Flight_International 28Jan2020

(Jacob Rumans) #1


16 | Flight International | 28 January-3 February 2020 flightglobal.com


Stealthy 5GAT has ambitious targets

Manufacturer nears first-quarter flight debut for versatile aerial target drone that could also fulfil Loyal Wingman role


ierra Technical Services
recently completed several
ground tests, including an engine
run, on its Fifth Generation
Aerial Target (5GAT).
The aircraft, which is powered
by two GE Aviation J85 engines
salvaged from retired Northrop
T-38 jet trainers, is intended to be
used as a stealth target drone for
the US Air Force (USAF).
“We ran both engines all the
way to [military] power at the
same time,” says Roger Hayes,
president and co-owner of Sierra
Technical. “We tested out our
flight controls – elevons and
rudders – and everything
worked well.”
The unmanned air vehicle
(UAV) should be ready for its first
test flight during the first quarter
of this year, Hayes says.
However, because the 5GAT is
inherently low-cost – estimated
by Sierra Technical to be less
than $10 million per production
copy – and has a low-observable
shape, the company is also open-
ly pitching it as an “attritable”
Loyal Wingman.
Attritable aircraft are a new
concept in aerial warfare: UAVs
so cheap that combat losses will
not break the bank. For example,
the USAF’s Loyal Wingman
programme is aimed at develop-
ing such assets for use alongside
its fleet of piloted fighters, such as

Sierra Technical Services UAV is powered by twin GE J85 engines and, priced at $10 million, may be suitable as attritable combat aircraft

Sierra Technical Services Sierra Technical Services

the Lockheed Martin F-35A.
They could also be asked to take
on dangerous tasks, or to operate
as robotic scouts.
Sierra Technical believes its
5GAT platform has abilities that
would give it advantages over
Kratos Defense & Security
Solutions’ XQ-58A Valkyrie, a
pioneering attritable UAV built in
collaboration with the US Air
Force Research Laboratory.

“It will be able to fly faster than
a Valkyrie. It will be more
manoeuvrable as well,” says
Hayes. “We believe that it has a
high potential of solving some of
the Loyal Wingman require-
ments, once they’re defined [by
the USAF].”
In particular, the 5GAT’s J
engines give it the ability to fly at
high subsonic speeds.
“We’re going to limit it to high
subsonic,” says Hayes. “It would
probably go supersonic without
much trouble, but none of the
structure was analysed or

designed for supersonic [flight],
nor were the inlet lips.”
The 5GAT was commissioned
as a stealth target by the US
Department of Defense’s
Director, Operational Test and
Evaluation (DOT&E), and super-
sonic flight was not part of its
mission requirements, explains
Hayes. It is designed to be a
disposable asset for mock air
combat and a sparring partner
that helps combat pilots learn
how to shoot down stealth air-
craft, such as China’s Chengdu
J-20 or Russia’s Sukhoi Su-57.
The DOT&E paid for the
aircraft to be designed, built and
flown after the USAF and US
Navy initially declined to build
stealth targets of their own.
However, the USAF last year
released a request for information
for its own stealthy Next-Genera-
tion Aerial Target, which could
replace the earlier effort.
As well as being stealthy, the
5GAT can manoeuvre at +7.5g
and -2g for short periods, though
it cannot sustain these.
“The aircraft will bleed off
energy very quickly due to
limitation of the thrust from
these engines,” explains Hayes.
“We can make 7.5g turns, but not
sustain them for very long – that
is basically a typical operational
The 5GAT can carry weapons

on external pylons, but does not
have provisions for an internal
weapons bay: a capability that
would require a major redesign.
“We can carry all kinds of
electronics, artificial intelligence
gear, [intelligence, surveillance
and reconnaissance] equip-
ment,” says Hayes, who declines
to make a detailed comparison
of the design versus the Valkyrie.
This is because Sierra Technical
helped to design the XQ-58A,
and he says it would be a
conflict of interest to disclose
such information.

Hayes notes that competing with a
business partner on a separate
product line happens frequently in
the US defence sector. “You know,
it’s strange bedfellows, but it’s com-
mon in the industry,” he says.
Because of the wide variety of
Loyal Wingman applications,
from air combat to intelligence,
surveillance and reconnaissance
roles, Hayes says he believes
there is room for both aircraft.
“For the Loyal Wingman there
are certain aspects that we believe
that the 5GAT or a derivative
would be very suitable, even
more suitable in some cases then
the Valkyrie,” he says. “And then,
there are many cases where the
Valkyrie would be more suitable
than the 5GAT derivative.” ■

“It will be able to fly

faster than a Valkyrie.

It will be more

manoeuvrable as well”
Roger Hayes
President, Sierra Technical Services
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