China is building High Speed Rail To Space!!!
deleted by creator
Which Final Fantasy game am I about to be living in?
FFX, the one where most of the world was flooded.
VIII for sure. The cool futuristic society in that one launched stuff to space with a railgun.
Yeah Esthar had a space gun that shot pods into space.
but at what cost?
I couldn’t find the cost of this project specifically, but China’s total space budget is $12 billion a year.
Pittance we sent that much to Israel this year
Must be nice to have a good government
Uhhh
Can someone tell me what velocity you need to launch an object at in order to reach orbit? And what accelerative forces you need in order to achieve that?
How big is this railgun? How are they handling heat from atmospheric friction? You have the same problem going up too quickly as you get coming down too quickly.
It’s probably a high speed launch assist, not the entire source of escape velocity.
That sounds so funny though.
How would you even do that? Build something like a particle accelerator except it’s a launching railgun the size of China?
I mean yeah why not if it means you can partially reach escape velocity with like solar powered electricity vs going the entire way 100% on burning rocket fuel
The Delta-V (change in velocity) to reach the ISS (400km) in Low Earth Orbit (LEO) is 9.4km/s. This is the absolute minimum so it doesn’t include things like drag or other inefficiencies. Getting to space takes only about 1.4km/s, just about all the rest of that delta-v is used to accelerate the spaceship to 7.6km/s. This is about the minimum speed, altitude, and delta-v to get into orbit and stay there. Going much lower than the ISS will have your orbit decay too much to stay in orbit for more than weeks or months. I think it would take about 8000m/s to orbit right at 100km but your orbit would decay really quickly at that altitude, you would only get a few hours of orbiting.
I think I answered you below about why you can’t to orbit using only a railgun.
Edit: Going from earth orbit to other places doesn’t take as much delta-v as you might think. Going from earth orbit to lunar orbit only takes about 3km/s and going from earth orbit to mars orbit takes 5.7km/s.
NASAs version of this is called StarTram, it’s feasible but there are some major technical hurdles.
In the prototype stage, the launch velocity at the end of the gun would not be anywhere near the 10 km/s you would need to achieve orbit. But you could reach a sizable fraction, say 3 km/s. Becuase the velocity gained during rocket flight is not linear with mass, having that 3 km/s inital boost would reduce your overall rocket mass by like 80%. The rocket would clear the atmosphere and then fire its motor to gain a stable orbit.
We can achieve 3 km/s with current technology, it would require like a 100 km long maglev in a very low pressure tube, likely built on the side of a mountain. It could probably reduce space flight costs by a factor of 10 if completed.
Building the proposed goal of a human rated version capable of reaching near 10 km/s at the end point would be much more difficult. The tube would have to span over 1,000 km and I don’t believe we have the technology yet to maintain the vacuum or supply enough power quickly enough to power it.
China is likely proposing to build a testbed system to start researching the concept. Probably on a larger scale than NASA has but nowhere near a complete system.
deleted by creator
You’d still need engines and fuel onboard, or you couldn’t circularize the orbit. The idea is more just get something out of the atmosphere with something that doesn’t itself have to be dragged along for the ride, then do the rest of it once you don’t have atmospheric drag and you aren’t fighting directly against gravity anymore.
It’s kind of the same as the idea of “what if the first stage was a big air-breathing plane that just, like, flew really high and really fast?” that keeps cropping up, just finding a way to make the first part of the process less absurdly expensive.
But no matter what you can’t put something into orbit with a single input of velocity unless that was enough to remove it from the Earth’s sphere of influence entirely, because you can’t make the lowest point in an orbit higher than the point you’re currently at.
I think the next evolution after the raillaunch would be a hybrid engine that breathes air and functions in a vacuum so we could have small SSTO craft.
deleted by creator
Absolutely impossible. The problem isn’t the angle, the problem is that orbits are circular. The “orbit” would have to go around in circular motion until until it reaches the point where it exited the railgun (after accounting for the rotation of the earth and all the other nonsense you need to account for).
What you said, but the orbits are elliptical. The periapsis (lowest orbital altitude) would be the point where the craft exits the rail launch - located within earth’s atmosphere.
deleted by creator
What if the interior of the railgun accelerator was all a vacuum and the exit point was really really really really tall? So that impact with atmosphere at the exit of the gun was lower.
The problem is that you still need an additional acceleration in order to get into an real orbit. In any theoretical orbit (without an acceleration) you’ll always go around in a circular motion until you reach your starting point, if your starting point is in the atmosphere then you’ll go around your orbit until you hit your starting point in the atmosphere again. This will obviously cause your orbit to decay. There are a few solutions.
- Just use a rocket engine. This is the simplest and most practical solution. Vacuum engines are very efficient and you don’t need that much fuel.
- Use a skyhook. This is a giant spinning thing in orbit. Your spaceship “grabs on” to an end of a line and takes momentum from the already orbiting skyhook station in order to get in orbit yourself.
- You might be able to do something weird with the Moon’s gravity in order to change your orbit. This would take a while and you would need a huge velocity from the railgun and your orbit would be very high and probably no circular, but there’s no physics reasons it wouldn’t work (I think).
I love the idea of combining the rail launch with a skyhook. Skyhooks always sounded like they would fail due to atmospheric concerns which this would alleviate.
deleted by creator
This is what StarTram is, the launch system maintains a vacuum. The system won’t work without that feature.
the answer to every infrastructure problem is high-speed rail
I hope they figure out how to do this with engineless commercial airliners (I know it’ll never happen but it would be cool)
High speed rail(gun).
Fuck it, I see no reason why a train couldn’t be shot between two tracks 100 miles apart
I want to see this as a Dahir Insaat animation
Well, you could make a “train” to orbit but your rail would have to be hundreds of kilometers long, dozens of kilometers tall, held up with wires and particle accelerators, and the train would probably just be a single car
Btw this would just accelerate the space plane so it doesnt have to burn as much fuel as otherwise. It’s not a literal train into space
It’s not a literal train into space
TFW, the cartoon Galaxy Express 999 lied to me…
I found a YouTube link in your comment. Here are links to the same video on alternative frontends that protect your privacy:
Don’t listen to them, comrade Xi will make Honkai Star Rail real.
Yeah but where I am it’s all Honkies with No Rail
Look up launch loops if you’re interested in trains to space
This is some
tier shit (approving)Elon get fucked …
This sounds so sick
While SpaceX’s reusable rockets have slashed satellite launch costs to US$3,000/kg, some scientists have estimated that an electromagnetic space launch system could drive those costs down to a mere US$60/kg.
China completely invalidating SpaceX’s business model would be hilarious.
NASA is banned from working with China, so it would be genuinely hilarious if they were the only group stuck paying $3k per kg.
I’m not sure what’s funnier. If China open sources the technology and NASA would have no choice but to switch to it, or they keep it proprietary and force the US to use spacex
The funniest outcome is this: They go open source, Elon takes the concept and tries to pretend he invented the tech himself. People call him out for it, but he doubles down claiming he’s never even heard of china. It gets built and explodes because he cut corners and did dumb shit. Elon immediately blames faulty Chinese tech.
Elon tries to build a space trebuchet to compete, the release mechanism gets a bug and slams a $50,000,000 rocket directly into the ground. Blames China and Chelsea Manning.
And retroactively blames those shifty [slurs] for stealing American tech that previously was just a series of doodles on a napkin
I think the funniest outcome would be Elon being forced to try to build a space gun to try to compete.
During fundraising events he shows videos of the prototype in action.
The video… (invidious front end for youtube used)
The SpaceX rockets being reusable barely put a dent in the price of launches, they were already cheap. probably has something to do with them using RP-1 fuel wich is is cheaper and easier to store and creates greenhouse gasses vs. the clean burning liquid hydrogen that NASA and ESA use.
It’s not for people or it would be too long (?)
I don’t think we know the payload specifications of the proposed vehicle that would use it
The article says that the railgun part accelerates the plane to mach 1.7 and then the rocket on the plane fires and it accelerates further.
The Concorde was designed to cruise at mach 2, so that’s a very survivable speed if the acceleration on the rail isn’t too abrupt, like you said.
I think the acceleration is the crucial part, the speed you are going at is irrelevant, just the change in speed
This is correct.
It’s still would be like 1-2 km, if they aim at 10g. And they still need to find another 20 machs from rocket booster.
Doing full railgun with small rockets is more poggers (without humans obv )
If you assume humans are frictionless spheres they could probably ride on that second one
They will be spheres if they do ride on it. Several in fact.
Tests will be carried out at 1.2 mile long low-vacuum track high-speed maglev test facility in Datong, generally used when researching magnetic levitation train technology
Within coming years, the Datong test facility will be extended to 37.2 miles long, to achieve a maximum operating speed of a staggering 5,000km/h.
biiiiig track incoming
That would still be a rough ride for a person, but it could absolutely revolutionize getting construction materials into orbit.
They’re building The Chandelier?
Those
for FF8 - you got your remake baby!If the railgun doesn’t have a giant revolver cylinder I will be highly disappointed.
I found a YouTube link in your comment. Here are links to the same video on alternative frontends that protect your privacy:
