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

  • From: Richard Nakka <richard.rocketry@xxxxxxxxx>
  • To: sugarshot@xxxxxxxxxxxxx
  • Date: Sun, 16 Mar 2014 10:43:05 -0500

Forgot to include the link to the 4-grain DD-Slot motor firing...! Here it is:



On Sat, Mar 15, 2014 at 4:40 PM, Richard Nakka
<richard.rocketry@xxxxxxxxx> wrote:
> 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:
> http://sugarshot.org/downloads/vic-2b_full_thrust2.jpg
> http://sugarshot.org/downloads/vic-2b_rupture.jpg
> http://sugarshot.org/downloads/vic-2b_post_sep.jpg
> http://sugarshot.org/downloads/vic-2b_thrusting.jpg
> http://sugarshot.org/downloads/vic-2b_burnout.jpg
>    Videos of test firing:
> http://youtu.be/4cagisNbk7M
> http://youtu.be/PdCHL2ZwsHk
>    Post-firing shots of nozzle cone:
> http://sugarshot.org/downloads/img_1668a.jpg
> http://sugarshot.org/downloads/vic-2b_cone_interior.jpg
>    Sketch showing proposed VIC-2C modifications:
> http://sugarshot.org/downloads/vic-2_nozzle_mod.pdf
> (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
> reported
> "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:
> http://sugarshot.org/downloads/cimg3638a.jpg
>    Aaron holding the rocket motor prior to the static firing:
> http://sugarshot.org/downloads/cimg3642a.jpg
>    Rick with the motor in place:
> http://sugarshot.org/downloads/dscn0065a.jpg
>     Motor thrusting:
> http://sugarshot.org/downloads/thrusting-1.jpg
> http://sugarshot.org/downloads/thrusting-2.jpg
>    Close-up of ignition, burning and ending:
> http://sugarshot.org/downloads/ignition.jpg
> http://sugarshot.org/downloads/4_diamonds.jpg
> http://sugarshot.org/downloads/ending.jpg
>     Post-firing pics of motor disassembled:
> http://sugarshot.org/downloads/dscn0212a.jpg
> http://sugarshot.org/downloads/dscn0215a.jpg
> http://sugarshot.org/downloads/dscn0216a.jpg
> http://sugarshot.org/downloads/dscn022a.jpg
>     Views of thermal liner, post-firing:
> http://sugarshot.org/downloads/dscn0366_bulkhead_edge.jpg
> http://sugarshot.org/downloads/dscn0367_nozzle_edge.jpg
> (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!
> http://sugarshot.org/sponsors.html#Donorservices
> -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.
> http://sugarshot.org/sponsors.html#Donors
> -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.
> http://sugarshot.org/tool-raffle/index.html
> or if you prefer a straightforward donation:
> http://sugarshot.org/contrib.html
> ---------------------------
> -Sugar Shot to Space is on facebook. Check us out.
> http://tinyurl.com/2exr92k

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