Introduction

Armored fighting vehicle (AFV) effectiveness and survivability are in large part dependent upon the selection of a tank’s engine. Various operational and technical factors come into play, but one of the most consequential decisions relates to the type of military engine technology selected – diesel or land gas turbine.

Engine requirements of AFVs differ significantly from engine designs used in civil applications. These differing requirements complicate the design appreciation process and require the development of specialist engines specifically to meet the demands of diverse military operational environments. Since many modern AFVs can weigh over 65 tonnes, it is accepted that engines need to produce more than 1000 kW in order to provide adequate mobility. The rule of thumb used is that the engine to vehicle mass ratio should exceed 20 hp/ton to prove a satisfactory level of automotive performance.

This report provides an overview of spark ignition and diesel engine technology and describes why most military vehicle manufacturers have chosen to produce AFVs that use diesel engines. This report then analyses the advantages and disadvantages of the gas turbine engines with comparisons drawn between the M1A2 Abrams, Challenger 2, Leclerc and Leopard 2 main battle tanks.

Diesel Dominance of Post WW2 AFV Design

There are three properties of combustion fuels that determine their suitability for use in an AFV. These consist of specific energy capacity per unit of volume, flammability and the manner of energy release¹. The specific energy capacity by weight of a fuel is often used to justify an argument for weight efficiency in commercial environments. Conventional commercial land vehicles need to carry less fuel as they weigh significantly less than an AFV. It is therefore appropriate for conventional land vehicles to specify effectiveness of a fuel relative to its specific energy capacity by mass. This is the case since conventional vehicles are not armored and thus not constrained by the requirement to minimise their volume under armor. Minimizing volume under armor is a critical design consider for armored fighting vehicles and such design approaches are driven by a fundamental understanding of the Iron Triangle guiding AFV design.

In order to meet satisfactory operational range requirements, AFVs must carry significantly more fuel, moreover, this fuel must be protected under armor to mitigate fuel explosion threats posed by different types of kinetic ammunition. Reducing fuel volume for the same energy capacity can reduce the required amount of armor, its weight and increase a vehicle’s operating range. The table below illustrates that whilst the specific energy of diesel and petrol are very similar; diesel is superior due to its higher energy density. Energy density, not specific energy, is the desired characteristic for AFV applications.

Table 1 – Fuel energy data from IOR Energy

AFVs are designed to defeat threats posed from a variety of chemical and kinetic ammunition types, such a high explosive (HE), armor piercing fin stabilizing discarding sabot (APFSDS) and high explosive squash head (HESH) rounds. Since World War II, there have been two main design weaknesses related to AFV design; specifically fuel and ammunition storage. Penetration of the AFV fuel tank by chemical and kinetic threat rounds can cause catastrophic fuel explosions. One particular benefit associated with the use of diesel fuel is that it has a significantly lower flash point than petrol and does not readily form a vapour at most ambient temperatures. This desirable chemical property of diesel makes it more stable and safer than petrol; history has now demonstrated that it is considerably safer to store diesel in an AFV than petrol.

Table 2 – Stability components of diesel and petrol

Diesel engines operate using different fuel ignition principles to petrol engines. Whilst petrol engines require spark ignition to create combustion; diesel engines ignite fuel under compression due to the lower autoignition temperature of diesel (see table 2). Petrol engines have relatively lower compression ratios than diesel engines which gives them a performance advantage per unit swept volume, however, diesel engines perform better under part load conditions.  This feature of diesel engine operation is extremely important in driving down the logistic burden associated with AFV fleets gross fuel usage and resupply operations. Diesel engines can sustain a high degree of forced induction whereas petrol engines suffer from efficiency loss at proportionally similar induction values⁴. Whilst not providing the same peak torque and power performance characteristics of petrol engines (on an equivalent swept volume basis), diesel engines have many desirable operational and technical qualities that enhance their appeal for use if AFV applications. The most important relate to reduced fuel flammability and lower specific fuel consumption.

Whilst petrol engines may give greater performance per unit of swept volume, diesel engine fuels have a higher energy density, are safer to store and perform better at part loads or under forced induction. Shortfalls in diesel engine torque and power performance and now easy overcome by the use of high-pressure turbochargers, albeit as the cost of increased engine complexity, cost and reduced reliability.  As such diesel engines have become the preferred military engine choice to petrol engines in AFV design. Notable exceptions to this are the U.S. Abrams and Russian T-80 series of tanks.

Issues and Features of Gas Turbine Engines Relative to Diesel Engines

The technology to integrate gas turbine engines into AFVs first appeared in production tanks with the advent of the Russian T-80 in 1978⁵. Although gas turbines are an effective competitor to reciprocating diesel engines, a number of technical considerations must be explored first to understand the relative advantages and disadvantages of the two technologies. The fuel consumption, endurance, reliability and maintainability must be weighed against the power to weight ratio and power density delivered by the gas turbine

Gas turbines were incorporated into early 3rd generation tanks such as the T-80 and M1A1. This is due to gas turbine engines being able to deliver significantly higher power to weight ratios and very desirable torque backup characteristics over the full engine operating speed range compared to that of diesel engines of similar outputs. Modern supercharging and turbocharging packaging solutions have bridged the gap in recent years such that diesel engined tanks now have similar power to weight ratio to that of ground turbines in tanks (see table 3 below).

Table 3 – Tank power to weight ratios and service entry dates⁶.

Power density is the engine power produced per unit volume of the engine. Gas turbines have higher power densities which reduces the volume under armor used by the engine. This is a desirable outcome as it increases the useable space under armor for other requirements such as ammunition storage. Gas turbines that incorporate a recuperator to reduce fuel consumption have a similar power density to diesel engines⁷. As such gas turbine engines retain a power density advantage over diesel but at the expense of considerably higher fuel consumption values.

Fuel consumption is proportional to the weight of the vehicle and overall driveline mechanical efficiency. When considering a like diesel and gas turbine vehicle, the gas turbine consumes significantly more fuel as it is most efficient when operating at high rpm (see figure 1 below), whereas the diesel is considerably more fuel efficient at part loads (such as idle). Part load engine operation is an unavoidable part of routine AFV military ground operations as they spend considerable time operating in a stationary mode whilst conducting surveillance, reconnaissance and other tactical tasks.

Figure 1 – Gas Turbine Specific fuel consumption vs engine load⁸

This causes gas turbine AFVs to have a limited operational dwell time or requires an auxiliary power unit to run ancillary systems whilst the engine is switched off.⁹ Although requiring more fuel, gas turbines have better torque backup characteristic than diesel engines particularly at low engine speeds. Whilst diesel engines produce torque drops away at low rpm, gas turbine engines torque increases almost linearly at lower rpm ranges (see figure 2).

Figure 2 – Gas turbine torque curve¹⁰

Gas turbines and diesel engines are considered to be similar in reliability when subjected to manufacturer specified maintenance intervals and procedures. Whilst the service intervals for gas turbines and diesel engines are comparable in civilian roles; the gas turbine is more sensitive to operation in adverse environments (such as deserts) due to its tighter tolerances and higher air intake rate¹¹. The regular inspection requirements of turbine engines are significantly more involved and can only be conducted by specialist personnel and specialist facilities. Replacement parts for turbine engines are significantly more expensive due to the aerospace nature of the exotic materials used to sustain high operating temperatures within the engine.

Gas turbines generate significantly less noise than diesel engines¹². Whilst a positive attribute, it is noted that most AFV noise is generated through the tracks and the motion of the vehicle itself. Gas turbine engines produce significantly more and higher temperature exhaust gas. This makes gas turbine engine AFVs more susceptible to detection and targeting by technologies using infrared optics and targeting by technologies using infrared optics within the targeting system. Consequently, gas turbine engines have an overall detrimental effect on the AFV survivability.

Implications of Engine Choice on Operational Effectiveness

The future operational effectiveness of heavy AFVs will be affected by the choice of engine technology as each has different advantages and disadvantages. The key technical issues worthy of consideration include power to weight ratio, through life maintainability, thermal signature, fuel consumption and power production.

Power- to-weight ratio. It is clear that gas turbine engines have a higher power density than diesel engines. For a given output, a gas turbine engine weighs less and takes up less volume under armor than its diesel counterpart. However, this fact does not take into account the ancillary systems used by the gas turbine. Gas turbines require larger air intake assemblies, heat exchangers and auxiliary power units to enable dwell time. Furthermore, gas turbine equipped AFVs must carry significantly more fuel than a diesel AFV for the same operating range. Whilst the exact breakdown of these components is beyond the scope of this whitepaper, one can observe that the French Leclerc AFV maintains a higher power-to-weight ratio than the M1 Abrams (as depicted in table 3) whilst differing in weight by only 3 tonnes. With arguably little discernible power-to-weight ratio difference between heavy AFVs using either a diesel or gas turbine, it appears difficult to justify the additional fuel burden on the logistics chain borne by ground gas turbine technology.

Through-life maintainability. As discussed above, gas turbines are a significant maintenance burden for any land force. Gas turbines require more frequent, more detailed, more specialised and more expensive maintenance than diesel engines. This can limit operational availability for three reasons: 1) AFVs must be accompanied by a significant logistics footprint wherever they go, reducing operational flexibility, 2) lower mean operating time between services reduces track miles that can be accrued thus reducing available training time, and 3) higher maintenance and fuel costs reduce operational activity due to significantly increased operating costs.

Thermal signature. Gas turbines produce a higher infrared signature as discussed earlier. Since anti-tank weapons pose a significant battlefield threat, AFV equipped with a gas turbine are likely to reduce the overall vehicle survivability when compared against diesel equipped AFV.

Fuel Efficiency. Gas turbine engines have significantly inferior specific fuel consumption rates at part load (see figure 1). It is most efficient to run the turbine at maximum rpm at all times. Even at peak fuel efficiency, gas turbines are significantly less fuel efficient (in the order of 10-20%) when compared to diesel engine of comparable power output. Poor fuel efficiency is the most significant and detrimental factor associated with gas turbine engines that do not operate continuously at 100%. In fact, the gas-guzzling, gas turbines used in the US Abrams M1 tanks during Operation Desert Storm (1991) are attributed to significantly slowing the operational advance of allied forces during the short nine-day campaign.

Engine Torque. Gas turbines have more desirable torque backup characteristic as discussed in paragraph 11. This is particularly beneficial to mobility performance when AFV need to operate at low speeds in marginal terrain or in support of dismounted infantry. This high torque provides excellent low-speed, tractive effort performance and thus greatly enhances vehicle mobility.  However, most of this operational advantage is largely negated by the use of diesel engined AFVs using skid steering transmissions fitted with hydro-dynamic torque convertors. Modern AFV powerpacks using German MTU-Renk engine-transmission combinations offer torque backup characteristics that almost match those of gas turbine units.

Recent Developments – Abrams M1E3

With the U.S. Army cancelling the M1A2 SEP version 4 program in 2023, Abrams’ tank modernization efforts have now turned to developing the M1E3 variant – a heavy tank with a hybrid electric drive.  In mid-December 2025, General Dynamics Land Systems delivered the first M1E3 prototype, marking a significant milestone. Operational testing is planned through 2026, so we will know shortly if this bold implementation by the U.S Army of a hybrid electric drive into a heavy tank finally provides the technology breakthrough that has been so elusive over the past 100 years in relation to military hybrid electric drive propulsion.

Conclusion

Gas turbines held a power to weight ratio advantage over conventional diesel engines from the late 70s to early 90s that saw their integration into AFVs like the T-80, M1A1 and M1A2. Diesel engines are not able to produce power densities greater than that of gas turbine itself, but modern military diesel engines can be integrated into an AFV utilising a whole of system approach that can equal or better a gas turbine. Gas turbines have favourable torque backup characteristics, but this must be weighed against increased IR signature, difficulties in maintainability and poor fuel economy. Whilst gas turbines have the capacity to produce higher peak performance, the throughlife requirements of an AFV must be considered in parallel.

Diesels perform effectively across a broad range of mission profiles, cost less to run and maintain, and have a smaller logistics footprint. Diesel AFVs are easier and cheaper to purchase and disperse amongst fighting brigades as they do not require as much specialist knowledge or equipment. As such, until the main drawbacks associated with gas turbine engines are overcome, diesel engines will remain the backbone of AFV formations.  Military vehicle enthusiasts now anxiously await the results of M1E3 operational testing to see if the U.S. Army’s bold move to implement of a hybrid electric drive into the Abrams tank succeeds and forever changes the direction of propulsion systems used in heavy combat vehicles.

Written by: Mark Eggler and Jesse Spiller

References:

1. Kenneth Macksey, Tank warfare : a history of tanks in battle, London : Hart–David 1971

2. Glenn Elert, Ignition Temperature of Gasoline, The Physics Factbook, 16 Jun 13

3. United States Department of Labor, Occupational Health and Safety Chemical Sampling Information, 16 Jun 13

4. Klaus, Handbook of Diesel Engines, Mollenhauer, 2010

5. Wilson, T—80U Main Battle Tank, FAS Military Analysis Network

6. Engine data drawn from wikipedia.org

7. Walsh, Fletcher, Gas Turbine Performance, Wiley & Sons, April

8. Retrieved from Honeywell.com

9. Rajput, Power Systems Engineering, Laxmi, 2006

10. Retrieved from www.chrysler.com on 16 Jul 13

11. Boyce, Gas Turbine Engineering Handbook, Elsevier,

12. Soares, Gas Turbines, Air, Land and Sea applications, BH publishing, April 2011

About the Eggler Institute of Technology

The Eggler Institute of Technology is led by Mr. Mark Eggler, Institute Director (Eggler Institute Group) and Dr. Daniel Eggler, Institute Director (USA). Both Mark and Daniel are highly regarded experts in the defense technical professional development field. Their commitment to excellence in education and training ensures that the Eggler Institute delivers high-impact, practical learning experiences that directly support the onboarding and upskilling of professional technical staff. Its courses are designed to equip new employees, lateral recruits from industry and military personnel transitioning into new roles with the necessary technical knowledge and skills required to be effective in their professional roles from day one upon returning to work after a course.

The Eggler Institute of Technology offers courses across 14 key categories, covering a broad spectrum of technical and professional disciplines critical to the design, development, manufacturing and sustainment of military technology. Furthermore, the Eggler Institute of Technology is one of the very few education and training institutions worldwide capable of delivering professional development courses in multiple flexible formats, including onsite, on-demand, live-online and hybrid. This breadth of capability enables the Eggler Institute to tailor education and training courses to meet specific professional development needs, ensuring that defense and industry organizations receive customized solutions aligned with their operational and strategic objectives.

If you would like to learn more about its world-leading military vehicle technology courses, these can be accessed here.

Lessons Learnt In Military Vehicle Capability Development And Acquisition?

Developing and acquiring military vehicle systems is a complex undertaking, demanding strategic foresight, engineering precision, and adaptive problem-solving. Over the past 20 years, numerous projects have highlighted both successes and challenges in delivering effective military capabilities. In Australia, key projects such as the M113 upgrades¹, the Bushmaster Infantry Mobility Vehicle², the Australian Light Armoured Vehicle (ASLAV) program³, and the Land 400 Phase 2 initiative⁴ offer critical insights into capability development. Meanwhile, in the U.S., programs like the Optionally Manned Fighting Vehicle (OMFV)⁵ and the Joint Light Tactical Vehicle (JLTV)⁶ showcase lessons in systems engineering and acquisition strategies. This blog post draws on these projects to highlight key technical challenges and lessons that can inform and improve future military vehicle capability development and acquisition processes to meet evolving demands in modern combat and operational readiness.

Managing Evolving Requirements and Scope Changes

One of the most significant challenges in military capability development is managing changing requirements and project scope. The M113 Armored Personnel Carrier upgrade, initially planned as a minor enhancement, evolved into a comprehensive overhaul due to shifting operational needs and strategic priorities¹. This led to delays, budget overruns, and increased complexity. Similarly, the U.S. OMFV program faced challenges due to evolving requirements that strained project focus and resources⁵. Both examples underscore the importance of a robust requirements management framework capable of adapting to change without destabilizing the project. Effective systems engineering demands early and continuous stakeholder engagement, disciplined change control, and a clear understanding of evolving mission needs to prevent scope creep.

Complex Systems Integration

Integrating new technologies and capabilities with existing platforms presents one of the most persistent challenges in military vehicle projects. The M113 upgrade and the OMFV program highlighted the complexities of merging modern systems—such as weapons, advanced electronics, and extended hulls—with legacy platforms¹⁵. Similarly, the JLTV program had to balance protection, payload, and mobility while integrating seamlessly into existing tactical systems⁶. GAO findings on the OMFV highlighted that integration efforts require clear methodologies, validated data, and objective force structure analyses to ensure reliability and compatibility⁵. Overcoming these challenges requires a holistic approach, involving comprehensive planning, rigorous testing, and proactive risk identification. Integration must be treated as a core element of systems engineering from the outset, ensuring interoperability and compatibility with existing military frameworks.

Designing for Survivability and Protection

The need to design systems that offer superior protection and survivability is a critical challenge for defense engineers. The Bushmaster Infantry Mobility Vehicle was developed to counter IED threats found in conflict zones like Afghanistan and Iraq through its innovative V-shaped hull design². This approach, which required extensive testing and refinement, highlighted the importance of adapting designs based on real-world feedback. Similarly, the JLTV program prioritized survivability against modern threats such as mines and roadside bombs while maintaining essential mobility⁶. GAO assessments of next-generation vehicles emphasize that design choices must accommodate future upgrades to remain effective over time⁵. This underscores the value of iterative design, real-world validation, and flexibility to address evolving combat demands.

The Importance of Test and Evaluation

Effective test and evaluation are critical components of military vehicle capability development and acquisition. Projects such as the Bushmaster Infantry Mobility Vehicle demonstrated that iterative testing and real-world validation are essential for refining designs and adapting systems to combat conditions². Similarly, GAO assessments of U.S. programs like the OMFV highlighted the importance of clear methodologies, data validation, and quantifiable metrics during testing to ensure reliable integration and performance verification⁵. Comprehensive test and evaluation processes help identify and mitigate technical risks early, enhance system reliability, and ensure that military vehicles meet stringent operational requirements before deployment. By prioritizing rigorous testing, defense organizations can achieve higher levels of performance, safety, and mission readiness.

Balancing Cost, Schedule, and Technical Performance

Balancing cost, schedule, and performance is a perennial challenge in military vehicle capability projects. The Land 400 Phase 2 initiative sought to deliver advanced combat reconnaissance vehicles while managing performance specifications within budget and schedule constraints⁴. Similarly, the Bushmaster project experienced cost overruns due to design modifications and evolving needs², while the JLTV program faced cost management challenges related to its ambitious requirements⁶. GAO reviews of next-generation combat vehicles stressed the importance of accurate cost estimation, transparent budgeting, and aligning requirements with available resources to ensure program viability⁵. Systems engineers must engage in transparent communication, risk analysis, and agile decision-making to optimize trade-offs without compromising mission-critical capabilities.

Addressing Technological Obsolescence and Upgrades

Modernizing legacy systems to remain effective in future operational contexts is an ongoing challenge. The ASLAV program sought to extend vehicle lifespans by integrating new technologies across multiple phases³. The U.S. OMFV program, which aims to replace the Bradley Fighting Vehicle, grapples with designing future-proof systems capable of accommodating rapid upgrades⁵. GAO findings emphasized the importance of modular open systems architecture for facilitating future integrations and upgrades, ensuring adaptability to emerging needs⁵. Addressing technological obsolescence requires forward-thinking lifecycle planning, modular design, and continuous technology readiness assessments to keep systems operationally relevant.

Ensuring Reliability and Maintainability

Reliability and maintainability are critical to the operational success of military vehicle systems. The M113 upgrades highlighted how modifying mechanical and electronic components can introduce new maintenance challenges, ultimately affecting operational readiness¹. Similarly, the Bushmaster project encountered significant reliability issues early on, with mechanical failures and manufacturing defects threatening its deployment². These challenges were addressed through close collaboration between defense stakeholders and industry partners, involving iterative testing, design refinements, and improvements to manufacturing processes. This collaborative approach transformed the Bushmaster into a highly dependable platform capable of enduring harsh combat conditions².

GAO assessments emphasized that designing systems for long-term reliability, maintainability, and modularity is essential for reducing lifecycle costs and maximizing operational readiness⁵⁷. To achieve this, there must be a strong focus on reliability engineering during capability development and acquisition, ensuring high levels of system availability and minimizing lifecycle costs. Defense projects should incorporate modular designs for easier repairs, establish robust supply chains, and provide comprehensive training to maintain operational effectiveness throughout the system’s lifecycle.

Common Technical Lessons Across Multiple Vehicle Projects

While each military vehicle project is unique, recurring lessons emerge across programs, including the M113 upgrades, the Bushmaster, the Land 400 Phase 2 initiative¹²³⁴, and U.S. efforts such as the OMFV⁵ and JLTV⁶. Robust systems integration is essential to ensure that new technologies work seamlessly with existing platforms and doctrines. GAO assessments of the OMFV emphasized that transparent methodologies and data validation processes are critical for ensuring reliability⁵. Adaptable and modular designs that accommodate evolving threats and enable upgrades without complete overhauls were highlighted across these projects, with the OMFV’s modular open systems architecture serving as a prime example⁵. Furthermore, the need for disciplined project management and cost-performance trade-offs, as demonstrated by the JLTV program⁶, reinforces the importance of a holistic and agile approach to systems engineering in military vehicle development and acquisition.

Harnessing Lessons for the Future

The challenges encountered in military vehicle capability development and acquisition highlight critical lessons for systems engineers, defense professionals, and technical leaders. Successfully addressing evolving requirements, managing complex integrations, balancing cost and performance, and ensuring long-term reliability are central to delivering effective military vehicle capabilities. Through disciplined requirements management, iterative design, proactive risk mitigation, and comprehensive lifecycle planning, military vehicle systems can be developed with the precision, adaptability, and resilience needed to meet both current and future challenges. By applying these lessons, defense professionals can transform complex projects into mission-ready solutions, ensuring their capabilities remain effective and adaptable to the ever-changing demands of modern conflict.

Empowering Defense Professionals, Technical Leaders, and Systems Engineers through Specialized Education and Training

At the Eggler Institute of Technology, we empower defense professionals, technical leaders, and systems engineers to excel in systems engineering, capability development, and acquisition. Our specialized military vehicle technology education and training course equip individuals with the knowledge, skills, and practical tools to navigate the complexities of military vehicle projects. By focusing on real-world applications, industry best practices, and collaborative approaches, we prepare leaders to drive capability development and acquisition success—ensuring that defense organizations can meet the challenges of today and anticipate the needs of tomorrow. You can learn more about our courses here.

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Footnotes

1. Australian National Audit Office (ANAO) Reports on M113 Upgrades
2. Australian Strategic Policy Institute (ASPI) Monograph: The Bushmaster – From Concept to Combat
3. ANAO Reports on ASLAV Program
4. ANAO Report on Land 400 Phase 2 Procurement
5. U.S. Government Accountability Office (GAO) Reports on Optionally Manned Fighting Vehicle (GAO-23-106549)
6. GAO Reports on Joint Light Tactical Vehicle (JLTV) (GAO-20-579).

About the Author

Mark Eggler, BE (Hons), MSc. 

Mark has over 30 years experience as a senior program manager, project manager and professional systems engineer working on complex military projects.  He has worked for the Australian Department of Defence and international OEMs on large scale military vehicle acquisition programs and now teaches technical leadership, systems engineering and military vehicle technology courses worldwide.

Is Additive Manufacturing A Game Changer For Military Spare Parts Obsolescence?

Keeping military systems up and running is crucial for any defense force, but have you ever considered how challenging it is to get spare parts for decades-old equipment? In many cases, the original manufacturers either no longer supply the parts needed—or worse, they’re out of business. So, what do you do when you need just a handful of these parts? Custom production runs can cost a fortune!

This situation becomes even more critical when you think about how important it is to fix equipment as close to the action as possible. Waiting for parts to arrive through traditional supply chains can take weeks, even months. Imagine the frustration and risk involved when vital systems are out of action for that long.

That’s where Additive Manufacturing (AM) comes into play. AM has the potential to revolutionize the way we handle these challenges. But before we get too excited, there are a few crucial, but often overlooked, issues that need to be addressed.

Material Certification and Performance Consistency

Have you ever wondered how reliable 3D-printed parts really are? It’s a question worth asking, especially in military applications where the stakes are high. The truth is, even though AM has made great strides, ensuring that printed parts consistently meet strict military standards is still a challenge. Achieving uniform material properties across different machines and batches isn’t as straightforward as you might think. And without standardized material certification, there’s always the risk that a part might not perform as expected—especially when it’s mission-critical.

Supply Chain Security and Cybersecurity Risks

What happens when you bring digital files into a traditionally physical supply chain? You open the door to cybersecurity risks. As AM becomes more integrated into defense operations, the reliance on digital files and data transfer increases, which makes these systems more vulnerable to cyberattacks. Could someone steal your IP or, even worse, tamper with your design files? It’s a scary thought, but one that needs serious attention. Robust cybersecurity measures aren’t just a nice-to-have—they’re essential if AM is to be a viable solution for military obsolescence.

Intellectual Property and Licensing Complexities

And then there’s the tricky issue of intellectual property (IP). With so many military platforms relying on old designs, navigating the maze of IP rights can be daunting. What happens if the original manufacturer is no longer around, or if the IP has changed hands multiple times? Using AM to reproduce these parts without established supply contracts might seem like a great workaround, but it’s not that simple. You’ll need to carefully navigate IP laws to avoid infringement. Sure, in wartime, the mission comes first—but those IP issues won’t just disappear when the dust settles.

Summary

In conclusion, while AM offers an exciting solution to the problem of military obsolescence, it’s not without its challenges. By tackling the issues of material certification, cybersecurity, and IP, the defense sector can truly unlock the potential of AM and ensure that our forces are always ready to respond.

If you’re interested in discovering how Additive Manufacturing can benefit your organization, we invite you to explore our course catalog.

We offer a variety of AM courses, including our specialized 3-day ‘Additive Manufacturing for Military Applications’ course. This course lives up to its name, covering essential AM technologies and diving into military-specific topics like Integrated Logistics Support (ILS) considerations, reverse engineering, and the role of AM in obsolescence management. Plus, we bring a 3D printer onsite, giving you practical insights and hands-on experience with the demands of printing parts.

Whether you’re aiming to boost your team’s capabilities or stay ahead in military technology, our courses provide the insights and skills you need to succeed.

About the Author

Daniel Eggler, BE (Hons), PhD. 

Dr Daniel Eggler has over 9 years’ experience delivering educational excellence in the field of mechanical engineering.

In his previous role, Daniel was a highly accomplished Lecturer at the School of Mechanical and Manufacturing Engineering at the University of New South Wales (UNSW). He was the School’s most senior mechanical design lecturer and led the revision of the School’s design curriculum. Keen to ensure theory met practice, he was also the lead academic of the SunSwift Solar Car program at UNSW. In recognition of his exemplary service, Daniel was awarded the UNSW Faculty of Engineering – Educational Excellence & Innovation award in 2019 and 2020.

Daniel brings across his considerable educational and instructional expertise into his current role as the Director of Education and Training at the Eggler Institute of Technology. He is incredibly passionate about delivering superior learning experiences to industry professionals across all specialist technical sectors, particularly Defense. He is deeply committed to redefining the impact of technical education, synergizing innovative software and evidence-based teaching methods to empower all who undertake studies with EIT.

Daniel graduated from UNSW with first class honors in Mechanical Engineering. He went on to complete his doctorate in Mechanical Engineering, specializing in acoustics, vibration, vibro-acoustics and active noise control, cloaking and illusions.

Improving Front-end Technical Defintion of Complex Projects

Acquisition of modern, complex military systems is generally a difficult process.  Recent history is littered with numerous examples of military projects that have failed to deliver. And unfortunately, many of these projects ultimately end up being cancelled with considerable losses in time, money and reputation to all involved.  What is so galling about all this massive waste is that it is usually completely avoidable. So let’s take a few minutes to understanding one of the most regularly occurring problems and describe some actions that can be taken to mitigate against it.

Inadequate project and requirements definition

This problem is regularly cited as the most common cause of project problems leading to cost overruns and schedule delays. The key driving issue here is the lack of time invested in adequately defining the key operational and technical requirements of the project.  This fundamental part of the project process often lacks analytical rigor and always seems to be deprived of enough time and money.  Depending on the complexity of a military program, one should be investing around 3% of the systems engineering budget to getting this project phase correct.

You probably think this is a relatively easy and straight forward issue to deal with but you are wrong.  For some reason, both government and defense companies struggle to get this fundament step right.   In dealing with this fundamental problem, it is wise to always invest a considerable amount of effort in developing a well-crafted Operational Concept Document (OCD).  The OCD – as it is commonly referred to – correctly captures the key operational requirements, systems functionality and technical risk associated with the project.  If prepared correctly, it forms the capstone document of the project and provides a strong foundation for building and delivering a successful military program.  The problem is OCDs are rarely worth the paper they are written on.  Why is this I hear you say!

Improving Operational Concept Documents

Well, the primary reason is that developing an effective OCD requires considerable professional skill in project-related military technology, high levels of operational and technical experience and an excellent grounding in a method to develop the document and its associated artifacts.  The sad truth is that few people develop the unique combination of these skills.  And its unlikely one will develop such skills as part of a normal professional career in government, the military or engineering practice.

So what’s the solution to this problem? Firstly, go and find a consulting or training company or someone in your organization that has developed at least three OCDs for moderate to high complexity systems. Once someone has been involved in developing at least three of these documents you can have some assurance that they know what they’re doing (but not always). The problem is you are unlikely to find such a person if you work in government.  Another good alternative is to hire a good training organization that can teach your team the essential knowledge and skills needed to develop effective OCDs.

Secondly, make sure the consultant or training organization has a properly documented methodology to support OCD development.  Such a method should involve all stakeholders and have a clearly defined process to correctly elicit requirements and a suitable database to capture the inputs and outputs of the process.  A reliable and proven technique involves the use of scenario driven workshops to elicit and capture operational requirements, measures of effectiveness and critical technical parameters.  Experience has shown that four to five workshops are usually sufficient to capture enough information to allow development of a good OCD.

And finally, the best way to maximize the effectiveness of the OCD development process is to make sure all people are trained if the OCD development method.

If you follow these few simple suggestions, then you can have some confidence that you’ll be able to develop a good OCD and your project will get off to the best possible start.

To learn more about the Eggler Institute of Technology’s specialist systems engineering courses and project management courses addressing this important issue, please visit our course catalogue.

About the Authors

Mark Eggler, BE (Hons), MSc, CPEng.Mr. Mark Eggler. Mark has over 30 years’ experience as a senior project manager, professional engineer and teacher of systems engineering, military vehicle technology and leadership courses. Mark has developed more than 30 courses covering different aspects of military technology which he delivers worldwide. He is also a visiting fellow at the University of New South Wales, Australian Defence Force Academy.

Military-Off-The-Shelf  (MOTS) Acquisition: It’s Easier Isn’t It?

By now you’ve probably heard it a thousand times over. ‘Buy MOTS and project schedule, technical and cost risk will evaporate’.  It’s a very seductive mantra in wide use throughout the world today.  But is it true?  And is it applicable to complex technology acquisition?

For all force development and acquisition professionals, understanding the key issues of the MOTS vs Development debate is essential to developing the correct acquisition strategy for complex military technology projects.

Key Point #1

It is important to recognise that most MOTS technologies are manufactured and developed to meet mission/user requirements (including tactics, techniques and procedures, TTPs) that are likely to differ from those of the acquiring country.  This fact produces design solutions that match the military culture and war fighting methods for which the technology was originally designed.

Now for militaries with similar war fighting doctrine and TTPs this shouldn’t pose a big problem.  But where this isn’t the case, acquirers of complex MOTS systems need to appreciate this fact and plan accordingly. Early trialing of military systems should discover such mismatches between offered designs and the user’s Tactics Techniques & Procedures (TTP).  Discovering such issues when in contract is usually costly and can cause significant schedule delay.

Key Point #2

Good reliability performance of military systems is a key component of mission success.  In fact, achieving good reliability is one of a project’s key technical requirements that must be planned for early, takes time to verify and consumes significant resources.

‘But we’re buying MOTS and we don’t need to worry about reliability’, I hear you say.  Don’t be fooled.  Reliability performance is strongly correlated to the operational environment of the military vehicle system.  For instance, if a military system’s mission profile used in the original design process emphasized cold/wet operations, then you can be confident that a MOTS system should achieve claimed reliability in a similar environment.

But for other environments – such as hot/wet – this isn’t likely to be the case.  The reason for this is that failure modes in equipment are dependent on the operational environment. Thus, operating MOTS technology in a new operational environment is likely to reduce reliability performance.

So to avoid poor reliability performance and its negative effects on mission availability and life-cycle cost, plan to do reliability testing as part of your MOTS systems engineering program.

Key Point #3

Another common headache encounter during complex MOTS programs concerns the systems integration of C4ISR systems.  Quite often the integration of these systems involves either current in-service equipment or new systems that the MOTS solution was not designed for.  Commonly encountered technical problems arise in the areas of electrical power budget, EMC/EMI interference, radhaz, and lack of suitable installation space.

Unfortunately for militaries acquiring MOTS technology, there is no simple solution to this problem.  The cost and schedule impacts of systems integration can be reduced by requiring tenderers to confirm technical feasibility of integrating C4ISR systems prior to contract signature. Providing the acquirer has clearly specified the systems to be integrated, then this risk can be readily transferred to the prime contractor.

To learn more about the Eggler Institute of Technology’s specialist systems engineering and project management courses addressing this important issue, please visit our course catalogue.

About the Author

Mark Eggler, BE (Hons), MSc, CPEng. Mark has over 30 years experience as a project manager and professional engineer working on complex military vehicle projects.  He has worked for the Australian Department of Defence and international OEMs on large military vehicle acquisition programs and teaches technical leadership, systems engineering and military vehicle technology worldwide.

For years you have probably heard – even been involved in – the never ending debate of ‘wheels vs tracks’ for combat vehicle applications.   This debate, which has often been ill-informed, has assisted little in understanding the key issues.  In this article, I will focus on some key facts concerning this matter and leave it to you to draw your own conclusion as to whether armies should invest in tracks or wheels for its combat vehicles.

Today, vehicle mobility is usually described by reference to obtuse metrics such as Nominal Ground Pressure (NGP), Vehicle Cone Index (VCI) or Mean Maximum Pressure (MMP).  These metrics, which are still widely used and spoken about, were developed well over 50 years ago in the US and UK.  Some of the key problems with these metrics are:

.   NGP whilst very simple to use offers no relationship between it and soil properties – a major problem when trying to determine vehicle mobility;

.   VCI was developed by the US in the 1950s based on large scale trials of vehicles operating in different soil conditions.  The results of this testing were used to empirically develop a factor know as the ‘Mobility Index’ and this value is used to derive wheeled and tracked vehicle VCI from charts.  The principal problem with VCI is that it uses a very complex set of vehicle parameters and is based on data from tests conducted on vehicle designs of more than 50 years ago.

This situation has reduced the credibility of VCI as an accurate indicator of vehicle mobility.  Incidentally, VCI is the key algorithm imbedded in the NATO Reference Mobility Model (NRMM).  Wong (2009) has recently written at length about the deficiencies in the NRMM, particularly related to the key track vehicle design parameters of wheel configuration, track tension and suspension design.

Roughly at the same time as the US were developing VCI, the UK developed its own metric for predicting tracked and wheeled vehicle mobility – Mean Maximum Pressure (MMP). MMP is considered easier to use and provides a more robust and reliable indicator of tracked vehicle mobility.  However, the use of MMP to calculate wheeled vehicle mobility is questionable and the validity of MMP was never verified by test. Any Army assessing the merits of wheeled vehicle mobility on the basis of MMP should exercise considerable care when interpreting the results.

More recently the UK has developed through an experimental program, the Vehicle Limiting Cone Index (VLCI). This is similar to VCI but calculated using what many today consider to be a more simple and accurate method. VCLI can be used with more confidence to calculate wheeled vehicle mobility. This result suggests that a strong case exists to review the traction models used in the NRMM.

Analysis undertaken by Ogorkowitz (2000) using the VCLI of 35 wheeled armoured vehicles in the weight range 8-40 ton is revealing. His analysis of these wheeled armoured vehicles operating in soft clay-like soils (Cone Index < 200kPa) shows that only the 4 lightest vehicles (< 13.5 ton) could move over this terrain.  When these wheeled vehicles reduced tyre inflation pressures to the ‘emergency’ setting to maximize mobility, only vehicles weighing less that 20t could pass over the soft, wet soil.

And remember at this tyre inflation setting vehicle movement is limited to speeds of around 20 km/h – not a great situation to be in if you are operating in a hostile environment.  This means that the best designed 6×6 and 8×8 wheeled armoured vehicles will need to weigh less than 20t if they’re to provide good tactical mobility. Given the threats on the battlefield today and the increasing shift towards higher levels of ballistic and blast protection, how many serious 6×6 and 8X8 armoured wheeled vehicles weigh less than 20t.

I’ll now let you make your own mind up over the merits of wheels vs tracks for combat vehicles needing to operate in soft soils.

To learn more about the Eggler Institute of Technology’s Military Vehicle Technology & Mobility courses, please visit our course catalogue.

About the Author

Mark Eggler, BE (Hons), MSc, CPEng. Mark has over 30 years experience as a project manager and professional engineer working on complex military vehicle projects.  He has worked for the Australian Department of Defence and international OEMs on large military vehicle acquisition programs and teaches military vehicle technology worldwide.

The information contained in this article is drawn from Eggler Institute of Technology short course: Introduction to Military Hybrid Drive Electric Vehicles.

Hybridisation is being pushed more than ever in today’s climate. Availability of fossil fuels is becoming increasingly scarce, whilst cost per gallon is rising. This places a greater emphasis on fuel economy.

The military is not exempt from this phenomenon, legally or logistically. Whether it is adhering to the latest US or European emission standards or pushing to get more range on a vehicle during operations, fuel economy is very desirable. So why is it that unlike the civil sector, military hybridization appears almost completely stalled?

As a matter of fact, the military has been chasing hybridization for years. As early as the 1940s, the US military converted a T-23 medium tank to an electric drive, although the electrification was abandoned after WWII, reverting back to mechanical and hydraulic drives (Khalil, 2009). This is not an isolated event with efforts to field electric/hybrid vehicles occurring regularly around ever 10 years. Yet to this day there is virtually no market presence for hybrid electrics in the military vehicle scene. This begs two very big questions – why militaries continue to pursue hybridization and what is stopping them.

There are many advantages to hybridization. Some of these include onboard power generation, reduced acoustic signature, silent operation, peak torque at zero speed that provides a significant lift to vehicle mobility and power regeneration.

However, let’s focus on what many military planners picture as the ultimate hybridization advantage – fuel economy and associated cost savings.

Military fossil fuel usage generates a serious logistic burden. This burden can range from 30-80 percent of convoy loads getting fuels to operational units, which not only dramatically increases costs but operational risks as well (Kramer et al, 2011).

According to Gen. Conway of the US Marine Corps, even though the military can purchase fuel around US $1 per gallon, it costs a further US $400 to transport it to the theatre of operations (Rosenthal, 2010). This is a staggering number. It becomes immediately apparent how increasing fuel economy would drastically decrease logistic costs and allow for more versatility in convoy load configurations.

There is limited publicly available information on what has been done to test fuel economy of hybridized military vehicles. This stems from the difficulties encountered when conducting such tests. Fuel economy is usually verified by computer simulated duty cycles (Butler, 1999). These are predetermined scenarios that simulate engine conditions during highway driving, suburban driving and so on.

However, the nature of military operations has many more requirements comparatively to a commercial vehicle.  Thus, generating military duty cycles is much more difficult as no standard is easily agreed upon (Antoniou, 2007).

There is evidence to suggest that by optimizing the hybridization configuration, light to medium vehicles could benefit from a 45.2% increase in fuel economy, with a 15% gain for heavy class vehicles (Goering et al, 2003).

Yet despite these impressive numbers there is still no presence of hybridized military vehicles. This is due solely to a hybrid’s available power density.

During operations, a military vehicle’s instantaneous power requirements are paramount. The ability to accelerate quickly and have 60% gradeability performance are crucial for military vehicles to provide high levels of tactical mobility.

Unfortunately, the technology is not there yet. Military hybridization utilizes commercial heavy vehicle technologies that are adapted for military use. These technologies, particularly high-power density, lightweight batteries, cannot meet the broad operational and environmental rigors of combat operations. So short of a major technological breakthrough, the current situation of military vehicle hybridization is expected to remain static for at least another decade.

I would like to leave you with this final thought. Until such time the power density of hybrid configurations rivals that of its mechanical/hydraulic counterparts, military HEVs will continue to remain an elusive possibility.

If you would like to learn more about the current state of technical development impacting military vehicle technology and military hybrid-electric drives, I encourage you to enroll in the Eggler Institute of Technology’s world leading Diploma of Military Vehicle Technology.

About the Author

Mark Eggler, BE (Hons), MSc, CPEng. Mark has over 30 years’ experience as a project manager and professional engineer working on complex military vehicle projects.  He has worked for the Australian Department of Defence and international OEMs on large military vehicle acquisition programs and teaches military vehicle technology worldwide. You can contact Mark here.

In another world first, the Eggler Institute of Technology (EIT) today launched the world’s first online course covering the design and technology used in military hybrid-electric drive vehicles.

EIT’s Director, Mark Eggler, said “This 2 hour short course provides an excellent overview into the concepts and technology used in the design of hybrid electric drives and their application to modern combat and logistic vehicles.”

“The course is aimed at anyone that desires a deeper understanding of the current state of play surrounding military hybrid-electric drives and technology.”

As well examining the technology that underpins military hybrid electric drives vehicles, it covers their historical development, current status, driving forces, and key operational and technical trade-offs faced faced by users and designers of this technology.

Full details about this new and exciting course can be access on the EIT website here.

In another world first, the Eggler Institute of Technology has today released its new online ‘Fundamentals in Capability System Design’ course.  The eight hour, self-paced, e-learning course, is designed to provide capability and acquisition staff with an understanding of the essential front-end methods and techniques used to design and develop complex capability systems.

It was commissioned and developed during the height of COVID-19 restrictions. The course addresses a core professional development need of the Australian Defence Organisation’s Capability Life Cycle (CLC) workforce. In the future, it will provide Defence and defence industry partners with education and training in the specialist area of capability system design.

“This is another significant milestone for the company. The Fundamentals in Capability Systems Design course fills a significant gap in the current global Defence education and training market. It places EIT as a world leader in this niche market segment. I am delighted that a significant number of Australian Department of Defence staff have now completed the first course” said Mark Eggler

Over the past decade, EIT has established itself as a globally trusted supplier of highly quality online and class-based education and training programs. It regularly exports its large range of specialist professional development courses to governments and defence companies around the world.