> http://en.wikipedia.org/wiki/WaveRider#Hypersonic_Sail_Waverider http://en.wikipedia.org/wiki/WaveRider#Hypersonic_Sail_Waver... First time I've seen this, t

> http://en.wikipedia.org/wiki/WaveRider#Hypersonic_Sail_Waverider 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.