Richard could say more about the pyro mid bulkhead but the forward motor was
ignited 10 seconds after the aft motor burn out by a separate copper thermite
igniter at the forward bulkhead end.
On Wednesday, September 6, 2017 6:28 PM, "shawn.mchatten@xxxxxxxxxxx"
<shawn.mchatten@xxxxxxxxxxx> wrote:
Thanks for the reply Rick. Lots of good info. I think I asked this a few years
ago on the sugpro list, but in regards to the plug in the dual pulse motor I
was wondering if there was something that would melt/burn away at a low enough
temp that would not start the second grain, allowing it to be lit by a separate
ignition source in the head end like a regular core burner. Didn't really get
any answers to something that would protect the second grain from the first
grain burn, but would still dissolve/melt/burn away to allow the ignition of
the second motor. I know SS2S experimented with a separate bulkhead but I was
thinking something more along the lines of something melting away. Shawn
On 2017-09-06 20:46, Rick Maschek wrote:
You are correct Shawn that was an end burner that was over a minute. The
longest core burner we've done so far is 18 seconds. With the multiple pours of
sugar propellant, that started when we cast grains for Sugar Shot with a bottom
plug 3/8" thick and used another for the compression on top. When the grains
were solidified, we pulled off the compression ring and 'topped off' the grains
to get another 1/4-3/8" propellant in the grains. Testing showed the bond
between the previous pour and the new pour was strong. We also did some
'Unigrains' made by casting one grain, pulling the mandrel almost out, adding
another casting tube and pouring more propellant on top of the previous grain,
pulling the mandrel almost out, adding another casting tube and pouring more
propellant, etc so that we essentially ended up with one long grain without the
segment gaps of BATES grains. On the RaD motors, we cast the AP in layers that
surrounded the previous AP both on the two ends and in the core. Imagine what
the propellant (web) looks like in the BATES grain 1 second after ignition.
That was the red propellant that burned away. Now imagine what the propellant
looks like after 2 seconds in the grain. That was the white propellant that
just burned away. The remainder left is the blue propellant. The blue
propellant was cast first using a large core and thick end plug. After that was
cured, the large diameter mandrel was pulled and a medium diameter mandrel
inserted into a medium end plug and the white propellant cast over the blue.
That process was then repeated with a small diameter mandrel and the red
propellant was cast over the white. Needless to say, it was a lot of work.
We've done two colors since but have not done the three colors again. If you
recall how the Sugar Shot 'Dual Pulse' motor worked, I also tried casting such
a motor in a single long tube by pouring one third the length, pulling the
mandrel, inserting a flammable 'plug' that would burn away, casting another
third, pull the mandrel, inserting a second plug on that and then one last pour
on top of that. The desired effect was for a 'pseudo' 3 stage rocket in a
single long motor. It didn't work well because after burning through the
flammable plugs separating the sections, the 2nd and 3rd chuffed from being
ignited at the nozzle end.
On Wednesday, September 6, 2017 3:50 PM, "shawn.mchatten@xxxxxxxxxxx"
<shawn.mchatten@xxxxxxxxxxx> wrote:
Rick, below you mention the longest CORE burner you have ever done is one
minute. Did you really mean end burner and if not then how big was that motor
and what was the burn rate of the fuel? That's a LONG burn for a core burner.In
one of your other posts you mention that you have experimented with multiple
pours of sugar into one grain. Did you cast at the end of each grain or along
the length of the grain (either inside the original core or around the outside?
Also did you use any adhesive/glue or just rely on the new batch of propellant
"melting into" and forming a good bond to the earlier cast?thanksShawn On
2017-09-06 15:13, Rick Maschek wrote:
I've built several for two applications, one is for gliders where you don't
need lots of thrust and the other for a sustainer/dart to give just enough to
keep up the momentum. If you don't require lots of pressure/high thrust, it can
be easier on a motor case than traditional BATES grains if the burn is less
than ten seconds since it is a single grain and does not have unprotected
segment spaces typical with BATES grains that would requires a liner. Longest
core burner I've done was just over one minute using KNSB. I tried making sugar
endburners for rockets. They require a super light rocket and a core on the
nozzle end for enough thrust to get the rocket moving that transitions to end
burning once the cored area burns away. The same effect can be done with using
cored and non cored BATES grains. Sometimes I will use a coreless grain next to
the bulkhead if I want tracking smoke from my sugar motor, just make sure to
inhibit the end next to the bulkhead. Attached is an example of what the
thrust profile would look like with a cored start that transitions to end
burning.
On Wednesday, September 6, 2017 6:14 AM, Nikolai Nielsen
<nielsen.nikolai86@xxxxxxxxx> wrote:
has anyone dabbled with end burner motors? i know that it would cripple the
thrust that the quantity of fuel could produce but it seems like it should work.
Nikolai Nielsen
