[SS2S-Main] Sugar Shot Weekly Activity Report -- Mar.10-24, 2014
- From: Richard Nakka <richard.rocketry@xxxxxxxxx>
- To: sugarshot@xxxxxxxxxxxxx
- Date: Wed, 26 Mar 2014 21:46:34 -0500
Highlights of recent developments on the DoubleSShot project
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-Vicente Alvero reports that the prototype Pyro Separation Device
(PSD) was once again tested on March 14th. A stiffer spring (k=57
lb/in.) was used to obtain a more forceful separation of the simulated
booster and coupler. The PSD functioned perfectly, wrapping up the
prototype testing. A number of recommended design improvements came
out of this prototype testing, and will be implemented in the flight
version PSD which will be designed and built in the near future.
Video of March 14th test:
http://youtu.be/TMcLrKlOk5o
-José Jimenez has kindly agreed to fabricate the VIC-2C nozzle
extension. José reports that he has ordered the material and will
begin machining next week.
-Design of the VIC-3 motor has commenced. This follow-up to the VIC-2
static test motor will incorporate the dual-burn concept, and will
consist essentially of a two-chambered VIC-2 motor. This motor will
test various technologies associated with this type of motor,
including ablative chamber liner material, CSD (Chamber Separation
Disc) and nozzle insulation design. A test stand is being built for
this motor in order to record chamber pressure, thrust and various
temperature measurements.
-Liam McQuellin, a member of Australian Space Research Institute (
http://www.asri.org.au/ ), has kindly offered to supply a temperature
measurement system for our static motor testing. The board has 8
independent k-type thermocouple interfaces, with all signal
conditioning and A/D being done onboard. A microprocessor takes values
from each channel, converts to degrees C or F, and outputs CSV through
a serial link via USB to a laptop.
-Yoann Gamet, a French engineer currently living and working in
Shanghai (China) has volunteered to a perform motor internal
ballistics study to better understand what goes on in a rocket motor
following ignition of the second phase of a dual-burn rocket motor.
Flow characteristics and heat transfer to the casing walls, in
particular, will be investigated.
-Rick Maschek has extracted the chamber pressure readings from the
video of the 4-grain DD motor test that took place on March 7th. A
plot of the pressure profile indicated that the pressure was initially
following the design curve well. Approximately half way through the
5.4 second burn, the pressure profile began to decay. The readings
were not available past the 3.4 second mark of the burn, as the video
camera had panned upward (on its own accord), resulting in the
pressure gauge being out of the field-of-view. The pressure decay is
hypothesized to be a result of the unusually large build-up of slag
that had pooled on the forward bulkhead, which likely blocked the
pressure port leading to the gauge. Rick reported that the slag was
almost entirely burnt propellant residue (potassium carbonate), as it
readily dissolved in water. There was very little in the way of grain
inhibitor residue (fiberglass/epoxy).
Pressure curve:
http://sugarshot.org/downloads/4-grain_dd_pressure_results.pdf
Photo of slag accumulation:
http://sugarshot.org/downloads/dscn9557_mass_on_scale.jpg
http://sugarshot.org/downloads/dscn9547_dd_residue.jpg
http://sugarshot.org/downloads/dscn9553_thickness.jpg
-A second static firing of the 4-grain DD rocket motor is scheduled
for April 5th at the FAR test site. This follow-up test will be
conducted on a vertical test stand, nozzle down, to reduce slag
accumulation. Chamber pressure will be measured, similar to the first
test.
THE SS2S TOOL-RAFFLE IS UNDERWAY. PURCHASE YOUR TICKET FOR A CHANCE TO
WIN, AND SUPPORT SUGAR SHOT IN OUR EFFORT TO REACH SPACE ON THE POWER
OF SUGAR.
http://sugarshot.org/tool-raffle/index.html
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