Defense News : “Retiring all of its U-2 spy planes and replacing them with Global Hawk UAVs won’t save as much money as the US Air Force had said it would, since the unmanned systems will need upgrades to handle the mission, according to experts and service data.”  

“To upgrade Northrop Grumman’s Block 30 Global Hawk, the Air Force intends to invest ‘about $1.77 billion’ over the next 10 years, said Maj. Gen. James Jones, deputy chief of staff for operations, plans and requirements. About $500 million of that is marked for a universal payload adapter that would allow U-2 sensors to be attached to the RQ-4 Global Hawk.”