http://www.space.com/11405-skylon-space-plane.html
http://www.reactionengines.co.uk/space_skylon.html
To demonstrate the application of SABRE engines to space access,
REL has designed SKYLON, the first vehicle designed to be powered by SABRE engines.
(http://www.reactionengines.co.uk/images/610/skylon_sabre_open_610.jpg)
SKYLON is an unpiloted, reusable spaceplane intended to provide reliable, responsive and cost effective access to space. Currently in early development phase, the vehicle will be capable of transporting 15 tonnes of cargo into space. It is the use of SABRE's combined air-breathing and rocket cycles that enables a vehicle that can take off from a runway, fly direct to earth orbit and return for a runway landing, just like an aircraft.
SKYLON will provide aircraft-like access to space to enable:
Operation from runway to orbit and back
Order of magnitude reduction in cost vs. existing technology
400 x improved reliability
Responsive access to space
European Space Agency Report, 2011
Because SKYLON is reusable (unlike current single-use space launchers) it can be purchased by companies and nations that want space access in a manner similar to current civil aircraft. As with aircraft, purchasing a vehicle will provide a much more cost effective option than trying to develop an independent launcher system.
What does the US have in concept that is not secret?
Maybe the US could eventually have something like this:
http://sploid.gizmodo.com/holy-crap-nasas-interplanetary-spaceship-concept-is-fr-1589001939
(http://i.kinja-img.com/gawker-media/image/upload/s--CBleSxb1--/arka1v2pcbroo4a0pj8e.jpg)
(http://i.kinja-img.com/gawker-media/image/upload/s--JHVdNyop--/c_fit,fl_progressive,q_80,w_636/fqakg2q4nqjveo3qrf7g.jpg)
Dr. Harold "Sonny" White is still working on a warp drive at NASA's Johnson Space Center. His work is still in the experimental stage but that doesn't mean he can't imagine what the real life Enterprise ship would look like according to his math.
I don't know anything about Einstein's equations but I can dream...but are we already there in the black world. It has been alluded to in statements by some of our space pioneers but why hasn't it come out?
IF Lockheed Martin are talking compact fusion (http://www.thelivingmoon.com/forum/index.php?topic=7483.msg104897#msg104897) reactors then my guess is they have something better already in operation in the black world.
QuoteLockheed believes its scalable concept will also be small and practical enough for applications ranging from interplanetary spacecraft and commercial ships to city power stations. It may even revive the concept of large, nuclear-powered aircraft that virtually never require refueling—ideas of which were largely abandoned more than 50 years ago because of the dangers and complexities involved with nuclear fission reactors.
http://aviationweek.com/technology/skunk-works-reveals-compact-fusion-reactor-details
Something is going on in the background.