First is the Boeing.
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From the look of this my first reaction is what is going on at Boeing??? The design is obviously all about function rather than form. The looks of the plane are secondary to what it can do. I see this as more of a freighter, but then I wonder how do you load the freight into the middle. Obviously this is a design exercise so the idea is efficiency. The option of 2 or 3 engines and turbojets and turbofans is interesting on the same platform. Methinks I'll take a pass on this one and hope that Boeing concentrates its efforts on military if they go forward with this design.
Next we have the offering from Lockheed Martin.
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At first look it appears to have one enormous engine, but that's just an optical illusion i believe. It looks like the second engine is obscured by the fuselage. The other net thing appears to be a box tail connecting both sides of the wing to the tail of the plane. I like the somewhat conventional style of the plane and think that most people will as well. Engine noise should be low in the front half of the plane and I'd guess the range would be fantastic.
Finally we have the version presented by Northrop Grumman.
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I really like the V-tails on this as they remind me of the F22 Raptor. The twin fuselages though are downright bizarre. There does not appear to be and way to move from one to the other. The flight deck is separated as well which from a safety perspective eliminates the threat of a crew takeover by a hijacker, but also prevents the passenger from getting their buh-bye from the pilot. Also the engines are right by the pilots. Lots of noise for them as well as the first class cabin(s). It reminds me of the Virgin Galactic transport plane and the Boeing offering is the Spaceship One. You don't think...????? Nah.