There are interesting similarities in the old Luftwaffe aircraft concepts to the modern aircraft flying now:
Similar to Rutan Boomerang
Similar to Adam A700 (Originally designed by Burt Rutan)
Similar to NASA Oblique wing (which was by the way done by Scaled Composites / Burt Rutan)
Almost like the Rutan SpaceShipOne
Some features of Rutan WhiteKnight 1
Wing dihedral and anhedral similar to Rutan Proteus
From up, this could be mistaken to Rutan Long-Ez
Hey I can find similarities to Rutan Vari-Viggen here
Here is the WhiteKnight 2 configuration obviously
Almost like Adam A500 (originally designed by Burt Rutan)
Ok, then what about these:
RAM-jet, back in 1946
First commercial jet aircraft was DeHaviland Comet. But was it invented there? Doesn't this have quite recognizable look. The airliners still have this configuration and look.
And finally, but not least, this one:
Governments are still flying people into orbit with less modern hardware than this, and the idea to this one was from 1929 originally!. Think of it - first flights to space were super-ancient designs (non-aerodynamic rockets) instead of what was thought tens of years earlier already. Even Space Shuttle is quite clumsy compared to what this could have been. I would not be surprised to see someday a rendering on a page of a science magazine, which would look exactly like this and have for example the Northrop-Grumman -logo on it. The sad part was that this was only considered as a bomber, everything was some sort of warplane, it somehow didn't occur to people back then that they could have done the first human space flight earlier than it was done. I wonder why wasn't Dr. Säger utilized in the space programs which followed couple of tens of years later. I am thinking what could be done if the rocket monorail-train was replaced with a MAGLEV-train (and the track would slope upwards inside a mountain to the altitude of couple of kilometers in a tunnel). Wow. If my hair was short, it would be most likely pointing to the ceiling now.
Seems like to design a novel plane, there are examples of about every possible configuration layout, which have been long forgotten already and nobody has maybe utilized it, it just is waiting for someone to find it. The history of unfinished aircraft concepts seems to be an interesting source for inspiration.
So, if there could have been a orbital space plane already in 1930s or so, and ramjets were thought about already back in the 1940s, how much then air travel has advanced in something like 70 years? Not at all, it seems. With modern materials and tools, the feasibility of these designs have increased, but the idea still is very old. And most modern designs are just copies of each other without anything new and creative.