Home' Defence Technology Review : DTR JUN 2015 Contents INNOVATIONS
DEFENCE TECHNOLOGY REVIEW | ISSUE 10 | JUN 2015
The LSAT 5.56mm CT LMG complete
with pouch of cased telescoped
ammunition. Images: Textron Systems
The US Army’s Picatinny Arsenal is taking part in the
development of a new, lighter version of the long-serving
M249 Squad Automatic Weapon (SAW) that reduces overall
weight by 47 per cent or from 7.94kg to 4.17kg.
The initiative leverages heavily off the development work
done by Textron Systems with its Lightweight Small Arms
Technologies (LSAT) redesign of the M249 SAW and is a
combined effort with the Joint Service Small Arms Program
Office at the US Army Armament Research, Development
and Engineering Center at Picatinny Arsenal and the US
Navy’s Office of Naval Research.
The LSAT weapon, now called the Cased Telescoped
Light Machine Gun (CT LMG), reconfigures the M249 SAW
to fire 5.56mm cased telescoped ammunition, requiring
significant rearrangement of components and detachment of
the firing chamber from the barrel. Other changes included
machining components down in size. No new or exotic
materials were used.
Custom-designed cased telescoped ammunition replaces
the traditional M855 brass cased ammunition. With rounds
contained within a plastic-based case, linked cased
telescoped ammunition weighs 39 per cent less than the
Live fire testing of the CT LMG was first undertaken by
soldiers at Fort Benning, Georgia, in September 2011 as
part of a technology readiness level 7 (TRL 7) assessment.
This included a Military Utility Assessment performed by the
Maneuver Battle Lab using eight CT LMGs, which fired a
combined 50,000 rounds of cased telescoped ammunition
during the three-week evaluation.
The CT LMG design was again assessed in the Army’s
Dismounted Non-Networked Experiment in August 2013 at
Fort Benning, where seven weapons and 9,700 rounds of
cased telescoped ammunition were provided to three rifle
squads and one weapon squad for a series of range events.
The squads recorded increased lethality at all ranges with
faster speed of engagement and better shot placement.
The CT LMG’s reduced bulk and weight improved soldier
US Army pushes case for lightweight M249
BELOW: The 5.56mm linked cased telescoped ammunition
developed for the CT LMG.
Active damping applied to CV90
mobility and led to more precise fire in standing and kneeling
Those and subsequent tests have confirmed that the CT
LMG is 12 per cent more effective in hitting the target, could
achieve 25 per cent more first-round target hits, and had
a 20 per cent improvement in short-range engagements
over the heavier M249 SAW. More than 85,000 rounds of
5.56mm cased telescoped ammunition from 10 CT LMG test
weapons have now been fired.
Testing has also indicated that the new external firing
chamber assisted in keeping the gun cooler and reduced the
likelihood of rounds cooking off in the chamber. The weapon’s
long-stroke, soft recoil system also contributed to better
Development of the CT LMG is continuing, with long-
term testing to determine the robustness of the design after
prolonged use. The next round of testing is scheduled to
commence in the third quarter of 2015.
Textron told DTR that the company will deliver a 5.56mm
cased telescoped carbine version of the CT LMG
demonstrated to TRL 6 in early 2016. It has also completed
a series of trade-off studies on weapon and cartridge sizing,
and has moved into detailed design and analysis for a
7.62mm machine gun using cased telescoped ammunition.
Along with the corresponding cased telescoped ammunition,
a 7.62mm machine gun operating system is planned for
demonstration at TRL 5 in early 2016.
– Ian Bostock
From left to right: 5.56mm cased telescoped, 5.56mm M855,
7.62mm cased telescoped and 7.62mm M80 rounds.
BAE Systems has successfully tested a suspension
upgrade for the CV90 tracked combat vehicle family inspired
by technology developed for Formula One racing back in the
Originally intended for ultra-lightweight carbon fibre racing
cars weighing 700kg at best, BAE Systems Hagglunds
engineers have adapted active damping for use on heavy
tracked vehicles such as the 35 tonne CV90.
Unlike conventional, passive suspension systems that
absorb the shock of rough terrain as it occurs, the active
damping system works by sensing the speed of the
vehicle and lay-out of the terrain ahead and responding
by pressurising the suspension to keep the
vehicle on a level plane at all times and its
tracks in contact with the ground as much as
Testing by BAE Systems has shown the
active damping system reduces vehicle pitch
acceleration by approximately 40 per cent.
As the tracks are able to remain in contact
with the ground for longer this translates into
greater agility and higher speeds. In recent
trials a CV90 fitted with active damping set a
new speed record on a rough terrain course,
beating the main battle tanks.
The increased stability across all terrain
types provided by the active damping reduces
vehicle wear and tear, which subsequently
results in lower through-life repair and support costs; this is
despite vehicles being able to travel 30-40 per cent faster
over rough terrain.
The smoother ride also has benefits for the crew in
reducing fatigue, a critical factor on the modern 24/7
battlefield. The vehicle’s reduced vertical motion also
increases the gunner’s probability of finding and hitting
targets when firing on the move.
The company may be aiming the active damping
upgrade to existing CV90 users, but especially Sweden
which is planning an upgrade of several hundred CV90s
in the short term.
– Ian Bostock
Testing of the active damping suspension system
on CV90 has proven its suitability for heavy
tracked armoured vehicles. Image: BAE Systems
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