Artillery Compendium-Armada April-May 2015

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The Multi Service-Standard Guided Projectile is a 127 mm naval ammunition which, fitted with a sabot, can also be fired by 155 mm howitzers to reach out to a mere 120 km with a 52 calibre gun. (BAE Systems)

Now in full production, the Excalibur IB aims at the international market. A laser guided version is under development. (Armada/P. Valpolini)

guide the ammunition with utmost precision onto its intended target, or a different target within the seeker field of view should the tactical situation change, or a moving target. No in-service date has been announced for the Excalibur-S, Raytheon awaiting a launch customer to finalise concepts of operation before starting the qualification process. Raytheon leveraged the Excalibur effort to develop a naval 127 mm guided ammunition, known as Excalibur N5 (for Naval 5-inch) that exploits 70% of the 155 mm round technology and 100% of its guidance and navigation system. According to Raytheon the new round will more than treble the range of the Mk45 naval gun, the company stating that testing “has provided Raytheon the data needed to progress to a live fire guided flight test in the near future.” BAE Systems MS-SGP (Multi ServiceStandard Guided Projectile) is part of a joint programme aimed at providing both shipborne and ground artillery with a long range guided artillery ammunition. The new round is a 5-inch (127 mm) affair which in a land version would be known as a saboted round. The guidance system leverages experience acquired with the LRLAP (Long Range Land Attack Projectile), the 155 mm developed for the Zumwalt-class destroyers and fired by BAE Systems 155 mm Advanced Gun System. The guidance system is based on GPS and inertial systems, an uplink allowing re-targeting the round in flight (time of flight to 70 km being three minutes

and 15 seconds). The MS-SGP rocket motor has been tested and a round performed a guided flight test from a naval Mk 45 gun, reaching a target at a range of 36 km with an error of only 1.5 metres and an angle of 86°. BAE Systems is ready to manufacture test projectiles for ground platforms; the challenge here is to verify the correct functioning of the breech block with the 1.5 metre long and 50 kg round (16.3 kg of which represent the HE warhead). According to BAE Systems the accuracy and angle of fall overcompensate the reduced lethality of the under-calibre ammunition, which also allows to reduce collateral damages. Another key role of incoming tests is to verify the performances of the retention device used to keep front canard guidance wings and rear wings closed until the round has come clear of the muzzle brake, a problem that does not exist on naval guns. The angle of fall, which can reach 90° compared to the typical 62° of a ballistic ammunition, allow the MS-SGP to be used in “urban canyons” hitting relatively small targets, which until now required to be neutralised by much more expensive weapon systems—the round is said to be well below the $45,000 mark. BAE Systems is gathering additional test data that allowed to refine the MS-SGP maximum range estimates. Based on our current test data maximum range is 85 km fired from a 39 calibre gun with Modular Artillery Charge system (MAC) 4 and 100 km with MAC 5 (which increases to 120 km from a 52 calibre gun). As for the naval version it has a 100 km range when fired from a 62 calibre gun (Mk 45 Mod 4) and 80 km from a 54 calibre (Mk 45 Mod 2). According to BAE Systems and US Army data, 20 MS-SGPs can achieve what requires 300 current 155 mm shells on a 400x600metre target. In addition the MS-SGP should reduce to one third the number of artillery battalions. A spiral programme is foreseen to give the MS-SGP increased performances, with a low-cost EO/IR seeker being envisaged to cope with moving targets. The US Navy plans to initiate an acquisition programme for the 127 mm guided round in FY2016, while the Army should follow at a later date. The Oto Melara Vulcano family of ammunition was developed with a view to increasing land and naval gun range and accuracy. Following an agreement between

Germany and Italy, the programme is now carried out jointly with Diehl Defence since 2012. While naval developments were carried out with 127 mm, and later 76 mm calibres, land variant work focussed on 155 mm. Three versions of the Vulcano 155 mm are in the last development stage: an unguided one known as the BER (for Ballistic Extended Range), a GLR (for Guided Long Range) available with IMU/GPS terminal guidance, and an additional variant with semi-active laser guidance (a far-infrared seeker is also foreseen but will be limited to naval rounds). The guidance section is located at front with four canards ensuring steering. Increasing range while keeping internal ballistic, chamber pressure and barrel length unchanged meant improving external ballistics and therefore reducing drag. A 155 artillery shell has a diameter to length ratio of about 1:4.7. A subcalibre option was thus adopted, bringing the ratio to about 1:10. A roll-decoupled tail section was also adopted to improve the

A mock-up of Oto Melara’s 155m Vulcano round that comes in extended range and guided versions, with respective ranges of 50 and 80 km when fired from a 155/52 mm gun. (Armada/P. Valpolini)

aerodynamic aspect and reduce sensitivity to lateral wind. The only downside came from the sabots, which require a relatively wide safe frontal area. The Vulcano BER is fitted with a purposely developed fuse which, for the 127 mm calibre, features four modes: impact, proximity, time, and height of burst. For the 155 mm the proximity mode is dropped. In the height of burst mode a microwave sensor allows to feel the distance from the ground, activating the exploding chain according to the programmed height. The fuse is programmed through electric

Compendium Artillery 2015

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Artillery Compendium-Armada April-May 2015 by Armada International & Asian Military Review - Issuu