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GTRI helps transform a T-6 trainer into a light attack aircraft

Fri, 06/15/2012 - 4:05am
GT Aircraft

Researchers from the Georgia Tech Research Institute are working with aircraft manufacturer Hawker Beechcraft to demonstrate Air National Guard and U.S. Air Force requirements on the AT-6, a light attack version of the T-6 trainer.

Researchers from the Georgia Tech Research Institute (GTRI) are helping convert an aircraft used to train pilots into one with intelligence, surveillance, reconnaissance (ISR) and light attack capabilities. The new aircraft would provide a less expensive alternative to legacy warbirds like the A-10 and F-16 and could be used by foreign military allies as well as U.S. homeland security agencies.

In recent years, changes in warfare have caused countries to rethink their mix of aircraft. Instead of an emphasis on jet-powered fighters, governments are turning to smaller turboprop planes to perform aerial reconnaissance and counterinsurgency missions—airborne snipers of sorts that can target specific enemy threats with little collateral damage.

Smaller, slower moving, more agile aircraft can provide greater situational awareness over an extended period of time. And they offer significant cost savings by being more fuel efficient and easier to maintain, explained Byron Coker, a GTRI principal researcher who is leading a demonstration program for the U.S. Air National Guard (ANG).

The program, which began in late 2009, is focused on developing an ISR and light attack platform tailored for ANG needs, executing a demonstration of this platform to include airframe and integrated system capabilities. The contract was awarded to GTRI through SENSIAC, the information analysis center at Georgia Tech that specializes in sensing technologies related to defense activities. GTRI has subcontracted with Hawker Beechcraft to demonstrate ANG and Air Force requirements on its AT-6C, a light attack version of the T-6 turboprop plane used by the U.S. Air Force and U.S. Navy to train pilots.

Taking an existing aircraft and adapting it for a completely different role demanded considerable systems-engineering muscle. Unlike the turboprops used for close air support and counterinsurgency missions during the Vietnam era, today’s light attack planes must be net-centric. GTRI's first task was to create an ISR platform, which included:

  • Radios that enable communication with other military aircraft.
  • A satellite radio so the plane can connect with networks while airborne.
  • An electro-optical/infrared (EO/IR) sensor that allows the aircraft to track individuals and items on the ground.
  • A downlink that allows imaging from the EO/IR sensor to be relayed to ground operations, mission control and other aircraft.

Installing this advanced communications equipment required a great deal of antenna modeling and analysis. "We had to make sure new systems being added wouldn’t electromagnetically interfere with existing equipment," said Coker, explaining that more RF equipment potentially increases the likelihood of interference. "Because the plane is smaller and more compact—about half the size of an F-16—the equipment is installed closer together."

An integral piece of the project was to develop an aircraft self-protection system that enables the plane to survive in operational theatre. In the ANG’s assessment, the primary threat comes from manpads—shoulder-launched missiles fired from the ground.

In response to this threat, GTRI engineers integrated a warning system that detects manpads, along with a dispenser system that fires flares to decoy the missiles. An electronic warfare management system ties the warning and dispenser systems together—and provides the pilot with easy control and display.

"The flares are dispensed automatically by the integrated system, which is critical because everything happens so fast," Coker explained. "If the pilot sees missiles coming toward him, it's too late. There's no way he could respond manually."

Extensive modeling and analysis was important to designing the self-protection system.

"Self-protection equipment has to be tailored for every aircraft," explained Dale Alter, program manager at Wichita-based Hawker Beechcraft. "You can take the same boxes and sensors from plane to plane, but where you put sensors on the plane and what they see determines how well the aircraft is protected."

Using GTRI-developed software tools, researchers determined the best spatial placement and orientation for the sensors, and then validated the results through simulation.

In October 2010, the researchers held a field test at the Barry M. Goldwater Range, the government's 1.9 million-acre training and development complex in southwest Arizona. "The feedback was excellent," said Alter. "In fact, the ANG reps said we did something that had never happened as far as they could recall: Everything worked perfectly the first time."

That meant the tweaking and re-testing that is common in most operational assessments wasn’t necessary. Alter attributes this home run to GTRI’s rigorous modeling, analysis, and bench testing prior to the operational assessment.

GTRI is now tackling the second phase of the AT-6 project, which will investigate the armament of the aircraft according to ANG specifications. The wish list of weapons includes gravity and laser-guided bombs, Hellfire missiles, laser-guided rockets, small-diameter bombs and 50-caliber machine gun pods.

The weapons integrations work is challenging from several perspectives, observed Courtland Bivens, a principal research engineer in GTRI who has worked extensively on the project, including initial risk-management and systems safety analysis. "A light turboprop plane can’t carry all of these weapons at once," he pointed out. "So we have to determine the optimal mix of weapons, their effectiveness—and then test the various combinations."

That's challenging as some of the weapons, such as Hellfire missiles, are primarily used on helicopters. "Just because they work on a helicopter doesn't mean they'll work on a fixed-wing aircraft," Bivens said. In addition, laser-guided rockets are a new weapon system that hasn’t been integrated on any fixed-wing aircraft yet, he pointed out.

GTRI engineers are also investigating human systems integration to ensure that the workload and division of labor on the new aircraft is reasonable.

A traditional ISR aircraft has a four-person team: two pilots in front and two operators in the back, Bivens explained: "Here, you're trying to do the same mission with two crew members. It's important to work through integration issues of the various systems and make sure the pilot still has situational awareness to accomplish the mission."

Work on the second phase of the project led up to an operational assessment to test weapons capabilities. That milestone was met as scheduled in early 2012.

The AT-6 project is significant because it gives GTRI an opportunity to work on a new aircraft platform. The institute has done many projects with legacy warbirds such as the F-16 and A-10. For example, after the first Desert Storm, ANG selected GTRI to integrate missile-warning, self-protection equipment on its A-10—and the success of that project was one of the reasons GTRI was selected to manage the AT-6 program.

"The project is really a great example of GTRI’s multidisciplinary abilities," Coker said. "Because GTRI has so many different areas of expertise to pull from, we can offer capabilities that other institutions can’t and not only provide customers with great solutions but also the ease of one-stop shopping."

Source: Georgia Institute of Technology

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