Richard,
My experiences have been mostly case ruptures and occasionally bulkhead
failures. We had static tested a motor with a titanium nozzle (allowed by
Tripoli because it is not steel) and it actually showed the aluminum case
mushrooming on impact with the concrete and the nozzle was still reusable. We
were testing it to save weight and get around the steel limitation should we
need to launch at Black Rock at a Tripoli event.
Titanium nozzle and welded bulkhead motor FAR test for Sugar Shot to Space
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Titanium nozzle and welded bulkhead motor FAR test for Sugar Shot to Space
WARNING: I was told it's loud so turn down the volume. Two static rocket more
tests at the FAR site on January 5...
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With the three fold price increase in ammonium perchlorate (now $19 a pound in
bulk drums) I am expecting a surge in people making sugar propellants as seen
in recent internet forum discussions. I am in hopes people will send in their
'data' on sugar motor CATO results regarding what happened with the steel
nozzle.
https://www.rocketmotorparts.com/Bulk_200_Micron_Ammonium_Perchlorate_Oxidizer/p1577809_10906409.aspx
My experience with steel nozzles that do blow out in CATO s on the pad it they
don't go very far ( f = m x a ). The force of a CATO acting on the large mass
of a steel nozzle for a limited time on the end of a motor doesn't allow it to
pick up much speed. And have never had a steel nozzle fragment but they are
looking for more testimony (data) from people other than just me.
I am fortunate to be able to launch with steel nozzles at FAR so this would
really be for people in other areas of the country/world wanting to launch
sugar propellant motors with steel nozzles at Tripoli Research events.
Rick
On Wednesday, October 30, 2019, 08:09:48 AM PDT, Richard Nakka
<richard.rocketry@xxxxxxxxx> wrote:
Rick, pleased to hear that Tripoli has given (provisional) approval for steel
nozzles on 'sugar' propellant for this year. Hope it is made permanent.My
experience with over-pressurization events with sugar propellant motors (and
other propellants types) is that the bulkhead normally blows off, not the
nozzle. Casing rupture has also occurred, depending on the design specifics. In
both scenarios, the nozzle has remained attached to the casing. The reason the
bulkhead blows off rather than the nozzle is that the chamber pressure is
higher at the bulkhead end of the motor, due to high flow velocity at the
nozzle end. Of course, this assumes attachment means are identical for both the
nozzle and bulkhead (e.g. snap-rings or number/size of fasteners). It is
straightforward to make the bulkhead attachment 'weaker' than the nozzle
attachment, as added assurance.
Richard
On Mon, Oct 28, 2019 at 10:33 AM Rick Maschek <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
Hi everyone,
Tripoli has given a provisional approval for steel nozzles on 'sugar'
propellant only for this year at research launches and with the ok of the
launch prefect. It is to determine if steel nozzle use will be allowed in the
future. They want data for tests and launches...especially, what happens to the
nozzle in the event of a CATO. How far does it travel from the launch pad, does
it fragment, what impulse motor. Nozzle is to be pointed down, not looking for
nozzle up or horizontal tests.
The price of ammonium perchlorate is now tripling (RCS price has just gone from
~$6 a pound to $19.99 a pound in bulk, $25 a pound in 20 pound lots) so many
people might be moving to sugar in the future or giving up rocketry. Let's not
let this opportunity for steel nozzle use vanish.
https://www.rocketmotorparts.com/Bulk_200_Micron_Ammonium_Perchlorate_Oxidizer/p1577809_10906409.aspx
So far this year all of my flights and tests have been nominal except for a
static test with a titanium nozzle so if anyone has CATO data with steel
nozzles on sugar rockets PLEASE submit before the end of the year
Rick
