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.
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.
[1] http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falc...
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.
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.
edit - and for the same reason there are also things that would work in KSP that would fail in the real world.
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'.
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.
.. 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...
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.
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.