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SpaceX lands rocket at sea second time after satellite launch

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Re: SpaceX lands rocket at sea second time after satellite launch

#111

Post by JshWright »

SagelyGuru wrote: post #104
ohitsdom wrote: post #98

Earlier quoted context omitted.

The current legs aren't flimsy, and they seem way less complicated than a gripper system would have to be. How would a gripper system handle off-centered landings? It would have to catch the falling rocket very quickly because there's not much fuel left in the tank to hover. Your proposed system would add a lot of complexity, all for the small decrease in launch mass.

Permanent decrease in launch mass is big money, whereas complications on the barge do not really matter. Like all good engineering problems, it only looks problematic at first sight and I am sure that SpaceX could rise up to the challenge. Use a big funnel mesh? However, I accept the comment that perhaps they are really practising for landings on Mars, where fair number of probes have overturned on landing.

> Use a big funnel mesh?

I'm not sure you realize just how fragile the stage is. The side walls are made of _very_ thin aluminum. Any landing support mechanism must put the impact force on the 'octaweb' structure that supports the engines. That's the advantage of the legs. They can be engineered to distribute the force exactly where they want it.

A significant problem with any sort of "catching" mechanism is that the load on the stage is far less predictable.

Re: SpaceX lands rocket at sea second time after satellite launch

#112

Post by geon »

ohitsdom wrote: post #98
SagelyGuru wrote: post #94

Good work! I still think that they should have some grippers on the barge, or a net, ready to spring and grasp the rocket on landing, instead of carrying flimsy legs all the way to space and back.

The current legs aren't flimsy, and they seem way less complicated than a gripper system would have to be. How would a gripper system handle off-centered landings? It would have to catch the falling rocket very quickly because there's not much fuel left in the tank to hover. Your proposed system would add a lot of complexity, all for the small decrease in launch mass.

> because there's not much fuel left in the tank to hover

They can't hover at all, since the throttle doesn't go low enough. They need to do the landing perfectly, on a single try.

Re: SpaceX lands rocket at sea second time after satellite launch

#113

Post by robbiemitchell »

manaskarekar wrote: post #100

Hosted webcast: https://youtu.be/L0bMeDj76ig Landing at 38:18mins https://youtu.be/L0bMeDj76ig#t=38m18s Great info on the thrusters on the first stage at 19:37. https://youtu.be/L0bMeDj76ig#t=19m37s Edit: Thank you and sorry about the time stamp link, I posted quickly from my phone. Hopefully it works on shortlinks.

You link directly a specific place by adding this to the URL: #t=38m18s

Re: SpaceX lands rocket at sea second time after satellite launch

#114

Post by JshWright »

rco8786 wrote: post #103
ohitsdom wrote: post #98

Earlier quoted context omitted.

The current legs aren't flimsy, and they seem way less complicated than a gripper system would have to be. How would a gripper system handle off-centered landings? It would have to catch the falling rocket very quickly because there's not much fuel left in the tank to hover. Your proposed system would add a lot of complexity, all for the small decrease in launch mass.

> Your proposed system would add a lot of complexity, all for the small decrease in launch mass. While I agree with your overall sentiment, I imagine that people building rockets make complexity tradeoffs to save tiny amounts of weight all the time.

SpaceX, on the other hand, has been willing to sacrifice some weight in order to reduce complexity and improve reliability and reusability.

Re: SpaceX lands rocket at sea second time after satellite launch

#115

Post by zupreme »

I remain confused about why SpaceX is getting so much fanfare and praise. What have they accomplished that NASA didn't already accomplish during the Apollo missions?

I know SpaceX is doing it all more cost effectively, because we have better technology, but have they actually accomplished anything tangible that NASA didn't a generation ago?

Re: SpaceX lands rocket at sea second time after satellite launch

#116

Post by Inconel »

TeMPOraL wrote: post #87
deanCommie wrote: post #81

Earlier quoted context omitted.

Most people aren't gay. Yet we still consider their feelings when we question hateful language. Most people aren't disabled. Yet every office building in the western world has wheelchair ramps and disabled bathrooms. Why alienate the employees who are working for the good of the Company, and the good of Humanity without considering the benefits for the Country (which is arbitrary and hereditary all too often) with no…

I don't see how chanting for a group, without any implicit or explicit diminishment of other groups compares to hate speech against sexual minorities. Also, chants are not a company policy, it's what employees spontaneously do in their own private space, which you saw on their own private broadcast. (If we're bringing SJW approach into this, then I think you're advocating the minority (SpaceX employees) should adapt…

I too find it hard to see how so many have conflated chanting for a group, in this case the USA, as being equivalent to actively admonishing another group. The employees at SpaceX aren't burning the flags of foreign countries or otherwise disrespecting or mocking them, they are simply expressing pride in the nation that many of us view as playing an instrumental part in our success.

I also don't know what could be done to remedy the situation, assuming its decided that a remedy is in order. I can assure everyone that to my knowledge the chants aren't at all staged, they happen organically and large numbers of employees participate in them.

Again, and I hate to be overly repetitive but I think its worth noting that while I don't partake in the chants myself, if we got word from higher up that this was no longer acceptable behavior I would be extraordinarily pissed. I don't care about the chants either way but the employees here are already sacrificing a lot for this mission, they don't need their spontaneous celebrations micromanaged.

The atmosphere during launches here is electric, and even I, someone who is usually extremely reserved and collected, often get emotional. Most of us work very hard and deal with a fair amount of stress, particularly in the week leading up to launch. If people want to let loose with some celebratory chants so be it.

I suppose we could all just start chanting SpaceX-SpaceX-SpaceX although somehow I have feeling someone would find that equally offensive as well.

I'm seriously starting to think SpaceX should just stop broadcasting the view from inside the Hawthorne facility.

Re: SpaceX lands rocket at sea second time after satellite launch

#117

Post by jacquesm »

zupreme wrote: post #115

I remain confused about why SpaceX is getting so much fanfare and praise. What have they accomplished that NASA didn't already accomplish during the Apollo missions? I know SpaceX is doing it all more cost effectively, because we have better technology, but have they actually accomplished anything tangible that NASA didn't a generation ago?

NASA landed a first stage on a barge to be re-used?

Re: SpaceX lands rocket at sea second time after satellite launch

#118

Post by throwaway2016a »

mabbo wrote: post #99
geerlingguy wrote: post #92

What's notable about this attempt (as opposed to the last) is that the first stage rocket was traveling twice as fast (4x the energy to overcome on landing), and didn't have enough propellant to do a 'boostback' burn. Instead, coming in very hot, the rocket had to use three engines (instead of one) to slow for landing. The last time this was attempted, the first stage put a nice hole in the deck of the drone ship. Se…

I suppose this is why people say "it's not rocket science".

Slightly off topic but I was watching a television show the other day and someone said they worked at NASA. The host then said "So you're literally a rocket scientist?"

And the guy said emphatically "Rocket engineer, there is a big difference"

I'm sure this particular task probably was a little bit of both. After all, they had to run several real world experiments to prove their calculations.

Re: SpaceX lands rocket at sea second time after satellite launch

#119

Post by Artemis2 »

zupreme wrote: post #115

I remain confused about why SpaceX is getting so much fanfare and praise. What have they accomplished that NASA didn't already accomplish during the Apollo missions? I know SpaceX is doing it all more cost effectively, because we have better technology, but have they actually accomplished anything tangible that NASA didn't a generation ago?

Did NASA land anything else than the Space Shuttle?

Re: SpaceX lands rocket at sea second time after satellite launch

#120

Post by nkrisc »

zupreme wrote: post #115

I remain confused about why SpaceX is getting so much fanfare and praise. What have they accomplished that NASA didn't already accomplish during the Apollo missions? I know SpaceX is doing it all more cost effectively, because we have better technology, but have they actually accomplished anything tangible that NASA didn't a generation ago?

I'm not sure you and I are following the same news. Granted, I was born in the 80s but I don't think NASA ever landed a first stage on a barge before.
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