Comments by "" (@charlesvan13) on "Can We Throw Satellites to Space? - SpinLaunch" video.

@cogoid It still means you're doing fiction. And the comparison with Theranos is apt. Any craft will fly apart long before you could spin it to the speeds necessary to get through the atmosphere. When the space shuttled SRB's were jettisoned it was going 3500 mph. That's twice the speed of a high powered rifle bullet. And that's still not anywhere near the speed and altitude they need to reach orbit. Theranos was a project that wasn't just a very difficult challenge. It was something that couldn't be done.
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@cogoid That's just speculation in the video, not things that have been done. A cannon launched vehicle would burn up in the dense lower atmosphere, if given the necessary velocity. Or, it would only go a couple miles before falling. A launch vehicle is going mach 5-8 when it stages, above the lower atmosphere. You need to give a projectile an even greater speed because it would have no thrust. It would burn up from the high speed in the dense lower atmosphere. A rocket can go > mach 5 because it's out of the lower atmosphere at that time.
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This is impossible. You could never get the velocities necessary by spinning the rocket. You need extreme speeds to get to space, and very extreme speeds 17,000 mph to reach orbit. The first stage of a rocket accelerates it to mach 5-8. If you spun a rocket that fast, it would fly apart.
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@lohphat Exactly. Theranos was a scam because they did not tolerate negative criticism. There is no way they can reach the speeds necessary with a centrifuge. When a rocket first stages, it's going many times the velocity of a high powered rifle bullet. The shuttle was going mach 5 when it jettisoned the SRBs. Try spinning a centrifuge at mach 5.
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@prestonl.2432 If you fire a rifle straight up, the bullet will leave the barrel at mach 2, but will only reach about 10,000 feet. This project is not even close to being workable.
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@prestonl.2432 If you had a mach 5 cannon, that would just be your initial speed. You wouldn't even make it 10 miles until the air resistance and gravity had you falling back to the ground. There are so many things wrong with this idea, that it's absurd. If you solved all the problems with getting a vehicle into space, you would just get a rocket with stages. A gun wouldn't get past 10 miles until air resistance and gravity took all its velocity. A rocket starts from 0 and speeds up, gaining acceleration as the fuel is depleted. And the atmosphere is thinning as it is speeding up. Airplanes can only go about mach 3 at most because the heating becomes extreme in the dense atmosphere. The Saturn V was going mach 8 when it first staged. It could go that fast because it was well past max Q, 40 miles high. A projectile launch vehicle wont work. You'd lose all your velocity to air resistance. With the Saturn V, stage 2 ignited with the rocket going 6600 mph. The second stage relies on that velocity. And accelerates to 15,500 mph.
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@prestonl.2432 You can't exit the dense lower atmosphere in a couple seconds. It takes a rocket a couple minutes and it's going about mach 5. At the speeds you're talking about, the craft would melt from the heat. And the centrifuge used to launch it would fly apart at a fraction of that speed.
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@akmalagassi7711 Except the title of the video is 'Can we throw satellites into space?" The answer is "No". Spin launch could only sling a projectile a couple kilometers. A huge artillery gun can send a projectile high. That's still just a projectile not a satellite. And that's at best into the upper atmosphere. A satellite is in orbit. If you actually solved all the problem of getting a satellite into orbit you would realize the "spin launch" and a gun wouldn't do it. And you'd reinvent the staged rocket.
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@elmercy4968 Those are missiles, not projectiles like this proposal. An X-15 rocket plane could go mach 6.7. We have had missiles that can get to space since the beginning of the Cold War. This is just an answer to the problem that has been solved. If you want the speed and altitude necessary to get to space, you need a rocket.
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@rusher2937 The only way you could get the upper stage to the necessary altitude and speed is to use a lower stage. You'd have to spin it to high mach speeds. It would just fly apart from the centrifigal force at much slower speeds.
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@bazoo513 2 km/s is over mach 5. It's impossible to reach that speed in a centrifuge. It would fly apart from the centrifugal force. Secondly, that wouldn't be enough because it would slow down from air resistance in gravity. A rocket is constantly accelerating with thrust.
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@greatgaloo602 Do the calculations of the centrifugal force in spinning the vehicle to mach 5. Even that wouldn't work. Because it would lose all its velocity from air resistance and gravity when it reached altitude, and ignited the rocket. These scams are done all the time. Waterseer -- a proposed device to get clean drinking water for poor rural areas by condensation. They didn't consider the energy needed to condense water, and that dehumidifier water is not clean. When they finally had a project it was a Chinese dehumidifier in their 3d printed plastic case. And the water isn't safe to drink. They eventually had to refund their funders, who were furious in having to wait years for a repackaged dehumidifier. Solar Roadways -- a plan to put solar panels on a road surface. First, the solar panels would be destroyed as a road surface. Second, they panels would be inefficient placed flat and with cars over them. The company has gotten several million in funding and there are no solar roadways. Trident breather -- a concept to take O2 out out of water to be used as a scuba device. Totally impossible. There's not nearly enough oxygen dissolved in water, even if you had a way of filtering it out of water. Fish have much different metabolism. The gofundme was shut down.
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@prestonl.2432 That project was only useful for launching bomb projectiles. The project he mentions never launched anything useful into space. Any rocket would be destroyed in the 15,000 g force of the gun blast.
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@prestonl.2432 OK. Here are the number. A radius 100 m rotating assembly accelerates the rocket to 2 km/s. That's 44 rpm. The acceleration on the rocket at that speed and radius is about 10,000 g. Say the rocket is 100 kg (a quite small rocket) That's 1,000,000 kg of force. The centrifuge will need to be built out of unobtainium.
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@prestonl.2432 " totally do-able." That's baseless. A rocket will actually have to be at least 1000kg. That will mean there will be 10 million kg of force on the rocket and centrifuge. And that's 10 million Kg of force with it's released. It will also be rotating at 450 rpm. So it will have a massive spin (head to tail) when released. This isn't going to work.
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@huntera123 Their planned centrifuge will produce 10,000 g of acceleration. The smallest rocket would be over 1000 kg. That's 10 million Kg of force. It will spin at 450 rpm. So furthermore, besides the extreme forces, the rocket will be spinning nose over tail at about 7 times a second. So it doesn't even send a stable projectile.
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@prestonl.2432 I'm making the point that it wont work as a first stage. You can't get near the velocities needed with a centrifuge. The rocket would fly apart before you could get near the needed speeds.
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@prestonl.2432 What might work would be a very long rail gun, using say magnets, to accelerate the rocket. But you'd have a problem in that rockets don't launch horizontally. And it would be a silly project -- a way of doing something more expensively. It would cost much more to build such a device than first stage boosters.
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@prestonl.2432 I've avoided getting smug. But this project is ridiculous and an obvious funding scam. The "space gun" launched a projectile, i.e. a large artillery shell to suborbital space. These engineering scams always start by hyping something that's impossible. Then they backtrack, until the project is forced to close under threat of lawsuits. A the HARP gun wont launch a rocket. Any device would be destroyed by the gun blast. But Spin Launch can't even remotely do that. It's a giant baseball pitching machine. It can't create the velocities needed. From their tests "The centrifuge ran at 20% of its maximum power, he said. He declined to give specific details about the projectile’s flight, but said it flew at supersonic speeds and reached altitudes of “tens of thousands of feet.” The projectile was instrumented and collected data, but did not have any active controls, instead flying a ballistic trajectory." Why do you think they declined to give specifics about the test? A real scientist or engineer doesn't do a test with no hard data. This is aerospace version of Theranos.
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@prestonl.2432 Again, you're playing the game these funding scams always do. The fact (likely BS) that you can launch a suborbital GPS computer that can withstand 15000 g, has nothing to do with Spin Launch. This will never launch anything into space. It cannot create near the velocities needed. Launching a camera 10,000 feet in a tumbling projectile, is like saying that a friends Cessna has gotten us partway to space. Even it gets closer. And even if it could the centrifugal forces would destroy any useful payload.
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@elmercy4968 A long barrel cannon can produce the speeds that SpinLaunch says they will obtain, about mach 5. But that's impossible with a centrifuge. Spin Launch also intends to launch a rocket, not an artillery shell. 12 km is also at about max Q for rockets, not out of the atmosphere.
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