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. Richard 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 >> >> >> > > >
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