Northrop Grumman P-ISR / "RQ-180"
In the 1990s, the USAF's AFRL (Air Force Research Laboratory) began to work on a concept named SensorCraft. Other than in conventional ISR (Intelligence, Surveillance and Reconnaissance) platforms, where existing airframes were fitted with sensors, in the SensorCraft all sensors should be an integral part of the airframe. Together with envisioned new developments in aerodynamics, materials, propulsion systems, and stealth technology, the result would be an unmanned platform, which could operate for several days virtually undetectable at altitudes above 18 km (60000 ft).
A core element of the design were to be active electronically scanned arrays (AESA) utilizing large flat areas of the airframe, most notably the airfoils. This required that the AESA radar antenna shares the loads in the wing structure, as well as a wing design which minimizes flexing and vibration. Around 2004, the basic concept for SensorCraft was a high-aspect-ratio joined wing design, where two sets of wings formed a kind of diamond planform. The approach was based on structural and radar signal generation considerations, but was rather risky, because joined wings like that were not well understood aerodynamically. Both Lockheed Martin and Northrop Grumman presented notional designs with more conventional layouts. LM's design was a comparatively traditional aircraft with a fuselage, a tail, and a straight high-aspect-ratio wing. NG had evolved their approach into a relatively conventional large stealthy flying wing.
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| Image: Northrop Grumman |
| Evolution of Northrop Grumman SensorCraft designs |
By 2006, advances in antenna array technology allowed to abandon the joined-wing idea, because so-called end-fire elements of AESAs could now emit high-powered beams parallel to the array's surface plane, e.g. towards the wing's leading and trailing edges. A wing-borne antenna array could therefore cover the full 360° field of view. Because of that, research focused on developing technology to build a very high aspect ratio wing which was both structurally sound and didn't flex so much as to degrade antenna performance. This required active aeroelastic controls, especially for gust load alleviation. The corresponding research project, conducted by AFRL, Lockheed Martin and Northrop Grumman, was named HiLDA (High Lift-to-Drag Active), and tested a 12% scale half-wing model of NG's SensorCraft design in a wind tunnel. It was demonstrated, that the active controls could reduce peak bending loads by 60%.
At that point, all the basic technology seemed to be ready for a full scale application for a specific operational requirement. This materialized in 2007. The AFRCO (Air Force Rapid Capabilities Office) had been appointed as lead for the development and testing of a new combat capability to solve the most critical operational shortfall, as identified by combatant commanders. It turned out that the most quoted problem was the lack of a Penetrating ISR (P-ISR) platform, which could provide persistent ISR in contested environments, where the existing U-2R and RQ-4 Global Hawk aircraft were too vulnerable.
After a classified competition, which involved Northrop Grumman, Lockheed Martin and Boeing, a large contract was awarded in 2008 to Northrop Grumman for the development of an unmanned P-ISR platform. The multi-billion dollar volume of that contract could be deduced from NG financial numbers, but the company didn't comment any further. Northrop Grumman's P-ISR UAV built heavily on the results of the SensorCraft research. Also, stealth technology and computational fluid dynamics had made significant progress since the design of the B-2, allowing a design with exceptional aerodynamic and low-observable performance.
At the Air Force base at Groom Lake, NV, new facilities were built specifically for the P-ISR test program. The secrecy went so far that the first flight on 3 August 2010 occurred at night. A night-time maiden flight was a first for Groom, and required new procedures and much more preparation than a first flight in daylight. But secrecy can only go that far, and in September 2011, Aviation Week & Space Technology was first reporting, that Northrop Grumman was building an unmanned stealthy ISR aircraft for the USAF. Two years later, the same magazine published a long article on the subject, incl. a somewhat questionable artist's rendering of the aircraft itself. The article also claimed that the UAV is designated RQ-180, without quoting any source. The number 180 looks like a "follow-up" to the Lockheed Martin RQ-170 Sentinel, but that doesn't appear too plausible, because the Sentinel's number was taken from LM's P-170 project number. There was also the P-175 Polecat, another flying-wing demonstrator from Lockheed Martin. 180 as a follow-on from P-170 and P-175 would be a reasonable guess for a Lockheed Martin project, but not so much for a Northrop Grumman aircraft. However, "RQ-180" nevertheless became the name, which is generally used for the P-ISR air vehicle in public articles and discussions. Needless to say, official sources don't even discuss the P-ISR program, let alone its speculative designation.
By mid-2016, nine EMD (Engineering and Manufacturing Development) UAVs had been delivered and flown. OT&E (Operational Test and Evaluation) flights had started around 2014, and in early December 2016, one of the P-ISR vehicles reportedly crashed on such an OT&E flight. The following table lists the alleged serial numbers and first flight dates of the 9 EMD vehicles:
| Air Vehicle | USAF Serial Number | First Flight |
|---|---|---|
| T1 | 04-0831 | 3 August 2010 |
| T2 | 08-0832 | 29 November 2011 |
| T3 | 08-0833 | 14 November 2012 |
| T4 | 09-0834 | 13 July 2013 |
| T5 | 10-0835 | 13 February 2014 |
| T6 | 11-0836 | 1 October 2014 |
| T7 | 12-0837 | 28 July 2015 |
| T8 | 12-0838 | 2015 |
| T9 | 12-0839 | 2016 |
In 2017, the first full-scale production aircraft joined the growing fleet. Over the following years, the program moved towards an IOC (Initial Operational Capability), incl. the (re-)activation of two squadrons, which allegedly fly the RQ-180 - the 417th TES "Phantoms" and 427th RS "Spartans".
In all these years, no reliable drawing, let alone a photograph, of the RQ-180 had reached the public. While the initial speculative renderings often showed a "cranked-arrow" planform with wings of moderate aspect ratio (looking a bit like a scaled-up X-47B), it seems more likely that the actual configuration features a straight leading edge and very high aspect ratio wings (reminiscent of Northrop Grumman's final SensorCraft design from 2006). Then, in October 2020, a Californian observer photographed an unidentified aircraft flying at altitude in broad daylight in the vicinity of Edwards AFB. It is a comparatively clear photo, and because of the planform, the speculations immediately turned to the RQ-180.
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| Photo: Rob Kolinsky |
| Unidentified aircraft, rumored to be NG's P-ISR UAV (a.k.a. RQ-180) |
It's true, that the photographed aircraft looks tantalizingly similar to what Northrop Grumman's P-ISR UAV is suspected to look like. On the other hand, it seems very strange that the Air Force, after having avoided any sighting whatsoever for 10 years, suddenly flies the aircraft in daylight over public land. As usual, official comments on the photo didn't come forward, and therefore there is no final verdict about the pictured aircraft's identity.
Specifications
No reliable, let alone officially confirmed, data about the P-ISR vehicle is available.
Main Sources
[1] Peter W. Merlin: "Dreamland, The Secret History of Area 51", Schiffer Publishing, 2023
Back to Directory of U.S. Military Rockets and Missiles, Appendix 4
Last Updated: 18 January 2024