201–210 of 216 posts
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"Explodes after landing" would be more accurate, I think.
and the "explosion" is borderline, it's very close to just "burns really fast", especially when you see what's left after the fire goes out: https://pbs.twimg.com/media/CY8-PdyU0AABqaa.jpg:large (there's quite a lot of rocket left)
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Yeah, I don't understand why they won't keep landing them on the ground like everyone else does. It's not like there's not enough space on Earth.
So if you launch out of Cali going west and separate stage 2 300 miles out.... What is under you to land on?
Hacker News has officially become a parody of itself.
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Heat shielding is needed, as well as extra landing engines that work outside of vacuum, since the second stage engine would destroy itself under atmospheric pressure. It's easy to see how quickly you start to get dimishing returns, but it would be cool if they could pull it off.
Some experiments were done in early 2000 with inflatable aerobrake. The concept was shown to work, but experiments weren't a complete success. However this technology I'm sure can be applied to the task of returning the second stage. https://en.wikipedia.org/wiki/Atmospheric_entry#Inflatable_h...
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and the "explosion" is borderline, it's very close to just "burns really fast", especially when you see what's left after the fire goes out: https://pbs.twimg.com/media/CY8-PdyU0AABqaa.jpg:large (there's quite a lot of rocket left)
That's a trick of perspective and scale, you are not seeing a rocket but one landing leg intact attached to the engine block. The tube exploded as you'd expect when it fell over and disintegrated. Not really important though, they got the hard part right.
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It would be convenient enough but the FAA isn't too happy with the idea of a 12-story missile full of explosive fuel and oxidiser flying over populated areas.
Yes, part of the inconvenience of course is that it's unlikely to be anywhere near the continental US.
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If you're going to build an expendable rocket designing it as a SSTO doesn't really make sense. With a single stage you can't shed the extra weight of the engines and rocket that got you out of the atmosphere and have to have engines that work both in atmosphere and in vacuum.
I agree. I'm just saying it's easier to make an expendable than a reusable one, because you don't have to allocate mass to return systems.
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Let's say they permanently remove one leg and it now always tips over on landing and has no stable landing configuration. Could they bill that as a self-landing rocket?
The point is that the ability to land is much harder to develop than the ability to stand up after landing. Improving the leg locking mechanisms is relatively trivial compared to developing the ability to turn a booster around in space, fly it back to earth and land on a floating platform. If I was involved in SpaceX then I would be proud to have helped solve such a tricky problem, and optimistic about fixing the far…
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That's a trick of perspective and scale, you are not seeing a rocket but one landing leg intact attached to the engine block. The tube exploded as you'd expect when it fell over and disintegrated. Not really important though, they got the hard part right.
I'd work on engineering that, if possible. I mean if 10% of rockets fall over, but you could get them to not explode then you'd still be up.
Getting the rocket to survive falling over is extremely difficult. It can't even survive normal flight loads without the propellant tanks being pressurized, because it needs the extra rigidity to avoid collapse.
The margins involved are extremely slim. For a more familiar point of comparison, consider that a 747-400 (which is about as long as a Falcon 9 is tall, not that this means a whole lot) weighs about 180 tons empty, and can carry about 170 tons of fuel. The Falcon 9 first stage weighs around 25 tons empty, and carries about 400 tons of fuel and oxidizer. (Note that numbers are approximate, since official numbers are hard to come by.) That means that, sitting on the pad and ready to go, a Falcon 9 first stage is about 95% fuel, and 5% everything else. That 5% has to account not only for fuel tanks, but engines, hydraulics, support structure to hold up the ~100 ton second stage and payload, landing legs, and everything else that makes it a rocket and not just a pair of tanks.
Now you bring it back, let it fall over, and catch it in a way that doesn't break it. This is something about as tall as a decent-sized office building, with a roughly zero tolerance for sideways force of any kind. Imagine tipping over the Statue of Liberty and catching it without bending anything.
It's orders of magnitude easier to make sure the rocket doesn't fall over in the first place. You want to concentrate your efforts where they'll have the best return, and in this case there's no contest, it's not even close.
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So if you launch out of Cali going west and separate stage 2 300 miles out.... What is under you to land on?
The entire world = California. Hacker News has officially become a parody of itself.
But some rocket launches come form the west coast, not all are Florida.
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So if you launch out of Cali going west and separate stage 2 300 miles out.... What is under you to land on?
Not to change your overall point, but you almost never launch west. When possible, you want to launch east, to gain the benefit of the Earth's rotational speed. Sometimes you launch north or south so you can go into a polar orbit which allows viewing more of the Earth. But there's pretty much no reason to launch west. One exception to this is if your launch site is located in a place where that's the only option, whi…