Camera Films Itself Getting Launched Out of a Centrifuge at 1,000mph (in prep for launching heavier payloads to space)

petapixel.com ^ | 5/07/2022 | James Deruvo

[Deaf Smith]

Yes, 5000 mph is muzzle velocity.

Velocity goes downhill from that point.

[Svartalfiar]

at speeds of over 5,000 miles an hour, plenty of speed to reach low earth orbit.

The minimum velocity required to achieve low-earth orbit is 18,000 mph. (Even discounting the problem of air friction.)

The author of this piece probably flunked 8th-grade Science class.

LEO is considered to be around 100-1200 miles. To reach LEO, you only need an initial velocity of ~4000 mph (from sea level), ignoring drag. To stay in orbit, of course, you need a lot more.

[Svartalfiar]

Spinlaunch gets package to 200,000 feet where rocket takes over and accelerates it to 17,500 mph.

No mention in the excerpt of any rocket to assist in attaining orbital velocity - should have been highlighted in the FIRST PARAGRAPH - but that is the only scenario I can imagine having even a chance of working.

Actually, third sentence has it:

"The concept requires no onboard fuel, so there’s no danger of explosions, and since it’s completely electrical, it offers a sustainable solution that doesn’t pollute the environment."

So, no idea how they expect these packages to stay in orbit, unless something already in orbit is zooming by with a net?

[Svartalfiar]

The Earth's gravity drops only insignificantly until you are many hundreds of miles above the surface, in space.

To get to half of Earth's gravity, you gotta be about 2.64MM meters, or 1640 miles, which is hundreds of miles past LEO.

[Svartalfiar]

Through a couple of these posts, what Fester is missing and Alex isn’t mentioning specifically - G-forces aren’t just from going forward(up): while spinning in the centrifuge, the centripetal acceleration is going to be extremely high, as in order to spin, you are ALWAYS accelerating towards the center of the circle, that’s how you’re changing direction. The faster you rotate, the higher the Gs. So, assuming the final velocity (initial/launch velocity, I mean final from the centrifuge) has to stay the same, you change your acceleration by either the square of the angular velocity (how fast you spin), or linearly with the radius of the circle. (I think the equation is a=w²*r, been a while.) So in order to reduce your G forces, you need to lower the acceleration, which means lowering the angular velocity, which can only be done by increasing your radius. I don’t remember the equation for this, but off the top of my head I think it’s something around cutting Gs in half requires four time the radius of the centrifuge. So it’s gonna get big fast, or you just have to stick with lots of Gs on your package.

[Hootowl]

Check Wikipedia for rocket details.

[Svartalfiar]

Check Wikipedia for rocket details.

Why would I trust Wikipedia on this? Wouldn't the company's webpage be more reliable? If there is a rocket, why does this article explicitly say the projectile has no onboard fuel/risk of explosion? What does the rocket use for go-go juice?

[alexander_busek]

So, no idea how they expect these packages to stay in orbit, unless something already in orbit is zooming by with a net?

Yeah: A net that would instantly vaporize as if struck by a meteor as soon as it "caught" the projectile.

Regards,

[alexander_busek]

what Fester is missing and Alex isn’t mentioning specifically [...] in order to reduce your G forces, you need to lower the acceleration, which means lowering the angular velocity, which can only be done by increasing your radius.

Quite correct, Svartalfiar!

Ultimately, this leads to a linear accelerator - for example, an electric rail gun. But I didn't want to "muddy the waters" by going down that road. Eventually, you end up realizing that a rocket sled would be more feasible. From there, it's only a step until you're back to a conventional, vertically launched rocket. Boring!

The article speaks of a centrifuge, so I stuck to that benighted premise!

Unless you're talking about a centrifuge the size of a Ferris Wheel (terribly impractical!), the g-forces will crush any projectile made of conventional materials.

Centrifuges of a "sensible" size could be used to lob, at best, tungsten projectiles slathered in ablative materials and containing - at most - a few kg of water into low-earth orbit. And even then, I'm thinking that some rocket-assist would be indispensable.

Regards,

[Hootowl]

I found the company’s website lacking in detail. That’s why I looked for additional info.

[Svartalfiar]

Yeah: A net that would instantly vaporize as if struck by a meteor as soon as it "caught" the projectile.

Probably. I would hope everyone can tell that wasn't a serious suggestion!

[Svartalfiar]

sl - 300ft d biggest ferris - 550ft d Ultimately, this leads to a linear accelerator - for example, an electric rail gun. But I didn't want to "muddy the waters" by going down that road. Eventually, you end up realizing that a rocket sled would be more feasible. From there, it's only a step until you're back to a conventional, vertically launched rocket. Boring!
...
Unless you're talking about a centrifuge the size of a Ferris Wheel (terribly impractical!), the g-forces will crush any projectile made of conventional materials.

I didn't mean linear, I was talking about making the centrifuge crazy big. Which, according to their website, it is already the size of some Ferris wheels - 300ft diameter. (Largest Ferris wheel ever is only 550ft.) So yea, it's bigger than the wheels at your local pop-up circus/carnival thing.

Still though, it's a pretty impractical setup, and I don't see them being very successful at putting much of anything into an actual orbit.

[Dust in the Wind]

Don’t know if it’s been discussed but I wonder how the imbalance of the wheel is compensated at release? Too much wear and tear.

[alexander_busek]

I didn't mean linear, I was talking about making the centrifuge crazy big. Which, according to their website, it is already the size of some Ferris wheels - 300ft diameter. (Largest Ferris wheel ever is only 550ft.) So yea, it's bigger than the wheels at your local pop-up circus/carnival thing.

We are talking at cross-purposes, I fear.

To reiterate: When you start talking about making the centrifuge bigger and bigger (in order to attain high speeds without high g-forces - a reasonable notion!), you soon smoothly transition to linear accelerators (electric rail guns), then rocket sleds, then conventional vertically launched rockets. That's simply how the conversation always evolves!

Regards,

P.S.:

"High-speed centrifuges are specialized centrifuges that reach maximum speeds between 18,000 and 25,000 rpm (they can generate around 60,000 g). They are cooled and normally have a vacuum system to prevent the rotor from heating up due to friction with the air." - website of Kalstein centrifuge manuf.

I would hate to have to design the safety protocols for a Ferris Wheel-sized centrifuge required to withstand even only 60 g! And that in a vacuum! And to then have to slide open a panel to release the projectile while at the same time dealing with all the problems of pressure-equalization!

[Colorado Doug]

I think that I watched Wiley E. Coyote using a system like this once. I believe that ACME holds the patent on the technology.

[Svartalfiar]

There’s a lot they haven’t mentioned.. The inside is a vacuum, so when the projectile is ‘fired’, first thing in does is hit a solid wall of air...