Thursday, April 23, 2009
Testing was conducted with a King Air aircraft serving as the UCAS surrogate. These tests are part of risk reduction to mature UCAS-D networking and navigation technologies known as Tactical Targeting Network Technology (TTNT) and Precision Global Positioning System (PGPS). These systems will support Northrop Grumman’s 45,000-lb UCAS demonstrator, known as the X-47B, which will participate in carrier trials in late 2011.
The program’s Aviation Ship Integration Team completed integration of Honeywell’s Enhanced GPS Inertial Navigation Systems (EGI) and Rockwell Collins’ TTNT equipment onto the nuclear powered aircraft carrier Feb. 18. Ten test team members remained onboard CVN-75 Feb. 20-28, collecting EGI and GPS sensor data in the representative shipboard environment 24 hours a day. The King Air flew from St. Mary’s County Regional airport in Maryland for four flight tests requiring over 15.6 hours of flying time to evaluate the real-time performance of the TTNT and PGPS systems.
‘‘The Precision GPS system allows the X-47B to have centimeter-level accuracy with 360-degree coverage around the ship – the type of performance we need for safe, autonomous launch and recovery operations,” said Glenn Colby, A⁄SI integrated product team leader.
The PGPS works by exchanging GPS and inertial measurement information over the TTNT network. TTNT, developed by DARPA, is the first military communication system designed from the ground up to support line-of-sight, ad-hoc Internet Protocol networks. The use of networking communications allows the UCAS-D system to deploy software applications at a fraction of the cost and time of traditional legacy systems.
‘‘When we first integrated our system with TTNT, we threw away 80 percent of the software we had written for older systems, like Link-16. Software development was incredibly rapid too – it only took us one month to get IP applications up and running, compared to three years we spent trying to make the software work on a legacy system. TTNT’s performance also allows us to run safety-of-flight applications over the network – something we’ve not been able to do before,” said Colby.
In the current UCAS-D system, six functions performed over legacy systems – navigation, approach and landing, radio communications, situational awareness, air traffic control, and command and control – are all integrated as software services over a redundant TTNT network. February’s tests were conducted to verify TTNT antenna installations, coverage, and performance in the shipboard environment. For the first time in flight trials, the Navy demonstrated a fully-redundant TTNT network.
‘‘If you’re going to have a completely networked communication system, you can’t rely on just one radio – it becomes a possible single-point failure. We worked with Rockwell to design redundancy into the radio network, so that if one platform radio fails, all of the communications seamlessly transfer over to the next radio – without the software applications having to do anything,” said Colby. For the first time in flight testing, the team demonstrated how a second radio seamlessly picked up connection to the network after a forced radio failure.
Aside from aircraft carrier launch and recovery, the UCAS-D program is also charged with demonstrating Autonomous Aerial Refueling (AAR) with an unmanned system. Partnering with both the Air Force Research Laboratory and NAVAIR’s Precision Strike Weapons program (PMA-201), the UCAS program will leverage the TTNT and PGPS architecture to perform Air Force- and Navy-style refueling operations with the X-47B. PMA-268 has exploited the scalability of the TTNT networking system so that the carrier demonstration and AAR communications and navigation architectures are interoperable.
‘‘We’re showing how one network can support multiple functions, with reusable software – without re-planning or re-designing the network,” said Colby.
“The Navy has not yet decided to procure an operational UCAS system beyond the demonstration,” said Capt. Marty Deppe, program manager for PMA-268. ‘‘But from a theoretical perspective, a carrier- based, air-refuelable UAS unleashes an ability to exploit the range and persistence potential of an unmanned system by allowing it to remain airborne much longer than the limits of human endurance.”
Deppe noted that a fully network-capable UAS launching from the carrier flight deck could significantly increase the standoff of a Carrier Strike Group (CSG) from potential anti-access threats, allow an earlier response to emerging tasks, and significantly extend loiter time on an ISR or weapons-ready orbit thus improving the response options of war fighting commanders and the national command authorities.
(Unmanned aviation public affairs submitted this article.)