So I ended up exhausted last night and spent thirteen hours drifting in and out of sleep. One of the drowsy thoughts I had was "but what if they were serious about it tho, I oughtta run the numbers." So to account for Am_u's observation that you get one, one orbit out of this device, I decided it should be a useful one. Thus, we're gonna go for GTO. That's 9.8km/sec, 10k if you're nasty. To account for the fact that said device needs to be useful, we're going to act like it needs to get a Falcon 9's payload to GTO. That doesn't matter tho it falls out of the equation. We're going to not modify the shit out of our payloads and presume they're gonna top out at 1.5G of stress. We're going to assume a circular maglev track big enough to accomplish this. We're gonna spin it around as many times as we need to accelerate to 10km/s using magnetic force. Once we're at velocity we're going to switch it to a straight line climbing up a mountain, it obviously won't be high enough, it obviously will still require a wicked ablative shield, it will require a track that looks like a blunderbuss because it's gonna be exciting up there, but let's get to the dealbreaker first. I wanted to draw a map of this, unfortunately the radius of the Earth is 6300km.
For posterity: By "one orbit", I do not mean "payload goes around the Earth only once before re-entry", I mean "one orbital inclination". Theoretically, by choosing when you ignite the second stage, you can fiddle with the inclination a little, but you don't have many options on that when a) you're not even close to orbital after the first stage and b) the second stage is a bottle rocket-like solid-propellant engine that, once lit, cannot be unlit. But yes, GTO at perigee is something like 10 km/s, a few hundred km high. Your first perigee, effectively, is when you come out of the launcher at a measly 2 km/s, 0 km high. According to the SpinLaunch wikipedia page, the second stage will fire around 61 km altitude, and hah, by then, you will not be traveling 2 km/s. Probably not even 1 km/s. For comparison, this Atlas V GTO launch has the second stage begin firing at 120 km, traveling at 5 km/s. If the second stage of an Atlas V is 7% of the initial mass, one million kg, that's 70,000 kg. In the lovely puff piece above, we are told that the SpinLaunch payload and second stage are 10,000 kg, combined. I don't think it really matters what the actual payload weighs, because unless SpinLaunch is also working towards developing the first instance of negative mass observed in the universe, there isn't a goddamn thing making it into orbit. I kid about SpinLaunch stickin' it to VC funders, but I'm sure the legacy will be one of embarrassment for the space industry. At this point, I'm surprised more people aren't speaking up about how much of a blatant scam this is. How's this on a red hat, btw? "MAKE VC VIETCONG AGAIN"
Yes but if we're trying to defeat "the tyranny of the rocket equation" let's fuckin' defeat that bitch, shall we? No "stages" we're zero-stages-to-orbit, goddamn it. What's funny is if you're willing to just accelerate in a straight line at 1.5G, you're at 10km/s after like 3200km. Which starts to make that rocket look positively frugal. 3Gs and I'm at 1300km, 10gs and I'm at a nice benign 100km track. 10gs is going to involve some compromises, for sure. You're probably not going to be higher than 10,000ft which is a bummer and which means yeah, you're going to need a second stage prolly. But you've got load in one direction, you've got it for a little over a minute and a half, you have no release mechanism to worry about, and aside from the heat of friction and the (substantial) complications of fluid mechanics, you're squarely in the realm of normie physics. It's a Grainger problem not an Unobtanium problem. Fuckin' Gerald Bull got 84kg 80km past the Karman Line with fucking cordite. There's no real way around the fact that the minute you leave the barrel you're slowing down. But there's also no real way around the fact that the minute you decide to go in a straight line you solve almost all of your problems. The minute they take public money it's over. Theranos would be much less of a cautionary tale if (A) they didn't bait the Army into evaluating their bullshit (B) they didn't give a bunch of Walgreen's customers spurious "you're going to die soon" test results.
At this point, I'm surprised more people aren't speaking up about how much of a blatant scam this is.
I got used to designing things for orbital flights, with those ~1.5 g accelerations. You don't even think about the static load, it's entirely about the noise / random vibrations environment. Then I did a sounding rocket, and the lead scientist forgot to mention that there's a 10 g static load on top of the noise. Those suckers really fire off quick, which is fantastic when you're trying to fly through a very dynamic auroral feature, but yeah I ended up putting in these ugly little splints at the last second to shore up some problem spots. No software analysis, and no QA, because sounding rockets are too cheap. Quick peer review. Worked like a charm. The idea of designing scientific instrumentation for a Mach 6 noise environment a few milliseconds after the jerk of -10,000 g's over 0 seconds (hopefully it's 0 seconds, for attitude control! Hey does anyone know what happens when you divide something by zero?) reverberates through my shit is so funny that I can't wait to talk about it with my old boss. Drag. It's proportional to the square of the velocity, and inversely proportional to altitude. Having the fastest portion of your "first stage" SpinLaunch equivalent while you're at your lowest altitude is so stupid. So, so stupid. Sure, but they shot almost straight up. So at (suborbital) apogee, the projectile had about zero velocity tangential to the axis connecting the projectile to the center of Earth. SpinLaunch will need to be angled only maybe 20 degrees or so above the horizon. The fact that their only field test facility was flinging shit straight up doesn't bode very well. Yes, a rocket begins by going straight up, but then angles over to push your tangential velocity up. The vertical-ish part of a rocket's ascent also gets you out of the thickest part of the atmosphere quickly, too. Meanwhile, ScamLaunch needs to travel through muuuuuch more atmosphere because of the release angle being close the horizon. There's no getting around that. I feel like the NASA evaluation they've committed to is plenty enough taking of public monies for me. Seriously, a space elevator is such a better direction to push in than this, and I'm not totally convinced that's feasible either. I wanna see how quickly tectonic drift becomes problematic, for starters. You gotta keep it dead center of the equator. If we could make the top anchored to a captured, well-controlled asteroid parked in GEO? Might work. We'd have no choice but to de-orbit shittons of space junk, tho. I still think a moon base shooting UV or even X-rays to de-orbit junk when facing the Pacific, once a day, is the best solution I've come up with, or heard anywhere, for that matter. The tracking software should... cost a few $'s.Fuckin' Gerald Bull got 84kg 80km past the Karman Line with fucking cordite.
Yeah, I know. my X Minus One heart really wants this to work on some level? For there to be some way to bend the equations to vanquish Tsiiolkovsky? But I mean... it's not like clever people haven't contemplated this shit for a while now. Gerald Bull was in it for the artillery, pointing shit at space was just the easiest way to get funding (until it became "pointing shit at Israel" at which point the Mossad, er, revoked his grant). I am fully aware that vanishingly few ballistic objects execute a 90 degree turn halfway through their path. This is why you must design for 10,000g apparently.Having the fastest portion of your "first stage" SpinLaunch equivalent while you're at your lowest altitude is so stupid. So, so stupid.
I really hope that pic is from actual promotional material, and not a Broadway show or something. That's alright, I'm OK.This is why you must design for 10,000g apparently.
That's Amoré af. "Moon hits your eye"? Shoot her in the eye right back. - SpinLaunch™ P.S. yeet