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

  • From: "Louis Schreyer" <info@xxxxxxxxxx>
  • To: <sugarshot@xxxxxxxxxxxxx>
  • Date: Thu, 20 Mar 2014 09:10:19 +0100

Hello,

I just watched the video, it looked to me that the burn was very unsteady. 
Is that because of the new grain design?

One thing I would recommend is for the camera men: Aim the camera higher,
the motor can be at the lowest point of the picture, not in the middle. Then
you can zoom further to the flame. A good highspeed-cam is also often very
helpful in seeing things you normally do not see, as well as a
Infrared-filter. You used one here. You sure want more sponsors, good sharp
images help getting them.

But the double-D seems promising, I thought of making a small double-D
motor, but I am still concerned what happens if the grain gets smaller and
falls down, blocking the nozzle. The sliver catcher is one solution, but it
may get closed due to the burn residue of sorbitol propellant. Also, under
Thrust in a rocket these motors show a different behaviour than upside down
in a test stand. (One thing for example is that I have a flame upside down
in the test stand, and only smoke and no flame when flying in a rocket).

Louis

PS: Secure the motor next time...This doesnt look very professional to me: A
hole in the ground, throw the motor in and light it.    A hole is good if
something goes wrong, but secure the thing (sand, gravel, stick etc. ) so it
cannot move and the flame goes up 90°, not 80°.
Guess what happens if the front bulkhead burns through to a 10 mm hole, you
will then have a nice flying whizzing 89mm motor ;-)




> -----Original Message-----
> From: sugarshot-bounce@xxxxxxxxxxxxx [mailto:sugarshot-
> bounce@xxxxxxxxxxxxx] On Behalf Of Richard Nakka
> Sent: Tuesday, March 18, 2014 3:01 PM
> To: sugarshot@xxxxxxxxxxxxx
> Subject: [SS2S-Main] Re: Fwd: Sugar Shot Weekly Activity Report -- Feb.24-
> Mar.9, 2014
> 
> 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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