171–180 of 207 posts
Are that engines reusable in a short time? or must they go through a mayor refurbishment after each flight?
Basically it is just refuel. The entire rocket is reusable. Musk mentioned in some interview it would take a couple of days.
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I've been on the Flight Software team at SpaceX for a little over three years. It feels a lot like a startup. The team is still relatively small and people are pretty passionate about what they are working on. The project variety is wide as well. Personally, I've gotten to work on low-level drivers and OS stuff, application code that runs on the vehicles and ground systems, Dragon's fault-tolerant platform, internal…
Hey! Can you spare some career advice for an aspiring aero engineer that wants to work on the software side of the rocket? If you could share what you would consider is a good path to follow to get to where you are right now, I would really appreciate it. I am a programmer at heart but even that could not pull me away from my love of space ;) so I decided to study aerospace engineering first.
Haven't heard much from Armadillo Aerospace in a while. Are they still active?
That aerial shot they have in the video is pretty neat... I wonder if they are using a UAV for that, or just some ballsy helicopter pilot?
".from SpaceX’s hexacopter." They have all the nicest toys!
I'm sure SpaceX's hex is big, powerful, and carries all sorts of nice toys, including having enough lift to carry an HD camera and stabilizer - but still, it's not that complicated to make one. I could probably make an HD-camera-carrying hex myself if someone was willing to sponsor the parts - including stabilization for the camera, onboard controller for extra smooth flight, etc. And I'm not a rocket scientist. :)
You want a hex for this sort of job because you can lose one rotor without crash-landing your sensitive HD gear. With a quad, you lose a rotor, the whole vehicle crashes.
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Even buying something off the shelf, that's not an absurdly expensive 'toy' ( If you build it yourself, you could put together a video platform like that for under $1k (including the gyro stabilized camera gimbal).
Hey JshWright, I recently got very interested in creating one of these and you seem to be pretty knowledgeable about this. Can you please give me advice on where a newbie can start with this? I would like to learn how to build one on my own from scratch. Thank you.
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I find this confusing. It's awesome, that's for sure. But it seems like lifting all the fuel needed to do a soft landing is inherently a tradeoff for less payload capacity. What is the benefit, then? Is it just so much cheaper to be able to re-use the first two stages?
Almost the entirety of the cost of an orbital launch is in manufacturing and operational costs. Cost of fuel is basically just noise. If you can reduce operational turnaround time and operational complexity, even at a cost of payload, then you'll save so much money it'll be worth it in the long term. SpaceX is aiming for a re-assemble, gas up and go workflow. If they can pull it off it might reduce their per flight l…
What if you have a payload container that was the size and weight limits of the second and third stage, which was put up into LEO by the first stage. The payload would then be picked up by vehicles already in orbit, and the first stage unit returns to earth.
Assuming that the payloads are simply building materials, to be assembled by bots in orbit....
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The video actually shows two stages and the Dragon capsule, which is payload. As to the use of staging, there are several reasons: 1) During the late stages of the boost, the one second stage engine is pushing only its single engine, fuel and tankage. You're no longer dragging around the nine engines of the first stage and their tanks. That weight saving means you get a lot more delta-V for each unit of expended fuel…
Good answer, thanks. I've been playing too much Kerbal Space Program, I assumed the first stage had already reached orbital velocity.
One way this is done is by making Kerbin a lot smaller than Earth. Specifically, over ten times smaller. This reduces the speed needed for low Kerbin orbit to around 2000m/s, while low Earth orbit needs around 8000m/s.
A factor of four in speed probably already sounds bad, but it's much worse than one might naively expect. The amount of fuel needed to accelerate a given payload to a particular speed grows exponentially with the target speed. A typical rocket engine exhaust velocity, both in KSP and real life, might be 4000m/s. When the target velocity is half the exhaust velocity, as is the roughly the case with Kerbin, then you need about 40% of your rocket's mass to be fuel. In other words, you can orbit about 60% of your total mass. When the target velocity is double the exhaust velocity, as is roughly the case with Earth, you need 86% of the initial mass to be fuel, so you can only orbit about 14% of the rocket.
In other words, if you're putting 1000kg into orbit, then in KSP you need about 700kg of fuel, while on Earth you need over 6000kg of fuel. For a single stage rocket, that 1000kg that you're putting into orbit includes fuel tanks and engines. You need much bigger engines and fuel tanks to lift 7000kg than you do to lift 1700kg, so a lot of that 1000kg you get into orbit is going to be empty fuel tanks and spent engines, not actually useful stuff.
Staging lets you work around this problem by letting you reduce the amount of useless junk you put into orbit. By dropping large amounts of empty fuel tank and spent engine early on, you no longer have to lift it all the way up, and you have more orbited mass left over for actually useful widgets.
A single stage that goes from ground to orbit isn't too hard in KSP. On Earth, it's right at the limits of technology. Nobody has operated a rocket as a single stage to orbit, but a couple of pieces of larger rockets are theoretically capable of reaching orbit from the ground on their own if flown by themselves. It's possible, but the amount of useful payload that such a thing can put into orbit is so small that it's not cost effective.
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On the bright side, SpaceX is so economical compared to NASA's past methods, that if it succeeds, we will all benefit. So what might be characterized as theft at one point in time, might eventually be seen as a great investment. Only time will tell.
For all Elon Musk's libertarian rhetoric, he sure disregards it whenever expedient.
OTOH, his pal Peter Thiel is pretty extreme. That's someone I'm not comfortable with.
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I'm not sure the savings would be as massive as you think (and would be offset by other costs). Parachutes (and associated equipment) are heavy, so you'll burn fuel lifting that extra weight. Parachutes are complicated, and would be an extra system to develop, test, and validate. Parachutes are annoying to repack/replace (increasing turnaround time). Parachutes put odd stresses on large objects when they deploy (incr…
> All that hassle to reduce the terminal velocity by a couple hundred miles an hour. That's the TLDR. The delta-vee from the parachute is not worth the trouble.
In short, same basic reason why we use wings and wheels to land airplanes rather than dropping them from a parachute when they reach their destination.
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The SRBs don't just impose higher operational complexity, but also far higher acoustic load that requires much higher structural strength and therefore weight on everything else.
They also complicate the range safety situation and make on-pad aborts after they've been lit impossible. Once they've been lit you're going wherever they're going, whether you like it or not.