Solid Propellants (Potassium perchlorate)

Solid Propellants (Potassium perchlorate)

Post by Larr » Sun, 11 Jul 1999 04:00:00



Quote:

>All true.  Just make the case safety margin twice as high and the expected
>pressut 50-75% of normal and hope for the best.  KP can be partially
>stabilized by adding ***, AP, and/or zinc.

>I actually think KP motors are cool because you get very high burning
>rates without much effort.

Problem is you can't get an expected pressure without accurate burning rate
parameters. The word, "Normal," implies you've had a success with the stuff
before. To get that success, you need some forgiveness, and KP is remarkably
unforgiving.

For those who misunderstood my objection before - it's not a stability
problem. (Many KP propellants are almost *too* stable to ignition attempts,
for example.) It's the high pressure exponents that make the stuff hard to
contain.

Regards
-Larry C.

 
 
 

Solid Propellants (Potassium perchlorate)

Post by Doug Gonc » Mon, 12 Jul 1999 04:00:00


I recently posted to rec.crafts.metalworking describing a vented bomb for
determination of pressure exponent. I have an experimental propellant ball
about an inch in diameter and it's proven difficult to ignite. This may
indicate something about the pressure exponent. I am hoping for an exponent
less than one, for stable burning. I read in a proplusion text that the
sensitivity of a propellant to initial temperature is more of a problem than
the possibility of a pressure exponent greater than one. It requires the
pressure exponent to be significantly less than one. I hope to test both.

Quote:
>Problem is you can't get an expected pressure without accurate burning rate

parameters.

Quote:
>KP is remarkably unforgiving.

This isn't model rocketry, that's for sure.

 Yours,

 Doug Goncz
 Experimental Machinist (DOT 600.260-022)
 Replikon Research (USA 22044-0094)
 http://users.aol.com/DGoncz or /ReplikonVA

 The ocean is the world's longest runway...

 
 
 

Solid Propellants (Potassium perchlorate)

Post by Jerry Irvi » Thu, 15 Jul 1999 04:00:00



Quote:


> >All true.  Just make the case safety margin twice as high and the expected
> >pressut 50-75% of normal and hope for the best.  KP can be partially
> >stabilized by adding ***, AP, and/or zinc.

> >I actually think KP motors are cool because you get very high burning
> >rates without much effort.

> Problem is you can't get an expected pressure without accurate burning rate
> parameters. The word, "Normal," implies you've had a success with the stuff
> before. To get that success, you need some forgiveness, and KP is remarkably
> unforgiving.

That true fact is why when dealing with KP formulas the only true test of
a design is to iteratively fire it.  Unfortunately no amount of
theoretical discussion here will be of very much help unless it is to add
things to make it ever less KP and ever more something else.

Quote:

> For those who misunderstood my objection before - it's not a stability
> problem. (Many KP propellants are almost *too* stable to ignition attempts,
> for example.) It's the high pressure exponents that make the stuff hard to
> contain.

> Regards
> -Larry C.

--
Jerry Irvine, Box 1242, Claremont, California USA

 
 
 

Solid Propellants (Potassium perchlorate)

Post by Jerry Irvi » Thu, 15 Jul 1999 04:00:00




Quote:
> I recently posted to rec.crafts.metalworking describing a vented bomb for
> determination of pressure exponent. I have an experimental propellant ball
> about an inch in diameter and it's proven difficult to ignite. This may

Why not put the equivelent of a burst diaphram over the vents (thin
phenolic or frangible plastic) so the ignition phase occurs at pressure.

Quote:
> indicate something about the pressure exponent. I am hoping for an exponent
> less than one, for stable burning. I read in a proplusion text that the
> sensitivity of a propellant to initial temperature is more of a problem than
> the possibility of a pressure exponent greater than one. It requires the
> pressure exponent to be significantly less than one. I hope to test both.

> >Problem is you can't get an expected pressure without accurate burning rate
> parameters.

> >KP is remarkably unforgiving.

> This isn't model rocketry, that's for sure.

>  Yours,

>  Doug Goncz
>  Experimental Machinist (DOT 600.260-022)
>  Replikon Research (USA 22044-0094)
>  http://users.aol.com/DGoncz or /ReplikonVA

>  The ocean is the world's longest runway...

--
Jerry Irvine, Box 1242, Claremont, California USA