On Armored Vehicles “Relative Armor”

Another issue is the relative armor …

As I mentioned in the rules, besides the thickness and slope, we must take into account the type of armor (rolled, face-hardened or cast [I´m not sure of the correct technical terms in English]) and its hardness rating.

This has been the biggest problem, as much of this data is unknown territory, or varies over time even in the same factory, so in when in doubt I have opted for the “most likely”.

Data is are entered for each sector of each tank and turret, taking into account which piece of armor the projectile is more likely to impact – here we have no choice but to make arbitrary decisions, due to the incredibly complex geometries, or places where different types of armor are superimposed. Again, I process this data (more than one hundred per tank) using a program that gives me the correct equivalent in millimeters of “relative armor”.

And now for the nightmare … system diagrams … As well as having to look for the plans for each vehicle (and version) – hence the bummer of having to make Italian, French, Polish or Hungarian tanks, which are not well documented and you have to draw on photos – you have to know how and where the ammunition was stored, and IN WHAT POSITION, since what can explode is NOT the explosive (which is super safe), but the propellant.  You have to figure out which system could be affected if a projectile enters from a certain angle for each sector.

This step – the “terminal ballistics” – is simply exhausting because you have to take into account so many factors and a computer can do it, but you´d have to put in so many parameters which would then lead to so many exceptions and dead ends, that I simply sought help (a person with clearly a lot more patience than me and a thousand times more systematic).

Ahhh, but next up are the cannons and projectiles … Because “logically” if two cannons use the same ammunition, that ammunition should cause the same damage to the target…. alas no …

For starters, the length of a cannon has a significant impact …

The propellant projectile comes in several formats. Some are like “threads”, but those used in the Second World War were usually like cylinders or tiny tubes of cordite, because of the importance of the SURFACE AREA that “burns” in a question of microseconds.

They can be as I say, a cylinder. And each cylinder of propellant becomes smaller and smaller as it´s consumed, thereby diminishing its SURFACE AREA.  This means that once it starts to “explode”, its strength decreases. Cylinders are used for relatively short barrels, as the outset of the shot produces the greatest amount of thrust, and this diminishes very quickly.

However if it is a tube of propellant, its outer diameter is reduced as it´s consumed, but it´s interior becomes greater, so once it starts to “explode”, its explosive force is almost constant.

This allows for longer cannons where the load of propellant can be calculated so that the force is maintained while the projectile travels through the bore of the barrel and disappears just when it leaves the mouth.

However there are very long cannons (measured in projectile calibers) and to continue pushing a projectile along a bore (where the space is ever increasing) requires a propellant that “explodes” with more and more force. For this, tubes with several internal channels (like the barrel of a revolver) are used, which when the propellant starts to “explode”, reduce their outer diameter, but increase the diameter of all the interior channels, exposing more and more SURFACE AREA.

So a 75mm projectile DOES NOT WORK the same on any 75mm cannon. The same projectile in a cannon which is too short may exit very slowly because not all the propellant has burnt when the projectile is already out there; in a normal length cannon (for its load) it will fly out exactly at its ideal speed, and in another longer cannon it may get stuck. This is called “Interior ballistics”.

Then there is also everything related to projectiles designed to explode on impact (again Terminal ballistics).  Just as the energy of an inert projectile decreases with distance (the further it goes, the less damage it causes), the energy of projectiles loaded with explosives is always the same (as it explodes upon impact, it makes no difference if the target is near or far, the explosive charge is the same).

And the damage produced by hollow charge projectiles bears no relation to speed, as the damage occurs when the explosives contained in it, project a jet of copper vapor onto a point, but this jet is affected by the projectile´s speed of rotation (because of the centrifugal force).

Mercifully, I have access to data from thousands and thousands of tests carried out in Bovington during the war, although in some cases (of weapons NOT tested in that industrial estate, now also a museum) I had to extract the data using another little program that I had to drum up.

Other data are more simple, such as those related to sights. I simply use the number of magnifications and the field of vision for each cannon. But for detection, what we did was take into account the number, position and turning capacity of “direct” sights (without lens), the artillery sights with lenses and the periscopes. In fact, you will see that some turrets have worse visibility “from the front” than at the sides, precisely because all the sights at the front had a magnifying glass, which reduced their angle of vision to a few degrees.

I got rid of all the messy bits so players could start playing from the outset. The game requires alot of though, so I wanted to save them all the previous calculations.

I eliminated some markers and the tank combat went from being an accounting exercise with dice, to an almost role-playing scenario, with the player announcing in each impulse what each crewman does (which aside from avoiding cheating and other such tricks, adds a certain vividness to the game).

The idea is that if someone has only two or three hours a week to play, these two or three hours should be for them to enjoy and play, not be frustrated, waiting for a dice or a card to appear. Players must go home satisfied, and although it is not within my control if they lose the fight, I will not let them “lose” their morning.