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Old 08-22-2012, 07:17 AM   #11
DanHoward
 
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Default Re: [HT] Body Armor - errata?

Yep. 1/3 less is a decent approximation. Though the few armour tests I've seen using titanium alloys suggest that it is worse at resisting weapons than the numbers would predict.
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Old 08-22-2012, 07:29 AM   #12
DouglasCole
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Default Re: [HT] Body Armor - errata?

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Originally Posted by DanHoward View Post
Yep. 1/3 less is a decent approximation. Though the few armour tests I've seen using titanium alloys suggest that it is worse at resisting weapons than the numbers would predict.
Not least of which that the hardest possible Ti alloy that I can find on www.matweb.com is Ti-13-11-3, which can be hardened to only Rc 50. "RHA" steel is supposed to be an analog to 4340 steel, and E4340 "H-steel" can be hardened to Rc 52 (most 4340 steels are less than Rc 45, but 4340 is NOT a good steel).

Good steels can easily be much, much harder, and thus resistant to "bite" (to use a non-scientific phrase) than Ti alloys, and this probably reduces the armor value somewhat.
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Old 08-22-2012, 07:33 AM   #13
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Default Re: [HT] Body Armor - errata?

For Titanium armour I would probably reduce the weight by a third and reduce DR by 1 compared to steel armour.
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Old 08-22-2012, 07:41 AM   #14
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For Titanium armour I would probably reduce the weight by a third and reduce DR by 1 compared to steel armour.
If the baseline here is a DR 6 chunk of armor, that's basically saying that using Ti increases the weight per unit DR due to inherent armor value, but decreases it due to density. If steel is the Base, you would multiply the weight of the armor by 1.16 due to effectiveness, but again by 0.6 for density, for a net weight reduction of 30% relative to steel.

"1/3 less weight of equivalent steel armor" is a fairly good approximation.
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Old 08-22-2012, 07:59 AM   #15
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If the baseline here is a DR 6 chunk of armor, that's basically saying that using Ti increases the weight per unit DR due to inherent armor value, but decreases it due to density. If steel is the Base, you would multiply the weight of the armor by 1.16 due to effectiveness, but again by 0.6 for density, for a net weight reduction of 30% relative to steel.

"1/3 less weight of equivalent steel armor" is a fairly good approximation.
Dan was suggesting *0.7 for density, so it's actually closer to -20% weight than -33% weight.
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Old 08-22-2012, 08:11 AM   #16
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No, it explicitly only refers to Basic Set.
Thank you.
I have the errata entered on my pdf and hard-copy (1/3 OFF, not of:))

Then the silk vest insert may be the only new errata: it covers torso front, weighs 6lb and is DR5F; the corselet covers both front & rear, weighs 12lb but has DR10?
Vest insert should either be about 3lb or about DR10F or the corselet only DR5:(
DR10F for 6lb, or DR5F for 3lb, actually matches Low-tech values if the TL5 doubling is used. Not sure I fancy a DR5 corselet but that would be the undoubled value...

Not errata but, also using doubled Low-tech values, the sentry Armor would seem to be more like DR22.
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Old 08-22-2012, 09:37 AM   #17
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For Titanium armour I would probably reduce the weight by a third and reduce DR by 1 compared to steel armour.
Compared to TL8 steel, the TL 4 "hardened steel" option from Low-Tech, or ordinary TL 3-4 metal armor?
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Old 08-22-2012, 11:09 AM   #18
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Default Re: [HT] Body Armor - errata?

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Either way, it's really not a hugely realistic ruling, of course -- treating all TL5+ steel the same.
The armour I know a little about is the kind that came in thick slabs on TL6 ships. The effectiveness of that approximately doubled during TL6 (as in, half the thickness was as good) mostly due to improved alloys and heat treatment.
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Old 08-22-2012, 11:15 AM   #19
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Dan was suggesting *0.7 for density, so it's actually closer to -20% weight than -33% weight.
Thats not right, though. Ti alloys are 4.4 (for Ti-6Al-4V), up to 4.8 density for the harder alloy I mentioned upthread. That is 56-61% of the density of low alloy steel (1070 is 7.87 g/cc), or 4240 alloy steel at 7.85.

So 60% the weight of equiv volume is a fact. The unknown is the protective value of an equivalent thickness.

I found a source claiming substitution of Ti for steel half-inch plate achieved a 25% weight reduction for equiv ballisric protection with "early" Ti alloy. They claim without proof a 1-1 substitution is legit...which I dont buy.

That suggests 25-40% weight reduction, with 33% being a centerpoint. Anywhere from a quarter to a third weight reduction is reasonable, though you will likely pay more the closer you get to a third.

The 1-1 claim isnt credible cause steel development is far from stagnant either!
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Last edited by DouglasCole; 08-22-2012 at 11:24 AM.
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Old 08-22-2012, 12:05 PM   #20
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Default Re: [HT] Body Armor - errata?

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The armour I know a little about is the kind that came in thick slabs on TL6 ships. The effectiveness of that approximately doubled during TL6 (as in, half the thickness was as good) mostly due to improved alloys and heat treatment.
That's why it's a WAG sort of thing. I we assume that the steel used is super awesome compared to the slag filled extremely skill intensive and often inherently flawed steel attempts from TL5- (which we have artifacts to support this, on average) and you'd get, as we did in HT, double Basic Set values. But, if on the other hand you assume every attempt at steel making is successful and producing exact perfect homogeneous and inerrant product (not possible at those tech levels, btw, which is why later steel processes are advances not only in price reduction by quality) then you get a different result. YMMV.
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