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