Page 42 - NAVAL FORCES 03/2017

Protection & Mobility

switchgear and cabling needed to send the DC power systems include fewer losses thanks Laser Weapons Maturing
Other promised advantages of well designed
power to the loads, while Power Conversion
Features Modules convert electricity from one voltage to the absence of reactive power, potentially a 20kW High Energy Laser (HEL) variant at
On the weapons front, Rheinmetall tested
lower acoustic signatures, better conversion
and/or AC frequency to another, and Energy
Storage Modules (ESM) store energy provided
sea in 2015 aboard a German Navy warship,
efficiencies due to a reduction in the number
by/to the electrical power system. Power Con-
storage devices that are inherently DC, such
trol Modules consists of software necessary to of conversion stages, plus opportunities to use while, the US Navy has conducted tests of the
30kW solid state AN/SEQ-3 fibre laser aboard
operate the power system and, finally, Propul- as batteries, super capacitors and fuel cells the LPD USS “Ponce,” destroying munitions
sion Motor Modules convert electrical power for what the authors refer to as power failure aboard small target vessels and downing a
into mechanical power to propel the ship. ride-through duties and de-coupling of pulsed UAV. Also known as the XN-1 LaWS, the
The “Zumwalts” themselves are powered loads. However, DC systems are not ready for weapon was developed by several US Navy
by two 45.4-MW Rolls-Royce Marine Trent naval service in relation to circuit breaking organisations and an industrial team led by
MT30 gas turbines driving Curtiss-Wright protection in high voltage applications, Meggs Kratos Defense and Security.
electric generators and a pair of and two and Pollard point out. There is potential confu- The service has also revealed its intention
3.8MW Rolls-Royce RR4500 auxiliary tur- sion here, as some “medium voltage” systems to fit destroyers and other ships with defensive
bine generators based on the MT5S engine. As work with what might otherwise be considered lasers and is working with Northrop Grumman
with the Type 45s, GE Power Conversion sup- very substantial voltages in the range 4,000- to develop a 150 kW laser to be tried at sea
plies the AIMs for propulsion, switchboards, 6,000V or more. aboard the Navy’s Self Defense Test Ship
propulsion converters, power management, While mechanical circuit breakers for such (SDTS), the former USS “Paul F. Foster”
power quality equipment and system engineer- applications are commercially available, they DD-964) during the third phase of its devel-
ing and integration. are heavy, slow and bulky. Solid state alterna- opment.
tives work much faster, but cause losses in the On 6 January, the UK MoD announced a £30
circuit when it is operating normally in its on- million investment in a laser weapon intended
Back to the Future with DC? state, its safety isolation performance depends to down or disrupt drones, missiles, fast attack
on the strength of the positive-negative (p-n) boats, and incoming mortar rounds. Under
That long term goal of a DC IPS may seem junction in the semiconductor material, and, the Directed Energy Weapon (DEW) project,
odd, as DC power came in with steam-driv- furthermore, they are not yet commer cially a consortium led by MBDA, with QinetiQ,
en warships in the late 19th Century and was available. Finally, the authors wrote, hybrid and Leonardo that also includes GKN, Arke,
being almost universally replaced by three- circuit breakers combine solid state compo- BAE Systems and Marshall, has two years to
wire AC systems in new western ships by the nents for speed of isolation with mechanical design, build, and then test the weapon, known
1950s. However, as R.W. Meggs and C. Pollard back up in case the p-n junction fails, but are as DRAGONFIRE, at sea and on land.
from BMT Defence Services argue in a paper more complex and, like their solid state coun- If successful, said the MoD, the first such
on protective devices for DC power networks terparts, remain unavailable commercially weapons could be fitted to RN vessels in the
published in November, DC has a number of and lack a mass market application to provide middle of the next decade.
advantages for future warships. economies of scale in production.
For example, much of the electrical power Meanwhile, power demand from sensors Rail Gun Progresses
is either consumed as DC in electronic equip- and weapons is set to continue its apparently
ment, or passes through a DC stage in pow- inexorable rise. For example, the AN/SPY- Electrically powered offensive weapons
er converters and motor drives. Meggs and 6(V) Air and Missile Defense Radar (AMDR) are also in the works, as BAE Systems is now
Pollard also point out that DC can transmit under development by Raytheon for the Flight working on the second phase of the electro-
about 23% more power than an equivalent AC III DDG-51 destroyers will require an increase magnetic rail gun project it was awarded by
system for a given mass of copper in the wir- in both their power generation and cooling ca- the US Office of Naval Research in 2013,
ing etc. pacities. and a hypervelocity guided projectile for it to
launch. In this phase, the company is to up-
grade the launcher and its pulsed power supply
from single-shot to multi-shot capability.
The Laser Weapon System (LaWS) Test firings already completed include a 33
is put through a systems check megajoule shot in 2010 from a laboratory gun
aboard the Afloat Forward Staging Base
(Interim) USS “Ponce” (AFSB[I] 15). at the Naval Surface Warfare Center-Dahlgren
Division, an energy level that the company
says would achieve a range 110 nm. This was
followed in 2012 by firings at what the compa-
ny terms tactical energy levels.
When fully weaponised, said BAE Systems
commenting on the February acquisition of
IAP, a long-time subcontractor on the develop-
ment programme, the gun will deliver hyper-
velocity projectiles to support the US Marines,
ground forces, as well as for ship defence. The
company claims it will be able to fire a projec-
tile 100nm at launch velocities of up to Mach
7.5 and impact velocities around Mach 5.
With weapons such as these, electrical
power systems will not only propel future
warships and run their services, sensors and
communications, but also fill their energy
magazines. NAFO
40 NAVAL FORCES III/2017