The Lockheed Martin RQ-170 "Sentinel" is a relatively new stealth Unmanned Aerial Vehicle (UAV) and is categorized officially as a "low observable Unmanned Aircraft System" (UAS) - insinuating stealth properties in its design. It is believed that the Sentinel (introduced in 2007) is a "cost-effective" UAV system built from available conventional aircraft/UAV systems with "stealth-friendly" qualities built into the design. The Sentinel is intended to reconnoiter and surveillance enemy elements at altitude through a myriad of available onboard systems. The end-product becomes a single-minded development that can, therefore, be procured in a short amount of time and within cost, allowing for services such as the US Central Intelligence Agency to tackle their covert missions with an effective platform. The "RQ" designation of the Sentinel marks the aircraft as a reconnaissance-minded, intelligence gathering platform - unlike the "MQ" series of armed UAVs such as the "Predator" and "Reaper". As its business is has been primarily centered with missions governed by the CIA, much of the Sentinel's details are still classified. The vehicle was developed and is supported by the ultra-secretive Lockheed Martin Advanced Development Programs unit - specifically charged with developing low-cost UAS solutions to fit US DoD requirements. The United States Air Force lists it as one of its active UAV systems but, of course, offers little in the way of design and performance specifications as of this writing.
The outward design appearance of the Sentinel is of a true "flying wing" as it lacks anything in the way of vertical tail surfaces or an empennage. The wing elements are well swept to the rear and sport rounded leading edges and a compound trailing edge. In many respects, the Sentinel looks much like a smaller scale version of the Northrop B-2 Spirit stealth bomber - particularly from the top and side profiles. The fuselage bulge contains a single powerplant - thought to be a General Electric TF34 series turbofan engine - while a payload bay is secured within the lower fuselage centerline area. The use of a centralized powerpant and payload compartment allows for the wings to realize their full internal advantage - for additional equipment or fuel stores. The air intake for the powerplant is of note for it is grilled in such a unique fashion as to be stealthy in nature. Of note is that the exhaust section is not shielded by the underlying wing surface as seen in other stealth aircraft. There are a pair of blisters appearing outboard of the fuselage bulge and are thought to contain additional communications or sensor equipment - perhaps giving the Sentinel beyond-line-of-sight (BLOS) capabilities. The undercarriage is of a conventional tricycle arrangement featuring a pair of single-wheeled main landing gear legs and a single-wheeled nose landing gear leg, all fully retractable. There is no evidence of the low observable (LO) features along the landing gear panel edges that are so prominent on stealth aircraft such as the F-117 Nighthawk, the F-22 Raptor and the F-35 Lightning II - all Lockheed products.
The windowed belly-mounted payload suite of the Sentinel is most likely modular and can range from full color, full motion real-time cameras to nuclear material "sniffing" sensors (for the detection of radioactive isotopes and the like). While a reconnaissance platform at its core, it is not out of scope that the Sentinel could be armed in the same fashion as the Predator with guided or homing missiles. It can also be assumed that the Sentinel would pack the latest in other IR and electro-optical systems required of the modern battlefield to fulfill its mission requirements.
The Sentinel remains a highly top secret product and so many of its performance specifications remain equally hard to come by and are therefore just estimates. Its jet-propelled nature does, however, allow it performance qualities that surely surpass conventional propeller-powered UAVs such as the Predator including a service ceiling well in line with modern military fighter aircraft - perhaps as high as 50,000 feet in some reports. Dimensions are thought to be in the vicinity of a 26 meter wingspan with a standing height equal to 1.84 meters. A length of 4.5 meters is also estimated based on available evidence.
Sentinels are operated by United States Air Force personnel from the 30th Reconnaissance Squadron out of the Tonopah Test Range in Nevada. The 30th operates under the 432d Air Expeditionary Wing of Creech Air Force Base Nevada which is governed by Air Combat Command. The group was online as early as 2005 and, in 2007, the Sentinel was clearly visible via still photographs at the Kandahar International Airport , assuming active participation in Afghan operations of the time. The RQ-170 was used to excellent effect in the pursuit of 9/11 mastermind Osama Bin Laden. The system reportedly was on station around the Pakistani town of Abbottabad where the fugitive was hiding in a sealed, well-protected compound in plain sight of Pakistani authorities. While Pakistani military lines of communications were monitored by US forces for possible connections to the Bin Laden hideout during the operation, US special forces elements (Navy SEALs) moved in and assailed the compound and its occupants, leaving the Taliban leader dead where he stood.
A lone RQ-170 was lost to the Iranians in December of 2011. The US military claimed initially that it was shot down but Iranian state television counter-claimed that their Electronic Warfare (EW) division hacked into the communications signal of the drone and effectively commandeered the aircraft while in flight. This Sentinel was being operated under the direction of the CIA and purportedly in support of ongoing operations in Afghanistan - however, spying on the Iranians proved a more suitable task, the Americans having used their drones for this purpose previously. The captured RQ-170 has since appeared in pictures and video showcasing the American product as a "trophy" of sorts with only minimal damage - a small dent to the portside leading wing edge - being noticed. Also it appears as though the main wing assemblies had been removed prior to showcasing - these either removed manually for transportation or broken from the fuselage in a subsequent crash landing. However, it is noteworthy that the RQ-170 did not appear with burn marks or heavy damage of any kind that is usually expected from an impact. The government of Iran has since filed a complaint with the UN about the American invasion of Iranian airspace. By all accounts, the provided Iranian television footage is authentic as the product mimics the Lockheed RQ-170 very closely. Iran's history of fabricating news, however, leads some to suspect its origins. Iran's close relationship with China also suggests that the technology may either be sold or shared with another US enemy.
The RQ-170 has also been notably tested in South Korean airspace, undoubtedly deployed there to help keep track of the ongoing North Korean nuclear weapons program.