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

  • From: Richard Nakka <richard.rocketry@xxxxxxxxx>
  • To: sugarshot@xxxxxxxxxxxxx
  • Date: Tue, 18 Mar 2014 09:01:27 -0500

Thanks for the comments, Cliff, always appreciated.
No pressure measurements were taken for this test firing (not
required). I have attached the design pressure curve to this e-mail.


On Mon, Mar 17, 2014 at 10:56 PM, Cliff Bates <cliff@xxxxxxxxxxxxxx> wrote:
>    A terrific firing, almost up to max thrust instantly !  This was like a
> Polaris missile igniting coming out of the water !
>    A shame about the nozzle skirt burn through, but not unexpected.  Notice
> in the other included test where the steel nozzle turned red hot almost
> instantly, and where the carbon nozzle blew out in the first test.  Anyone
> interested might download NASA's, "Solid Rocket Motor Nozzles".
>    The current mod to correct the problem looks to be about right on.  Love
> those instant, no messing around ignitions !
>    Any pressure read obtained ?
> ----- Original Message ----- From: "Richard Nakka"
> <richard.rocketry@xxxxxxxxx>
> To: <sugarshot@xxxxxxxxxxxxx>
> Sent: Sunday, March 16, 2014 8:43 AM
> Subject: [SS2S-Main] Fwd: Sugar Shot Weekly Activity Report -- Feb.24-Mar.9,
> 2014
>> Forgot to include the link to the 4-grain DD-Slot motor firing...! Here it
>> is:
>> https://www.youtube.com/watch?v=vXaRzSZEbOA
>> Richard
>> 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

Attachment: vic-2b design pressure curve.jpg
Description: JPEG image

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