PAUL LEWIS & GRAHAMWARWICK /WASHINGTONDC
Company hopes design will meet UCAV needs of both forces although final requirements are not defined
Northrop Grumman has unveiled its concept for an unmanned combat air vehicle (UCAV) operational system (UOS) it hopes will meet the needs of the US Navy. The company is also confident that, following the planned establishment of a Joint Programme Office (JPO) later this year, the concept will dovetail with the US Air Force's shift in requirements towards a larger, longer-range platform than previously envisaged.
"Our design at this point is focused on the navy as a customer, but from what we've seen of USAF requirements changing and its UCAV design going from an X-45A to a B to a C, air force requirements appear to fall in line with those of the navy," says Kenney Linn, Northrop Grumman director business and strategy development. "We've had positive feedback and we think the UOS design has good applicability for the air force mission," he adds.
The UOS is sized in anticipation of a UCAV-N requirement in the 13,400-18,000kg (30-40,000lb) gross weight class, with a 12h-plus endurance and with folding outer wings to enable it to fit on an aircraft carrier deck. It has a single powerplant on the centreline flanked by two internal payload bays, each large enough for a 900kg Boeing JDAM GPS-guided bomb. The fuselage closely resembles the much smaller kite-shape X-47A Pegasus company-funded demonstrator, with the addition of cranked outboard wings for added range and low-speed carrier approaches.
UOS work has been funded by the Defence Advanced Research Projects Agency (DARPA) and the USN under Phase IIA of the UCAV-N demonstration programme. Three times the amount of computational fluid dynamics calculations and wind tunnel testing was conducted on the design compared with the recently flown Pegasus. Boeing and Northrop Grumman await Phase IIB contracts to develop and fly by early 2006 a UCAV-N demonstrator system (UDS), which Linn describes as a "system tool kit to get to UOS".
The degree of fidelity between Northrop Grumman's UOS and planned X-47B UDS demonstrator will depend on how far the USN wants to go beyond simply proving carrier compatibility ashore, available funding, and the addition of any USAF requirements. Phase IIB is already a year late and the navy is keen to begin work ahead of the creation of the JPO, which has become clouded by service jockeying for lead of the office, and whether DARPA will continue to oversee the UCAV-N demonstration, once established.
Northrop Grumman, in the interim, has stopped flying the X-47A after its successful first flight in late February until it "knows how best to utilise it in support of the next phase of UCAV-N", says Linn.
Boeing plans to shortly resume flight testing of its two X-45As under Block 2 of the DARPA/USAF UCAV demonstration. It is focusing on multi-ship co-ordinated flight with one operator controlling two X-45As in the real world and up to four air vehicles in simulation. It will culminate in the vehicle performing a pre-emptive mission to suppress enemy air defences and dropping a small smart bomb.
X-45 demonstration leadership is due to transfer from DARPA to the USAF at the end of September and the conclusion of Block 2 Two more blocks remain within the initial Spiral 0, phase of the programme. Block 3, to be completed in the second quarter of next year, is a smart single-ship demonstration in which ground-station functions such as automated routing and replanning will be migrated to the air vehicle.
Block 4, to be completed at the end of 2004, is a smart multi-ship demonstration, involving "dynamic responding, rerouting and replanning in a co-ordinated fashion", says Boeing. Its contract covers the follow-on Spiral 1 phase of the programme, but this is now in flux following the Pentagon's decision to form the JPO. Work on the enlarged X-45B is expected to switch to the even larger X-45C to meet USAF and USN range requirements. It is expected to more closely resemble the company's earlier X-46 batwing design originally pitched for UCAV-N
"There is ongoing work to bring navy activity [into Spiral 1], but it has not been agreed how to structure that activity. There is a lot of talk about an X-45C, but no official direction," says Boeing UCAV programme manager Darryl Davis, who expects to get word from the Pentagon this month. "The redirection will allow us to satisfy the objectives of Spiral 1 for the USAF and the USN's carrier suitability demonstration with a vehicle that can satisfy both requirements," he adds.
The direction UCAV takes at the end of these two parallel demonstrations efforts and whether one or both of the X-45C and X-47B become UOS hinges on the JPO and how the two services' operational requirements are developed. "The JPO will have to shepherd the requirements process. It will need to develop common and unique requirements, mature technology and processes and decide on a solution, be that a single design or distinct air vehicles," says Linn.
Davis adds: "This does not necessarily mean a Joint Strike Fighter-like approach to air vehicle commonality. A lot of things will not change from the B. There will be the same things in a different airframe."
Source: Flight International
