if we really want to know, it seems we have to ask the chinese geek hackers.
yep!
BBC News - Chinese hackers 'compromise' US weapons systems designs
"The compromised US designs include those for advanced Patriot missile systems called PAC-3, an Army anti-missile system known as Thaad, and the Navy's Aegis ballistic-missile defence system, according to the Washington Post.
The F/A-18 fighter jet, V-22 Osprey aircraft, Black Hawk helicopter and the Navy's new Littoral Combat Ship were also compromised.
The F-35 Joint Strike Fighter, the most expensive weapons system ever built, was also cited on the list."
bet they don't try to back engineer the F35 though....