UDT 2020 Warhead technologys impact on future capability Andrew Carr - - PDF document

UDT 2020 UDT Extended Abstract Template Presentation

UDT 2020 – Warhead technology’s impact on future capability

Andrew Carr1, Andy Burn2, Philip Cheese3

1Chief Engineer - Underwater, BAE Systems, Portsmouth, UK 2 Deputy Chief Engineer – Heavy Munitions, BAE Systems, Glascoed, UK 3Weapons Operating Centre Chief Technologist, UK MoD, Bristol, UK

Abstract — New materials and processes are emerging, potentially enabling significant improvements in warhead performance at reduced cost, small order quantities and reduced time to market. The UK’s Centre of Excellence for Energetic Materials is working together with industry to rapidly research and develop a number of key technologies and reduce the time to market of improved products, enabling greater defence capability. Three of the key technologies are: -  Resonant Acoustic Mixing – enabling the in-case manufacture of warheads with improved formulations  High Density Reactive Materials – improving the effectiveness in the UWW domain through use as reactive cones and liners  Flow Synthesis – allowing the production at scale of current and novel energetic materials. The UK is also working collaboratively to reduce time to market through Smart Qualification which will enable the rapid insertion of technology updates to meet new threats. I will discuss how these technologies may impact the underwater battlespace and enable the introduction of improved and novel capabilities in this arena.  Torpedoes

• Improvements to lethality of current systems and potential to reduce warhead size.

 Anti-Torpedo Torpedoes

• Enabling greater effect from ATTs and potential ATT/ASW weapons

 Depth Charges

• Improvements to safety/lethality of current systems or novel, small depth charge capability enable new concepts of
• peration

 Mine Countermeasures

• Reduced cost/size of mine neutralisers

1 Introduction

Energetic Materials and warhead technologies have incrementally improved in recent years, largely to improve their safety characteristics to meet Insensitive Munitions requirements. Novel energetic materials have been manufactured in small quantities but many have proven difficult to scale up and hence have not yet found their way into defence

• products. Performance enhancements have been limited by

traditional manufacturing techniques and the ability to safely and consistently produce high quality energetic fills. Recent advances in materials production technologies now have the potential to allow dramatic improvements in performance at reduced cost and faster time to market.

2 New Technologies

2.1 Resonant Acoustic Mixing This is a modern manufacturing technique that mixes materials by oscillating rapidly with a relatively large displacement, generating high energy levels up to 100g. It continuously monitors mixing conditions to maintain the system at its resonant frequency, both delivering maximum power and with greatest efficiency. Faraday instabilities – non-linear waves caused by a high amplitude periodic driving force – are created on the surface and within the material, resulting in rapid, thorough mixing. This technique is particularly useful when the mixing vessel is the casing of the article to be filled. This removes the need to transport and pour high solids loaded material and allows compositions to be developed that were previously impossible to fill into products at scale. Recent work undertaken in the UK has indicated the potential for significant improvement to blast and shaped charge performance by using this manufacturing technique to fill charges with current materials, when compared with planetary mixing. Mixing in case allows for a significant reduction in process

• waste. Process control is automatic, although it will require

strict quality control on incoming ingredients. The opportunity to increase solids loading should only improve matters further. 2.2 High Density Reactive Materials These are a new class of materials being investigated to increase the lethality of warheads comprising metals such as aluminium, titanium or zirconium. They cannot be detonated, but are capable of releasing significant energy through rapid oxidation

• reaction. Indeed they can provide greater energy than

traditional explosives per unit mass, but at a reduced rate. Current activities have largely focussed on their use in air and have been demonstrated to provide significantly

UDT 2020 UDT Extended Abstract Template Presentation/Panel greater levels of target damage when used as casing materials, when compared with standard warhead or bomb bodies. Modern additive layer manufacturing techniques can now be employed to manufacture HDRM as a structural element of a munition, although the mechanical properties required may constrain the exact choice of material

• allowable. Generally, the greater the strength required, the

lesser the energy it can contribute to the system. For underwater applications, research is more limited but BAE Systems is working together with MBDA to develop HDRM casings with RAM tailored explosive formulations for underwater effect. 2.3 Flow Synthesis This is a technique that is widely used within the chemicals manufacturing and pharmaceutical industries but is only now being implemented within the defence sector for the manufacture of energetic materials. Continuous flow reactors are used which improve heat transfer (due to large area: volume ratios) and mixing due to the smaller scales used. In general the processes are safe as thermal mass is dominated by the equipment and reaction volumes are

• small. However there is significant activity to ensure that

this remains the case for the manufacture of energetic materials. The technique has the potential to allow the manufacture at scale of novel energetic materials. As it is a continuous process, the quantity of material produced can be tailored to meet requirements, significantly reducing process waste. Flow synthesis gives a potential route to manufacture

• f novel energetic materials in useful quantities. There are

several candidate materials that have the potential for significant performance and safety improvements, particularly in the underwater domain. Currently these are either prohibitively expensive, or simply not available in the required quantities for use in underwater weapons.

3 Smart Qualification

This is a generic term for improved qualification methodologies based

• n

a more fundamental understanding of materials properties. In the main, current qualification testing is old- fashioned and provides a relative result based on experience from other systems. This has performed well from a safety perspective, and has helped to drive safety improvements, but is on the point of failure where new energetic materials act differently from expected. By focussing on more small scale scientific tests, we should be able to reduce overall costs of qualification, whilst significantly reducing the time to market of individual munitions. Resonant Acoustic Mixing is one area driving the need to improve current methods of qualification and batch proof testing. The potential for in case mixing of warheads leads to the dilemma of how to handle batch sizes of one. Process control and automation together with strict control

• f dose quantities and incoming ingredients is the likely

answer, but again the key parameters that influence safety and performance may need to be better understood.

4 Underwater weapons opportunities

The technologies highlighted above create considerable

• pportunities to improve the effectiveness of current

weapons and enable more rapid development of future systems. Current systems may be manufactured in small quantities to meet demand by using RAM mixing alone. This may provide some improvement to performance from improved mixing, creating more homogeneous fillings and potentially improved interaction with shaped charge liners. Further improvements may be gained from using a RAM tailored explosive. The solids loading of the fill may be substantially increased as the mix in case process does not involve interaction with moving metal stirrers, or the need for moving the mixed material through pipes. The above two opportunities require no new materials, merely a change to mixing technique or the formulation. By changing the cases to HDRM, coupled with RAM tailored explosives, even greater performance can be

• btained. Current sacrificial liners can be changed to

HDRM with relative ease, although oxygen rich formulations would be required to make best advantage from this technology. The additional effect could significantly improve the effectiveness of modern warheads to defeat more advanced platforms. Flow synthesis provides a route to implementation of novel energetics, which when coupled with RAM and HDRM allow the creation of novel, high performance warheads to replace current designs in a number of applications. The trend towards smaller, lighter platforms may necessitate the use of smaller weapons. It would be impossible to replicate the effectiveness using traditional formulation and manufacture, however the techniques above could provide similar explosive effect from a reduced size/mass warhead. 4.1 Anti-Submarine Warfare Heavy and lightweight torpedoes are likely to remain at current sizes due to the requirement to effectively acquire and track targets, necessitating an effective sonar head. Modern Submarines have greater protection and so, more effective blast or shaped charge warheads will be required to defeat them. The techniques mentioned would allow significantly improved explosive performance when combined to produce significantly greater output in the same volume. They could also be combined with the ever increasing interest in smaller swarming systems to provide similar levels of effect in a smaller system. The potential to combine the output of several smaller systems is another area of interest, but one that requires further work to understand how to best utilise a combination of shaped charge and blast output. 4.2 Anti-Torpedo Systems Hard kill Anti-Torpedo solutions are increasingly in demand and current lightweight torpedoes are optimised for anti-submarine warfare. It would be ideal to have one

UDT 2020 UDT Extended Abstract Template Presentation/Panel solution that deals with both threats, thus reducing the requirement to manage different weapons. The simplest opportunity would appear to be to improve the blast/bubble effect of a lightweight torpedo whilst retaining shaped charge performance for its primary ASW role. By increasing the amount of energetic material within the warhead and adding an HDRM liner, more conventional lightweight torpedo designs could provide a greater blast or bubble effect in addition to the primary shaped charge. This would improve effectiveness against small, fast moving targets where a shaped charge jet is unlikely to have a direct effect. 4.3 Depth Charges With the proliferation of submarines and UUVs, there is increased interest in simpler and cheaper depth charge systems as more and more nations seek to counter the underwater threat. Also littoral combat is of increasing interest over blue water warfare. The current stock of depth charges are generally of a cold war design, following on from WWII concepts. Future systems may need to replace legacy energetic fills with more powerful materials, or indeed to enable greater effect from smaller, and/or guidable systems. Again, a combination of techniques above give a potentially significant improvement in overall lethality in both cases. 4.4 Mine Countermeasures Mine warfare systems are unlikely to require any significant increase in performance. The two key areas of exploitation are likely to be: -

• 1. Reduce cost through the RAM mixing, in case of

current explosive formulations

• 2. Reduce system size through use of novel

materials, whilst not exceeding current costs

• 3. Batch size of 1 warhead manufacture, as an

almost on-demand capability

5 Impact to future capability

Improved effectiveness of shaped charge, blast, and dual effect warheads will enable a proliferation of future systems able to meet a number of user needs. Smaller systems will be able to attain an improved level of lethality and be able to be deployed more rapidly by being gun or rocket launched. They may be deployed from a greater number of platforms, from traditional submarines, surface ships and air platforms to future UUVs, USVs and UAVs, delivering a persistent threat or defensive capability. Future underwater warfare may look significantly different to today, with USVs in shallow water conducting ISTAR or other missions. Limitations on future platform space and carrying capacity may require miniaturisation of weapons and the use of swarms may mean that dual effect or tuneable warheads are required to give mission flexibility.

6 Conclusions

Three independent and complementary technologies are within the grasp of the warhead designer.  Resonant Acoustic Mixing, allowing greater energetic materials solids loading to be delivered, in batch sizes from 1 at potentially reduced cost.  High Density Reactive Materials, allowing a greater underwater blast/bubble to be created from structural elements of the weapon.  Flow Synthesis, providing a route to manufacture for high performance novel materials. Together these have the potential to impact the design

• f new warheads to improve lethality or to create new,

smaller payloads with similar effect. New qualification methods will allow these technologies to be exploited, brought to market, and fielded against new threats much more quickly.

7 Acknowledgements

For example, the UDT Conference Committee thanks Davide Borra and UDT Committee Member Paolo Proietti for the use of the IEEE MIMOS Conference template format.

8 References

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9 Author/Speaker Biographies

Andrew Carr List 50-word author/speaker biographies for each author or speaker if your extended abstract describes a panel

• presentation. List each author’s name in bold type

followed by the short biography and a space between each biography. Andy Burn Philip Cheese

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