4 ms·
> When you hit orbital height, your velocity is in the wrong direction. Wait, why is your velocity in the wrong direction? You're right that you need to add a
by feoren 5y ago
> When you hit orbital height, your velocity is in the wrong direction.
Wait, why is your velocity in the wrong direction? You're right that you need to add a whole hell of a lot of horizontal velocity to reach orbit, but you do have ~400 meters per second of horizontal velocity borrowed from the surface rotation of the Earth. You're not going the wrong direction -- there's nothing you need to counter-act. You just need your 2nd stage (assuming we count the initial throw as a 1st stage) to provide all that velocity. The fuel you need to do that was launched up with you. What's the problem? It's a hell of a lot easier than the way we do it now.
> How do you ... survive forces involved
Yes, that is the real problem.
> The projectile has a carp ton of angular momentum after release
No, the centrifuge has a crap ton of angular momentum, some of which is converted to linear momentum in the projectile upon release.
- cjensen 5y agoYep, the "wrong" velocity is what you suggest: the horizontal velocity is missing. Keep in mind the horizontal velocity is the critical detail that distinguishes "orbits" from "crash landings." There is no conversion to linear momentum. The projectile is rotating once per turn of the centrifuge. Nothing they do eliminates that angular momentum. That's why in the linked video the projectile is, on close examination, rotating wildly. It's also why the projectile's nose exits the apparatus at a very different location than the tail.
- feoren 5y agoI play Kerbal Space Program, so I know a thing or two about orbital mechanics! (I'm only 30% joking -- many of the answers on the Space Exploration Stack Exchange say "Go play Kerbal Space Program, then you'll understand). Yes, that horizontal velocity is hard to attain, but that's what 2nd stages have always been for. We're only talking about replacing the 1st stage, which is by far the most expensive. You're still way better off already being at orbital height, never having to accelerate directly against gravity and through all that air resistance. And the speed you need to reach orbit is less the higher up you are. > The projectile is rotating once per turn of the centrifuge. I keep trying to challenge this, but I think you must be right. I was thinking the angular velocity would be smaller than the arm, but it must be the same. Still, the angular momentum can be much smaller. And I'll paste my proposed (possibly infeasible) solution to that from another answer: Attach the payload at two points in a narrow V, equidistant from the center of mass. In the instant before release, fire pistons that slightly extend the upper arm and retract the lower arm, applying the exact amount of force you pre-calculated was needed to counteract the differences in rotation between those two points. Release while this (hopefully uniform) force is still being applied. Yeah, you're jolting the hell out of your payload, but that's peanuts compared to what it's about to experience anyway.
- Brian_K_White 5y agoThe projectile is rotating at the same rpm as the arm it was attached to.