AFVs in Space Gamer

[aramis]

Something design systems should avoid is giving bonuses for sloped armor and some cost in mass. A sloped plate covering an area weighs exactly the same as a vertical plate covering that area with the same line-of-sight thickness. Also, the additional "ricochet" benefit of sloped armor isn't really a thing nowadays.

Modern penetrators are actually designed to turn into the armor, so highly sloped armor can be a bit less protective. And advanced energy weapons don't richochet.

One reason armor is sloped nowadays is that thinner plates are *much* cheaper and easier to to manufacture and can be made with fewer defects. Rolling mills have a maximum thickness of plate that they can make.

Actually, sloping slightly reduces overall armor mass for the same thickness of slab, as a rectangular solid maximizes the surface area... and multiple slopes interact to shave surface area as well as volume... but that's a minor bit. The other benefits are the main reason to do so.

On the other hand, sloped armor is no benefit vs many air attacks, as they come in closer to perpendicular to the face...

 

[tbeard1999]

Actually, sloping slightly reduces overall armor mass for the same thickness of slab, as a rectangular solid maximizes the surface area... and multiple slopes interact to shave surface area as well as volume... but that's a minor bit. The other benefits are the main reason to do so.

Well my co-designer of FFT flat told me that there was no difference in mass between a sloped plate and a vertical plate covering the same area with identical line of sight thickness. He earned an engineering degree in materials science with honors from MIT, so I took his word for it.

 

[tbeard1999]

Rolling mills have a maximum thickness of plate that they can make.

Of course, you can cast a piece to be as thick as you want. However, cast steel armor is about 5-10% inferior to rolled homogenous steel armor. When dealing with modern MBTs, this can be significant.

 

[mike wightman]

Well my co-designer of FFT flat told me that there was no difference in mass between a sloped plate and a vertical plate covering the same area with identical line of sight thickness. He earned an engineering degree in materials science with honors from MIT, so I took his word for it.

That's not mathematically or physically possible.

Take a 1 m2 2cm steel plate at 90 degrees to the impactor - the projectile has to penetrate 2 cm of steel.

Now tilt the plate to 45 degrees, the projectile now has to penetrate a bit more steel 2.8cm to be precise.

 

[aramis]

That's not mathematically or physically possible.

Take a 1 m2 2cm steel plate at 90 degrees to the impactor - the projectile has to penetrate 2 cm of steel.

Now tilt the plate to 45 degrees, the projectile now has to penetrate a bit more steel 2.8cm to be precise.

Likewise the volume drops and the SA drops when you slope a side within the same bounding box ... given a box 1x2x4m
Slope the 1x2m "front" 45°.
you replace a 1x2 m front and a 1x2m chunk of the 2x4m top with a 1.414x2m plate, as well as removing 1/2m² from each 1x4m slab. you've removed about 1.586m² of face, ignoring the lower overlap at the corners. You also lose 1m³ of enclosed volume.

 

[kilemall]

Well my co-designer of FFT flat told me that there was no difference in mass between a sloped plate and a vertical plate covering the same area with identical line of sight thickness. He earned an engineering degree in materials science with honors from MIT, so I took his word for it.

The point of sloping ofttimes is to have a thinner piece do the work of a thick vertical piece while providing protected volume for crew or equipment. The thinner piece may end up weighing as much as a boxier vertical setup, but that's because it's covering more surface.

A lot depends on what sort of environment and opponents the tank will operate against and supporting arms as to whether it's a good tradeoff.

 

[tbeard1999]

That's not mathematically or physically possible.

Take a 1 m2 2cm steel plate at 90 degrees to the impactor - the projectile has to penetrate 2 cm of steel.

Now tilt the plate to 45 degrees, the projectile now has to penetrate a bit more steel 2.8cm to be precise.

I meant that a sloped piece of armor weighed the same as a vertical piece that had the same line of sight thickness. The vertical piece will be thicker and shorter than the sloped piece, but will weigh the same.

Or, a sloped piece of armor that is the same width as a vertical piece and that has the same line of sight thickness as the vertical piece will be longer and thinner but weigh the same as the vertical piece.

I think that I expressed it poorly the first time around when I said "same area". I didn't mean that each piece had the same area. I was thinking of same area viewed head on.

 

[mike wightman]

Ah, that makes sense now.

 

[BlackBat242]

However, only considering the vertical plate vs sloped plate ignores the horizontal plate needed to cover the top of the area enclosed by the vertical armor (and its weight)... the sloped plate covered horizontal area as well as vertical.

Otherwise you are talking about an open-topped vehicle without any protection from above.

 

[infojunky]

But is the level of slope of a particular bit of armor really that important a detail?

 

[Condottiere]

Yes.

But not against mesons.

I've considered whether it's worthwhile introducing it for spaceships.

 

[infojunky]

Yes.

Why?

 

[Condottiere]

Because that's how armoured vehicles are designed.

Projectiles either bounce off or have a more protection to penetrate, in a straight line.

 

[infojunky]

Because that's how armoured vehicles are designed.

I reiterate is it important for a simplified vehicle design system?

 

[Condottiere]

I think you have to, otherwise there's no point in trying to put yourself in a favourable firing position, like behind.

Mass combat, probably would take too long without a computer.

 

[infojunky]

I think you have to, otherwise there's no point in trying to put yourself in a favourable firing position, like behind.

I am really not sure how you got to that conclusion.

Mass combat, probably would take too long without a computer.

Y'all know that is a completely different thread?

 

[tbeard1999]

But is the level of slope of a particular bit of armor really that important a detail?

Not in a vehicle design system. As noted earlier, with modern weapons, sloped armor offers no "ricochet" protection; line of sight thickness is what matters. And, in the case of modern APFSDS long rod penetrators, sloped armor offers a bit less protection because of the behavior of the penetrator. Bottom line -- it's a needless flourish that should be baked into the design sequence.

 

[kilemall]

Not in a vehicle design system. As noted earlier, with modern weapons, sloped armor offers no "ricochet" protection; line of sight thickness is what matters. And, in the case of modern APFSDS long rod penetrators, sloped armor offers a bit less protection because of the behavior of the penetrator. Bottom line -- it's a needless flourish that should be baked into the design sequence.

Er.

If I understand your phrasing, LOS Thickness WOULD be determined by the angle of the slope along with the actual thickness of the plate. Relative firing position and the angle of the round/EW shot could make for radically different armor values.

Also, angling the tank hull vs. a known assailant can increase relative armor in the horizontal plane.

Striker simplifies this which makes sense especially given that a lot of our vehicles are going to be gravitic, therefore flying.

So the real question of whether to bother with precise angles and their effects is how much fidelity are you building into your movement and firing rules?

Super crunchy? It counts. Striker-level? Simplified, 45 degrees is not different from 30 or 60. GEV-type CRT abstract results? Might edge up armor value by one, or take away by one if the opponent has greatly superior maneuvering. Otherwise just as well to ignore.

Something like that fighter-maneuver game for Traveller starships would be necessary for grav tank duels.

Computer sims can do this as a matter of course, probably not worth it for most paper RPGers.

 

[infojunky]

Bottom line -- it's a needless flourish that should be baked into the design sequence.

Ok, I am not crazy then...

I am not against a detailed design system for a game centered on armored warfare, 90% of what I do is character based and as such hyper detail isn't necessary. In general the biggest concern is weather those tanks main guns can do damage to the ships hull....

 

[Jame]

Ok, I am not crazy then...

I am not against a detailed design system for a game centered on armored warfare, 90% of what I do is character based and as such hyper detail isn't necessary. In general the biggest concern is weather those tanks main guns can do damage to the ships hull....

Decide what dramatic/story effect that you want it to have.
Even if you dont want it topenetrate, roll damage to make it a dramatic fight,dramatic escape a la Star Wars.
"Did it penetrate?!?"
"Yer bein shot at! You gotta deal with that first!"
"First!? First I give em my fist!" BLAM! "HOW YOU LIKE A FIST OF LASER YA *******TANK!"