[SS2S-Main] Sugar Shot Weekly Activity Report -- Feb.24-Mar.9, 2014

  • From: Richard Nakka <richard.rocketry@xxxxxxxxx>
  • To: sugarshot@xxxxxxxxxxxxx
  • Date: Sat, 15 Mar 2014 15:40:58 -0600

Highlights of recent developments on the DoubleSShot project
- On Saturday, March 1st, Vicente Alvero test fired the VIC-2B
experimental rocket motor. This was the second test firing of the
VIC-2 motor, and differed from the first in two ways:
1. the composite nozzle cone attachment was modified to make it more secure
2. the grain configuration was changed to that originally intended for
this motor (two unrestricted grain segments)
The primary purpose of this test firing was to ascertain how well a
carbon-fibre nozzle cone would hold out. Approximately half way
through the 2.5 second burn, the cone burnt through just aft of the
nozzle throat, and separated from the motor. This test clearly
demonstrated the intense heating that occurs in this region and that
normal composite material is not suitable. The latter half of the cone
survived the firing largely intact and will be used for the next test.
A steel "nozzle extension" will be fabricated, which will connect the
nozzle throat to a truncated cone. Another modification to the motor
will be a phenolic insert in the convergent part of the nozzle. This
will investigate how well phenolic stands up to the intense heating of
the flow as it enters the throat region.
    Close-up video-captures of motor firing:
   Videos of test firing:
   Post-firing shots of nozzle cone:
   Sketch showing proposed VIC-2C modifications:
(videos/photo courtesy Vicente Alvero)

-On Friday evening, March 7th, the 4-grain DD-slot 89mm motor was test
fired. Because the rain forced a scrub of the planned March 2nd test
at the FAR site, Rick Maschek and NASA USLI Citrus College student
Aaron Bunch, performed the static firing at the Jean Dry Lake in
Nevada. As this was a straightforward static test with solely chamber
pressure being measured, all that was needed was a 10" hole dug into
the ground of the lake bed. Ignition was via an e-match and slice of
38 mm APCP propellant and two strands of AP propellant draped over the
fiberglass inhibited top surface of the top Double-D grain. The motor
firing appeared nominal and good pressure readings were obtained. Rick
"Because the sun had set, a flame was recorded on the high speed
digital video cam that shows up to four mach diamonds. Thermal sensor
labels were applied to the nozzle, mid and forward areas of the motor.
The only record was on the red labels near the aft end."
"Everything is reusable...even the lining is in good shape". A sheet
of 3/32" (2.4mm)  EPDM (rubber) thermal liner was used for the motor
and contributed to the uncharacteristic dark grey exhaust smoke. Must
be why Scott uses the EPDM, it works great. The thickness looks the
same at the bulkhead and gradually gets thinner as you go down to the
nozzle though there was complete coverage and you could still see the
cuts I made on all four sides. Just 'guessing', I'd say half the
thickness burned away at the nozzle end. That might mean a thinner
piece could be used but let's hold off on that till we do the six
grain test...higher pressure and more erosion."

"The only area of 'concern' was on the two sides near the top where I
had the APCP propellant for the igniter. I ran strands of it from the
top APCP disk that the e-match lights and the strands may have fallen
down and against the rubber when the motor was inverted. We will know
better when I do the six-grain test at FAR since it will be vertically
mounted on an I-beam. I will also try to secure the AP ribbon to the
propellant sides for the next test. The Red RTV (protecting the
bulkhead) was also almost burned completely away and that is not
normal so I think too much APCP was at the bulkhead end."
   Aaron Bunch preparing to dig hole in dry lake bed:
   Aaron holding the rocket motor prior to the static firing:
   Rick with the motor in place:
    Motor thrusting:
   Close-up of ignition, burning and ending:
    Post-firing pics of motor disassembled:
    Views of thermal liner, post-firing:
(photos and video courtesy Rick Maschek)

-The next planned motor firing will be the 6-grain DD-Slot motor which
is planned to occur on April 5th at the FAR test site.

-Markus Bindhammer reported that the recent balloon flight of the
robot astronaut "Cosma" was a partial success. Markus wrote: "The data
are not very useful as the data were only logged while waiting on the
ground waiting for lift-off for several hours. An internal time
prevent that data are only logged for 3.5 hours. I will build an
improved version of Cosma, more balloon flights are planned this year,
but not currently scheduled."

-Grant Saviers has been added to "Donors of Goods & Services" for his
recent donation of two precision pressure transducers, which were sent
to Chris King. Thanks again for your generosity, Grant!

-An Avionics telecon was held Sunday March 2nd, and was attended by
Chris King, Hans Olaf Toft, Mattias Lampe, and Richard Nakka. Mattias
reported  progress on the design of a de-spin controller. Mattias
procured various parts for testing, such as various types of motors
(in-runner, out-runner and brushed motors). Chris brought up a good
point about the possible concern of motor bearing lubricant
out-gassing in a vacuum. This will be investigated. The next telecon
is scheduled for March 16th .

-SS2S welcomes (and thanks) Daniel Larsen as our newest Bronze Donor.

-Tickets sales are going well for the SS2S Tool Raffle, but we still
have a ways to go until we reach our goal. Those recent rocket motor
test firings led by Rick Maschek and Vicente Alvero were really
impressive. But remember, rocket motor testing is expensive, and
fund-raisers such as this are an important strategy to pays the costs.
or if you prefer a straightforward donation:
-Sugar Shot to Space is on facebook. Check us out.

Other related posts:

  • » [SS2S-Main] Sugar Shot Weekly Activity Report -- Feb.24-Mar.9, 2014 - Richard Nakka