Should your next car be an EV?


Image from

By Jastej Singh Matharu

The answer to that is ‘it depends’. Just like any other decision, this decision will also factor the concerns you have and what reality is.

To begin the most important criteria normally would be the range an electric car is able to give. Why? Because this will be an EV and while an internal combustion car can be refueled within minutes, the fuel of an EV, that is the charge in the battery, takes a prolonged time to fill. Even fast chargers typically take about an hour to charge the battery of an electric car. So if you compare just on this one issue the internal combustion engine wins because of it’s sheer convenience of refueling. So the range an EV gives between charges is a major factor to be considered.

You would need to decide what is the range you need in your EV. A car which is used only for city driving would need lesser range than a car which is planned to be used for long distances on highways.

Charging stations for electric cars have yet to come up in India. On the other hand internal combustion engine cars have refueling stations around every corner.

Having said that one must also consider that potentially we have a charging station in every home. If you want to wait for the infrastructure for charging stations to come up then you should not be buying an EV at this point of time. However if you feel that it is possible for you to set up a charging station at home, which is, for slow charging, just a matter of plugging in to a 15 ampere electrical point, then in that case your range anxiety is misplaced. For while every home is not a refueling station for an internal combustion engine car, it is a refueling station for an EV. Electricity is being delivered to every home unlike fossil fuel.

So if you are convinced that you will be able to charge your EV every night when it is parked at your home, then buying an EV as your next car becomes an option which you may like to consider.

The next issue is how much do you drive on an average per day. If you drive your car a 1000 km or so per month it means that your car covers 30 to 40 kms per day. If you drive your car 2000 kms per month then it covers 60 to 80 kms per day. And if the monthly distance is 3000 kms then it is 90 to 120 kms per day. As the starting range of EVs today is 100 kms it follows that an EV may be considered as an option for the next car by someone who drives less than 2000 kms per month. If you are unable to charge your EV at a place other than your home you would like to buy an EV only if your need for range is less than 100 kms per day. Of course with time, as office parking lots instal charging points, charging outside of your home would become easier.

As of now the only assured charging point you may have for some time is the one you install at your home. This must therefore be a factor in your decision to consider buying an EV as your next car.

EVs range starts from about 100 kms and goes up to as much as 900 kms for the top end cars. There is a relationship between the range a car gives and it’s cost. Typically higher ranges mean higher cost. So the other factor which comes in is how much would you like to pay for the car.

For somebody who has been buying the smaller hatchbacks rather than luxury cars the maximum cost may be around Rs 8 Lakhs. Typically an EV version of a car will cost 40% more than the internal combustion engine version. So you are paying more to start with. Undoubtedly the running cost of an EV will be lesser than an internal combustion engine car. This may offset the initial higher cost.

Handling of a car, the ride and comfort, brake design features and safety features are also important design parameters of a car. These can be imported from internal combustion engine variants and used more or less as they are.

In the internal combustion engine car, the most important part is the engine as it is expensive and has a life which means it may have to be replaced after a certain amount of usage. In the EV the electric motor can last longer and is not the most expensive part but the battery is. The battery of the EV would need to be replaced after 6 to 8 years and it will be expensive to do this. So this is another factor you must consider. It also follows that the resale value of an electrical vehicle will be decided by the amount of life left in it’s battery.

One interesting feature of the EV market is that it has a number of startups which are offering EVs along side of the mainstream manufacturers. This has become possible because the ease with which an electric motor can be designed into an electric car. However a key challenge startups face is developing the capacity to manufacture EVs at the scale needed by the market. Mainstream manufacturers do not face any such problem as they are already in the mass manufacturing market. Further technologies like car suspension, transmission, steering, braking and safety features are well refined and available with mainstream car manufacturers.

This issue may impact the after sales service capability of a car manufacturer, and may therefore also be another factor while deciding to buy an EV.

A large variety of EVs are now available in the world market. A scatter chart has been made from data available at Electric vehicle database [1]. This chart is for cars costing up to 50000 Euros.

Consider the cars which are having a range of upto 200 kms and a price of 30000 Euros or less. The following cars are available within these parameters[1].

SEAT Mii Electric, Skoda CITIGOe iV,Citroen C-Zero,Peugeot iOn,Volkswagen e-Up! ,

Smart EQ Fortwo coupe, Smart EQ forfour, Volkswagen e-Up! ,Sono Sion, MG ZS EV, Volkswagen ID.3.

Cars in this bracket are becoming available in India as well. Tigor EV is now available for a cost of INR 12.59 Lakh which is equivalent to 16000 Euros. It has a range of 213 kms and a battery of 21.5 kWh[5]. E Verito is available at a price of INR 13.17 Lakhs[6] which is equivalent to 16600 Euros. This car has a range of 140 kms and a battery of 13.91 kWh[7].

If you consider the area of the chart for range between 200 kms to 500 kms and the cost from 30000 Euros to 50000 Euros then a considerable number of currently available EVs come in this area. The list below shows the vehicles out of these which have the highest sales in Europe in August 2019[2].

Tesla Model 3, Renault Zoe, Nissan Leaf e+, BMW i3, VW e-Golf, Hyundai Kona EV, Kia Niro, Hyundai Ionic Electric, Smart Fortwo EV.

From this list Hyundai Kona has already been launched in India and is available for a price of INR 23.71 Lakhs which is equivalent to 30000 Euros. Also Renault Zoe is expected to be launched in 2020 and may be available for a price of INR 8 Lakhs which is equivalent to 10000 Euros[3] considerably lower than the cost in Europe, so we will have to wait and see what finally comes out as an offer when this car is launched.

The Indian market is very price sensitive and any car giving a range of more than 200 kms and offered at a cost of INR 8 Lakhs or thereabout is likely to attract buyers in numbers. Therefore if the Renault Zoe is made available at the price of INR 8 Lakhs it could become a popular EV in India.

Some more EVs which may become available in the near future are Wagon R Electric, Mahindra eKUV100, Tata Altroz EV, Tata Nexon EV, Ford Aspire EV, Mahindra XUV300 Electric, MG ZS EV and Audi e-tron[8].

It is to be noted that homegrown designs are being offered by Tata Motors and Mahindra, this for me is a matter of rejoicing. If these brands are able to take on the competition in the Indian market from international brands then they will be able to offer their EVs in the global market. This is something one will follow with interest.

Here is another scatter chart for prices from 50000 Euros to 100000 Euros [1].

In the 50000 Euros and above price bracket and having a range of more than 300 kms we the following cars which are in the first 20 highest selling EVs in Europe in August 2019.

Jaguar i-Pace, Tesla Model S

JLR is a subsidiary of the Indian automobile company Tata Motors. So it is a matter of pride for both companies that Jaguar i-Pace is competing effectively with the Tesla car.

The third scatter chart covers EVs costing more than 100000 Euros[1]. This has the high end cars.

One of the main challenges that all EV manufacturers face is how to increase battery capacity and battery efficiency. Getting battery efficiency higher than 16 kWh/100 km is proving to be a challenge. Battery sizes of cars are restricted by the size of the car itself, therefore the range of the car gets restricted.

Battery efficiency as a result becomes a factor to be considered when choosing an EV.

Here is a chart comparing price with battery efficiency[1].

Cars having battery efficiency better than 16 kWh/100 kms, that is those which are on the left of the 16 kWh/100 km line in the chart above, are listed below:

Smart EQ Fortwo, Sono Sion, Renault Zoe, Mini Cooper SE, Hyundai Kona Electric.

Interestingly three of the above cars, that is, Smart EQ Fortwo, Renault Zoe and Hyundai Kona Electric figure in the top 20 selling EVs in August 2019[2]. Is there some correlation between battery efficiency and car sales? There does seem to be some.

So returning to the original question, ‘should your next car be an EV?’. Well the answer to that is, certainly, if you are looking at driving from upto 1000 to 2000 kms in a month and you are using the car within a city for daily commutes this is a good time to consider buying such a car because you will be able to use it by charging it overnight every day. And technology is improving so buying an EV as your next car is going to keep becoming an even more attractive option.

Overall the percentage of EVs on roads worldwide are going up. In the first half of 2019 in Norway 58% of the new cars purchased were electrically chargeable! [4]

This is a sure indicator that volumes of EVs on roads of all countries are likely to go up.

The main point is would you be driving one such car?


[1] Electric vehicle database


[3] Autoportal


[5] News18




Are electric vehicles the future?


Image by

Are electric vehicles the future?

By Jastej Singh Matharu
[The automobile industry is in an exciting new stage of transition in search for relevance]

As an automobile engineer all things related to motorized vehicles are of interest to me. What I find especially fascinating at the present juncture is the way the auto industry is changing and transforming.

Here in India the sector is passing through a rough time where the demand for vehicles has dropped and all companies are passing through a trying time. Even if you look at the larger picture around the world you find a similar drop in demand in many other markets.

It seems that the car industry the world over is going through a churn of sorts.

So what is really happening? Let us look at the new technologies which are now emerging. Technologies which some time back were considered to be niche and were used only by select  companies and are now being adopted by all as mainstream. For instance, owning a hybrid automobile has now become more or less common place. There are a large number of such models available from many companies.

These cars are running on the internal combustion engine which is being assisted by an electric motor. But what truly seems to be changing is the emergence of the pure electric vehicle.

While earlier pure electric vehicles were being produced by only a few companies now mainstream companies are coming out with a pure electric versions of even some of their best selling models.

So how does one determine where this changing environment is headed. The one thing which gives a sure picture of where things are going is how companies are investing. Where is money being spent by automobiles companies and by companies which buy automobiles in bulk.

Amazon is buying 100000 Revian EVs which will be used by Amazon as delivery vehicles. And the first 10000 vans are expected to go into service in just another 2 to 3 years [1]. This is a huge order. It is worth noting that Revian, the company which will supply the vans is a non mainstream automobile company. In fact it is a company in which Amazon has invested. Making it clear that Amazon feels that this is to it’s benefit. This massive investment nudging the automobile market towards an EV future.

It increasingly appears that the idea of EVs is something which is now amongst us. And it is emerging and getting reflected in various forms.

If you look at the two wheeler industry it can be noticed, that alongside the mainstream companies, a large number of startups have emerged which are offering pure electric  two wheeled vehicles.

There is an ease with which new companies are now able to start up and give competition to established automobile companies.

There would be many factors influencing this trend but it appears that one of the main reasons is the simplicity of the electric motor which is now replacing the internal combustion engine.

The internal combustion engine has been there for a century but the challenge with it  is that a vertical movement of pistons in an engine has to be converted through a crankshaft into a rotational movement.

Another issue is that the range of speed which the internal combustion engine offers. This range is insufficient to cover the entire speed range which is needed by the vehicle wheels which are being driven by it. So we have to bring in a gearbox and step up or step down the gears in order to cover the entire range. This brings in the need of a clutch, essentially losing the simplicity of mechanism.

On the other hand the electrical motor, which while being simple, is able to give us a torque curve which the combination of the internal combustion engine, the clutch and the gearbox arrangement can only aspire to achieve.

So in the electric motor we have a simple driving engine which is giving the best possible torque curve and which is more or less covering the entire range of speed which the driven wheels of the vehicle need.

So this simplicity of the engine, the electric motor, is making it possible for startups to build competing pure electric vehicles.

Once you got the engine and the transmission simplified things start to fall in place. The fact is that technology for manufacturing electric motor is well stabilized and this implies that startups can source these motors easily.

They do not have to go through a huge design and development cycle which would be needed for developing an internal combustion engine.

So as this idea of pure electric vehicle on our roads is taking root. If the mainstream automobile companies take time to switch to pure electric vehicle and the flow of change is not fast enough, then in all likelihood manufacturers may move ahead and create new markets which all companies will have to follow to remain relevant.

In a way compelling the mainstream automobile industry to move faster towards this change.

Recently there was an announcement that Tata Motors has developed a new pure electric power-train called Ziptron[2]. This is a clear indication of things to come as they will be able to fit this power-train to power many of their existing popular models.

Toyota, which is one of the front runners in developing hybrid vehicle technologies, is offering a vehicle which has solar panels fitted on it[3].

Jaguar which has made considerable investment in developing their pure electric car I-Pace. Similarly other companies have also developed pure electric models. It was recently reported that in the UK market the Jaguar I-Pace pure electric car has become a top seller[4] in it’s genre.

In an interview given by Ralph Speth the JLR Global CEO recently he has mentioned that the growth in customer demand of EVs is faster than expected and the supply of batteries is not able to catch up for sufficient cars to be produced[5]. More manufacturers of large batteries are needed to meet this demand.

A roadblock in this future of the EV is the issue of lack of proper infrastructure such as charging points. But even here if you look at the world over you find every country moving in the direction of providing more charging points.

It is remarkable that automobile companies are themselves taking interest in installing charging stations. It was reported recently that VW is planning to install 4000 electric charging stations in Germany by 2025[6]. Tata Motors has taken the initiative to come up with electric charging points in coordination with Tata Power and they are planning to create 300 electric charging stations[7].

The supply of batteries is likely to improve as companies invest in new battery manufacturing plants in anticipation of increased demand. Exide is opening a plant for vehicle batteries which will be operational by this year’s end[8]. Tatas are setting up a battery manufacturing plant with a large investment[9].

All this may lead to cheaper batteries which will bring down the cost of pure electric vehicles. Once batteries become cheaper and once we are able to have larger batteries than the cost of the vehicles will come down and their range will increase.

So it seems that the automobile sector is heading towards introducing more pure electric vehicles.

When we finally  move away from a pure internal combustion engine vehicle to a pure electric vehicle, there will be exaltation in being able to contribute to the reduction of pollution which remains a major problem in many large cities of the world. The consumer could possibly feel that by going in for an electric vehicle they may be able to contribute towards the reduction of pollution.

The internal combustion engine powered vehicle will be there for many vehicle applications which cannot be covered by pure electric vehicles. And there will be also be a large number of hybrid vehicles.

It does seem though that eventually, sooner rather than later, we will see a rise in the number of pure electric vehicles on our roads.

It is an idea whose time is here and the events occurring all around us today attest to that reality.

As Victor Hugo famously said “No force on Earth can stop an idea whose time has come”.

[1] Amazon orders 1 lakh Rivian EVs as delivery vehicles, Autocar India.
[2] Tata Motors up the ante in EV space with new engine, The Economic Times.
[3] Toyota Motor is trying to figure out how to make a car run forever, Business Standard.   
[4] Jaguar I-Pace Tops Pure Electric Vehicle Sales In Q2 In The UK, Car and Bike.
[5] I wouldn’t say the worst is over for China: Ralf Speth, JLR, Economic Times.
[6] Volkswagen To Install 4000 EV Charging Stations In Germany By 2025. Car and Bike.
[7] Tata Motors partners Tata Power to install 300 EV charging stations. liveMINT.
[8] Exide’s Gujarat plant to produce batteries for EVs to be operational by year-end. Financial Express.
[9] Tata plans to invest in lithium ion battery manufacturing in Gujarat. Business Line.

Electric Armoured Fighting Vehicles?

 By Jastej Singh Matharu

Let us examine the possibility of having an electric Armoured Fighting Vehicle (AFV).

Electric components have always been a challenge in the design of AFVs. For example In the case of tanks a large number of services which are utilised need electrical power. A tank uses electricity for radio and intercommunication, for the wipers, for the various types of night vision devices, for the computer systems, for the automotive auxiliaries like the various types of pumps, the gauges, the navigation equipment, lighting systems, ventilation systems, gun control system and the fire control system.

To cater for these electrical loads, like any other vehicle the tank also has batteries that are charged by using the power from the main engine. Some tanks have an auxiliary engine for charging the batteries thus conserving the life of the main engine. Also the auxiliary engine operates at a much lower level of noise than the main engine.

In a tactical situation a tank often needs to function in silent watch mode. During this time the tank uses the power stored in its batteries. It follows that we need to have batteries with sufficient capacity to allow functioning of the tank in such a mode.

The heaviest drain on the batteries is during starting. To get around this problem certain tanks have an air starting system, in which air bottles are charged by a compressor getting drive from the main engine and this pressurised air is used for starting the engine.

So in a tank, say which is in the 40 tons to 50 tons range, you will have a 1000 bhp plus engine, which will be the largest component of the vehicle and occupy considerable space in the engine compartment.

If we were to replace the engine with an electric motor, we would need a very large battery to power this motor.
This will be a major problem because the envelope of the tank has to be kept very tight. An increase in the volume of a tank makes it heavier as additional armour protection becomes necessary. The weight penalty would become unacceptably high. An electric powered tank will have to wait, therefore, for the design of very high energy density batteries, much more powerful than the present day lithium ion batteries.

However, as lithium ion batteries have higher energy density than lead acid batteries, we could replace the existing lead acid batteries of tanks with lithium ion batteries. This will increase the time for which the tank can operate in silent watch with its main engine turned off and thus operate with no noise and a much smaller heat signature. This can be of advantage in a tactical situation. To that extent there is a case for increasing the battery capacity of tanks by replacing the present day lead acid batteries with lithium ion batteries.
It follows that being able to design high energy density lithium ion batteries will help in designing a better tank.

Moving away from tanks let’s go on to a lighter AFV, say we look at the Armoured Personnel Carrier (APC) or the Infantry Combat Vehicle (ICV). An ICV often needs to be amphibious and may have a tracked or wheeled configuration. In this case, because the vehicle is lighter than a tank, therefore it becomes more conducive to the possibility of being powered electrically.

A purely electric vehicle would need a fairly large battery, and there is another aspect which will come in, and that is that normally when we are operating in a battle area, the availability of electricity is unlikely. Therefore, while you may be able to have a fully electric ICV in a peacekeeping role or a policing role, it may not be a viable option in the case of a battle area even though it may be feasible to design such a vehicle.

However, a hybrid ICV may become a possibility. In such a vehicle the balance between the capacities of the internal combustion engine and the electric motor will have to be decided with a lot of care.

In a purely electric vehicle the logistics of transporting fuel to it will disappear. In a hybrid vehicle the fuel consumption will reduce and refueling logistics will ease out somewhat.
Where the electric vehicle has a clear advantage over the internal combustion vehicle is that the torque curve of the electric vehicle is the best possible torque curve. It provides very high torque at slow speeds thus making the electric ICV very agile from rest and at slow speed. This is an advantage in a tactical situation. The electric ICV will not need gears and the driver could make it accelerate quickly just by pressing the accelerator pedal.

Another advantage which an electric ICV will have over the internal combustion engine ICV is the ability to move silently. This will be a big advantage in a tactical situation. Therefore the hybrid ICV again seems to suggest itself as a possible option.

In a tracked ICV an internal combustion engine drives the tracks through a driveline and sprockets. However, in a wheeled ICV each wheel has to be given drive. This means that you have the engine at one end of the vehicle, usually the front end, and you have to transmit this drive mechanically to all the wheels through a system of drive shafts and differentials and you need to provide for differential locks and inter axle locks so that the vehicle is able to pull itself out of a difficult position. This adds a large amount of weight to the overall weight of the vehicle.

On the other hand, in the case of an electrical vehicle while the battery will be large and will have considerable weight but the drive to the wheels will be much lighter as compared to the mechanical drive needed in an internal combustion engine, as each wheel will have its own electric motor.

These motors can be very easily utilized through a computer which can be designed to control the motion of these motors. 

This will allow the driver to engage different drive configurations. Let us take a six wheeled vehicle and say that two wheels are slipping due to inadequate surface grip, you just cut the drive to the motors driving these wheels and extricate the stuck vehicle by giving drive to the remaining four wheels which are not slipping. This will be a very powerful advantage of having an electrical vehicle.

The next thing which comes is that ICVs need to be amphibious, over here we need to ensure that the electric motors are totally sealed and kept free from any possible water ingress.

Also an amphibious vehicle has to propel itself in water. This may be done by the wheels, or propellers or water jets. Traditionally such drives have been difficult to achieve, as these were mechanical drives. On the other hand it will be easy to give an electric drive to a propeller through an appropriately placed drive motor. 

The designer of an electrical vehicle will have much more flexibility as compared to the designer of an internal combustion engine vehicle. An electrical ICV will be equally agile on land and on water.

In any AFV whether a tank or an ICV there is a need for having a minimum speed which is needed to operate in a tactical environment. Also there will be a need to have adequate top speed on both roads and cross country. Here also the electric powered vehicle will be better as the electric motor gives excellent torque at slower speeds without any need of changing gears.

For vehicles which are even lighter than ICVs like armoured reconnaissance vehicles the hybrid vehicle may become a viable option.

Storing liquid fuels in AFVs has always been a challenge as this gives rise to a fire hazard problem. Any reduction in fuel storage requirements will reduce this hazard. Thus there is an advantage of having electric or hybrid vehicles.
Maintenance requirements of electric vehicles are typically less than internal combustion engines.

Internal combustion engines are vulnerable to quick wear and tear in deserts as dust may be ingested. To prevent this air cleaning systems have to be designed and maintained with perfection. Electrical vehicles will have no such problem.
Broadly speaking as far as design is concerned; in a tank you would have a more powerful electrical system with lithium ion batteries, which will give a tank a greater ability to operate silently. In ICVs you may have hybrid vehicles which will be very agile both on water and land, and in the case of the lighter reconnaissance armoured vehicles you may be able to have vehicles which may be fully electric or hybrid vehicles. Hybrid vehicles have higher ranges of operation with the same amount of fuel thus easing the logistical load of supplying fuel.

Storing and transporting fuel is a major challenge in any operation and any easing of this load will free resources for other logistic tasks. Though conversely spare battery packs will have to be provisioned for the electric and hybrid vehicles. However, if we were to use a standardised battery pack in all vehicles it would also lead to helping out with other battery powered equipment which we already have in a battle area.

Finally it appears that with the technology available in the civilian electric vehicle industry, such as better batteries and motors, it looks that the day is not far when we will see vehicles which have large capacity batteries or full fledged electric or hybrid armoured fighting vehicles in the battlefield milieu.

My Thoughts on Main Battle Tank Design

 By Jastej Singh Matharu

[I have recorded my thoughts and transcribed them. So the text may come across like a conversation. I have been associated with Armoured Fighting Vehicles since 1984 mainly as a maintenance engineer and also for a few years I worked on design related to an engine retro-fitment project. I also taught tank technology for a couple of years.]

Essentially if you look at a tank it has everything that a vehicle has got and then a lot more. I will talk about the battle tank; ground upwards, something like if you were to talk about a car tyres upwards.

First and foremost what is in touch with the ground is what we call the running gear which is consisting of the tracks and the bogie wheels which ensure that the tank is able to move. The running gear is getting its drive from a sprocket which is connected from the engine compartment and in order for the tracks to go around smoothly on the other end we have an idler which allows the tracks to go around and lay itself below the road wheels which are also called bogie wheels.
No alt text provided for this image

In order to hold the tracks on the bogie wheels we have something called a horn which is there on every track link and the bogie wheels are in pairs; the horns are going through the bogie wheels between the bogie wheels and that’s why when the tank is turning the tracks do not come off or in the language of armoured fighting vehicle the tracks do not shed.

The bogie wheels are in turn connected to the hull of the tank through the suspension system. Typically the suspension system has got axle arms with some sort of a suspension mechanism which absorbs the shocks from the ground. So as the tank moves there is a combination of a spring and a damper in every suspension. The purpose of the spring is to absorb the shock and every time the tank hits a bump the spring compresses to absorb the shock and does not transmit directly to the hull; in addition to this, so that the tank does not keep bobbing up and down we have the shock absorber or what we call the damper which dampens the up and down bobbing of the spring. With this system we get connected to the hull and there are a variety of suspension systems. They can be coil spring pneumatic spring or other designs.

Now we move on the hull. Typically the hull of a tank is divided into three parts. In front is the driver’s compartment, there are tanks which have got the engine right in front, but usually the driver’s compartment comes in front.

Then we have the fighting compartment and in the rear of the tank we have the engine compartment from which the drive goes out the sprocket which I had mentioned earlier.

The driver’s compartment since it is only having the need of holding a driver it normally has space on either side of the driver so this space can be used for storing ammunition or fuel or batteries, things like that.

Behind the driver’s compartment is the fighting compartment. The main element which is there in the fighting compartment is the turret in this compartment you would have three people the commander the loader and the gunner. Certain tanks have got an automatic loading system, in that case in the fighting compartment the loader is replaced by the automatic loading mechanism. In this case the fighting compartment has only the commander and gunner. New tanks are coming up which will have no one in the fighting compartment. It will be all automated.

Behind the fighting compartment we have the engine compartment. While between the driver’s compartment and the fighting compartment there is really no separation and there is no bulkhead. The driver can exit out of the fighting compartment and the commander and loader can exit out of the driver’s compartment. But in the case of the connection between the fighting compartment and the engine compartment there is a bulkhead. The purpose of the bulkhead is to totally isolate the engine compartment, for obvious reasons, because the engine will have gasses and fuel and fumes which are not good for the crew so the engine and the crew are kept separate.

This bulkhead has various features, for example it will have inspection plates from where we can peer into the engine compartment, specially during maintenance and it will have a number of wires and looms ad pipes going from the fighting compartment to the engine compartment. For electrical connections normally sockets are used.

The engine compartment has the engine, the transmission and the final drives which in turn connect to the sprockets. The sprockets get the drive from the final drive and then run the running gear.

The engine compartment will have the various systems, the engine itself, the lubrication system, the cooling system, the fuel system, the electrical system, the air intake system, the fire fighting system and such like systems.

The engine compartment as I said will be enclosed and the cooling will be achieved through the means of a cooling fan. The cooling fan can achieve cooling in various ways. One way is where it throws out air from the engine compartment creating a low pressure and this results in air being sucked into the engine compartment through the radiators. Normally there will be a number of radiators, water, oil, hydraulic and such like.

The engine compartment will also have an inlet for the air to the air cleaner which will supply air to the engine inlet.

There will also be a passage for the exit of the exhaust from the engine compartment.

Usually tanks have diesel engines but one has a gas turbine engine. Some time tanks have a main engine and an auxiliary engine.

A word over here about the auxiliary engine and the starting system. Normally the starting of a big engine takes a lot of current and drains the battery. So we could have an auxiliary engine which will recharge the battery. This is needed if the electrical starting is the main starting of the tank. However in certain tanks the starting is through air starting in which case the auxiliary engine is dispensed with. And then you have the air starting in which case the main engine keeps the air bottle charged and the stored air pressure is used for starting the main engine thus conserving the electric charge of the battery.

The purpose of the battery here is to give enough power for the tank to be able to operate it’s electrical systems with the main engine being switched off. If you had the auxiliary engine that could keep running as being smaller it produces very little noise and heat. Starting the main engine would be a give away of your location. So having an auxiliary engine or not is a result of a balance which has to be made.

Tank design is all about balancing one type of requirement with another.

Coming back to the fighting compartment. The main thing which is there is the turret. The turret is mounted on turret ring in the hull. The turret is able to rotate 360 degrees. The electrical connection of the turret to the hull is through some sort of a device like a rotary base junction which is placed at the bottom of the turret from where the turret rotates. In this manner we achieve the supply to the many electrical systems in the turret.

The main thing which the turret houses is the main gun of the tank. The main gun is a huge gun. Main guns of tanks fire very high velocity projectiles. So an important part of the design here is how to contain the recoil of the gun within the space of the turret.

In the turret there are two more important systems. These are the gun control system and fire control system. The purpose of the gun control system is to allow the commander or the gunner to rotate the turret at will and to acquire targets. The purpose is to quickly swivel the turret around and bring the gun onto the target.

The fire control system decides the manner in which the gun will be fired. Nowadays tanks have the stabilising system which means irrespective of how the hull is moving the gun remains locked onto the target. This is what makes the tank a very lethal weapon. A tank can move very fast and at the same time remain locked onto the target and fire accurately. This is the final aim of the designer of the tank.

The gun itself can be rifled or smooth bore. The main purpose of the gun is to be able to fire a projectile which will defeat the adversary tank’s armour. So high velocity rounds are needed and a variety of ammunition has been invented for this.

Coming back to the hull. It is very important for the designer to make a hull which is able to protect the tank from the adversary’s projectiles. Here again the issue of balance comes. Normally the frontal part of the tank, which is known as the frontal arc is heavily protected and the sides, rear and bottom less so. It is impossible to protect a tank heavily from all sides.

A variety of armours have been developed. There used to be the monolithic armour which was a chunk of steel, now new armours have come up which are designed to defeat projectiles without too much of a weight penalty.

The classic balance a tank designer has to achieve is between the firepower and the mobility and the protection. The running gear, the engine the sprocket these all provide the mobility aspect. The firepower is by the gun, it’s calibre’ the speed of the projectile’ accuracy of the projectile and the ability to be able to move and fire.

Protection is through the armour.

It is obvious that if you want a bigger gun it means it will be heavier and the tank’s weight will go up.

Similarly if you want to increase the protection the tank’s weight goes up.

If you want now to put in a bigger more powerful engine you need more space in the engine compartment this will make the tank’s hull bigger which in turn will again require protection.

So in tank design one thing leads to another and you have to strike an optimum balance based on your requirement.

Various armies according to their requirements based on their own situations have designed different tanks. A lot of technology goes in to ensure that you are able to get the optimum firepower, mobility and protection as per your own requirements.

It is expensive technology. Developed after tremendous research and development. 

In spite of the variety of other weapons, both on the ground and in the air, the main battle tank remains the most lethal weapon on the battlefield even today