So, if you research the history of space exploration, you’ll find one result keeps happening over and over and over and over.

They keep exploding.

It’s not surprising. Their basic foundation is that they are rockets. Even from their original designs, rockets have always been built with the purpose of exploding. They’re weapons. But, before they were weapons, the ORIGINAL idea, was to use the propulsion to exit Earths atmosphere and into space. The only problem is that when this was being designed, I forget the guys name, but he was a scientist that the nazis had captured. He designed the rockets for space craft. Hitler then took the designs and thought “Let’s blow up London!”

So, once the war was over, the United States came over, and recruited him into NASA. His designs were how NASA got started. Modified versions of his original designs are what Apollo 11 used to get to the moon. So, the design CAN work. However, there were 10 Apollo missions before that didn’t reach the moon. The first one ended disastrously.

The Challenger shuttle ended in disaster.

Even though they aren’t NASA, recently in the past month Elon Musk’s SpaceX had an explosion. Jeff Bezos also had a rocket explode. So this is still an issue.

And I always wondered, what would happen if you just took a commercial jet, and flew above the clouds? Well, they DO fly above the clouds. So what would happen if you just kept going “up”?

And I’m sure you can’t just grab a stock Delta Airlines 747 and fly into orbit, but why not design a space craft, which more resembles the take-off of an airplane? Drives forward really fast, and then lifts? Except it’s not flying NYC to LA. It just keeps lifting and lifting, until it’s in orbit.

You could put thrusters on it to go forward in space. And then for landings, you wouldn’t drop off into the ocean. You’d just land at an airport. The crazy thing is, the people of NASA are so talented, that they could route the whole thing, in a way that they land at whichever airport they want. So they’d know ahead of time NOT to schedule any landings or takeoffs for this 3 hour period of time when the space craft lands.

And I bet with enough time, they could get the experience to reduce that 3 hours, into 15 minutes. Knowing exactly when they’ll arrive. Also no more of this breakaway pods that fall back to earth after detatching, or the other ones which just float out in space forever.

But I’m sure I can’t be the only one with this idea, so I figure the most likely is that it’s a scientific restriction. Where they can’t do it, because…and this is where the explanation would be.

Anyone know the explanation?

  • cecilkorik@piefed.caEnglish
    35·
    7 days ago

    We usually say “it’s not rocket science” to mean something is not that hard. Well, this IS rocket science, and it IS that hard. You can explore the mechanics of these issues in a decent space simulator like Kerbal Space Program (1 is a bit janky but still the gold standard, 2 sucks and is abandonware), Juno: New Origins (I find the career mode contains a lot of nonsense distracting from actual rocketry) and Kitten Space Agency (free, superb simulation but pretty alpha/indev status, hardcore, and no handholding)

    So, there are a few problems you’re facing right out of the gate:

    1. Rockets are HEAVY. The fuel is typically somewhere between 90 and 99% of the mass of the entire vehicle. It is functionally just a bunch of metal tubes and cavities full of fuel and a little bit of hardware and electronics to make it all work. The phenomenon known as the “tyranny of the rocket equation” is the cause of this. For every extra bit of distance you want to go, you need to propel not just the rocket itself that extra distance, but also enough fuel to propel that additional fuel that you will need. When up to 99% of your mass IS fuel, adding more distance means mostly you’re just moving fuel, and that means it takes more fuel to move that fuel, and so on. It’s fuel, fuel, and more fuel all the way down.
    2. Rockets are inefficient. Chemical rockets are almost so inefficient that if they were even a little bit less efficient than they are, they would be theoretically incapable of escaping Earth’s gravity and reaching orbit. You have very little margin to operate within. We have to use the very best, lightest, densest, and most powerful fuels because we really don’t have a lot of wiggle room here. Earth’s gravity is quite strong, and our atmosphere is quite thick, and our best chemical fuels available are only barely capable of the task that reaching orbit requires of them. That’s the other part of why the rockets have to be 90%+ fuel, it’s to satisfy the rocket’s gluttonous inefficiency.
    3. You need a rocket. Why do you need a rocket you ask? Well, technically, you might be able to do it without one, but it would an even more horrible experience and practically adds so many other issues, which we’ll talk about later. You would have to do all your propulsion in the atmosphere (or even worse, on the ground) where that thrust is actually at its least efficient due to atmospheric resistance. You need a rocket because a rocket is the only type of propulsion that a) works in an atmosphere and b) works in a vacuum at the same time, and c) provides enough thrust to achieve a thrust-to-weight ratio of greater than 1 (in other words, can push the rocket upwards more strongly than the Earth’s gravity can pull it back down) and d) actually gets more powerful and accelerates faster (same engine thrust is now pushing vastly less fuel) as you get out of the atmosphere at exactly when you most need it and it’s working most efficiently for you. Propellers obviously do not work in vacuum. Jet engines also do not work in vacuum, because they cannot ignite and burn their fuel without oxygen (and oxygen is actually the heavier part of the rocket’s fuel, so even if you develop a complex hybrid air-breathing jet/rocket engine, you don’t gain much efficiency anyway). Ion/plasma engines do not have enough thrust to weight. Anything else is pretty much just a rocket with extra weight and complexity. So rockets it is.

    What happens when you bring a jet up to higher and higher altitudes at higher and higher speeds? Well, it’s not good. There is actually a graph of airspeeds and altitudes that shows an aircraft’s safe operating envelope and the area you are describing (high altitude, max speed) is known as the “coffin corner”. An aircraft relies on air to fly, as the air gets thin, you lose the lift you need to stay airborne, or you need to go even faster so you are getting more upward force from the limited air. All else being equal, you would eventually just reach a point where you cannot climb any further, all your “up” is being used to keep you where you are. The problem is, NOT “all else” is equal. The other thing that happens at high altitude is that your engine which is an air breathing engine (jet or piston, they both use atmospheric oxygen to burn their fuel) have less oxygen available, and can burn less fuel, and produce less power. Eventually, you no longer have enough air to climb and you no longer have enough air for your engine to maintain your speed and at this point your aircraft starts to become uncontrollable. You may enter aerodynamic stall, your engine may “flame out” and shutdown, or both!

    Now I know what you’re thinking, why not just use a rocket once you get to that point? Well, a few problems with that too. First of all, it takes a long time to get to that point. Secondly, rockets are heavy. If you need a big, heavy-lift plane to carry your space-plane for a long time, turns out that needs a lot of fuel anyway, and your rocket is going to have to be pretty small. But now it’s going to have to haul not just itself, a 90+% fuel rocket, it also has to haul an airplane with dead-weight jet engines. So it can’t be really small. It’s going to have to be really big. Which means your heavy-lift airplane now has to be really, REALLY big. Ok, so detach from the airplane you say! Brilliant idea, this helps a bit, but not as much as you think. Yes, now you can have a small rocket again. But wait, rockets already do this! Rockets typically separate either a bunch of boosters, or a “second stage” at about the same point that an aircraft would be able to reach. So… you still end up about as inefficient as a rocket is going to be, you just took a lot longer to get there, it’s a lot more complex, and you still have a really big bloody plane to deal with. For the record though, it’s not impossible nor completely impractical. This is what Scaled Composites is doing. Maybe it will work, it hasn’t been fully proven yet, but it’s interesting, and potentially promising.

    The short version of the answer can basically be boiled down to just be… for reaching orbit, you need a LOT of lateral speed. The atmosphere STRONGLY resists you trying to go any sort of supersonic speed, much less the incredibly hypersonic speed you need for orbit, and will either incinerate you, or force you to waste most of your fuel, or both. The fastest way out of the atmosphere is straight up. It may seem inefficient, and in some ways it is, but it is also necessary. The only mechanisms we have that are capable of reaching those altitudes to first escape the atmosphere so we don’t incinerate ourselves and waste fuel, and then additionally reaching the extreme orbital speeds that are needed to orbit once the atmosphere is no longer a problem, without using heavy, complex, and vacuum-unsuitable air-breathing engines, are rockets and artillery guns. And as for the idea of firing things into orbit out of a really big gun, well, people have had that idea too, and it has even more problems, mostly having to do with not turning your cargo and passengers into a paste.

    Edit: Extra detail that may help put into perspective why this air-launch idea doesn’t really help as much as you might imagine: “12,000 m (39,000 ft) is only about 4% of a low Earth orbital altitude, and the subsonic aircraft reaches only about 3% of orbital velocity, yet by delivering the launch vehicle to this speed and altitude, the reusable aircraft replaces a costly first-stage booster.”