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Fuel is a small cost relative to everything else. But the extra weight is a concern, it limits payload to orbit. Try flying the first stage back to the launch

Fuel is a small cost relative to everything else. But the extra weight is a concern, it limits payload to orbit. Try flying the first stage back to the launchpad in Kerbal Space Program while delivering a useful payload to orbit! It's instructive. KSP really develops your intuition for rocketry, everyone commenting in this thread ought to buy a copy.

greglindahl 12y ago
You did note that the OG2 flight 1 payload was about 1/4 of the max? And the next 2 flights aren't going to try landing because they need all the fuel to get a big payload into GTO[1]? SpaceX seems to have all this under control, even if you can't imagine that it will work out. [1] http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falcon-9-rocket-first-stage http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falc...
- XorNot 12y ago
  You also always have the option of just building a heavier lift rocket - which is what SpaceX is starting to spin up for. I'd imagine the F9H's successor/bigger brother is going to be designed with provisions for the same type of return profile.
  - InclinedPlane 12y ago
    According to SpaceX the Falcon Heavy will only fly with reusable first stages. That will bring the payload down but the payload was very high before. The Falcon Heavy should still be able to lift more than 20 tonnes to LEO, which is equivalent to the Delta IV Heavy. And with reusability it should be able to do so at a cost comparable to or cheaper than today's expendable Falcon 9s.
lotsofmangos 12y ago
Kerbal space program is a fun game, but you cannot use it for budgeting real launches, especially in this case. It only has minimalist physics, especially with fluid dynamics, which governs much of a first stage recovery.
- pokpokpok 12y ago
  It also "scales down" the universe and the time/thrust needed to leave orbit. still a fantastic educational resource!
  - lotsofmangos 12y ago
    Is definitely good educationally, but I wouldn't use it to argue against the plans of people who build rockets for a living any more than I would use experience of playing Risk to lecture an Admiral on international warfare.
    - deleted 12y ago
      [deleted]
    - m_mueller 12y ago
      I'd argue that KSP holds as an upper limit for what's possible - if it doesn't work in KSP, it won't work in the real world (while the opposite doesn't hold true necessarily).
      - lotsofmangos 12y ago
        That makes no sense. KSP hasn't got proper aeronautics and also hasn't got n-body physics. There are plenty of things that work in the real world that would fail in KSP. edit - and for the same reason there are also things that would work in KSP that would fail in the real world.
        m_mueller 12y ago
        > There are plenty of things that work in the real world that would fail in KSP. Do you have an example for that? > edit - and for the same reason there are also things that would work in KSP that would fail in the real world. That's what I wanted to say with 'the opposite doesn't hold true'.
        12y ago
ceejayoz 12y ago
With a truly cheap reusable system, it may finally make sense to send more smaller payloads and assemble in orbit.
Crito 12y ago
On the topic of KSP: Some guy on /r/spacex modded KSP to hell for realism then recorded a video demonstration of how the boost-back will/could work: http://www.reddit.com/r/spacex/comments/1z6vyt/boostback_demonstration_video/ http://www.reddit.com/r/spacex/comments/1z6vyt/boostback_dem... The first video explains the modifications to the game, mainly more realistic aerodynamics, realistic fuels and engine capabilities, a realistic planet and launch site. The second video is him actually performing the mission. There are a few differences between what he did and what we now know is actually planned, but it's still pretty damn close and demonstrates the feasibility of the concept in a pretty intuitive fashion.
InclinedPlane 12y ago
Sure, you limit the payload to orbit. But on the other hand you end up with an extra orbital rocket stage in your possession. Given that this is a roughly $45+ million commodity at present, that's a significant savings that justifies the payload reduction.

greglindahl 12y ago

You did note that the OG2 flight 1 payload was about 1/4 of the max? And the next 2 flights aren't going to try landing because they need all the fuel to get a big payload into GTO[1]? SpaceX seems to have all this under control, even if you can't imagine that it will work out. [1] http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falcon-9-rocket-first-stage http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falc...

XorNot 12y ago
You also always have the option of just building a heavier lift rocket - which is what SpaceX is starting to spin up for. I'd imagine the F9H's successor/bigger brother is going to be designed with provisions for the same type of return profile.
- InclinedPlane 12y ago
  According to SpaceX the Falcon Heavy will only fly with reusable first stages. That will bring the payload down but the payload was very high before. The Falcon Heavy should still be able to lift more than 20 tonnes to LEO, which is equivalent to the Delta IV Heavy. And with reusability it should be able to do so at a cost comparable to or cheaper than today's expendable Falcon 9s.

lotsofmangos 12y ago

Kerbal space program is a fun game, but you cannot use it for budgeting real launches, especially in this case. It only has minimalist physics, especially with fluid dynamics, which governs much of a first stage recovery.

pokpokpok 12y ago
It also "scales down" the universe and the time/thrust needed to leave orbit. still a fantastic educational resource!
- lotsofmangos 12y ago
  Is definitely good educationally, but I wouldn't use it to argue against the plans of people who build rockets for a living any more than I would use experience of playing Risk to lecture an Admiral on international warfare.
  - deleted 12y ago
    [deleted]
  - m_mueller 12y ago
    I'd argue that KSP holds as an upper limit for what's possible - if it doesn't work in KSP, it won't work in the real world (while the opposite doesn't hold true necessarily).
    - lotsofmangos 12y ago
      That makes no sense. KSP hasn't got proper aeronautics and also hasn't got n-body physics. There are plenty of things that work in the real world that would fail in KSP. edit - and for the same reason there are also things that would work in KSP that would fail in the real world.
      - m_mueller 12y ago
        > There are plenty of things that work in the real world that would fail in KSP. Do you have an example for that? > edit - and for the same reason there are also things that would work in KSP that would fail in the real world. That's what I wanted to say with 'the opposite doesn't hold true'.
        12y ago

ceejayoz 12y ago

With a truly cheap reusable system, it may finally make sense to send more smaller payloads and assemble in orbit.

Crito 12y ago

On the topic of KSP: Some guy on /r/spacex modded KSP to hell for realism then recorded a video demonstration of how the boost-back will/could work: http://www.reddit.com/r/spacex/comments/1z6vyt/boostback_demonstration_video/ http://www.reddit.com/r/spacex/comments/1z6vyt/boostback_dem... The first video explains the modifications to the game, mainly more realistic aerodynamics, realistic fuels and engine capabilities, a realistic planet and launch site. The second video is him actually performing the mission. There are a few differences between what he did and what we now know is actually planned, but it's still pretty damn close and demonstrates the feasibility of the concept in a pretty intuitive fashion.

InclinedPlane 12y ago

Sure, you limit the payload to orbit. But on the other hand you end up with an extra orbital rocket stage in your possession. Given that this is a roughly $45+ million commodity at present, that's a significant savings that justifies the payload reduction.