Boeing Frontiers
April 2003
Volume 01, Issue 11
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The UCAV program’s unsung hero

'Surrogate' aircraft used for the X-45A reduce cost, time and risk


The UCAV program’s unsung heroSurrogate aircraft have long been a mainstay of Boeing test programs because they lower flight-test costs.

They also allow a test program to proceed more quickly with development to achieve results that—if real aircraft were used—would normally involve more time and expense. Most important, they reduce risk for the real test aircraft, especially an unmanned air vehicle. That's because the surrogate carries a pilot, who can manually take control of the aircraft should a problem arise during unmanned operations.

To achieve these time, cost and risk benefits, the Unmanned Combat Air Vehicle (UCAV) program is using a T-33—a trainer version of the F-80 Shooting Star first flown in 1949—as a surrogate UCAV for certain aspects of flight testing. For instance, the surrogate was recently used to verify the X-45A's ability to operate in the same airspace as manned aircraft. In this case, the UCAV program used a T-33 built in 1955, which Boeing has owned for three years as part of a fleet of three T-33s. The other two are used for F/A-22 and AWACS avionics testing.

During flight tests at Edwards and Eglin Air Force bases, the T-33 was equipped with an avionics pallet fully representative of the X-45A UCAV system, which allowed it to autonomously fly preplanned mission routes. This approach also allowed operators on the ground to control the T-33 as if it were a UCAV.

The T-33 surrogate UCAV flew in and out of controlled air space many times per flight, integrating with other aircraft in the traffic pattern, said Mike Harlan, Boeing X-45A Test and Operations manager.

"No one has ever tried to do anything like this before," Harlan said. "This was a demonstration that they would never have let us do with the unmanned demonstrator unless we had achieved tens of thousands of hours of successful flight testing. In that respect, the T-33 is worth its weight in gold."

Not only is the T-33 a known platform with low overall operating and maintenance costs, but it also has two seats in the cockpit to allow someone to sit behind the pilot and monitor the equipment.

Because the aircraft was originally equipped with bulky 1955 electronics, it provides a huge area in front of the aircraft to accommodate the 350-pound electronics pallet that contains all the core avionics that make a UCAV fly. Those electronics, he said, have been used to support UCAV testing even before the X-45A took its first flight.

During the latest tests, the T-33, behaving as a UCAV, flew among other military and civilian aircraft and some rotorcraft.

"We were able to use the airspace without the need for it to be cleared out each time," Harlan said. "It was a total success in terms of the autonomous control of the aircraft. At no time did the pilot have to take control of the aircraft due to concerns about traffic and safety."

The T-33 will be used in May to test the next upgrade to the UCAV system and will continue to shoulder the risk as the program proceeds into an operationally representative robust prototype that will demonstrate the military and operational value of the UCAV system.

UCAV is a joint effort of the Defense Advanced Research Projects Agency, the U.S. Air Force and Boeing.


How it works

The T-33 contains an avionics pallet that allows it to behave as a UCAV would. The avionics system is brought on line through the simple activation of the software by ground-based flight-test engineers using a laptop computer.

Mission control station operators working from a mobile unit housed in a large van monitor the autonomously flying aircraft from the ground. The hands-off pilot aboard the T-33 also monitors the system and will take manual control only if necessary. From an air traffic control perspective, the T-33 is indistinguishable from a UCAV aircraft.

The UCAV program used the T-33 to demonstrate key Air Traffic Control operations at the Edwards and Eglin air bases. As the T-33 autonomously flew pre-planned routes around the bases, operators in the mission control station on the ground interacted with air traffic controllers to alter the T-33's flight as necessary for air traffic separation, de-confliction, holding, and simulated missed approaches. None of the actions adversely affected base tempo or day-to-day operations.



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