My first efforts in composite propellant used PSAN. The burn rate of
ANCP with 20% Mg is comparable to low-end APCP. I don't know of any AN
formulations that reach the burn rate of the faster commercial APCP
mixtures like Blue Thunder, etc. I do know that none of the burn rate
catalysts I tried that are employed in APCP had any measurable effect on
AN formulations, at least not at 1% or lower concentrations. I've heard
that ammonium dichromate and/or Prussian blue at higher concentrations
may work for AN but never tried them.
The hygroscopic nature of AN was a serious annoyance in my attempts,
especially when dealing with isocyanate curatives that are very
moisture-sensitive.
In the past, AN propellant containing 20% (expensive to buy and to ship)
magnesium was quite a bit more expensive than APCP. However, the cost of
AP has gone up rather a lot recently, so the cost of AN propellant that
contains 20% Mg may now be comparable to that of AP propellants. I
haven't checked.
In the amounts, particle sizes, and motor sizes generally used by
amateurs, any shock sensitivity that may be exhibited by AP is
immaterial. The Challenger accident shows the SRBs continuing to
burn---not explode---following the initial explosion. I don't expect
any amateur to make anything as large as a shuttle SRB. At least, not
in the foreseeable future. :-)
One legal issue worth consideration in the US: APCP has been
specifically excluded from BATFE's list. ANCP has not. "Ammonium
nitrate explosive mixtures" are on there.
Best -- Terry
On 8/5/2020 8:04 PM, Joshua Carr wrote:
After completing John Wickman's course we made some APCP motors and let John do all the mixing himself.--
In his manual he mentions that AP is shock sensitive.
For this reason he actually recommends AN as an oxidizer for amateurs.
Lower ISP but in his terms /'safer'/.
/'Technical grade AN can be used'/ as an oxidizer, as long as it's stored in the right conditions.
The Mg ratio in his AN propellant is 20%, with 20% binder.
Gives a burn rate similar to APCP with a burn rate exponent of ~0.6.
_Re: Beirut_
Here's some good sources from Australia <https://www.scimex.org/newsfeed/expert-reaction-massive-explosion-rocks-lebanons-capital-beirut>, apparently only a small fuel fraction (a couple percent) is enough to detonate AP, under the right wrong conditions.
Kind regards,
*Joshua Carr*
---- On Wed, 05 Aug 2020 13:21:39 +0930 *Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx>* wrote ----
The shelf life of ANCPs isn’t necessarily short. If the AN is
phased stabilised well enough and the propellant is processed with
enough cleverness and it’s completely inhibited from moisture, the
shelf life can be extended to years although that’s at the expense
of some performance as phase stabilising AN adequately doesn’t
come for free.
Troy
*From:*arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>] *On Behalf Of *Henry Vanderbilt
*Sent:* Wednesday, 5 August 2020 12:59 PM
*To:* arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
*Subject:* [AR] Re: Beirut blast due to ammonium nitrate???
To sum up, a reserve stock for tac ballistic missile production is
possible, as practical AN motor designs exist, but they tend not
to have great shelf life.
