Home' Defence Technology Review : DTR JUL 2016 Contents 15
DEFENCE TECHNOLOGY REVIEW | ISSUE 22 | JUL 2016
The US Defense Advanced Research Projects Agency
(DARPA) has awarded Phase 1 contracts for its Gremlin
unmanned aerial vehicles (UAV) concept, marking the first
major milestone for the program.
The Gremlins program seeks to develop innovative
technologies and systems enabling aircraft to launch volleys
of small, low-cost and reusable UAVs and safely and reliably
retrieve them in mid-air.
Such systems, or ‘gremlins’, would be deployed with a
mixture of mission payloads capable of generating a variety
of effects in a distributed and co-ordinated manner, says
So called for the imaginary, mischievous imps that became
the good luck charms of many British pilots during World
War II, the program envisions launching groups of UAVs from
existing large aircraft such as bombers or transport aircraft –
as well as from fighters and other small, fixed-wing platforms
– whilst those aircraft are outside the effective range of
enemy air defence systems. Once the gremlins complete their
mission, a C-130 transport aircraft would retrieve them in the
air and carry them home, where ground crews would prepare
them for their next use within 24 hours.
The gremlins’ expected service life of about 20 uses could
provide significant cost advantages over expendable systems
by reducing payload and airframe costs and by having lower
Aurora Flight Sciences announced on 18 April that a
sub-scale vehicle demonstrator (SVD) of its highly innovative
LightningStrike vertical take-off and landing (VTOL) X-Plane
for the Defense Advanced Research Projects Agency
(DARPA) flew successfully for the first time at a US military
facility on 29 March.
The flight of the SVD met an important DARPA risk
reduction requirement for validation of the aerodynamic
design and flight control system. “The successful sub-
scale aircraft flight was an important and exciting step
for Aurora and our customer,” said Tom Clancy, Aurora’s
mission and maintenance costs than conventional platforms,
which are often designed to operate for decades.
The Phase 1 contracts have been awarded to four
teams – Composite Engineering, Dynetics, General
Atomics Aeronautical Systems and Lockheed Martin –
whose proposals cover a spectrum of innovative technical
approaches to the program requirement.
Phase 1 is designed to pave the way for a proof-of-concept
flight demonstration that would validate an air recovery
concept of multiple gremlins UAVs. The program plans to
explore numerous technical areas, including:
• Launch and recovery techniques, equipment and aircraft
• Low-cost, limited-life airframe designs that leverage existing
technology and require only modest modifications to
• High-fidelity analysis, precision digital flight control, relative
navigation and station keeping.
– Matthew Mendenhall
Gremlins UAV program moves ahead
Sub-scale VTOL X-Plane flies
ABOVE: The sub-scale LightningStrike VTOL X-Plane
demonstrator during its first flight on 29 March. Image: Aurora
BELOW: DARPA’s Gremlin concept for low-cost, retrievable
and reusable UAVs awarded contracts in late March to four
companies. Image: DARPA
chief technology officer. “Our design’s distributed electric
propulsion system involves breaking new ground with a flight
control system requiring a complex set of control effectors.
This first flight is an important, initial confirmation that both
the flight controls and aerodynamic design are aligning with
our design predictions,” he said.
On March 3, 2016, DARPA awarded Aurora the Phase II
contract for the VTOL X-Plane contract following a multi-year,
Phase I design competition.
The VTOL X-Plane program seeks to develop a VTOL
demonstrator aircraft able to achieve a top sustained flight
speed of 300-400kt, with a 60-75 per cent increase in hover
efficiency over existing VTOL aircraft. Aurora’s design is a first
in aviation history: an aircraft that can demonstrate distributed
hybrid-electric propulsion using a synchronous electric-drive
The SVD aircraft weighs 147kg and is 20 per cent the size
of the full scale demonstrator Aurora will build for DARPA in
the next 24 months. The wing and canard of the SVD utilise
a hybrid structure of carbon fibre and 3D printed fused
deposition modelling plastics to achieve highly complex
structural and aerodynamic surfaces with minimal weight.
Aurora will now focus over the next year on further
validation of the flight control system and configuration of the
full scale VTOL X-Plane demonstrator. – Staff Reporters
For more detail see ‘DARPA backs breakthrough VTOL X-Plane design’ in
the April 2016 issue of DTR.
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