Volume 46 | Issue 7 | August 2004
J-UCAS X-45A Represents an Evolutionary Step in Technology and a Look at Future Aviation
By Jay Levine
The Boeing X-45A unmanned aerial vehicle project is marking new milestones in flight research and reaching new goals with help from Dryden personnel and resources.
Gary Martin, Dryden X-45A program manager, and 1st Lt. Devon Christensen, Air Force Flight Test Center X-45A deputy project manager, recently explained some of the groundbreaking achievements of the program and Dryden's role in boosting the project to new heights.
Work with the X-45A is a joint U.S. Air Force, U.S. Navy and Defense Advanced Research Projects Agency effort that may eventually lead to a full-scale acquisition program. The project evolved from being called the Unmanned Combat Air Vehicle - UCAV - program to Joint Unmanned Combat Air Systems, or J-UCAS, in 2003, when the Department of Defense combined various service-specific UCAV efforts under one umbrella.
Dryden's role began early in the program's history, in 1999. That's when original agreements were signed and tasks were assigned leading to the ground and flight testing of the first X-45A. The first X-45A vehicle arrived at Dryden in November 2000 and ship number two arrived May 15, 2001.
Dryden's early roles included technical and engineering support and providing a home for the project. More specific tasks included ground vibration tests, propulsion system tests, key ground control law research and development and taxi testing before the aircraft took to the skies in May 2002.
In fact, officials from The Boeing Company - Donald V. Drouin, X-45A structures team lead, and C. Bradley Hershey, X-45A air vehicle integrator - sent a May 2003 letter to Dryden's then-research engineering director, J. Larry Crawford, and aerostructures research branch chief Stephen Thornton, thanking key Dryden personnel for excellent support.
"...I want to take this opportunity to thank you both for the great NASA support of the Boeing Structures group. We clearly would not have been as successful from risk, cost, and schedule standpoints if it were not for the dedication, hard work, and technical ability of your NASA team."
The letter went on to identify two Dryden employees who made specific contributions."
Specifically, both Starr Ginn and Natalie Crawford have done a great job supporting the Boeing UCAV Structures group over the past three years, specifically in the area of Structural Dynamics. Their hard work, dedication, and expertise have helped contribute to our success. Starr's support started in September 2000 with ground vibration test planning and development and continued with the actual GVT, engine tests, LST/MST/HST (low-speed, medium speed and high speed) taxi tests and UCAV first flight (May 2002)," the letter stated.
Ginn, then a mechanical engineer, designed an elaborate test fixture to enable the ground vibration tests that measured the aircraft's structural mode interaction in order to update the analytical model and calculate the vehicle's flutter margin. The X-45A ground vibration test was one of the largest-scale tests of its kind conducted at Dryden.
"...Their effort definitely helped the Boeing Structures group get the job done right, safely and on schedule," the letter concluded.
The X-45A flight research demonstrated a number of firsts, including the first autonomous (pre-programmed) control of an aircraft's movement from hangar to sky. Those first steps on the early flights were a showcase for Dryden talents. The X-45A was the first autonomous UAV to taxi around other piloted aircraft to an active runway and, like manned aircraft, taxi onto the center line of the runway and take off after receiving clearance - all with minimal human intervention.
A team of Dryden engineers designed the vehicle's ground control system, Martin said. That effort was lead by Lou Lintereur, a Dryden control system engineer, with Cheng Moua and Valerie Gordon. Autonomous controls are not routinely designed for ground operations, Lintereur said in a July 2002 X-Press interview.
In order to develop that control system, the team designed control laws for all weight-on-wheel conditions at taxi, takeoff and landing. The designs, Lintereur said, relied heavily on simulation models. As a result, the success of the X-45A has reinforced confidence in those design tools. The X-45A flights routinely conclude with the aircraft, after braking to a safe speed, taxiing itself off the active runway, parking and shutting itself down while waiting for the ground crew to secure it for tow back to the hangar.
Another area in which Dryden assists is with the Boeing T-33 that operates as a surrogate for the X-45A to enhance safety and identify challenges early in each flight research phase. Dryden staff augments Boeing pilots in flying the T-33, including Dryden pilot Dana Purifoy. Marty Trout is qualified to fly in the flight test engineer seat behind the pilot. Freddie Graham, of Dryden's aircraft maintenance branch, regularly assists the Boeing T-33 crew chief in preparing the aircraft for its missions.
Prior to the X-45A's first mission, the T-33 carried the vehicle management system computers, which contain the global positioning satellite receivers and inertial measurement units, as well as other components such as command link radios and mission computers necessary for mission execution. The T-33 flew the mission profile on autopilot to validate mission plans and as a training exercise for the team, support personnel and range safety officer. In autopilot mode, the T-33 flies as if it were an X-45A.
Use of the T-33 helped mitigate project risk; a T-33 was flown with the X-45A as if it were a second of the Boeing UCAVs, foreshadowing the recent success of flying two X-45A aircraft simultaneously under the control of the same pilot/operator. Use of the T-33 enabled a manned and an autonomous aircraft to be flown together for the first time and software to be validated in advance of the multi-vehicle flights.
Earlier this year, inert munitions testing with the X-45A began at Edwards Air Force Base bombing range in March, and testing was completed by dropping a GPS-guided small smart bomb at the Naval Air Warfare Center Weapons Division at China Lake, Calif., in April.
Tests in recent weeks included the much-heralded multi-vehicle flights. Using the software validated on the T-33, the two X-45As flew together in a loose formation in which they were positioned far apart. Closer-in formation flying will be tested as researchers become more comfortable with the formation algorithm software and response of the two aircraft, Martin said. May 27 marked what might be the first time a UAV pair taxied together in formation. The research has been a success so far, the team reported.
"This was a pretty loose formation by formation standards," Martin explained. "The vehicles were not meant to get any closer than 4,000 feet and our standard formation is going to be a mile apart - a 1,000-foot vertical separation, 500-foot lateral separation and 5,000-foot longitudinal (separation). The software checks to determine how close the vehicles are; if they get closer than 4,000 feet, it 'breaks' the formation. It's pretty spread out, but it's the first time two UAVs have flown a formation of any kind."
Martin said that while the project provides some of its own data services, the Dryden aeronautical test range support plays a large role.
"(Dryden) provides radar, long-range optics, video, chase aircraft support and photographic support from the back (seat) of the chase. We provide shop support on an occasional basis, as they need it. They're more or less self sufficient, but they occasionally run across the need for a battery, or machine work," he added.
"This is an unusual program for us in that we don't have responsibility for flight safety or mission success. DARPA is responsible for mission success and Boeing is the responsible test organization for airworthiness (flight safety), with DARPA oversight," Martin said.
Maj. Vic Martinez (Ret.), Air Force Flight Test Center J-UCAS (X-45A) lead engineer, agrees that the X-45A project is a unique one. Martinez joined the program in 2002 and described his experiences on the project at Dryden as "awesome."
"Working on a DARPA project is different from a usual acquisition project because there's much less red tape - meaning things can be accomplished in a smoother fashion," he said. "It's also a little different because Boeing, rather than the Air Force, is the responsible test organization."
Dryden has aided the X-45A project with range support, facilities and office space for about 25 employees of Boeing Integrated Defense Systems assigned here to work on the program. Dryden full-time employees number four, with 13 FTEs, or full-time equivalent positions (the equivalent of about 25 people) dedicated to supporting the project.
Also at work on the project are 12 full-time Air Force Flight Test Center personnel and two Air Force Test and Evaluation Command personnel. Andy Gutierrez is lead systems engineer from the Air Force and is frequently at Dryden from the fighter/bomber program office at Wright-Patterson Air Force Base, Ohio.
First Lt. Christensen coordinates activity among the Air Force,
NASA and DARPA via the 452nd Flight Test Squadron. He reports to squadron commander Lt. Col. James Wertz on program activity and test flight schedules and keeps the squadron apprised of issues such as flight schedule conflicts. The latter issue falls to Boeing's Tracy Reese, an operations controller, to resolve.
Dryden has been "instrumental to the program," Christensen said.
"NASA also has provided facility support above and beyond the hangars - we use the NASA control room in (building) 4800 to monitor our flights and get video of ground operations. NASA set up fiber (optic) connections and communication connections to the antenna sites used around the base to maintain command and control between the ground control station, mission control station and aircraft during an operation," he said. "NASA has definitely set up a lot of infrastructure for us to be able to execute our flight tests."
Dryden's John McKee, senior range control officer, explained that Center range staff members worked to tie Boeing into the Center's infrastructure and arrange for two-way communication so Boeing researchers could operate seamlessly from their Test Operation Support Center, a separate facility near Dryden's Research Aircraft Integration Facility.
McKee said some of the information provided by range personnel includes radar data, telemetry, system health and status, video, situational awareness data, command uplinks, fiber optic links and power. A difficult aspect of the X-45A inert munitions tests at China Lake was coordinating communications among Air Force, Dryden and China Lake staff.
For decades Dryden has worked on a number of projects involving remotely or autonomously controlling aircraft. For that reason, McKee said he knows what to ask customers in order to learn what they need so arrangements can be made to accommodate them.
"When you come here to the Center, you're engrossed in your airplane and your test program," he said. "All of this (range) stuff out here is invisible to you. You become more aware of it once you meet me, because I have to make sure I can make all the pieces fit. You may need to make changes on your aircraft to be compatible with our end or know we can make changes on our end that are compatible. A lot of things have to work right the first time - because you don't get a second chance."
McKee credits the team approach of the partners for much of the program's success.
Christensen also pointed to the efforts of Air Force maintenance crews on the X-45A, who come to work at 3 a.m. on flight days to prepare two research vehicles for flight. Tech. Sgt. Michael Cook of the Air Force Flight Test Center explained some of that work.
"It can be hectic, but we've done this long enough now that we're pretty efficient at preparing the two vehicles for a research flight," Cook said. "Freddie Graham is our liaison with Dryden, although our maintenance staff is pretty self-contained. Most of the time, we do the flight preparation the day before because of the extensive inspection we do on both vehicles, and then complete the final preparations in morning.
"We give it a final look over, and ensure that the necessary equipment for launch is ready and that everyone is familiar with their assigned duties for the day."
Dryden staff is responsive when the X-45A has a need, Cook noted.
"They helped with machining parts for us and with fabrication of one-of-a-kind items. They were really good about that type of stuff, and testing we needed in the labs - use of the atmospheric chamber to test parts and the loads labs tests of the vehicle's landing gear.
"We've had a lot of support from Dryden," he said.
The Air Force maintenance team is led by Senior Master Sgt. Dale Mullins, maintenance superintendent, and includes staff sergeants Troy Altevers, Michael Fountain, Christopher Harsh and Gabriel Patton; Tech. Sgt. Waylon Nez and Senior Master Sgt. Ronald Neuschwanger, former maintenance supervisor.
Dryden's Tony Ginn is available to the project as an operations engineer and also is qualified as a test conductor.
In addition, Dryden provides an X-45A chief engineer in Ross Hathaway, who primarily assists with scheduling, safety reviews and risk management engineering.
Work with the two X-45A aircraft in the current phase of the project is expected to be complete in 2005. Lessons learned on the development program will be incorporated into the X-45C model, delivery of which to the test site is expected in late 2006 or early 2007, with first flights slated for 2007. In addition, the Boeing J-UCAS aircraft will be joined by J-UCAS Northrop Grumman X-47B air vehicles, also set to arrive in 2007.
Roy Smith, Boeing X-45A Edwards Air Force Base site manager and test director, said Boeing is responsible for the design, engineering and flight test of the X-45A in conjunction with DARPA under an advanced development program that will demonstrate UAV technologies.
"I think the relationship we have with Dryden, NASA and the Air Force is an extremely beneficial one to all parties," Smith said. "We're coming up on the four-year anniversary (of the project) and we've done an extreme amount of flight test in a short period of time. A lot of that has to do with the relationship we have with NASA and their ability to understand risk, technological advancements and flight test.
"I think it's really important, when you work on an advanced program, that all of your teammates need to work in an open environment. The communication we have among NASA, DARPA and the Air Force is completely open. We share all our information technology with our teammates. I think that shows there's a true team on this program."
In fact, Dryden officials are setting their sights on meeting the needs of a J-UCAS program with talents that mesh with Dryden's historical role in flight research - integration of complex systems.
The innovative common operating system being designed to operate both Boeing X-45A and Northrop Grumman X-47 J-UCAS aircraft marks J-UCAS as an area in which this proud heritage of aerospace integration leadership might potentially be well employed.