Sciencemadness Discussion Board

Martini glass SC?

Justin - 29-5-2010 at 22:06

I have two martini glasses both with a diameter of 4.5in at the rim. I want to break off the stem and use it in a SC, my only concerns are with the inconsistant thickness of the glass. I have some 4in PVC pipe to confine the explosive however some glass will overhang outside the pipe, will this have much impact on the performance of the SC? A martini glass was an obvious choice for a glass lined SC since it's conical, cheap and easily obtainable. Thanks everyone for your input.

Paddywhacker - 30-5-2010 at 00:04

You want to use a snapped-off glass in your own Superior Colliculus, or somebody elses? I hope you know what you are doing.

devongrrl - 30-5-2010 at 01:18

I wonder if it is possible to use disposable plastic martini glasses for this ? For one thing they are cheaper!

psychokinetic - 30-5-2010 at 01:27

Whoosh. Over my head.

What's an SC? Yes, I tried to find out myself first.

gnitseretni - 30-5-2010 at 05:19

Uhm, we have a HUGE SC thread, why didn't you post in there?

As for your question, the overhang won't be a problem. Sometimes, with small charges, it even comes in handy as it can serve as standoff.

Justin - 30-5-2010 at 12:22

SC=Shaped Charge, Ya i realize there is a huge SC thread, i just thought it'd get more attention as a new thread.

Rain - 30-5-2010 at 12:31

:mad:This is one of the reasons I loved Roguesci.Those moderators would instantly ban a person wasting space by posting a new thread like this.

devongrrl - 30-5-2010 at 12:45

We don't have Nazis here, all our mods are intelligent and capable.

hissingnoise - 30-5-2010 at 12:45

It's not easy to find anal-retentiveness lovable. . .
How do you do it?

Rain - 30-5-2010 at 12:55

I thought flaming was against the forum rules.It must be some past-bound anger.Maybe from being banned previously?Who knows...

hissingnoise - 30-5-2010 at 13:02

Quote:
Maybe from being banned previously?Who knows...

Yaaay. . . And on my first post. . .

Sedit - 30-5-2010 at 18:31

Quote: Originally posted by Rain  
:mad:This is one of the reasons I loved Roguesci.Those moderators would instantly ban a person wasting space by posting a new thread like this.



Really? Thats why you love RS? Because this is your first post and even thru my beer goggles it seems way more worthless then the opening post. If this was the site you love so much you would be banned way quicker then the person that started this thread so please kindly Shut the fuck up!

Justin - 30-5-2010 at 19:43

Quote: Originally posted by devongrrl  
I wonder if it is possible to use disposable plastic martini glasses for this ? For one thing they are cheaper!
. Never heard of a plastic lined SC, not sure how it would react to the extremes of a SC. Only way to know for sure is to try it! But hey I only paid $5 for two martini glasses new. I'm sure u could find some used ones for wayy cheaper. Better stick with proven materials like copper, steel and glass IMO but I highly encourage experimentalism!!!

Microtek - 31-5-2010 at 00:59

In "Liners for Shaped Charges", Held uses a ranking of liner materials based on maximum jet speed times the square root of the liner density. He further states that, as a rough approximation, max jet speed can be estimated as 2.34 times "bulk sound velocity" of the liner material.
Now, I'm not entirely certain of what he means by bulk sound velocity, but from the numbers in the table (table 1) it seems to be the speed of longitudinal waves.

The speed of longitudinal waves can be calculated if shear and bulk moduli or Young modulus and Poisson ratio are known, but the interesting point is that the formula features the square root of the density in the denominator.
In the ranking formula, this cancels out with the square root (density) factor.

This means that as a means of ranking liner materials, you can simply use the square root of (K+ 4G/3), where K is the bulk modulus and G is the shear modulus. Or you could look up longitudinal sound velocity and multiply that with the square root of the density.

As an even simpler (and less accurate) method you could just use the square root of Youngs modulus.

There are probably many aberrations that would deviate from this ranking system (for instance, it rates steel higher than copper), but it accurately predicts several well known phenomena such as the fact that lead is very poor, that aluminum is decent and so is glass.

@ Devongrrl:
From this, it should be apparent that no polymeric material is suitable as a shaped charge liner. However, many ceramic materials are quite effective.
An interesting test of the extremes of this rule of thumb would be to try a diamond liner.....

[Edited on 31-5-2010 by Microtek]

Haw

Randle Patrick - 31-5-2010 at 07:43

Quote: Originally posted by Paddywhacker  
You want to use a snapped-off glass in your own Superior Colliculus, or somebody elses? I hope you know what you are doing.
Let's not get all tectumological here.

VladimirLem - 31-5-2010 at 07:54

It definitely works...even with "low power explosives" like ANNM-AL will the results good enough for that job



chief - 31-5-2010 at 11:47

Plastics have a _much_ lower speed of sound, compared to glass ...
==> Something that would be expected to control some detonation would at least have to be different from air ...
==> ... glass also has a higher density ...

grndpndr - 9-6-2010 at 04:06

Quote: Originally posted by devongrrl  
I wonder if it is possible to use disposable plastic martini glasses for this ? For one thing they are cheaper!


Youd get what youd payed for,better than a hole cut in c4 the shape of a cone, but still a very simple monroe effect SC.Noticeable but far from effective.:(

Glass funnels really arent that expensive are they?or for that matter wallyword champagne glasses
A great link was sent my way for IIRC 1in brass approx 45% cones very inexpensive.Button supplys IIRC.Great for micro size slighly larger CSC's.I havent his permission or Id share.
Maybe an oz?- 1/2 oz HE, microscale great for testing a varietyv of variables keep a person busy for some time.