9 ms·

SpaceX to Debut Upgraded Falcon 9 on Return to Flight Mission

82 points by situationista 11y ago

gadrfgaesgysd 11y ago
Looks like they are taking the software approach to fixing things.
- creshal 11y ago
  Still an improvement to the Von Braun approach, I'd guess.
  - kakali 11y ago
    What's the Von Braun approach? I mean, his work was a model for hardware reuse and improvement every launch. (I think considering the Atlas, Titan, and Saturn 1.)
    - creshal 11y ago
      V2.
- ceejayoz 11y ago
  They've been working on the Falcon 9 1.2 for a long time. It wouldn't make sense to go back to 1.1 to fix a known problem with a strut.
- deleted 11y ago
  [deleted]
Symmetry 11y ago
The other side to the upgrade to the Falcon 9 is chilling down the fuel more than normal so that it shrinks and they can fit more of it in the rocket's tanks.
- avian 11y ago
  Do you have any reference for that? It seems to me that further cooling already liquified fuel doesn't give you any noticeable difference in volume.
  - Nogwater 11y ago
    r/SpaceX has a lot of good info. Check out the "What are the differences between the Falcon 9 v1.1 and the upgraded Falcon version popularly called the v1.2?" FAQ here: https://www.reddit.com/r/SpaceX/wiki/faq/falcon https://www.reddit.com/r/SpaceX/wiki/faq/falcon This Wikipedia page has a mention of super-chilling: https://en.wikipedia.org/wiki/RP-1 https://en.wikipedia.org/wiki/RP-1
  - mikeash 11y ago
    Why not? According to a random page I found on the internet, kerosene has a coefficient of thermal expansion of 0.00099 per Kelvin. If you can cool it by 50 degrees then you'll be able to store about 5% more fuel in the same volume of tank, which is a nice little upgrade.
smoyer 11y ago
"I want to stick a landing this year" That's a gymnastics phrase for landing on your feet (with no bounce) during a dismount and is a pretty appropriate analogy for what they're trying to do with the Falcon 9 first stage. To carry the analogy further, the second landing attempt could have been a "one hop" landing if they'd had a bigger drone ship. The first landing (which needed a bit more propellant to keep the stage upright) would have succeeded as a "one step" dismount - if the stage could actually take a step with it's legs.
- ohitsdom 11y ago
  I wouldn't take that phrase too literally. I take it to mean that she wants them to actually land a rocket (not necessarily on all feet with no bounce). The other attempts were "landings", but they blew up. Bounce or no, if they land the rocket upright, I think that's sticking it.
  - ethbro 11y ago
    The problem as I understand it, and I think what smoyer was talking about, is that there are no other viable landing methods for the rocket than "feet" first. Sufficient thrust is only available from the main engines, and those only point in one direction. So if it starts to tilt off vertical then the rocket has no way to right itself after a point (and certainly no way to counteract gravity). Gravity + tall enough rocket + landing on side = boom (or crumple). So "stick it or bust"?
    - ohitsdom 11y ago
      There are cold gas thrusters on top of the first stage that fire to keep its balance. If it lands in an uneven manner and starts to tip, those should be enough to maintain the landing. You can see them working in the video embedded in the link below. They only didn't work in that instance because the main rocket motor fired too long at it was too much for the small thrusters. http://www.spacex.com/news/2015/06/24/why-and-how-landing-rockets http://www.spacex.com/news/2015/06/24/why-and-how-landing-ro...
akshayB 11y ago
I just want to see a Klondike Bar in middle of ocean and a pencil on top of it.
benihana 11y ago
>that features engines with increased thrust, providing an increase in performance of about 30 percent. I'm not a rocket engineer but this sounds like a mind-blowingly good increase. Is it just that they're early in the development of the engines and since they're taking an iterative approach this is just low hanging fruit? Even if that's the case, 30% increase seems impressive.
- InclinedPlane 11y ago
  It's not low hanging fruit so much as it's a matter of systematically working the way up to higher and higher branches, and taking the time to build higher and higher ladders. You'd be surprised how little iterative development there is in traditional aerospace must often.
- VLM 11y ago
  By careful selection of metric goals, impressive results can be achieved with little change. (this is a summary of modern american corporate process LOL). So if your metric is pounds of payload delivered to orbit, for example, rockets are usually pretty heavy compared to the payload delivered so a rather small improvement in thrust to weight ratio can have seemingly extreme improvement in pounds delivered. You're still launching a million pounds sitting on the pad, its just removing a mere 300 pounds of insulation over than million pound booster means you get 1300 of payload delivered instead of 1000. Rockets have all kinds of interesting problems with thermal limits and combustion instability and its very easy to defeat those problems at considerable weight penalty and then when telemetry consistently shows the nozzle temp is fine at full flow rate and projections show 80% flow is fine, then next model has microscopically smaller pipes or whatever. And repeat many times and next thing you know you've gained quite a bit of performance. Its hard to add fluid flow baffles to an existing system, but if it works with existing baffles its usually much easier to slowly remove them. There is another spacex specific issue that to do the "land on a barge" thing general opinion is they overspec the marketing numbers to about 30% less. I don't know how much, if any, current improvement is lowering that to 27% or whatever. If you were to give up on recycling boosters and one-shot the booster, the marketed performance specs would go up a bit without any engineering changes (well other than software to land wouldn't be necessary, LOL).

82 points by situationista 11y ago

gadrfgaesgysd 11y ago

Looks like they are taking the software approach to fixing things.

creshal 11y ago
Still an improvement to the Von Braun approach, I'd guess.
- kakali 11y ago
  What's the Von Braun approach? I mean, his work was a model for hardware reuse and improvement every launch. (I think considering the Atlas, Titan, and Saturn 1.)
  - creshal 11y ago
    V2.
ceejayoz 11y ago
They've been working on the Falcon 9 1.2 for a long time. It wouldn't make sense to go back to 1.1 to fix a known problem with a strut.
deleted 11y ago
[deleted]

Symmetry 11y ago

The other side to the upgrade to the Falcon 9 is chilling down the fuel more than normal so that it shrinks and they can fit more of it in the rocket's tanks.

avian 11y ago
Do you have any reference for that? It seems to me that further cooling already liquified fuel doesn't give you any noticeable difference in volume.
- Nogwater 11y ago
  r/SpaceX has a lot of good info. Check out the "What are the differences between the Falcon 9 v1.1 and the upgraded Falcon version popularly called the v1.2?" FAQ here: https://www.reddit.com/r/SpaceX/wiki/faq/falcon https://www.reddit.com/r/SpaceX/wiki/faq/falcon This Wikipedia page has a mention of super-chilling: https://en.wikipedia.org/wiki/RP-1 https://en.wikipedia.org/wiki/RP-1
- mikeash 11y ago
  Why not? According to a random page I found on the internet, kerosene has a coefficient of thermal expansion of 0.00099 per Kelvin. If you can cool it by 50 degrees then you'll be able to store about 5% more fuel in the same volume of tank, which is a nice little upgrade.

smoyer 11y ago

"I want to stick a landing this year" That's a gymnastics phrase for landing on your feet (with no bounce) during a dismount and is a pretty appropriate analogy for what they're trying to do with the Falcon 9 first stage. To carry the analogy further, the second landing attempt could have been a "one hop" landing if they'd had a bigger drone ship. The first landing (which needed a bit more propellant to keep the stage upright) would have succeeded as a "one step" dismount - if the stage could actually take a step with it's legs.

ohitsdom 11y ago
I wouldn't take that phrase too literally. I take it to mean that she wants them to actually land a rocket (not necessarily on all feet with no bounce). The other attempts were "landings", but they blew up. Bounce or no, if they land the rocket upright, I think that's sticking it.
- ethbro 11y ago
  The problem as I understand it, and I think what smoyer was talking about, is that there are no other viable landing methods for the rocket than "feet" first. Sufficient thrust is only available from the main engines, and those only point in one direction. So if it starts to tilt off vertical then the rocket has no way to right itself after a point (and certainly no way to counteract gravity). Gravity + tall enough rocket + landing on side = boom (or crumple). So "stick it or bust"?
  - ohitsdom 11y ago
    There are cold gas thrusters on top of the first stage that fire to keep its balance. If it lands in an uneven manner and starts to tip, those should be enough to maintain the landing. You can see them working in the video embedded in the link below. They only didn't work in that instance because the main rocket motor fired too long at it was too much for the small thrusters. http://www.spacex.com/news/2015/06/24/why-and-how-landing-rockets http://www.spacex.com/news/2015/06/24/why-and-how-landing-ro...

akshayB 11y ago

I just want to see a Klondike Bar in middle of ocean and a pencil on top of it.

benihana 11y ago

>that features engines with increased thrust, providing an increase in performance of about 30 percent. I'm not a rocket engineer but this sounds like a mind-blowingly good increase. Is it just that they're early in the development of the engines and since they're taking an iterative approach this is just low hanging fruit? Even if that's the case, 30% increase seems impressive.

InclinedPlane 11y ago
It's not low hanging fruit so much as it's a matter of systematically working the way up to higher and higher branches, and taking the time to build higher and higher ladders. You'd be surprised how little iterative development there is in traditional aerospace must often.
VLM 11y ago
By careful selection of metric goals, impressive results can be achieved with little change. (this is a summary of modern american corporate process LOL). So if your metric is pounds of payload delivered to orbit, for example, rockets are usually pretty heavy compared to the payload delivered so a rather small improvement in thrust to weight ratio can have seemingly extreme improvement in pounds delivered. You're still launching a million pounds sitting on the pad, its just removing a mere 300 pounds of insulation over than million pound booster means you get 1300 of payload delivered instead of 1000. Rockets have all kinds of interesting problems with thermal limits and combustion instability and its very easy to defeat those problems at considerable weight penalty and then when telemetry consistently shows the nozzle temp is fine at full flow rate and projections show 80% flow is fine, then next model has microscopically smaller pipes or whatever. And repeat many times and next thing you know you've gained quite a bit of performance. Its hard to add fluid flow baffles to an existing system, but if it works with existing baffles its usually much easier to slowly remove them. There is another spacex specific issue that to do the "land on a barge" thing general opinion is they overspec the marketing numbers to about 30% less. I don't know how much, if any, current improvement is lowering that to 27% or whatever. If you were to give up on recycling boosters and one-shot the booster, the marketed performance specs would go up a bit without any engineering changes (well other than software to land wouldn't be necessary, LOL).