A small California-based aviation firm has announced that it recently completed engine and flight control testing on the ground on a stealthy unmanned aircraft known as the Fifth Generation Aerial Target, or 5GAT. The firm says that this design, which it originally developed as a stealth aerial target, could also serve in the "loyal wingman" role with manned combat jets and perform other operational missions. Aviation Week was first to report that Sierra Technical Services had completed its first prototype 5GAT and had finished the various testing on Jan. 13, 2020. FlightGlobal subsequently published another report on these developments with additional detail about the unmanned aircraft's capabilities. The company says it hopes to fly the drone for the first time by the end of March of this year.

"We ran both engines all the way to [military] power at the same time," Roger Hayes, Sierra Technical Service's President told FlightGlobal. “We tested out our flight controls – elevons and rudders – and everything worked well."

Sierra Technical Services

Sierra Technical Services has not yet provided the exact physical specifications for the 5GAT, but has said in the past that it is dimensionally similar to a T-38 Talon jet trainer. A PowerPoint presentation from 2012 says the drone is only about 20 pounds heavier than the empty weight of a T-38, as well. The 5GAT is also powered by a pair of General Electric J85 engines that actually came straight from a T-38, too. Additional components came from F-5 and F/A-18 jets, according to AviationWeek, which has helped keep costs low. Sierra Technical Services has not given a hard figure, but says that unit price for the drones will be under $10 million. Still, despite this use of parts from other aircraft, the 5GAT's overall planform is considerably different from any of those designs, especially its rear-positioned diamond-shaped wings and intakes, which loosely resemble those of the F-22 Raptor. Pictures from the company website indicate that the drone uses honeycomb composite structures in its construction, as well as snaking intakes that hide the fan faces of the J85 engines, both features common to modern stealthy aircraft.

Sierra Technical Services 5GAT prototype.

Sierra Technical Services

Sierra Technical Services A honeycomb composite structure used in the construction of the 5GAT.

Sierra Technical Services One of the 5GAT's snaking engine intakes.

Sierra Technical Services also has not provided many specifics about the drone's performance, including its top speed. The company says that the two J85s allow it to fly at high-subsonic speeds and could potentially enable it to break the sound barrier. "It would probably go supersonic without much trouble, but none of the structure was analyzed or designed for supersonic [flight], nor were the inlet lips." Hayes, the firm's President, explained to FlightGlobal. For comparison, the T-38 is capable of flying at up to Mach 1.3 for short periods. Hayes also said that the 5GAT was capable of performing maneuvers up to 7.5 g and -2 g, but only for short periods. "It cannot sustain plus 7.5 g or negative 2 g. The aircraft will bleed off energy very quickly due to limitation of the thrust from these engines," he said. "We can make 7.5 g turns, but not sustain them for very long – that is basically a typical operational scenario." All of these features and capabilities are in service of the mission that 5GAT was originally intended for, which is acting as a surrogate for new and emerging stealth fighters and other advanced combat jets, and even drones, that U.S. military fighter pilots are increasingly likely to encounter in any future large scale conflict. The drone itself has been in development since at least 2006, when the U.S. Air Force first funded a design study for a low-cost, stealthy target drone to better reflect advanced opposing aircraft. An interesting team, which included former employees of Lockheed Martin's Skunk Works advanced design bureau and students from the Air Force Academy, crafted the original conceptual design.

USAF Early 5GAT concept art.

The Pentagon's Office of the Director of Operational Test and Evaluation, or DOT&E, subsequently took charge of the program. In March 2017, in cooperation with the U.S. Army Corps of Engineers (USACE), it finally awarded Sierra Technical Services a contract to build an actual prototype. Almost exactly two years later, DOT&E and USACE exercised an option in that contract and agreed to buy a second 5GAT prototype. Now, Sierra Technical Services says it is also hoping to expand its plans for 5GAT to using the drone as a low-cost loyal wingman, which would work in groups with manned aircraft, and potentially in other optional roles, such as intelligence, surveillance, and reconnaissance. 5GAT does not have space for an internal weapons bay in its present configuration, but it can carry stores on pylons under the wings, though doing so would impact its stealthy signature. The ability to carry internal electronic warfare and expendable countermeasure payloads, as well as other electronic systems, does appear to be part of the design. Concept art from the firm's website, seen at the top of this story, shows one of the unmanned aircraft firing decoy flares to defeat an AIM-9X Sidewinder missile that an F-35 Joint Strike Fighter, seen in the background, had fired.

ITEA