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Guys please. The sideways oscillation of the rocket is an obvious control loop problem. When it's working correctly, the booster will remain rock solid vertica

Guys please. The sideways oscillation of the rocket is an obvious control loop problem. When it's working correctly, the booster will remain rock solid vertical and land gracefully. Elon's (now deleted?) tweet said as much. Let the real rocket scientists fix their rocket. They know how. It's really unbelievably close to working. Amazing really.

tsotha 12y ago
The fact that he deleted it implies they decided that wasn't the case after all, or at least wasn't the whole story. They didn't handle media very well this launch, what with the fumbled video release and then a retracted tweet.
- hahainternet 12y ago
  > The fact that he deleted it implies they decided that wasn't the case after all, or at least wasn't the whole story. It doesn't. That's just your impression you are placing upon the tweet. Deleting it says nothing when you are the head of multi billion dollar organisations. Perhaps he didn't want to give their competitors information that could help them model F9. > They didn't handle media very well this launch, what with the fumbled video release and then a retracted tweet. This is just ridiculous nitpicking. SpaceX usually gives us camera views from inside the goddamn LOX tanks on the stages. 'Didn't handle media very well' my arse.
- weego 12y ago
  Didn't handle the media well? Some dickhead multi-millionaire who puts all his money into hedge funds and is pretty much just a negative drain on humanity can worry about their media image but how about we let the people putting their money into building space rockets do the space rocket thing.
- ceejayoz 12y ago
  He also deleted a tweet to John Carmack telling him to work for SpaceX. Don't read too much into a deletion.
- saraid216 12y ago
  My read on the deletion is that they didn't want bad press going into the next attempted landing, which is going to be on land.
  - tsotha 12y ago
    Is it? Do you know which flight?
    - saraid216 12y ago
      This is all I know: https://news.ycombinator.com/item?id=9387929 https://news.ycombinator.com/item?id=9387929
InclinedPlane 12y ago
Precisely. Looks like a classic control oscillation, possibly due to lag in the system. There are only a zillion ways to handle this sort of thing as it's an enormously common case. In fact it's within the realm of possibility that the "fix" for the next landing is just a tweak of some PID coefficients.
- baq 12y ago
  i'd guess the lag was accounted for, but due to something bad happening with the valve, it was different than expected. i don't do control theory but i'd assume there's a way of detecting this situation. maybe the valve needs an extra sensor or something?
grecy 12y ago
> Let the real rocket scientists fix their rocket By speculating and proposing questions and answers, we're all learning and increasing our understanding of the domain. We're not causing any harm, so I think it's quite healthy for us to speculate and question what's going on and how it might be fixed. In fact, we even enjoy spending our time on it.

tsotha 12y ago

The fact that he deleted it implies they decided that wasn't the case after all, or at least wasn't the whole story. They didn't handle media very well this launch, what with the fumbled video release and then a retracted tweet.

hahainternet 12y ago
> The fact that he deleted it implies they decided that wasn't the case after all, or at least wasn't the whole story. It doesn't. That's just your impression you are placing upon the tweet. Deleting it says nothing when you are the head of multi billion dollar organisations. Perhaps he didn't want to give their competitors information that could help them model F9. > They didn't handle media very well this launch, what with the fumbled video release and then a retracted tweet. This is just ridiculous nitpicking. SpaceX usually gives us camera views from inside the goddamn LOX tanks on the stages. 'Didn't handle media very well' my arse.
weego 12y ago
Didn't handle the media well? Some dickhead multi-millionaire who puts all his money into hedge funds and is pretty much just a negative drain on humanity can worry about their media image but how about we let the people putting their money into building space rockets do the space rocket thing.
ceejayoz 12y ago
He also deleted a tweet to John Carmack telling him to work for SpaceX. Don't read too much into a deletion.
saraid216 12y ago
My read on the deletion is that they didn't want bad press going into the next attempted landing, which is going to be on land.
- tsotha 12y ago
  Is it? Do you know which flight?
  - saraid216 12y ago
    This is all I know: https://news.ycombinator.com/item?id=9387929 https://news.ycombinator.com/item?id=9387929

InclinedPlane 12y ago

Precisely. Looks like a classic control oscillation, possibly due to lag in the system. There are only a zillion ways to handle this sort of thing as it's an enormously common case. In fact it's within the realm of possibility that the "fix" for the next landing is just a tweak of some PID coefficients.

baq 12y ago
i'd guess the lag was accounted for, but due to something bad happening with the valve, it was different than expected. i don't do control theory but i'd assume there's a way of detecting this situation. maybe the valve needs an extra sensor or something?

grecy 12y ago

> Let the real rocket scientists fix their rocket By speculating and proposing questions and answers, we're all learning and increasing our understanding of the domain. We're not causing any harm, so I think it's quite healthy for us to speculate and question what's going on and how it might be fixed. In fact, we even enjoy spending our time on it.