Sciencemadness Discussion Board

testing friction and shock sensitivity your self ?

DubaiAmateurRocketry - 13-9-2013 at 12:21

Has any one here made his own sensitivity measurer ?

Does a sudden hit of a hammer count as a shock sensitivity checker ?

if so, how do we build one that can actually, get some data out of it ? say for example a table for dropping a mass at a certain hight that is calculated to give X newtons force.

Has any one built his own ? Because i want to see the different sensitivity of some of my propellants containing little RDX, RDX can imrpove isp but also RDX is not safe, so before an engine test, I want to see if it is really safe or not.

Ral123 - 13-9-2013 at 12:54

If it detonates all the way in a straw, initiated only with AP, then the sensitivity allows reliable use a secondary.
Your hammer tests won't be much good determining how stable will the burn rate/safety of a propellant mixture be. AN mixtures aren't exactly sensitive, but the burn rate is less stable then ammonium perchlorate mixture IIRC.

Fantasma4500 - 14-9-2013 at 07:57

i think if you search NH4MnO4 aka ammonium permanganate what i remember is that there is a thread on it, made by axt
he measures it in centimetres of dropheight with i believe a 1kg weight

100 cm dropheight = 1 .. >>physics<< im not sure what its usually called..
30 cm dropheight is described as 0.30, i could be wrong although..

DubaiAmateurRocketry - 1-11-2013 at 06:02

Quote: Originally posted by Antiswat  
i think if you search NH4MnO4 aka ammonium permanganate what i remember is that there is a thread on it, made by axt
he measures it in centimetres of dropheight with i believe a 1kg weight

100 cm dropheight = 1 .. >>physics<< im not sure what its usually called..
30 cm dropheight is described as 0.30, i could be wrong although..


Can i have a link of that threat you're talking about ?

Thanks.

Dornier 335A - 5-11-2013 at 13:32

Impact sensitivity is usually measured in newton metres, Nm. The falling weight usually weighs 2 kg, so a fall heigh of 100 cm means an impact sensitivity of 1 m*9.82 N/kg*2 kg = 19.64 Nm. As an example, pure RDX has an impact sensitivity of 7.5 Nm.

A simple impact sensitivity testing rig shouldn't be too hard to build. A weight, something to guide it with, and some type of anvil to place the sample on is what's needed. To get more reproducible data, one can use a confinement device like this:


Friction sensitivity on the other hand is measured in newton.
Quote:

The sample is placed on a roughened 25*25*5 mm porcelain plate,which is rigidly attached to the sliding carriage of the friction apparatus.A cylindrical porcelain peg, 10 mm in diameter and 15 mm in height, with a roughened spherical end (radius of curvature 10 mm), is placed on top of the sample; the rod is tightly clamped and may be loaded with different weights with the aid of a loading arm. The load on the peg may vary between 0.01 and 1 kp in a small apparatus and between 0.5 and 36 kp in a large apparatus. The porcelain plate moves forward and back under the porcelain peg; the stroke length is 10 mm in each direction. The two ends of the peg will serve for two trials and the two friction surfaces of the plate will serve for three trials each. The figure reported is the smallest load of the peg which causes deflagration, crackling or explosion of the test sample at least once in six consecutive trials. The quantity of the test sample is 10 mm3.

Explosives. Sixth Edition. Rudolf Meyer, Josef Köhler, Axel Homburg

[Edited on 5-11-2013 by Dornier 335A]

Fantasma4500 - 8-11-2013 at 08:14

yea sure..

https://www.sciencemadness.org/whisper/viewthread.php?tid=11

its not an actual thread, its a post in a thread although this seems to be a favored procedure to follow..
the AN:KMnO4 ratio you can twitch about for your liking ofcourse

please dont burn these things off anywhere youre not in for cleaning up.. MnO2 is produced on combustion, in which i dont hope you will ever have bad experience in removing because its just a hell