Back in the 90s we made our 38mm reloads linerless with BATES grains. We did
put an O-Ring between each grain and compressed them together a bit and we also
made the casing wall a fraction thicker than standard. We never experienced
burn through. Not sure about temper loss, but we never experienced a casing
failure.
Troy
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of William Claybaugh
Sent: Friday, 2 February 2018 5:21 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Phenolic regression rate
Anthony:
That makes sense but why then use liners to backup Bates grains? Just belt and
suspenders or is the ability of the motor wall to soak up heat partly playing
here? Does a thinner wall—or non aluminum—risk over heating, thus requiring a
liner that isn’t needed when the wall is relatively thick aluminum and the burn
time short?
Bill
On Thu, Feb 1, 2018 at 10:43 AM Anthony Cesaroni <acesaroni@xxxxxxxxxxx
<mailto:acesaroni@xxxxxxxxxxx> > wrote:
Assuming a stable chamber pressure and minimum gas equalization path between
the grain inhibitors and insulation/case, the Bates grain joints are generally
considered a stagnation area. Heat soak notwithstanding.
Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
<http://www.cesaronitech.com/> http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx> ] On
Behalf Of William Claybaugh
Sent: Wednesday, January 31, 2018 6:51 PM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Phenolic regression rate
Troy:
In theory, the joint of two adjacent BATES grains exposes the underlying liner
to the full duration of the burn; on that basis we might use the liner
thickness and burn time to deduce longevity.
However, Garboden didn’t use a liner on the 9” ballistic dart vehicle and had
no problem in five flights and three static tests (albeit w/ a 4.5 second burn)
which leaves me thinking there may not be—in practice—any significant heat leak
at the joint between BATES grains.
So I dunno too.
Bill
On Wed, Jan 31, 2018 at 4:41 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> > wrote:
Bill, dunno. I’d be surprised if you needed that much wall. I’ve used 2-2.5mm
wall for long(ish) burn (~7sec) larger motors and they held up fine although
they were BATES grains so… dunno
Troy
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx> ] On
Behalf Of William Claybaugh
Sent: Thursday, 1 February 2018 10:16 AM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Phenolic regression rate
Troy:
Let me add that given 0.8 mm and a (conservative) 1.2 second burn, it follows
that this liner was good for about 0.66 mm per second, implying a need for 6.66
mm for a 10 second burn.
With enough similar data it will be possible to estimate a number, with
variance, that at the low end allows for a (probably) safe flight.
Bill
On Wed, Jan 31, 2018 at 4:05 PM William Claybaugh <wclaybaugh2@xxxxxxxxx
<mailto:wclaybaugh2@xxxxxxxxx> > wrote:
Troy:
Thanks, that’s very useful.
Bill
On Wed, Jan 31, 2018 at 3:54 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> > wrote:
Okay, I wasn’t sure if it was for a liner or nozzle or whatever, but rereading,
it’s obvious it’s for a liner. Okay, many moons ago I developed a 29mm
reloadable solid that was specially designed for maximum performance (230s Isp
@ ground level). Propellant was 75% AP, 7.2% metals, 17.8% organics and chamber
pressure was generally run between 750-1000 Psi. I utilised a paper phenolic
liner for the casing that measured ~25.4mm OD x ~0.8mm wall. Propellant grain
was a C-Slot (ie. one side of the liner exposed to the total burn duration).
Burn time was generally between 1.2 – 1.6 secs.
I was also trying to make the system with motor recovery which turned out to
be problematic due to the combination of the pressures involved and the
paper-phenolic tube I was using for the tracking smoke column. This resulted in
a lot of testing (about 200 static tests) to get the whole thing nailed down.
Anyway, the liner was marginal – generally didn’t burn through, but was right
on the edge.
Troy
Troy
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx> ] On
Behalf Of William Claybaugh
Sent: Thursday, 1 February 2018 9:28 AM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Phenolic regression rate
Ignacio:
Hazel and Huang reference (page 382 of the 1992 AIAA edition) an emperical
equation for silica-phenolic exposed to NTO and hydrazine-like combustion
products.
I’m looking to develop a similar understanding for paper-phenolic and solid
propellant. I can do that if I get enough user experience as to what did not
burn through.
Bill
On Wed, Jan 31, 2018 at 3:13 PM ignacio belieres <ignacio_belieres@xxxxxxxxxxx
<mailto:ignacio_belieres@xxxxxxxxxxx> > wrote:
Bill,
I believe you can find something similar to what you are looking for in huzel
and huang. I implemented a version of the ablative model described there and it
seemed to give fairly reasonable results.
Cheers,
IB
-------- Original message --------
From: William Claybaugh <wclaybaugh2@xxxxxxxxx <mailto:wclaybaugh2@xxxxxxxxx> >
Date: 1/31/18 7:03 PM (GMT-03:00)
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Phenolic regression rate
Anthony:
I do understand the many variables; I’m just looking for user experience.
If I can get enough data on what doesn’t burn through I can estimate how thick
XX needs to be for the 10 seconds at which I’m looking.
Bill
On Wed, Jan 31, 2018 at 1:34 PM Anthony Cesaroni <acesaroni@xxxxxxxxxxx
<mailto:acesaroni@xxxxxxxxxxx> > wrote:
Depends where in the motor, the grain geometry, the gas velocity and conditions
as well as the type of phenolic, the reinforcement used as and any fire
retardants added.
Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
<http://www.cesaronitech.com/> http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx> ] On
Behalf Of William Claybaugh
Sent: Wednesday, January 31, 2018 3:08 PM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Phenolic regression rate
Does anyone have any data on how long I can expect XX phenolic to survive the
conditions in a solid rocket motor?
Anecdotal data helps: if some part of the phenolic wall was fully exposed to
hot gas and was xx.xx inches or millimeters thick and did not fail; that’s
data. If it did fail, that is data too.
I’m adept at squeezing trends out of limited data but 20 or so usable data
points are sort of a minimum; I’m very happy to share any conclusions I may
reach.
Bill