Steve Jackson Games Forums [Cutting-Edge Armor Design] Real World SCA-legal Armour and Ballistics Armour
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02-07-2018, 11:32 AM   #2
mlangsdorf

Join Date: Aug 2004
Location: Austin, TX
Re: [Cutting-Edge Armor Design] Real World SCA-legal Armour and Ballistics Armour

Quote:
 Originally Posted by Icelander Going a little more modern, how would we stat a full suit (well, back, breast and sides of torso) of AR500 Armor Lightweight Level III+ Body Armor, as well as whatever plate carrier is necessary for it?
The 10x12" plate weighs 5.5 lbs and protects against .308 rounds, but not 5.56 AP rounds, so call it DR 23. Simple math puts 1 sqft of the stuff at DR 23 weighing 6.6 lbs.

Armor weight is SA x WM x CW x DR. CW of a solid plate is 1, weight is 6.6 lbs, DR is 23, and SA is 1 sqft. A little algebra and the WM of the stuff is 0.286 - call it 0.3 for simplicity. That's better than TL7 titanium alloy or TL8 ultra-strength steel, but not as good as TL8 titanium or polymer composite.

You can do similar math to get the CM, which works out to \$20 - which is probably too low. I'm going to arbitrarily double it to account for the difference between a GURPS TL8 \$ and 2017 USD.

It's DR 23, and 0.21" thick, so it has DR 109/in. Max DR on a human is 27 for a 1/4" plate.

You can do the same math for the 10x14", soft body plate but I'd just treat it as improved kevlar.

So all that works out to:

Polyurea coated lightweight steel armor: WM 0.3, CM \$40, DR/in 109, Max DR 27, Notes -, Construction R/S.

A suit of the polyurea coated lightweight steel plate, worn over a suit of the AR500 Hybrid ballistic weave:
Steel armor: LSA 21.35, WM 0.3, CM \$40, CW 0.8, CC 5, DR 24: 123 lbs, \$24600
Ballistic weave: LSA 21.35, WM 0.08, CM \$120, CW 1, CC 1, DR 10: 17 lbs, \$2050.

Since armor weight and cost is linear with DR, we can drop the steel armor to DR 8, reducing the weight to 41 lbs, the cost to \$8200, and count on the ballistic weave to catch stragglers. The combination is just over 1/4" thick, weighs 58 lbs, costs \$10250, and will stop 5.56mm rounds and significantly slow down .308 rounds.

Unfortunately, you're already breaking the Lord of Darkness cost point. Let me come back on optimizing this stuff - I have some ideas.
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 02-07-2018, 11:43 AM #3 fula farbrorn   Join Date: Nov 2014 Re: [Cutting-Edge Armor Design] Real World SCA-legal Armour and Ballistics Armour you could use your own armorer and buy sheets of AR500 from https://www.leecosteel.com/ar500-500f-steel-plate.html looking at that page you might need 30 of their 96X96 inch sheets, though i might be WAY off since im operating on a lack of sleep then you can get the Kevlar for the gambeson here http://www.cstsales.com/aramid_fabric.html all in all probably a tad under 3k usd not counting the hours spent making it into a suit to add 20 10X12 pieces of AR500 steel was marked as 1700 usd on amazon, and i figure you can get further savings from more of them being ordered, the kevlar is way cheaper https://www.amazon.com/TEMCo-Square-.../dp/B00O3KL8C2
02-07-2018, 12:10 PM   #4
Icelander

Join Date: Mar 2006
Location: Iceland*
Re: [Cutting-Edge Armor Design] Real World SCA-legal Armour and Ballistics Armour

Quote:
 Originally Posted by mlangsdorf The 10x12" plate weighs 5.5 lbs and protects against .308 rounds, but not 5.56 AP rounds, so call it DR 23. Simple math puts 1 sqft of the stuff at DR 23 weighing 6.6 lbs.
By NIJ standards, Level III armour needs to be DR 25 to be actually rated to stop 7.62x51mm NATO from full-length barrels. Average damage is 24.5, after all.

Level III+ is not a recognised NIJ standard, but it is used by many manufacturers. Assuming that the tests were performed correctly, the highest damage round mentioned puts it at DR 29-30, by GURPS standards, stopping 7.62x51mm AP rounds (not APHC, and old-school AP puts it at 7d(2)*0.6 = 24.5(2)*0.6 = 49*0.6 = 29.4).

Note that some AR500 armours were recalled for failing to meet advertised standards, but the currently sold versions allegedly meet these standards, as they just had to go through independent testing. That said, I wouldn't mind DRs that were 1-2 points lower than they ought to be, on account of this being cheap and dirty ballistic armour from a disreputable manufacturer.

Quote:
 Originally Posted by mlangsdorf Armor weight is SA x WM x CW x DR. CW of a solid plate is 1, weight is 6.6 lbs, DR is 23, and SA is 1 sqft. A little algebra and the WM of the stuff is 0.286 - call it 0.3 for simplicity. That's better than TL7 titanium alloy or TL8 ultra-strength steel, but not as good as TL8 titanium or polymer composite. You can do similar math to get the CM, which works out to \$20 - which is probably too low. I'm going to arbitrarily double it to account for the difference between a GURPS TL8 \$ and 2017 USD. It's DR 23, and 0.21" thick, so it has DR 109/in. Max DR on a human is 27 for a 1/4" plate.
I'm pretty sure that with a hardness of BHN 460-544, this abrasion resistant 'AR500' steel is not going to be easily shaped into anything other than Solid plates or, at most, very gently curving ones.

For the purposes of the design system, it looks like most of the commercially available AR500 steel armour is effectively Trauma Plates, which are usually Solid, i.e. Ceramics (which can only be Solid).

I actually don't know if there are steel alloys with DR this high available today which can be manufactured as articulated plate armour, as opposed to just plate inserts of high DR ballistic protection that you use to protect the most important 40% to 60% of your Torso hit location (using up to four plates, front chest, back and two sides).

On the other hand, I found real examples of 3/8" thick trauma plates made from this steel, so it looks like the 1/4" limit does not necessarily hold true for Solid plates, as opposed to articulated-armour Plate construction. I think ceramic trauma plates can be more than 1/4" too, so it has precedent.

Note that some adventurer useful gear costs the same or is even cheaper than when GURPS 4e was published. As such, I use a generic scale of GURPS \$ = real-world \$, but prices for individual goods may change.

I haven't made up my mind whether or not body armour prices generated by the 'Cutting-Edge Armor Design' match any particular year. In any case, let's not use any modifier to Cost unless we find that there is a need to apply them generically to all materials or specifically to types of materials we have discovered to have changed in price from the reference prices used in GURPS.

Quote:
 Originally Posted by mlangsdorf Polyurea coated lightweight steel armor: WM 0.3, CM \$40, DR/in 109, Max DR 27, Notes -, Construction R/S.
We've got price information on Solid trauma plates made from this material. Slightly less than 1 square foot with DR 23-30, depending on the validity of the testing, seems to cost \$100-\$200, depending on specifics.

Quote:
 Originally Posted by mlangsdorf A suit of the polyurea coated lightweight steel plate, worn over a suit of the AR500 Hybrid ballistic weave: Steel armor: LSA 21.35, WM 0.3, CM \$40, CW 0.8, CC 5, DR 24: 123 lbs, \$24600 Ballistic weave: LSA 21.35, WM 0.08, CM \$120, CW 1, CC 1, DR 10: 17 lbs, \$2050.
Are you aware of any real world full-body suits made of Kevlar, aramid weaves or similar materials?

Would not wearing the same thickness as about Level II or Level IIA concealable vests over the entire body, limbs, joints and everything, not cause some flexibility issues? To say nothing of heat issues?

I'm prepared to apply such if appropriate.

Quote:
 Originally Posted by mlangsdorf Since armor weight and cost is linear with DR, we can drop the steel armor to DR 8, reducing the weight to 41 lbs, the cost to \$8200, and count on the ballistic weave to catch stragglers. The combination is just over 1/4" thick, weighs 58 lbs, costs \$10250, and will stop 5.56mm rounds and significantly slow down .308 rounds. Unfortunately, you're already breaking the Lord of Darkness cost point. Let me come back on optimizing this stuff - I have some ideas.
Jay-zus!

Do you believe that you could get this built in the real world for anything close to this price point? Are there even companies which would make a full-body ballistic suit, as opposed to protecting the important parts, as almost every commercial product I can find does?

I had imagined that most of the limbs, as well parts of the lower abdomen and maybe basically anything which needs to be shaped to the body, as opposed to utilising a gently curved Solid trauma plate, would be made from traditional steel, by some company marketing to re-enactors, because the extremely high DR hardened steel would be too hard to work into any kind of actual armour shape.
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Last edited by Icelander; 02-07-2018 at 12:14 PM.

02-07-2018, 12:30 PM   #5
Icelander

Join Date: Mar 2006
Location: Iceland*
Re: [Cutting-Edge Armor Design] Real World SCA-legal Armour and Ballistics Armour

Quote:
 Originally Posted by fula farbrorn you could use your own armorer and buy sheets of AR500 from https://www.leecosteel.com/ar500-500f-steel-plate.html looking at that page you might need 30 of their 96X96 inch sheets, though i might be WAY off since im operating on a lack of sleep
Ok, so here's where I really need help from forumites who are hobby smiths, machinists, material scientists or at least more handy than I am...

What kind of equipment do you need to work steel with this kind of hardness?

Won't you ruin the hardening trying to reforge it into other shapes?

Can you do anything with it using the kind of tools that you might have at a home workshop or some kind of garage business working with metals?

What about using the tools you might have at an automobile chop-shop?

If you need specialised tools to work with it, are we talking about tools costing a couple of hundred dollars, a couple of thousand, as much as a car or as much as a new house?

If it matters, assume access to several people with Machinist 10-12, at least one with Machinist 14+ and a bunch of people with Mechanic in the 8-12 range, as well as a couple of custom detailers and/or men who build improvised APCs for the cartels, with Armoury (Vehicle Armor) 10-12, Blacksmith 10-12, Machinist 12+, Mechanic (Automobile) 14+ and maybe some Engineering.

Also, they'd have access to some gunsmiths with Armoury (Small Arms) at 12+.

I don't really know how plausible it would be to assume that the Knight Templars have a member or an associate with Armoury (Body Armour). I guess that Dabbler and 1-2 points in it might make sense for the mechanics, machinists or gunsmiths if they have been trying to custom-build armour for a couple of years now, though.

Quote:
 Originally Posted by fula farbrorn then you can get the Kevlar for the gambeson here http://www.cstsales.com/aramid_fabric.html all in all probably a tad under 3k usd not counting the hours spent making it into a suit
The Knight Templars are lucky in that regard, at least if Sewing skill is useful* for working with Kevlar. They can get as many maquiladora girls, seastresses, tailors or knock-off fashion desiners as they want to kidnap and have already been noted for disappearing a lot of girls who work in factories that make clothes or other consumer goods.

*Yes, I assume that you'd need specialised machines and knowledge if you want to cut it or otherwise tailor it, but Sewing might at least offer a default.
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 02-07-2018, 12:38 PM #6 mlangsdorf   Join Date: Aug 2004 Location: Austin, TX Re: [Cutting-Edge Armor Design] Real World SCA-legal Armour and Ballistics Armour Ballistic black knight harness, take 2: DR 20 polyurea coated light steel armor solid skullcap: 1.4 sqft, WM 0.3, CM 40, CW 1, CC 1, DR 20: 8.4 lbs, \$340 DR 5 transparent laminated polycarbonate eyeslits: 0.1 sqft, WM 0.25, CM 50, CW 0.8, CC 5, DR 5: 0.1 lbs, \$25 DR 6 hard steel plate neck and face: 1.3 sqft, WM 0.5, CM 3.5, CW 0.8, CC 5, DR 6: 3.15 lbs, \$55 DR 20 polyurea coated light steel armor plate over the vitals: 1 sqft, WM 0.3, CM 40, CW 0.8, CC 5, DR 20: 4.8 lbs, \$960. DR 12F/6B hard steel plate torso other than vitals: 6 sqft, WM 0.5, CM 3.5, CW 0.8, CC 5, DR 9 (average for calculating cost/weight): 21.6 lbs, \$380 DR 8F/4B hard steel plate arms, legs: 10.5 sqft, WM 0.5, CM 3.5, CW 0.8, CC 5, DR 6 (average for calculating cost/weight): 28.35 lbs, \$500 DR 4 hard steel plate hands, feets: 1.4 sqft, WM 0.5, CM 3.5, CW 0.8, CC 5, DR 4: 2.25 lbs, \$40 DR6 improved kevlar undersuit: 21.35 sqft, WM 0.08, CM 120, CW 1, CC 1, DR 6: 10.25 lbs, \$1230 Total is 78.9 lbs, \$3530. A little over weight and budget, but the protection is good. The important parts are completely resistant to 7.62mm rounds and the arms and legs are nearly resistant to 5.56mm rounds from the front. You can stand in a fire for 45 seconds without worrying about burning or heat. The biggest weak point is the eye slits at DR 5. against bullets and axes (-4 DR against other damage types) DR 26 over the skull and vitals, DR 21 over the rest of the front torso, DR 15 over the face and neck, DR 14 over the arms and legs from the front, DR 10 for the hands and feet and back of the limbs, DR 12 for the back torso. An obvious way to save weight would be to replace the steel on the limbs with aluminum, but at 3.5x the cost of hard steel, it wasn't feasible for the \$3000 budget. Dropping the limb armor down to DR4, front and back, would also save about 10 lbs and DR 10 is sufficient to stop 9mm bullets. At the upper level of protection, titanium composite is 40% the weight of hard steel but 30x as expensive. Using titanium composite for the limbs would drop the weigh by 17 lbs, but would raise the cost by over \$14000, so it's not really feasible. __________________ Read my GURPS blog: http://noschoolgrognard.blogspot.com
02-07-2018, 01:14 PM   #7
Icelander

Join Date: Mar 2006
Location: Iceland*
Re: [Cutting-Edge Armor Design] Real World SCA-legal Armour and Ballistics Armour

Quote:
 Originally Posted by mlangsdorf Ballistic black knight harness, take 2: DR 20 polyurea coated light steel armor solid skullcap: 1.4 sqft, WM 0.3, CM 40, CW 1, CC 1, DR 20: 8.4 lbs, \$340 DR 5 transparent laminated polycarbonate eyeslits: 0.1 sqft, WM 0.25, CM 50, CW 0.8, CC 5, DR 5: 0.1 lbs, \$25 DR 6 hard steel plate neck and face: 1.3 sqft, WM 0.5, CM 3.5, CW 0.8, CC 5, DR 6: 3.15 lbs, \$55 DR 20 polyurea coated light steel armor plate over the vitals: 1 sqft, WM 0.3, CM 40, CW 0.8, CC 5, DR 20: 4.8 lbs, \$960. DR 12F/6B hard steel plate torso other than vitals: 6 sqft, WM 0.5, CM 3.5, CW 0.8, CC 5, DR 9 (average for calculating cost/weight): 21.6 lbs, \$380 DR 8F/4B hard steel plate arms, legs: 10.5 sqft, WM 0.5, CM 3.5, CW 0.8, CC 5, DR 6 (average for calculating cost/weight): 28.35 lbs, \$500 DR 4 hard steel plate hands, feets: 1.4 sqft, WM 0.5, CM 3.5, CW 0.8, CC 5, DR 4: 2.25 lbs, \$40 DR6 improved kevlar undersuit: 21.35 sqft, WM 0.08, CM 120, CW 1, CC 1, DR 6: 10.25 lbs, \$1230 Total is 78.9 lbs, \$3530. A little over weight and budget, but the protection is good. The important parts are completely resistant to 7.62mm rounds and the arms and legs are nearly resistant to 5.56mm rounds from the front. You can stand in a fire for 45 seconds without worrying about burning or heat. The biggest weak point is the eye slits at DR 5. against bullets and axes (-4 DR against other damage types) DR 26 over the skull and vitals, DR 21 over the rest of the front torso, DR 15 over the face and neck, DR 14 over the arms and legs from the front, DR 10 for the hands and feet and back of the limbs, DR 12 for the back torso.
This is very much the kind of thing I'm considering, yes. Thank you.

Now, to get something like this in the real world, how plausible is that?

The price, first of all. The calculated prices in the article are probably meant to be for commercially produced pieces of armour, I imagine. Or, at least, there should be a major difference in price between something that is manufactured in the hundreds of thousands to equip a military and something that is custom-made for a crazy re-enactors.

I might need to hit the Knight Templars with a huge price increase for any piece which they cannot get mass-produced from a factory somewhere and modify to fit into their panoply.

Any non-standard tailoring, like a ballistic vest that also includes sleeves and material to cover the abdomen and hip area, will probably mean a price increase if they buy custom-made commercial designs or require them to obtain the kind of machines which can cut Kevlar or other aramids into the desired shapes.

And I'm pretty sure that an articulated Plate fauld over the Abdomen is more expensive than a breastplate, ounce by ounce, as it requires a much more complex shape and design not to cripple mobility.

To avoid massive Cost increases for realism purposes and/or massive penalties to mobility, I would be fine with armour that doesn't actually have 100% coverage. Chinks in armour or even Partial Coverage for certain, hard to armour locations, might well be the only solution for the ballistically useful parts of the armour.

Coverage in line with a historical knight might be achievable, but would probably need to be bought from a company specialising in re-enaction armour or similar and could only be made form materials that their production methods could handle. This probably means good steel, but not the hardest possible alloys or anything that you couldn't work with using whatever tools such companies own.

Well, unless I'm wrong about how hard it is to work AR500 and similar steels. If you can custom order them in any shape you want, as opposed to just sheets or gently curving sheets, that would change things. Does anyone have data about how hard it really is to work?

Or if anyone could find links to or even anecdotal evidence of real world blacksmiths, machinists or custom shops who offer to make armour or other complex shapes out of steel alloys with this kind of hardness.

Quote:
 Originally Posted by mlangsdorf An obvious way to save weight would be to replace the steel on the limbs with aluminum, but at 3.5x the cost of hard steel, it wasn't feasible for the \$3000 budget. Dropping the limb armor down to DR4, front and back, would also save about 10 lbs and DR 10 is sufficient to stop 9mm bullets. At the upper level of protection, titanium composite is 40% the weight of hard steel but 30x as expensive. Using titanium composite for the limbs would drop the weigh by 17 lbs, but would raise the cost by over \$14000, so it's not really feasible.
Considering that the opportunity cost* of each military Type 56 rifle being used to equip the full-fledged cartel soldiers is at least \$2,500+ and gunmen senior enough to consider having such armour would probably carry a much more expensive Norinco CQ-A clone of the M4A1**, \$3,000 isn't really that high. I could see the final price being higher than \$3,000, easy.

However, as I said, I think custom designs ought to carry a mark-up over mass-produced ones, so what the design system calls \$3,000 might well come out to \$10,000+, if someone had it made in real life.

I'm trying to apply the rules in the article to designs that are not merely mechanically legal, but would actually work in reality. This means that total coverage is probably extremely expensive and comes with significant heat and mobility drawbacks.

As a design goal, we should look at equivalent coverage to actual military TL8 ballistic armour for the stuff that actually stops bullets, with lower DR steel, maybe thin Kevlar or something even easier to work with, being used to cover the more complex areas of inconvenient shape.

*Regardless of what you paid for it, you could sell it on the black market in northern Mexico at \$2,500 or more.
**Opportunity cost might be \$5,000+, as that's what you'd probably be able to sell one for, given that semi-automatic Colt L6920 carbines that are neither selective fire nor with the more tacticool shorter barel are selling for \$3,000+.
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Last edited by Icelander; 02-07-2018 at 01:43 PM.

02-07-2018, 01:45 PM   #8
mlangsdorf

Join Date: Aug 2004
Location: Austin, TX
Re: [Cutting-Edge Armor Design] Real World SCA-legal Armour and Ballistics Armour

Quote:
 Originally Posted by Icelander We've got price information on Solid trauma plates made from this material. Slightly less than 1 square foot with DR 23-30, depending on the validity of the testing, seems to cost \$100-\$200, depending on specifics.
Right. DR 25 for 5.5 lbs at \$110 for a solid plate works out to a CM of \$20.

Cost = Weight x CM x CC.
CM = Cost / (Weight x CC). CC is 1 for solid, so \$110/5.5 = \$20.

Weight = SA x WM x CW x DR.
WM = Weight / (SA x CW x DR). CW is 1 for solid, and a 10x12" is 5/6 sqft, so 5.5 / (5/6 * 25) goes to 6 * 5.5 / 5 / 25 goes to 6.6 / 25 or 0.264. I'd originally calculated from DR 23 and got something closer to 0.3.

As far as working metals with absurdly high Brinell numbers, I assume you would work the metal while it's a lot softer and then case-harden the final form. You can (and people traditionally did) case-harden fire arm components, because you want to do the precision machining on low carbon alloys but have high carbon alloys for wear resistance in the final gun. If you can case-harden a revolver frame, you can case-harden a breastplate (though I am not a metallurgist and have only the vaguest idea of how you would do it).

I also suspect that armor like this is one of those things that is really expensive to buy one-off, but only moderately expensive to buy in lots of 100+. What your cartel would want to do is make a prototype or three out of low carbon steel, come up with a fake movie production company or similar cover story, and then have the cover company solicit bids for 100+ copies of the suit made from the proper materials. The companies who already have equipment to make metal in weird shapes and at high hardness levels will get back to you with a hopefully cost-effective solution.

Of course, if you can't afford 100 suits, you may be in a situation where can't afford to buy 10 suits, either, because you have to hand-make each one at great expense.
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 02-07-2018, 01:47 PM #9 Anthony   Join Date: Feb 2005 Location: Berkeley, CA Re: [Cutting-Edge Armor Design] Real World SCA-legal Armour and Ballistics Armour The other alternative is to just add cosmetics to bog-standard ballistic plates. __________________ My GURPS site and Blog.
02-07-2018, 02:03 PM   #10
Icelander

Join Date: Mar 2006
Location: Iceland*
Re: [Cutting-Edge Armor Design] Real World SCA-legal Armour and Ballistics Armour

Quote:
 Originally Posted by Anthony The other alternative is to just add cosmetics to bog-standard ballistic plates.
Well, my original thought is effectively 'soft ballistic armour + high hardened steel sold as cheaper alternatives to ceramic ballistic plates', with SCA-legal steel armour being added to that, as, yes, more of less cosmetic accessories, with a 'gorget', pauldrons and limb armour in, say, 16 gauge steel that was fairly easy to work giving DR 3-5, depending on exact steel and the skill of the smith.

For example, this set comes in stainless steel or mild, cold-rolled steel. I'd give it either DR 4 or DR 5, depending on whether I felt it was better or worse than RHA. Having been modelled on historical armour might let it rate DR 5, for appropriately protective shape.

Maybe add some more soft steel plates in a brigantine cuirass that has the actual hardened steel as a centerpiece, to get the right look, give knife protection and prevent injury when meth-crazy 'Knights' inevitably start sword fighting at their 'business meetings'. Total cost, around \$3,000, depending on how expensive it is to get something that looks like a gambeson made out of kevlar (and possibly some cloth covering).

This kind of get-up would be kind of a minimal bar in looking knightly for those who wanted to play at being inner circle, around the crazy leader and his most cultist followers.
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Last edited by Icelander; 02-07-2018 at 02:14 PM.

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