Bill, I haven’t really done a lot of measurement with propellants with over 8%
metals. Most of the stuff I’ve done with high metals didn’t involve careful
measurement. Performance didn’t appear to be anything particularly special with
the stuff I did burn/fly with high metals but I can’t give hard numbers.
Given that high metals should offer a theoretical boost to specific impulse
and propellant density, one would expect to see a noticeable increase in
performance per volume of propellant, but most of my motors were probably too
small to properly utilise the energy density with including them.
Regards,
Troy
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On ;
Behalf Of William Claybaugh
Sent: Saturday, 31 March 2018 1:44 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Accounting for cured HTPB in ProPEP
Troy:
What about over 8%? I note that 15-16% is highest performing but that in
(amateur) practice greater than 8% proves no better. Is that your experience
too?
Bill
On Fri, Mar 30, 2018 at 7:12 AM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> > wrote:
Yup, that's the way I've always done it and my measured results (for
propellants with metal inclusions <8%) have been pretty representative of sims.
Troy
-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx ;<mailto:arocket-bounce@xxxxxxxxxxxxx> ]
On
Behalf Of James Padfield
Sent: Friday, 30 March 2018 9:57 PM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Accounting for cured HTPB in ProPEP
So do you simply include the HTPB and the isocyanate as separate components
of the formulation?
On 30 March 2018 at 12:48, Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> >
wrote:
It's something I've never worried much about. The MW of a typical HTPBmolecule is in the thousands and when you react it with (say) a typical
diisocyanate, it's only the very ends (hydroxyl) of each molecule that are
affected ie. none of the bulk hydrocarbon chain that we generally are focusing
on for our thermochem.
.0329
Troy
-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx ;<mailto:arocket-bounce@xxxxxxxxxxxxx>
] On Behalf Of James Padfield
Sent: Friday, 30 March 2018 8:50 PM
To: Arocket@xxxxxxxxxxxxx <mailto:Arocket@xxxxxxxxxxxxx>
Subject: [AR] Accounting for cured HTPB in ProPEP
How do you account for cured HTPB in ProPEP and similar thermodynamic
tools?
For example, let's say I have a composite propellant with a binder
that uses
R45 HT at 5.70%, and this is cured with IPDI at 0.54%.
There are entires for R45 HT and IPDI of course, but in reality what
is present in my cured propellant is 6.24% of a cured polyurethane.
I have just noticed that there is an entry in the PEPCODED.DAF file
titled "HTPB/CURATIVE" - is this a generic entry for cured HTPB?
G 475 HTPB/CURATIVE (JOS) 656C 978H 5N 13O 0 0 -498
Or does it not really matter and I am worrying about something that
really has no significant effect on the outcome of the calculation?
Thanks,
James
