[spicybright]

I'm still scratching my head thinking of how much force will be crushing the rocket and satellite for an hour. I know space stuff needs to be super durable, but surely the G's it'll experience over an hour will be more grueling than a traditional rocket, no?

[h2odragon]

> "At this point the spacecraft will be subjected to a peak force 10,000 times greater than Earth's gravity, something opponents believe will seriously affect its structural integrity and the safety of its complex electronics."

Centrifugal projectile weapons scale up poorly and have issues even at BB gun scale. Envisioning what happens with a 200lb projectile; leave aside the laughable velocities they're talking, and I want to be well distanced from these people when they power shit up.

I think this is a device for separating investors from money.

[pengaru]

I just assumed they fully expect to pivot into the defense industry.

[jasonwatkinspdx]

This isn't very appealing to defense either, due to the slow spin up.

[pengaru]

This isn't my area of expertise, but judging from some of the extreme physics they're dealing with I'm assuming they're solving problems with potentially lucrative military applications.

[jasonwatkinspdx]

They aren't solving anything, and no, there's no potentially lucrative military applications. This is just an investor scam. Dunno if the founders are true believers it or not, but this thing has 0% chance of producing anything interesting.

[TeMPOraL]

Hypersonic anti-ship missiles are a hot topic these days, maybe this is related.

[bfuclusion]

To get a rough idea of the numbers if this was a rail gun and accelerating linearly: 1G is 32 feet/second 32 feet /second is ~22 mph They're accelerating to 5000mph so they need to crush things at 1G for ~230 second or just under 4 minutes.

If I understand correctly, this would hold for angular acceleration too, since they'd just release at some point. Can someone correct me if I'm wrong?

[jseutter]

You're probably correct, but there is more.

Take a 200 pound payload, add some rocket to it, let's say 10x the weight to be generous, then spin it in a circle 200 feet in diameter. You're looking at 18 thousand tons of force spinning it at 5000mph. So you're spinning 4 navy destroyers worth of force in a circle, which means you need a latch mechanism that can not only hold that much force, but release it at the exact moment to exit the biggest vacuum chamber ever created through a door that just opened at the right time, generating a mach 6+ shock wave at about 0 meters distance from the door and somehow not destroying it in the process. I don't know that it is impossible, but it is highly improbable. They'd probably have a burst disk rather than a door, because that would let you use the capsule as a bullet to penetrate the exit.

In the article they mention the payload experiencing 10000g, so they must be planning on a circle greater than 200 feet in diameter. I can't find numbers on existing satellites, but I remember reading that rockets typically top out at 6g acceleration and figure on a 10x momentary acceleration due to vibration. To tolerate 10000g the payload being launched will need to be built like a tank, rather than the relatively light current designs. To ease that requirement you could submerge the payload in liquid, but that would decrease your usable payload accordingly.

It would be impressive if they could actually pull it off. I think it would be useful for limited applications. I have watched science fiction shows where mass accelerators could basically nuke planets without radioactive fallout. Maybe this would be something similar.

[inetsee]

Having read "The Moon is a Harsh Mistress" a looong time ago, I have sometimes wondered why no one has ever tried to use rail guns as launch mechanisms. I vaguely remember from not so long ago that one of the criticisms was that the acceleration forces would crush any fragile parts like electronics, but is it still true that electronics can't be hardened to survive the acceleration forces? Are there other problems that make the idea of rail gun launchers simply impossible?

[beervirus]

A rail gun would work from the moon, where there's no atmosphere. On earth, the projectile would attain its highest velocity (right as it leaves the rail gun) in the thickest part of the atmosphere (at ground level).

And just for a sense of scale, escape velocity from earth's surface--assuming no atmosphere at all--is 25,000 miles per hour. The projectile is going to tear itself apart in atmosphere at those speeds.

[dboreham]

Main problem is to avoid being assassinated by Mossad.