AFVs in Space Gamer

[tbeard1999]

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 values...

Correct, but my point is that it doesn't matter because sloping armor does not save mass -- a sloped plate with 100mm armor line of sight is longer and thinner than a vertical plate with 100mm line of sight, but weighs exactly the same. Thinner plates are much easier to make, so there is a manufacturing advantage to,using thinner plates and sloping them.

Assume a 1m high by 3m wide frontal area that you want to protect with 10cm armor. A vertical plate -- 1m x 3m x 10 cm -- is option 1. Option 2 is a 45 degree inclined plate 3m wide with a 10cm line of sight that covers the same 1m high area will actually be about 1.44m x 3m x less than 10cm thick. But it will weigh exactly the same as Option 1. So there's really no reason to get into armor slope in a design system.

With early APDS kinetic energy rounds there was an additional richochet effect for sloped armor. However, modern APFSDS long rod penetrators are actually designed to turn in to the armor. So sloped armor is a bit less effective.

My point is that sloped armor should simply be assumed by the design system.

 

[Timerover51]

With early APDS kinetic energy rounds there was an additional richochet effect for sloped armor. However, modern APFSDS long rod penetrators are actually designed to turn in to the armor. So sloped armor is a bit less effective.

My point is that sloped armor should simply be assumed by the design system.

All armor-piercing projectiles tend to turn into the armor upon impact, not just the most recent ones. The longer the projectile, the greater the stress on it of turning into the target plate. If the stress is too great, the projectile breaks up.

Next, current modern tanks are no longer using monolithic alloyed steel armor, but Chobham laminate armor composed of a mixture of titanium and ceramic plate. The laminate is not conducive to curves in the manufacture, which is why current tanks have a large number of flat plates sloped to various angles. If a fin-stabilized discarding sabot round hits at a great enough angle, it either ricochets or breaks up. The advantage to the fin-stabilized round is that it concentrates more energy on a smaller spot that the standard spin-stabilized round. In either case, the extremely high velocity of the round is brutal on the barrel, with corresponding short accurate barrel life, and major problems of barrel droop after firing several rounds in rapid succession. The result is a weapon that is optimized for attacking heavily-armored enemy tanks, with limited capability of infantry support.

 

[jec10]

Actually, photographic evidence from recent conflicts and released archival material suggests that the whole "ceramics" and composite laminate thing was a red herring. Most MBTs today appear to use a form of NERA "bulging armour" (e.g. Abrams, Merkava, Challenger, Leopard, T90, etc)

 

[Timerover51]

My apologies for bumping this thread, but I finally looked at the article on designing Armored Fighting Vehicles (AFV) in the Space Gamer No. 44, and I would like to make a sone comments with respect to it.

The article does give some idea as to the Time Line of Tech Level, as the M1 Abrams is listed at Tech Level 8, which is correct. However, Tech Level 6 is the minimum Tech Level for AFV design, which is clearly incorrect. The tank and the armored car were used in World War One on a fairly wide basis, which should put the earliest AFV at Tech Level 5, and if your really pushed it, late Tech Level 4. It would depend on how you worked the Tech Levels.

Next, a major item is left out for the earlier AFV, and that is fuel. Current AFV have this unfortumate tendency to be fuel hogs, the M1 Abrams turbine engine being a case in point. The fastest way to stop an armored advance dead in its track is cut off its fuel supplies. Fuel does consume internal protected volume, which can be costly. Quite a few AFVs in World War 2 and since have made use of external fuel tanks which are used and then jettisoned, hopefully before combat. I will not get into a discussion on the issue of gasoline verses Diesel as fuel.

Then there is the issue of Chain Guns and Gatling Guns. The AH-1S and the Bradley both use chain guns, which have a variable firing rate of between 1 to 600 rounds or better per minute. The A-10 carries a massive 30mm Gatling Gun, larger and heavier than a Volkswagen, firing either depleted Uranium rounds or high-explosive rounds, selection up to the pilot. The 30mm round fired by the helicopter is considerably different than the one used by the A-10. The Bradley can fire either a discarding sabot round or an HE round, again the selection of the gunner.

I will need to look a bit more on the various cannon, but there should be a bit more difference between the various projectile guns. I will not get into the energy weapons I will also need to take a further look at suspension systems and speed. The Christie Tank chassis could run on either wheels or treads, and could hit up to 60 miles per hour on roads, given its modified aircraft engine power plant. The article was also written about the time that reactive tank armor began to appear, along with sensors for detecting laser target designators and automatically triggered smoke screens upon the detection of a designator.

I will have to see about posting some of my World War 2 armor penetration data, along with getting out my Ogorkiewicz books and get some of that data up as well.

I would still say if someone wants to work with Tech Level 8 to 9 AFV and earlier, a good encyclopedia of tanks would be very helpful. There have been some very interesting designs over the years.

 

[tbeard1999]

My apologies for bumping this thread, but I finally looked at the article on designing Armored Fighting Vehicles (AFV) in the Space Gamer No. 44, and I would like to make a sone comments with respect to it.

The article does give some idea as to the Time Line of Tech Level, as the M1 Abrams is listed at Tech Level 8, which is correct. However, Tech Level 6 is the minimum Tech Level for AFV design, which is clearly incorrect. The tank and the armored car were used in World War One on a fairly wide basis, which should put the earliest AFV at Tech Level 5, and if your really pushed it, late Tech Level 4. It would depend on how you worked the Tech Levels.

Next, a major item is left out for the earlier AFV, and that is fuel. Current AFV have this unfortumate tendency to be fuel hogs, the M1 Abrams turbine engine tecing a case in point. The fastest way to stop an armored advance dead it its track is cut off it fuel supplies. Fuel does consume internal protected volume, which can be costly. Quite a few AFVs in World War 2 and since have made use of external fuel tanks which are used and the jettisoned, hopefully before combat. I will not get into a discussion on the issue of gasoline verses Diesel as fuel.

Then there is the issue of Chain Guns and Gatling Guns. The AH-1S and the Bradley both use chain guns, which have a variable firing rate of between 1 to 600 rounds or better per minute. The A-10 carries a massive 30mm Gatling Gun, larger and heavier than a Volkswagen, firing either depleted Uranium rounds or high-explosive rounds, selection up to the pilot. The 30mm round fired by the helicopter is considerably different thon the one used by the A-10. The Bradley can fire either a discarding sabot round or an HE round, again the selection of the gunner.

I will need to look a bit more on the various cannon, but there should be a bit more difference between the various projectile guns. I will not get into the energy weapons I will also need to take a further look at suspension systems and speed. The Christie Tank chassis could run on either wheels or treads, and could hit up to 60 miles per hour on roads, given it modified aircraft engine power plant. The article was also written about the time that reactive tank armor began to appear, along with sensors for detecting laser target designators and automatically triggered smoke screens upon the detection of a designator.

I will have to see about posting some of my World War 2 armor penetration data, along with getting out my Ogorkiewicz books and get some of that data up as well.

I would still say if someone wants to work with Tech Level 8 to 9 AFV and earlier, a good encyclopedia of tanks would be very helpful. There have been some very interesting designs over the years.

When we designed A Fistful of TOWS 3, we used the work of Paul Lakowsky, who’s done the most exhaustive unclassified work on modern tank armor protection and penetration. (His data also undergirds the Steel Beasts computer game). It helps that my co-designer is an engineer with a degree from MIT in Materials Science.

Anyhow, we published our game ratings (all of which index to real world values) at www.fft3.com . That might be useful, as it covers AFVs from ~1930 to 2020.

An easy trick for the Traveller referee is to take a modern vehicle, file the serial numbers off and upgrade it to whatever tech level you want.

 

[whartung]

I would still say if someone wants to work with Tech Level 8 to 9 AFV and earlier, a good encyclopedia of tanks would be very helpful. There have been some very interesting designs over the years.

If you want a bunch of armor in game terms, Twilight 2000 has a couple of books filled with vehicles.

 

[Timerover51]

If you want a bunch of armor in game terms, Twilight 2000 has a couple of books filled with vehicles.

I am well aware of that, as I have some of them. However, if you want coverage of earlier vehicles, that does not quite fill the bill. I think that it would be possible to design a tank using Tech Level 4 technology without making it into a steampunk vehicle. Remember that the tank went from concept in Winston Churchill's mind to combat use in less than two years in 1915 and 1916. The various bits were there, they just needed to be put together.

 

[Timerover51]

When we designed A Fistful of TOWS 3, we used the work of Paul Lakowsky, who’s done the most exhaustive unclassified work on modern tank armor protection and penetration. (His data also undergirds the Steel Beasts computer game). It helps that my co-designer is an engineer with a degree from MIT in Materials Science.

Anyhow, we published our game ratings (all of which index to real world values) at www.fft3.com . That might be useful, as it covers AFVs from ~1930 to 2020.

An easy trick for the Traveller referee is to take a modern vehicle, file the serial numbers off and upgrade it to whatever tech level you want.

I was thinking more of the earlier Tech Levels of vehicles. Most modern tanks are solely designed to fight other tanks, with little or no concern about the task of supplying mobile infantry support. World War Two tanks, for the most part, were capable of doing both jobs, some better than others.

 

[infojunky]

Weird, I just had the source article out again.

Pondering the volume displacements for each of the size categories listed in the article, mostly in ship squares. Thus a light vehicle would fit in a 2 by 4 space, medium in a 3 by 6 space, and a Heavy in a 4 by 8 space, with all the smaller measurements being a square in terms of height.

 

[tbeard1999]

I was thinking more of the earlier Tech Levels of vehicles. Most modern tanks are solely designed to fight other tanks, with little or no concern about the task of supply mobile infantry support. World War Two tanks, for the most part, were capable of doing both jobs, some better than others.

I think that the US, at least, is re-thinking that. The latest upgrade package for the M1 Abrams includes a phone (something that the M48 and M60 series' both had) for infantry to communicate with the tank crew. Also, several manufacturers are now producing genuine HE rounds for the Rheinmetal 120mm smoothbore. I was never much of a believer in "dual purpose" HEAT rounds.

 

[Timerover51]

Weird, I just had the source article out again.

Pondering the volume displacements for each of the size categories listed in the article, mostly in ship squares. Thus a light vehicle would fit in a 2 by 4 space, medium in a 3 by 6 space, and a Heavy in a 4 by 8 space, with all the smaller measurements being a square in terms of height.

I would not get too hung up on figuring vehicle dimensions based on weight.

The U.S. M-3 Stuart light tank of World War 2 weighed in at 12.7 metric tons, and was 178 inches long, 88 inches wide, and 99 inches high. Converting to metric, that would be 4.5 meters long, 2.2 meters wide, and 2.5 meters high, all dimensions approximate to tenths of a meter. This would be a Light Tank per the article. That would equate to a floor space of 2 by 3 ship squares.

The U.S. M-4 Sherman, with 75mm gun, weighed in at 30.5 metric tons, or a Light Medium based on the article. Its dimensions were 232 inches long, 103 inches wide, and 116 inches high. That gives approximately 5.9 meters long, 2.6 meters wide, and just under 3 meters high. That would equate to a floor space of 2 by 4 ship squares.

The U.S. M-47 Medium, with a 90mm gun, weighed in at 44 metric tons, so a Heavy Medium per the Space Gamer article. The dimensions were 278 inches long, not counting gun, 138 inches wide, and 111 inches high. That equates to 7 meters long, 3.5 meters wide, and 2.8 meters high. That would equal for floor space 3 ship squares wide by 5 ship squares long.

The World War 2 German Tiger 2, or King Tiger, weighed in at 75 tons, so a Heavy by the article. Its dimensions were 286 inches long, not counting the gun, 151 inches wide, and 122 inches high. That equals, in metric, 7.3 meters long, 3.8 meters wide, and 3.1 meters in height. In ship squares that would be 3 by 5 in floor space. That is the same as the U.S. M-47, about 31 tons lighter, and considerably less than the 4 by 8 that you give for a Heavy based on the article.

You need to think of an AFV as having a specific volume for the task that it is to do, and added armor, which quickly increases mass, does not increase that volume all that much.

A World War 2 M-5 Half-Track weighed in at just under 9 tons, so a Light vehicle by the article. Its dimensions were 249 inches long, 88 inches wide, and 91 inches high. In metric, that equals 6.3 meters long, 2.2 meters wide, and 2.3 meters in height. That would be 2 ship squares wide and 5 ship square long, or a larger floor space that the much heavier Sherman. That is because it was designed to carry a crew of 13 men, basically a 2 man crew and an 11 man infantry squad.

The M-3 Grant carried a crew of 7 men, along with a 75mm gun in a hull sponson, a 37mm gun in the turret, along with three .30 caliber machine guns, was a bit lighter than the Sherman, but had roughly the same dimensions as the Sherman. It does have a bit less armor for its greater internal volume.

 

[Timerover51]

A couple of things to keep in mind with respect to World War 2 or Tech Level 6 tanks. As near as I can make out, the cost of a WW2 Sherman or Grant tank came out at about $1.00 per pound of vehicle weight, but that does reflect the enormous production numbers. A WW2 light tank is going to cost a bit more per pound, because of the cost of the engine, generally close to that of the larger medium, being a higher percentage of the total cost, so call it about $1.25 per pound. Korean War era tanks look like they ran about $2.00 a pound, based on shorter production runs, and an increase in labor costs to build the vehicle.

As for fuel consumption, that looks to be somewhat less that one mile per gallon for the mediums, slightly over one mile per gallon for the lights, and more like 2 to 3 gallons per mile for the heavy vehicles.

Edit Note: Aside from the pricing, all the information is taken from official U.S Army technical manuals. The pricing comes from a variety of sources.

 

[infojunky]

I would not get too hung up on figuring vehicle dimensions based on weight.

Heck I was just looking at some rough ballpark figures based on a size classification system provided in the article. This is Traveller after all and things have to moved by ships.

As such my pondering where like the article a rough guesstimation of a thing. Consider this, how much volume does a robot designed by the jTas robots article's size classification system take up?

 

[kilemall]

A shortcut I am taking is using the latest vehicle design book for MgT2E and just stripping out the MgT bits.


That system gives you a fast development path, internal volume, shipping dtonnage, and all that good stuff with the least pain.



There is also a CE version, it's more fiddly with power plants and such, but largely the same concept.



Assuming I am using CT/Striker and I usually would be, the armor usually works out ok for the light stuff, and I just halve the heavy armor values. Strap on Striker weapons and it comes out 'good enough'.


For CT resolution on just light ATVs/AFVs, you could probably just use the armor as a total pen system, i.e. if the damage is equal to or less then the armor it doesn't go through, otherwise it does. If you care about spall, you are probably not looking for a fast and dirty resolution anyway.



I seem to recall someone had posted a CT vehicle damage system, I'd probably wedge that in there (if I wasn't already using Striker).

 

[sabredog]

I loved this article when it came out. It was just barely pre-Striker and does a good job of designing and fighting vehicles without getting so bogged in the math the players get lost.

I still use it for the majority of designs because of the simplicity.