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 AMSubject: [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 secure2. 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