Lockheed openly discussing the Penetrating High Altitude Endurance UAV in 2003 as an in house effort:
http://www.entrepreneur.com/tradejournals/article/99696777.html
A snippet:
"The Skunk Works is also studying a Penetrating High-Altitude Endurance (PHAE) unmanned aerial vehicle (UAV) as a potential successor to the Northrop Grumman RQ-4A Global Hawk. The effort is based on a company "conviction" that the US Air Force--and possibly other users--will need a more "survivable" globally ranging UAV. Global Hawk was successfully tested for the first time over Afghanistan last year whilst it was still officially in its advanced concept technology demonstration (ACTD) phase. A PHAE demonstrator vehicle may also be in the offing. "If we decide we need one, we could build it within a year," Kacena says. The Skunk Works PHAE study, which commenced this year, stemmed from initial analysis of the Afghanistan campaign. Had Global Hawk faced a more severe surface-to-air missile (SAM) threat, especially from Russian-developed S-300/400 long range systems, it is questionable whether it would have been able to operate in such an environment, Kacena says. Whilst Global Hawk makes use of some low observability (LO) features, it was never designed as an all-out stealth vehicle--a capability that was to have been vested in the cancelled DarkStar. Survivability, Kacena says, is not just a stealth issue-the platform must also be able to adapt to increasingly complex electronic warfare and information warfare environments."
