Editing Tank (section)

===Engineering constraints===
[[File:Arjun MBT bump track test.JPG|thumb|The Indian [[Arjun MBT]]'s [[hydropneumatic suspension]] at work, while moving over a bump track.]]
A noted author on the subject of tank design engineering, [[Richard Ogorkiewicz]], outlined the following basic engineering sub-systems that are commonly incorporated into a tank's technological development:{{sfn|Ogorkiewicz|1991|p=}}{{page needed|date=May 2012}}
* Mobility  (through chassis design)
* [[Engine#Combustion engine|Engines]]
* [[Transmission (mechanics)|Transmissions]]
* [[Suspension (vehicle)|Suspensions]] and [[running gear]]
* Soil-vehicle mechanics
* [[Tank gun|Guns]] and [[Ammunition#Ordnance ammunition|ammunition]]
* [[Ballistics]] and mechanics of guns
* Vision and sighting systems
* Illuminating and [[Night Vision#Night vision technologies|night vision]] systems
* [[Fire-control system|Fire control systems]] for main and auxiliary weapons
* [[Gun data computer|Gun control systems]]
* [[Precision-guided munition|Guided weapons]]
* [[Vehicle armour#Armoured fighting vehicles|Armour]] protection
* Configuration
To the above can be added unit communication systems and electronic anti-tank countermeasures, crew ergonomic and survival systems (including flame suppression), and provision for technological upgrading.
Few tank designs have survived their entire service lives without some upgrading or modernization, particularly during wartime, including some that have changed almost beyond recognition, such as the latest Israeli [[Magach#Versions|Magach]] versions.

The characteristics of a tank are determined by the performance criteria required for the tank. The obstacles that must be traversed affect the vehicle's front and rear profiles. The types of terrain specified to be traversed determine the maximum permissible track ground pressure.<ref name="performance reqs">{{Citation|title=Journal of the United Service Institution of India, Volume 98|year=1968|publisher=United Service Institution of India|url=https://books.google.com/books?id=iZI8AQAAIAAJ|page=58|url-status=live|archive-url=https://web.archive.org/web/20180327160324/https://books.google.com/books?id=iZI8AQAAIAAJ|archive-date=27 March 2018}}</ref>

Tank design is a compromise between technological and budgetary constraints and tactical capability requirements. It is not possible to maximise firepower, protection and mobility simultaneously, while also incorporating the latest technology and being economically viable.
For example, in the case of tactical capability requirements, increasing protection by adding armour will result in an increase in weight and therefore decrease in mobility; increasing firepower by installing a larger gun will force the designer team to increase armour, the therefore weight of the tank by retaining same internal volume to ensure crew efficiency during combat. In the case of the Abrams MBT which has good firepower, speed and armour, these advantages are counterbalanced by its engine's notably high fuel consumption, which ultimately reduces its range, and in a larger sense its mobility. And most enhancements add to cost.

Since the Second World War the economics of tank production, governed by the complexity of manufacture and cost and the impact of a given tank design on logistics and field maintenance capabilities, have also been accepted as important in determining how many tanks a nation can afford to field in its force structure.

Some tank designs that were fielded in significant numbers, such as [[Tiger I]] and [[M60A2 Starship|M60A2]] proved to be too complex or expensive to manufacture, and made unsustainable demands on the logistics services support of the armed forces. The ''affordability of the design'' therefore takes precedence over the combat capability requirements.
Nowhere was this principle illustrated better than during the Second World War when two Allied designs, the Soviet [[T-34]] and the US [[M4 Sherman]], although both simple designs which accepted engineering compromises, were used successfully against more sophisticated designs by Germany that were more complex and expensive to produce, and more demanding on overstretched logistics of the Wehrmacht. Given that a tank crew will spend most of its time occupied with maintenance of the vehicle, engineering simplicity has become the primary constraint on tank design since the Second World War despite advances in mechanical, electrical and electronics technologies.

Since the Second World War, tank development has incorporated experimenting with significant mechanical changes to the tank design while focusing on technological advances in the tank's many subsystems to improve its performance. However, a number of novel designs appeared, with mixed success, including the firepower of the Soviet [[IT-1]] and [[T-64]], and the crew protection of the Israeli [[Merkava]] and Swedish [[S-tank]], while for decades the US's [[M551]] remained the only light tank deployable by parachute.

{{Further|Tank classification}}