AW&ST 의 RQ-170 Sentinel 관련 상세 기사

 

 

 

New Details

RQ-170 payload lost in Iran is identified

Aviation Week & Space Technology, 01/02/2012

Authors : Bill Sweetman and David A. Fulghum

 

The first clear pictures of the center-line reconnaissance bay on Lockheed Martin’s RQ-170 Sentinel show that the small unmanned aircraft was carrying sensor balls mounted in an internal compartment with specially treated transparent panels — developed for the F-22 — when one of them crashed in Iran on Dec. 4.

 

The new pictures were taken at Kandahar airport in Afghanistan on Sept. 30. The images show that a wheels-up landing would have inflicted massive damage to the bay and sensor package. That package is “similar to some of the podded electro-optical/infra-red [EO/IR]systems” used by other non-stealthy aircraft and unmanned aerial systems, says a veteran black-world engineer with insight into U.S. UAS programs.

 

Images of RQ-170 were taken at Kandahar Airport on Sept. 30 that clearly show the centerline sensor bay (left), a closeup of the FMV sensor ball from the front (right) and a side shot showing the UAV’s sensor-packed payload spaces above and below the wing (below). The accident was caused by a “lost [data] link, followed by, or simultaneous with, another malfunction,” says a second official involved with the program. Putting the loss into perspective, “We’ve lost over 50 MQ-1s [Predators] and 9s [Reapers], so this should not be a surprise.”

 

The U.S. Air Force squadron that flew Sentinels was activated in 2005 and the stealthy, unmanned aircraft was first photographed at Kandahar in 2007. Early RQ-170 operations were conducted from both Afghanistan — with CIA involvement — and South Korea.

 

The RQ-170s were brought back to the U.S. in 2009, re-equipped with a full-motion video (FMV) camera, and then redeployed to Afghanistan, say USAF intelligence officials. At that time it was operated by the USAF 432nd Wing’s 30th Reconnaissance Sqdn. (RS), then at the Tonopah Test Range Airport in the northwest corner of the USAF Nevada Test and Training Range. The wing also flies the Predator and Reaper, and the Tonopah base was once the clandestine home of the F-117 stealth fighter.

 

Prior to refitting, the aircraft carried a long-range, EO/IR camera thought by U.S. analysts to be used for monitoring missile tests and other activities in sparsely populated eastern Iran.

 

The RQ-170’s operational altitude of 50,000 ft. gives it an advantage over other lower-cost UAVs and the manned RC-135 Cobra Ball (for monitoring foreign missile tests) that are restricted to about 30,000 ft. and below. However, the Sentinel is not a high-end, very low-observable stealth design with sophisticated sensors. It is instead a robust, reduced-signature, sensor truck designed to maintain high sortie rates.

 

Other stealth design features include a variant of the “toothpick” leading-edge profile developed for the B-2. Stealth dictates sharp leading edges, but bluff shapes are better for aerodynamics and stability. The compromise on the RQ-170 and B-2 is to make the edges sharp at their ends, where more radar scattering is most likely, and more blunt at the mid-point.

 

Initially, flights are thought to have been conducted along the borders of Afghanistan avoiding the airspace of neighboring countries. However, after adding shorter-range FMV, the aircraft operated in Pakistan’s airspace to monitor the compound of Osama bin Laden, and later over Iran, defense officials say.

 

The RQ-170 has a dual history of operations for both the CIA and Air Force.

 

Some analysts believe the aircraft was originally funded after the Joint Unmanned Combat Air Systems demonstration program was terminated in early 2006, as a near-term platform with adequate — but not advanced — stealth qualities to support a USAF airborne electronic attack (AEA) technology demonstration. However, the 30th RS was activated on Sept. 1, 2005. That may indicate that other, unknown UAVs are in its stable.

 

That effort culminated in an experimental deployment to South Korea in the summer and fall of 2009, and paved the way for a larger, classified UAV now under development. By the fall of 2007, however, the CIA had acquired the first of a small number of RQ-170s, fitted with what appears to be an off-the-shelf, full-motion-video sensor and a satellite communications (sitcom) system.

 

The choice of FMV suggests that Iranian nuclear and missile research facilities may not have been the primary target of the CIA’s mission. A long-range oblique photography (Lorop) camera would be better suited to such fixed targets. FMV is more valuable in operations like the bin Laden raid — where the sensor can monitor activity around a target — and the CIA may well have been concerned that Pakistani air-defense radar tracking of Reaper operations would leak to Pakistan-based insurgents.

 

FMV is a key component in the new field of activity-based intelligence analysis conducted by the National Geospatial-Intelligence Agency. NGA analysis brings together all available intelligence data to build a more complete picture of a target of interest. In preparation for the Pakistan raid, the presence of bin Laden was deduced without a man fitting his description actually being seen. A helicopter crash during the raid also revealed the existence of a small fleet of helicopters modified for low noise, radar and heat signatures.

 

The new photos confirm that the RQ-170 is a small aircraft, with a wingspan of 45 ft. and an overall length of just over 17 ft. Major components of the landing gear appear to be drawn from the T-6 trainer, but with the wheels, lower struts and linkages rotated through 90 deg. so the main gears retract forward and the nose gear retracts to the right of the centerline.

 

The sideways-retracting nose gear is unusual, but leaves more of the limited centerline length available for payloads. The photos clearly show that the primary reconnaissance payload is a sensor ball covered by a “greenhouse” comprising three panels of radar-reflective, infrared-transparent material. Such materials may be classified, but they are not new. They were developed for the F-22 when it was still expected to carry an infrared search-and-track system. The V-shaped canoe fairing also could accommodate a small side-looking radar.

 

The twin overwing bulges most likely accommodate dual satcom antennas. This would allow the RQ-170 to use whichever antenna is on the “shadow” side of the vehicle, relative to the most severe radar threat. The center section is too short to accommodate a serpentine inlet duct — hence the reversion to the grid-shielded inlet used on the F-117. It is not clear how the problem of inlet icing is addressed. The F-117 used a retractable wiper/chemical spray system, stowed in a step in front of the inlet and operated by the pilot, who was supposed to detect ice visually with the help of a lamp in the fuselage side.

 

 

  ⓒ Iranian TV