BTW: fixed that issue. Wasn’t the graphics at all. The allocated precision of 1
variable (duh)
www.propulsionlabs.com.au/filament_winder/Winder_Sim.zip
<http://www.propulsionlabs.com.au/filament_winder/Winder_Sim.zip>
Troy
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Troy Prideaux
Sent: Sunday, 14 February 2021 1:49 PM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: KN-sorbitol, no-nozzle, core burner motor case
A mate was interested in making a filament winding machine and asked me to
assist with the math – which was actually pretty straight forward in theory.
Whipped up a BOE spreadsheet and a little simulator which I never really got
the graphics quite right for.
Nevertheless, for anyone interested (here it is – for windows OS):
www.propulsionlabs.com.au/filament_winder/
<http://www.propulsionlabs.com.au/filament_winder/>
It’s purely an educational tool for those not knowing where to start with such
a project
It uses the same ancient graphics libraries I used for GrainsCAD (20 years
ago!) and as I said: I never really got the graphics it right. It struggles
with long skinny mandrels.
So if you stick with mandrel geometries like 150mm diam x 1000mm long, it
should work well enough to provide an idea.
The important equations are in the help file and I’ve tried to explain it all
as simply as possible with that pdf.
Troy
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx] On Behalf Of JAMES ROSSON
Sent: Saturday, 13 February 2021 9:53 AM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx> ; Dr Edward Jones
<RocketPioneer@xxxxxxxxx <mailto:RocketPioneer@xxxxxxxxx> >
Subject: [AR] Re: KN-sorbitol, no-nozzle, core burner motor case
Make your own fiber reinforced cases?
Can use a bench top sized metal lathe with automated threading capability to
DIY a filament tube winding machine. Then use the lathe to reduce OD to
standard dimension after resin cure. Lots of waste, giant mess; but can be
cheap, if don't care about labor costs. Custom tube mfg have made prototype
samples this way for over 4 decades that I have bought custom tubes.
Small lab winders are available commercially new, and occasionally see them in
used machinery market.
Grab a text book on filament winding to learn more.
YMMV
On February 12, 2021 at 3:28 PM Dr Edward Jones <RocketPioneer@xxxxxxxxx
<mailto:RocketPioneer@xxxxxxxxx> > wrote:
Starting with the "62.5-gram Rule" [* below], I'm developing a
nozzle-less core burner with that nominal grain weight. Formulations
are well-characterized. "No metal components" is also part of the
paradigm. While experiments continue, I'm using a 0.7-inch OD grain of
7.0-inches L, with the web equal to the core diameter, about
0.25-inch.
One other intent is to minimize motor dry weight, and every milligram
matters. Thus I aim for highest possible maximum mass fraction in a
non-metal case of about 7" L x 0.7" ID.
Chamber pressure peaks at about 100-psia, midway in the burn. At
burnout, Pc is somewhat less, yet not trivial.
I'm starting with strong, thin cotton paper, rolled with minimal
adhesive. I'm considering impregnating the paper with boric acid
and/or sodium silicate, to minimize burn-thru at burnout. Likewise,
Tyvek may proved a better choice, impregnated or otherwise.
Since composite fiber tubing is quite pricey, anyone have ideas for
other ways to make this ultra-light motor case work?
Thanks in advance.
Edward
* On 08/11/2006: The Department of Justice is amending the regulations
of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) to
clarify that the requirements of part 555 do not apply to model rocket
motors consisting of ammonium perchlorate composite propellant, black
powder, or other similar low explosives, containing no more than 62.5
grams of total propellant weight, and designed as single-use motors or
as reload kits capable of reloading no more than 62.5 grams of
propellant into a reusable motor casing. This final rule is intended
to provide rocketry hobbyists with guidance to enable them to enjoy
their hobby in compliance with the safety and security requirements of
the law and regulations.