant here) needs about 4 to 5 inches (~11.5 cm) of steel shell thickness to keep from deforming due to the delta between pressures over long periods of time. A relatively flat interface of pi*(50m)^2 area between "medium" vacuum and 1 atmosphere will require an absurd amount of material to prevent implosion. After considering it for while, I don't think building it underground gets you anywhere. Maybe if you hollowed out a cavity somewhere under 1 km of granite? With an investment cost large enough to do something like that, and considering how likely it is to eventually fail and destroy itself (see my comments above), this is still nothing but a fairy tale. Even if miracle after miracle after miracle got SpinLaunch a functioning facility, I can guarantee you that the energy costs would make the traditional method of using rockets much, much more feasible. Approaching this from a carbon emissions standpoint might see the two methods a little closer, but now we're talking a 300+ man-hours case study, and I already have like two jobs. note: too defeated for unicode today, bruv. I'm just glad that I made it back here to naysay some more :).
I thought it's done for thermal buffer and isolation, not just structural support of all the steel/whatever would make the chamber, no? I only unicode this easily because 3rd+ level keys are a thing. I chose right ctrl for my 3rd level, so making symbols like ² or ³ is RCtrl + 2 or 3, respectively. Plus it's much better than switching language layouts fifty times a day and comes with a buttload of nifty symbols (≤≥÷≠ßπµ).I don't think building it underground gets you anywhere. Maybe if you hollowed out a cavity somewhere under 1 km of granite?
too defeated for unicode today
The idea of a successful transition from a vacuum tube to sea-level-ish atmosphere while traveling at Mach 6 is probably the funniest part. That's 2 kilometers per second. When your shit hits air, the shock wave will be more than strong enough to critically damage your facility. Like, remember that yuge nosecone on that new whats-a-plane you posted? We'll just make it longer, and curved, guys, so it can go around the tube, of course. This is gonna work, I just know it!! ThurberMingus: thanks to you too, I'm cracking up. Edit: no, no, the best part is when it's casually mentioned that SpinLaunch will also require a boost from rocket propulsion to finally make it to orbit. So we're gonna do all of this with... a bomb... at 10,000 g's... hahahkhahahah
SpinLaunch and Theranos perfectly represent our era: Impossibly optimistic promises (read: fraud) backed up only by a shiny PR campaign and orange bronzer. Nah, I'm just kidding, what a salty skeptic I am. You probably didn't hear about it, what with the modern news cycle, but the Mars One guy touched down on Mars yesterday with the first batch of 5,000 colonists. I'mma ask this again: Hypothetically, what should I peddle to the normie 'boomers on NextDoor?
It is the encapsulation of the triumph of Castle In The Air Theory over Fundamental Value Theory. The value of things that can be bought at Series A and sold at IPO is far, far higher than the value of things that will eventually make money. I have thoughts about your Nextdoor Boomers. They are complex.
I highly doubt this will work, but I love to see VC pumping millions into ideas like this. They’ll all likely lose their money, but it’s rare to see experimentation on this scale. So much of this class of money is typically spent in rent-seeking, regulatory capture, or ”financial services”. I prefer paying a bunch of engineers to try something nuts.
As a scientist and an entrepreneur you should not be celebrating this. The idea is so bad that those of us who took high school physics are dunking on it. It is so transparently false that there's no hope of it ever achieving anything. But enough rich douchebags have watched that "Here's to the dreamers" Apple spot that they're pouring money into stupidity because it's stupid. That's money that didn't go somewhere worthy. That's money that is never intended to celebrate spaceflight, it's money intended to be made off the greater fool. Theranos blocked development of a lot of necessary testing services. I was following it avidly because there's a duopoly of Quest and Lab Corps and they both suhuuuuuk and it would have been great if someone had just said "we're spending a billion dollars to bring customer service to the testing industry" but since we got stuck with "this device the size of a rubik's cube is going to prevent cancer" the Quest and Lab Corps duopoly is even stronger now.
This sounds regrettably naive. I've worked on the mechanical design of space instrumentation for quite a few missions. The guy that they quote in the Wired article is 100% correct when he points out that 10,000 g's will destroy essentially any satellite payload. So, for this to ever be feasible, we just need to figure out how to completely scrap all existing knowledge of satellite payload engineering and start from scratch. Guys, this is gonna work! I just need another four billion dollars by Sunday.
Surprisingly, 10,000g won’t do much of anything to solid state material. I’ve spun a grape at 5000g, and to my disappointment, after 10 min, it still looked like a grape. We use up to 200,000g to separate lipids from serum in plastic tubes. The issue is that centrifugal force only gets interesting if you have a free mass of significant density compressing the mass of interest. Maybe I’ll take some pics and spin a grape at 10,000g this week to demonstrate.
Cool! Please, do so. Could you do it on both seedless and 'normal' grape? How long does it take your centrifuge to get to those speeds? EDIT I'd also love to get data like lengths (arm, grape), masses and whatever else you can measure without being inconvenienced. I'm intrigued by the mystery of the unsquashable grape, but wouldn't want to impose beyond what I wrote before.Maybe I’ll take some pics and spin a grape at 10,000g this week to demonstrate.
I believe you, but satellite payload designs are driven by material considerations entirely unrelated to assuming a static load more than 1,000x the current norm (~3 g). Just off the top of my head, a PEEK high voltage detector fixture engineered to sit inside of an aluminum housing assembly (known to exist) is donezo. Honestly, I'd enjoy eating my words and seeing this concept work. It just won't, perhaps especially when considered from a practical costs vs. revenue perspective. We want that grape vidja/pics though. And we know you're not doing genetics stuff, it's really uranium enrichment. ;) ;) ;) "hello, FBI", m'POTUS, etc.