mbat. The reality of
the 21st Century is that the battle space is specifically oriented to
littoral environments. The Navy's Littoral Combat Ship (LCS) is
optimized for flexibility in the littorals as a mission reconfigurable
system of systems, both manned and unmanned. The LCS
achieves its joint force multiplier effect through the use of
unmanned air, surface, and underwater vehicles. The LCS's
primary roles in ASW operations will be force defense, self
defense, and Intelligence, Surveillance and Reconnaissance (ISR)
against quiet diesel threats in the littorals. The LCS will deploy
Unmanned Surface Vehicles (USVs) to form a wide, persistent
sensor front in order to sweep the sea lines of communications
ahead of transiting maritime forces, or to form sensor barriers
Active Source
Draco USV
Dipping Sonar
Towed Array
Torpedo Launcher
(Future)
Figure 1: Draco provides a complete USV system capable of handling ASW sensor systems, and potential
future payloads, such as a torpedo launcher for surface warfare.
ahead of a threat. USVs will deploy towed arrays, dipping sonars,
and multistatic systems, as well as torpedoes. Command and
Control and data relay capability between ship and USVs will be
accomplished through a combination of traditional line-of-sight,
satellite, and future over the horizon communications via
communications through relay payloads on unmanned aerial
vehicles.
SYSTEM DESCRIPTION
The GDRS ASW USV Draco is based on innovations in high-
payload, high-speed small craft design and unmanned systems
technology to provide a highly capable unmanned surface vehicle
meeting the strenuous demands of multiple missions. While
designed specifically to address ASW mission needs, Draco
possesses margin through careful design selections enabling it to
also meet the needs of many MIW and SuW missions. Following
is the description of Draco, which is loosely organized as craft and
core systems, with the intent to convey the broad ability of Draco
to handle a variety of payloads beginning with the three currently
identified ASW payloads, as shown in Figure 1. The design
presented is open, flexible, and modular, forming a solid basis for
initial capability and future growth both to additional payloads and
mission capability, and to increasing levels of autonomy.
Through system level design practices, Draco is built to endure the
rigors of the open ocean environment by first considering the
locations of sensors and core electronics for optimal performance
and maximum environmental protection, and by redundant system
design to provide graceful degradation of key systems ensuring
the USV remains operational following a subsystem failure. Key
sensors and subsystems are identified in Figure 2.
CRAFT AND AUXILIARIES
Draco offers a high-performance yet affordable and low-risk suite
of hydro-mechanical capabilities to field fully supportable multi-
mission capable USVs. The principal characteristics are listed in
Figure 3. The hull form, illustrated in Figure 4, is based on
successful anti-slamming bow features of the ONR HDV-100
ocean prototype and the high-speed efficiency, stability and sea
keeping features of the Bladerunner Round Britain record holder.
The Navatek SAM MKII incorporates the Bladerunner air
entrapment tunnel hull design which provides superior static and
dynamic stability as well as a patented cushioning effect to
mitigate sea state-induced motions over the entire USV
operational profile.
A foldable arch provides the ability to raise and lower surveillance
sensors while maintaining a level operating attitude for the
sensors. This enables Draco to operate using onboard sensors for
launch & recovery while the arch is retracted, and perform mission
operations with the sensors in a more optimal location with the
arch raised. The arch is based on an electrically-actuated four bar
linkage design that maintains a level sensor deck during arch
deployment and allows mechanically linked antenna and light
masts to fold compactly during arch retraction.
Arch with sensors
Dual / redundant propulsion
system (engines / waterjets)
Electronics and other auxiliary systems
embedded in hull
High speed
hullform
Common electrical and hydraulic power
for ASW Mission Payloads
Hard attachment points
for ASW Mission Payloads
Communications for
remote video and data
Prototype
under
construction
Figure 2: Important features of Draco, such as embedded electronics and redundant systems enhance
system performance and reliability. Draco is powered by two Yanmar 6LY3A-STP engines and
Kamewa FF310 waterjets to handle craft propulsion and power
generation needs, and support the towing requirements of the
various ASW payloads. The engines and waterjets are controlled
by a vector control system which provides thrusts vector control for
low speed maneuvering and a computer interface for the
command and control system to effectively control the USV. The
engines are capable of operation on diesel and JP-5 fuels.
Electric power is generated onboard by an engine-driven
generator system providing redundant 1.2 kW @ 14 VDC, 6.5 kW
@ 28 VDC and 40 kW @ 350 VDC power. Additional power
conversion electronics provide 110 VAC for specific USV and
payload needs. Power distribution is handled by the embedded
Power Distribution Unit, enabling real-time switching and power
management, and monitoring of loads on all power circuits. The
PDU also contains remotely resettable circuit breakers and fuses
to provide short-circuit and overload protection. Total power for
payload use is at least 2.8 kW @ 28 VDC, 3.3 kVA @ 110 VAC,
and 16 kW @ 350VDC.
Thermal management of electrical and electronic subsystems is
accomplished with chilled water. A redundant chilled water system
reliably provides 16,000 BTUs of cooling for mission systems and
an additional 16,000 BTU for the core electronics with a degraded
operational capacity of 50% in the event an engine or cooling unit
should fail.
An FM-200 based fire extinguishing system is located below deck
in the engine room for fire suppression. This system is ideal for
marine engine compartment protection where the potential for a
fire hazard may occur. It will operate automatically through heat
activation and also has a manual feature to permit anyone
onboard the craft to discharge the fire suppression system.
The engine room has two bilge pumps; all other spaces have
single pumps. Every pump has its own bilge water switch. All of
the bilge water switches are automatically monitored by the core
system and the bilge pumps are controllable via the control system
and manually at the helm.
Draco is equipped with an electrically driven hydraulic unit to
provide 14 GPM at 3000 psi for mission system use. The
hydraulic system is controllable both electrically and via solenoid
valve, permitting the core system to manage hydraulic system
power usage as the USV performs its mission. Additional features
of the hydraulic system are 100% filtration and heating/cooling of
the fluid, enhancing reliability of the system and extending its
operational temperature range.
An interface will be provided on the USV to connect a portable
operator control station (POCS) to the core system for performing
pre-mission startup and system checkout, launch & recovery
operations, and post-mission status monitoring and shutdown. In
casualty and test situations, as well as emergency conditions, the
POCS can be taken aboard the USV and electrically
interconnected with the core system to bypass radios and take
direct control of the USV.
Deck hard points and interface panels are provided to facilitate
installation of a payload to the USV. The deck hard points are
load rated for the expected wave slamming environment with a
2,276 kg (5000 lb) payload installed. The above deck electric,
communication, hydraulic, and chilled water services will be
supplied at foredeck and aft deck locations to ease integration
issues with payloads.
A number of off-board interfaces are provided to support system
startup/checkout, maintenance, and system shutdown while
aboard the LCS. The USV will be stowed on an ISO-van
compatible cradle and tied down using tie down points integral to
the USV hull. This cradle doubles as an on-road method for
transporting the USV. Additionally, hull-mounted fuel system
fittings are provided for fueling/defueling operations, and the USV
also has seawater connections onboard to allow operation of the
USV engines while onboard the LCS.
Draco will be capable of being launched and retrieved in sea
states up to SS4 with the sea frame operating on best heading
both with and without the mission payload installed. It can be
launched, retrieved and handled by a four point lift, belly band lift
and ramp lift.


Patented or patent pending by Navatek, LTD. Images courtesy of Navatek, LTD.
Figure 4. The stable, ride-cushioning USV hull is derived from
other proven innovative hull forms.


Characteristic

Threshold/Objective
Design Goals
Length
12.2m (max)
10.9m
Beam
3.6m (max)
3.25m
Max Wt (w/o payload)
7,700 kg
7,700 kg
Payload
2,276 kg
2,276 kg
Payload deck space
Carry MS-OBS, UTAS
and UDS
32 m
2

Max Speed
35/30 kts
35kts
Towing 1600/800 lbs
20/10 kts
1600/20 kts
Sea Keeping & Stability:
Stable Ops
SS4/SS3
SS4
Survive
SS6/SS4
SS6
Launch & Recovery
SS4/SS3
SS4
Endurance
48/24 hrs
24 hrs
Figure 3. Principal Characteristics of Draco.
COMMAND AND CONTROL PROCESSING
The USV core electronics leverage COTS/MOTS technologies
packaged to operate within and withstand harsh environmental