Also worth noting: Paul Kelly was looking for an N2O hybrid preheater grain
propellant that utilised an oxidizer he could make himself easily. I suggested
NaClO3+Epoxy as an option as it was shortly after I went through testing that
stuff in solids and I had an old electrolysis cell to offer to get him started.
After a few amazingly spectacular casing->shrapnel conversions, it was soon
abundantly clear that the amount of propellant required for the preheater grain
was only a small fraction of what we required for APCP as the exponent really
kicked in with a U/C valve N2O hybrid ignition - well beyond our expectations.
Troy
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Troy Prideaux
Sent: Tuesday, 7 August 2018 8:58 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Cheap Solids? Amonium Nitrate: catalysis vs sensitization
Mark,
I didn’t really have a problem with the tiny grains – or at least in the
boiler plate motors I tested them in. Well, I cracked a few graphite nozzles
from over pressuring but can’t remember experiencing anything significant until
I started scaling up – which was also accompanied by more adventurous fuel
experimentation – a methodology and practice doomed for nasty surprises.
I agree that the exponent is manageable *IF* you’re really disciplined with
the development. The margins for experimenting with different fuels or
additives or processing techniques than what you’ve already proven is a lot lot
tighter than a typical APCP. Issues with porosity or binder wetting or
structural integrity with the propellant will be magnified exponentially.
Which is not to suggest there’s no place for trying different fuels or
whatever – just that you need to be extra careful about thorough
characterization 1st with tight controls on maintaining what’s been
characterized to be workable when scaling up.
Troy
From: <mailto:arocket-bounce@xxxxxxxxxxxxx> arocket-bounce@xxxxxxxxxxxxx [
<mailto:arocket-bounce@xxxxxxxxxxxxx> mailto:arocket-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Mark C Spiegl
Sent: Saturday, 4 August 2018 1:10 AM
To: <mailto:arocket@xxxxxxxxxxxxx> arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Cheap Solids? Amonium Nitrate: catalysis vs sensitization
The exponent is the issue with these oxidizers.