06-06-2012, 02:53 PM | #11 |
Join Date: May 2012
Location: Further than you think.
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Re: How tough is BPC actualy?
As far as I can see as with most types of Handwavium, Biphase Carbide is as tough as the game needs it to be and no tougher.
And with this (un)helpful comment, I shall now leave the thread. Last edited by Leila Ross; 06-07-2012 at 10:57 AM. Reason: Misspelled Biphase Carbide. |
06-06-2012, 05:37 PM | #12 |
Join Date: Aug 2005
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Re: How tough is BPC actualy?
I'm afraid a straightforward comparison of blast overpressure to material tensile strength is not useful as even a first-approximation analysis of the vulnerability of a vehicle to blast effects. Yes, they are both in units of force per unit area, but it's still an apples-to-oranges comparison.
An answer really requires a more detailed engineering analysis of possible failure modes. For example, say the driver's hatch has an area of 2.5 square feet and we are looking at a 1,200 psi overpressure. The load on the hatch from the overpressure is 3,000 pounds evenly distributed. I can think offhand of three failure modes that would have to be analyzed: 1 - Is the hatch sealing good enough to prevent the 1,200 psi blast wave from propagating into the crew compartment and injuring / killing the crew? 2 - Will the structure supporting the hatch (hinges, hatch seat, etc.) fail under the 3,000 pound blast load? 3 - Will the hatch itself fail structurally due to the blast load? Answering #2 and #3 will require an analysis of the bending and shear loads imposed on the structures. The strength of the material will be key to this analysis, but it's not a simple matter of comparing overpressure to tensile strength. Rather, the peak stresses will have to be calculated and compared to the strength of the material. Qualification: I am a degreed engineer. TWB |
06-07-2012, 07:14 AM | #14 | |
Join Date: Apr 2012
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Re: How tough is BPC actualy?
The original post is off by a factor of 1,000,000.
To quote from the rulebook: Quote:
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06-07-2012, 07:22 AM | #15 | |
Join Date: Oct 2005
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Re: How tough is BPC actualy?
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06-07-2012, 03:28 PM | #16 | ||
Doctor of GURPS Ballistics
Join Date: Sep 2004
Location: Lakeville, MN
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Re: How tough is BPC actualy?
2.5 square feet = 360 square inches
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1200psi is pretty serious overpressure, I think. That's like 80 atm.
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06-11-2012, 12:04 AM | #17 |
Join Date: Apr 2012
Location: Maine, by the ocean.
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Re: How tough is BPC actualy?
This is what I'm talking about. I'm a friggin english major. We need more technical discussion. I like actual math, and what I came up with originally took me about an hour and a half of digging and research. I simply couldn't imagine that some part of the tank wouldn't fail under the stress of pressure or even a tac-nuke and point blank range. The largest atomic cannon shell had a yield of 15 kilotons (15,000 tons of tnt, same size as Hiroshima). each shell is 365 kilos (about 800 pounds) and is 1384mm or 4 and a half feet long. The M65 Atomic Cannon from which it was fired had a muzzle velocity of 625 m/s (2060 ft/s), for a nominal range of 32 km (20 mi), and weighed 77 metric tons. The shell alone (never mind the nuke inside) at that speed and weight causes how much force? 1/2mv squared right? that equals over 71 thousand kilo-joules if my crappy math is right.
Is that not a significant amount of force?
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06-11-2012, 01:51 AM | #18 |
On Notice
Join Date: Apr 2007
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Re: How tough is BPC actualy?
I would just be happy to know what one centimeter of BPC is rated in 4e GURPS terms.
Whats its DR? Yes, I'm working on my own G:OGRE 4e project.
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06-11-2012, 09:50 AM | #19 |
Join Date: Nov 2010
Location: Arizona
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Re: How tough is BPC actualy?
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06-11-2012, 04:42 PM | #20 | |
Join Date: Aug 2005
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Re: How tough is BPC actualy?
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TWB |
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