Unfortunately the only propellant grains under 24 mm diameter are "18mm"
Blue Thunder grains (slightly over a half-inch diameter). The sparky
propellants Metalstorm and Metalstorm DM both produce smoke (white and
black, respectively) but are only available in 54mm and larger diameters.
I don't know how fast they burn but most AT propellants burn at
1/16"-1/32" per second at atmospheric pressure. You'd want to check
with them for better numbers.
If a cylindrical grain is not a requirement it would be simple to cut a
square (or octagonal, cut the corners off the square) grain from a
larger chunk, and coat the outside with epoxy or some other inhibitor.
A large old-fashioned cork borer, properly sharpened, would give nice
cylinders. Might take some experimentation to get it right.
BTW my understanding is that Metalstorm's white smoke is
aluminum/magnesium/zinc oxides. At a guess, Metalstorm DM's black smoke
is either carbon from a fuel-rich propellant, or elemental zinc in
aerosol form, vaporized in the chamber.
Best -- Terry
On 10/29/2020 2:15 PM, roxanna Mason wrote:
Because my liquid rocket ignitor fabrication kit was stolen, along with the rest of my rocket equipment, I'm considering just that, Aerotek grains. I just need to look at the compositions to get the closest match to mine which has Mg filings loaded into 3/4" estes cardboard body tubing. Sounds like you know the various grains better than I do which is next to nothing. Requirements are slow burning,i.e. 1/16"/sec @ 1atm lots of sparks and a smoky/rich exhaust. 34" long grains give a 10-12 sec burn time. The ignitors are for that Texas high school 1.5KLbF LOx/Kerosene flight rocket to be flown at FAR.--
Thank you for any help,
Ken
On Thu, Oct 29, 2020 at 11:51 AM Terry McCreary <tmccreary@xxxxxxxxxxxxxxx <mailto:tmccreary@xxxxxxxxxxxxxxx>> wrote:
Are commercial composite propellants unsuitable for this? A 14"
grain of Blue Thunder(TM) propellant, just under an inch in
diameter, cast in cardboard tubing, is $12. RCS has a dozen other
propellants, slow (Black Jack), fast (Warp-9), sparky (Metalstorm)
if BT isn't suitable. They also have a few propellants in smaller
diameters, plus phenolic tubing insulators to fit the cardboard
tube if that is desirable. Not as much fun as making your own,
but reproducible and inexpensive.
https://www.rocketmotorparts.com/Blue_Thunder__Propellant_Grains/cat1577810_1952803.aspx
Best -- Terry
On 10/29/2020 1:10 PM, ken mason wrote:
Remove the nozzle first to extend burn time at atmospheric pressure.-- Dr. Terry McCreary
I made my own custom grains formulated with things that burn
vigorously in an oxygen atmosphere. Burn time ~ 10 sec plus embed
a thermocouple 1/8" from the end of the grain to verify the
ignitor is burning before opening your prop valves.
K
On Thu, Oct 29, 2020 at 11:03 AM Gram Nylen
<dmarc-noreply@xxxxxxxxxxxxx
<mailto:dmarc-noreply@xxxxxxxxxxxxx>> wrote:
This is just an inexperienced shower thought, but could one
use a small Estes motor in some kind of orthogonal mount
flush to the chamber wall as a liquid engine igniter?
On Oct 29, 2020, at 10:58 AM, Doug Jones
<rocketplumber@xxxxxxxxx <mailto:rocketplumber@xxxxxxxxx>>
wrote:
I second the recommendation for a spark torch igniter, which
will also serve as a team building exercise that improves
confidence. Once you have a reliable ignition system your
team can move on to the next level.
On Thu, Oct 29, 2020, 10:55 AM roxanna Mason
<rocketmaster.ken@xxxxxxxxx
<mailto:rocketmaster.ken@xxxxxxxxx>> wrote:
From personal hands-on experience with TEA it's not ,my
first choice for an ignition system. TEB costs an order
of magnitude more,i.e. $20 vs $200/gallon as of 20 years
ago. It depends on what you're igniting, how many
times,how often, ground vs flight,etc.. I prefer a pyro
for one shot or limited cycles and a so called 'torch'
ignitor for multiple and repeatable ignitions.
K
On Thu, Oct 29, 2020 at 4:04 AM Dr Edw Jones
<Rocket.Pioneer@xxxxxxxxx
<mailto:Rocket.Pioneer@xxxxxxxxx>> wrote:
Any guidelines for storage and handling of small
amounts of these tetraethyl compounds?
Any recommended purveyors of small amounts?
Thanks, Edward Jones
Professor Emeritus
Murray State University
Murray KY 42071