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Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by lotsofmangos on Tuesday July 22, 2014 @05:03PM (#8071539)
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.
Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by pokpokpok on Tuesday July 22, 2014 @05:23PM (#8071632)
It also "scales down" the universe and the time/thrust needed to leave orbit. still a fantastic educational resource!
Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by lotsofmangos on Tuesday July 22, 2014 @05:27PM (#8071654)
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.
Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by m_mueller on Tuesday July 22, 2014 @08:22PM (#8072293)
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).
Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by Crito on Tuesday July 22, 2014 @09:07PM (#8072419)
I wouldn't say that. SSTO's are pretty trivial in KSP (even rocket SSTO's with only classical chemical engines, none of the RAPIER/SABRE stuff).

8 Rockomax 48-7S (little orange engine, stuck on with 8 small cube struts) + 1 Rockomax X200-32 Fuel Tank (the large gray tank, one size below the big orange tank) will put a capsule in orbit around Kerbin pretty easily. No such luck in real life.

Typically KSP engines have worse performance than real engines, but Kerbin is pretty small.

Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by m_mueller on Tuesday July 22, 2014 @10:48PM (#8072675)
> 8 Rockomax 48-7S (little orange engine, stuck on with 8 small cube struts) + 1 Rockomax X200-32 Fuel Tank (the large gray tank, one size below the big orange tank) will put a capsule in orbit around Kerbin pretty easily. No such luck in real life.

That's what I meant by 'the opposite is not necessarily true'. My argument was that if something does not work in KSP, it probably won't work in real life (which was refuted by another commenter because of missing Lagrange points). IMO it still holds true for basic rocket designs and their capabilities for LEO / GEO. To my knowledge, all real world rocket designs have been replicated in-game (albeit with much lower complexity of course) and demonstrated to work.

Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by lotsofmangos on Tuesday July 22, 2014 @08:43PM (#8072353)
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.

Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by m_mueller on Tuesday July 22, 2014 @09:30PM (#8072468)
> 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'.

Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by Laremere on Tuesday July 22, 2014 @09:57PM (#8072549)
All of these take advantage of Lagrangian points, which aren't present in KSP: http://en.wikipedia.org/wiki/List_of_objects_at_Lagrangian_p...

Not really applicable to this discussion, but one instance which is highly applicable is that you can't control two ships in KSP at once. If your lower stage needed to do a powered land which an upper stage was still accelerating into orbit, you couldn't replicate that in ksp.

Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by m_mueller on Tuesday July 22, 2014 @10:42PM (#8072661)
> If your lower stage needed to do a powered land which an upper stage was still accelerating into orbit, you couldn't replicate that in ksp.

.. Unless your name is Scott Manley ;-). But yes, good point about Lagrangian points [1]. I wasn't aware that KSP is only a two-body-simulation - interesting how the game can hide that with its sphere of influence implementation.

[1]http://forum.kerbalspaceprogram.com/threads/18623-Lagrange-p...

Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by simonh on Tuesday July 22, 2014 @10:50PM (#8072680)
Quick save at stage separation, fly the upper stages to orbit. Go back in time (reload the quicksave) and fly the upper stage back to the landing site.
Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by lotsofmangos on Tuesday July 22, 2014 @10:56PM (#8072697)
How about very tight hypersonic atmospheric slingshot maneuvers using aerodynamic lift from the shockwave generated by a flexible waverider lifting body? I think it would have significant problems modeling that without some serious modding. http://en.wikipedia.org/wiki/WaveRider#Hypersonic_Sail_Waver...

Also, my point with the logic is that when looking at the differences between physics in KSP and the real world, we are dealing with overlapping, rather than nesting sets.

Re:SpaceX Soft Lands Falcon 9 Rocket First Stage by m_mueller on Wednesday July 23, 2014 @03:00AM (#8073203)
> http://en.wikipedia.org/wiki/WaveRider#Hypersonic_Sail_Waver...

First time I've seen this, thanks. You certainly have a point that feasible designs in KSP vs. real world aren't completely nested. When I was arguing about KSP being an upper limit, I didn't really think about the SSTO case - at least the stock simulation certainly doesn't hold up to be able do any kind of feasibility check for horizontally launched vehicles.