Anyone have a RAS AERO file for the Super Loki rocket motor?

Discussion in 'High Power Rocketry (HPR)' started by criticalvector, Oct 27, 2019.

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  1. Oct 27, 2019 #1

    criticalvector

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    I'm trying to find one and am having trouble. I want to test out what apogee it would hit if just the booster (no dart) was launched from 10k feet AGL.
     
  2. Oct 28, 2019 #2

    Homer_S

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    Question: what is this motor? It is fairly trivial to go from motor test curve data to engine file (RASP format).

    Homer
     
  3. Oct 28, 2019 #3

    Reinhard

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    Last edited: Oct 28, 2019
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  4. Oct 28, 2019 #4

    manixFan

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    For those interested, here's the technical details. I recall seeing a formula somewhere that included 10 micron AP. Scary stuff.

    Most references show the motor burn time as 2.1 seconds, rather than the 2 seconds shown in the chart below.


    Tony

    Loki motor.png
     
    Last edited: Oct 28, 2019
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  5. Oct 29, 2019 #5

    MClark

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    Made a few hundred of them.
    Not scary at all.
     
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  6. Oct 29, 2019 #6

    cherokeej

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    Bryan?
     
  7. Oct 29, 2019 #7

    manixFan

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    My guess is though that you weren't using 10 micron AP in a garage with a bread mixer. From everything that I know about any ultra fine particle, special care and handling is required. Everyone I've talked to that used ultra-fine AP did so remotely. But obviously I don't have real-world experience making commercial motors. I'd be interested in hearing how you handled such small particle sizes in processing.


    Tony
     
  8. Oct 29, 2019 #8

    MClark

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    10 micron isn't very fine in commercial world, 2 micron is! Essentially everything we made that used AP had 5-15 micron depending on burn rate required.
    The AP in the Loki series is hammer mill ground, Mikropulverizer, stored in oven at 140f to keep dry and used within 48 hours. Other than dust issue not a problem to work with. Always wear your respirator.

    M
     
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  9. Oct 29, 2019 #9

    manixFan

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    Good info, thanks for that. So hammer mill as in smashing it? I know folks who ball mill AP but I've not heard of hammer milling it. I suppose then it would have to be sieved to separate out the right sized particles (same as with ball milling)? Not that I am planning on trying it anytime soon but still I've always been a big fan of the Loki Dart and our very first BALLS project was a boosted dart. The performance of the Super Loki motor never fails to amaze me, it was just a beast for its size.


    Tony
     
  10. Oct 29, 2019 #10

    MClark

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    No need to screen, the way the Mikropulverizer works it acts like a centrifugal separator and the larger particles keep going around until broken up. For BIG motors it’s the way to go, ball milling takes too many batches and time.
     
  11. Oct 29, 2019 #11

    Chuck Rogers

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    Make sure to enter the Nozzle Exit Diameter for the motor (below the motor selection input), to vary the thrust of the motor with altitude in RASAero II, and to get the correct Power-On CD for the Booster.

    Make sure also that the thrust curve is a sea level thrust curve. RASAero II assumes the data in the rasp.eng motor file is a sea level thrust curve.

    And there is a Dart (No Thrust) thrust curve in the rasp.eng file that comes with the software. Just select the Dart (No Thrust) motor from the motor selection menu for the Dart. Again, below the motor selection input is the motor Nozzle Exit Diameter, just leave this at 0.0000 in for the Dart.

    Running a Boosted Dart on RASAero II is explained in the Users Manual starting on Page 112.


    Charles E. (Chuck) Rogers
    Rogers Aeroscience
     
  12. Oct 29, 2019 #12

    Reinhard

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    The thrust curve is based on the flight simulation found on the table on page 34.2 (p43 according to the pdf). It is probably not safe to assume it is a sea level thrust curve. It is also not completely consistent with the data that @manixFan posted from the same report. Based on these design characteristics, it is an 40kNs motor whereas the data points only add up to about 38kNs.

    I guess the file is good enough for having fun with the simulator, but if anybody has the real motor laying around, resolving the inconsistencies should be attempted.

    Reinhard
     
  13. Oct 29, 2019 #13

    manixFan

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    Wow, I looked at the Mikropulverizer website. Very interesting machine, but it does not look inexpensive. I had not idea something like that even existed. This has been a great thread, learn more new stuff all the time.


    Tony
     
  14. Oct 29, 2019 #14

    manixFan

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    Here's some additional data on the SLD. I have a manual that details the actual formula, but I won't post it here due to the prohibition on posting that type of material outside of the research forum. But maybe Mark can explain the numbers listed for the AP particle sizes? I don't understand the distribution range at all. TIA.

    The screen shots are from the PDF at:

    https://apps.dtic.mil/dtic/tr/fulltext/u2/750796.pdf


    Tony


    thrust-curve.png sizes.png
     
    Last edited: Oct 29, 2019
  15. Oct 29, 2019 #15

    MClark

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    I have that book.
    The as received size is nominal 200. But in the barrel it is a range of sizes. The PDF has a % where it should say Mesh. A stack of screens is used and the percentage retained is as shown. Ground size at the time book was written was done by a Fisher subsieve. It’s a hocus pocus device that determines size by porosity of a compressed column. Very operator dependent. Reality at Aerodyne (who made most of them) was they never changed the settings on the Mikropulveriser and didn’t measure size. If burn time was good that’s all that matters.
     
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  16. Oct 29, 2019 #16

    Chuck Rogers

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    And it is the sea level thrust curve.


    For digitizing the data into the rasp.eng format, for those who haven't used it, the ThrustCurve Tracer (TCtracer) over at the ThrustCurve.org website is a really handy tool.

    http://www.thrustcurve.org/tctracer.shtml


    Charles E. (Chuck) Rogers
    Rogers Aeroscience
     
  17. Oct 29, 2019 #17

    FredA

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    Learn something new all the time.....
    Usually I'd setup the motor file to match the launch conditions set in RASAero.
     
  18. Oct 29, 2019 #18

    manixFan

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    Ok, so I have too much free time on my hands. I digitized the graph in Photoshop to extract the thrust data. (I didn't know about the tool Chuck mentioned above.) Here's the graph and .eng file I got. (.eng file is below the graph.)


    Tony

    Super-Loki-graph.png
     

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    Last edited: Oct 29, 2019
  19. Oct 29, 2019 #19

    MClark

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    Numbers that stand out is the complete booster with fins, interstate, everything is 51 pounds, 37.5 of that is propellant.

    it is also partly spin stabilization.
     
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  20. Oct 30, 2019 #20

    Binder Design

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    A very important thing to consider in this thread.....While everybody in the hobby are concerned about using spherical particles for easier processing, milled particles give higher burn rates and better mechanical properties for high g applications. That's the reason I've always milled.
     
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  21. Oct 31, 2019 #21

    Ez2cDave

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  22. Oct 31, 2019 #22

    manixFan

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    So, can you explain your milling process in more detail? (Maybe start a new thread rather than derail this one.) I ask because I have a large amount of 400AP that I would love to turn into either 90 or 200.

    Thanks,


    Tony
     
  23. Oct 31, 2019 #23

    FredA

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    Milling results in somewhat random particle distributions.
    The trick with milling to try to yield the SAME particle distribution on the output from batch to batch which is usually just done by attempting to load and run and mill exactly the same every time.
     
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  24. Oct 31, 2019 #24

    MClark

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    400 can be ground to 200 or 90 average particle size but will not be the equivalent to "as received" from the barrel. The ground material will have a greater size distribution, lots of fines.
    However this can be an advantage, usually mixes better. Since most do not have ability to measure particle size grind enough to make test grains, fire. If too slow grind longer, to fast grind less.
     
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  25. Oct 31, 2019 #25

    manixFan

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    Maybe I wan't very clear in my question. I am interested in the process Mike uses for milling his AP. For example, until this thread I had never heard of a Mikropulverizer machine, which obviously is an ideal solution. But it's likely beyond my budget. I am looking for a technique/process that can be used at a small/inexpensive scale and yet still have decent results. I have a lot of 400 that I would like to turn into smaller sizes. But I'd rather start with a reasonably tried and true method than reinvent the wheel.

    The only method I've witnessed used ceramic balls (I think they were steel balls coated in ceramic) used in what looked like a big rock tumbler. It worked well enough for the guy who used it. But I'd like to know if there are alternate methods that might produce better results.


    Tony
     
  26. Nov 3, 2019 #26

    Binder Design

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    I use this with ceramic media: https://www.dillonprecision.com/dillon-s-cv-2001-vibratory-case-cleaner_8_8_23658.html Don't waste your time with other inexpensive vibratory mills like the ones they sell at Harbor Freight. I burned up a couple of those and the plastic housing disintegrated on one.

    The key is to not necessarily go for a set particle distribution by screening and over analyzing, but instead, be consistent every time about how much you load the mill with and how long you run it for. For this, I just measure the same amount by volume, and then I have the mill on a digital timer. This ensures it will be the same, every time. That's the key. Good luck!
     
  27. Nov 6, 2019 #27

    manixFan

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    That's exactly what I was looking for. I'm well familiar with Dillon gear so I can see how it is better than other mills. Obviously it will take some experimenting and I need to buy some sieves, but it gives me a good starting point.

    Plus, I can use it to clean all the empty brass I have saved up.


    Tony
     
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  28. Nov 7, 2019 #28

    criticalvector

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    Wow guys, I stopped getting notifications I didn't know this thread blew up! Thank you for all the help! let me fill in the details of why I asked this question. My schools team for some reason wants to put the Super Loki motor on top of a liquid booster and use Loki as the sustainer to reach 100km with no dart. Someone was thinking that if Loki was launched from 10,000+ feet AGL that it should reach 100km. So I was looking for the files so I could actually sim it and see. I think the sims said it hits like mach 7 or something which I don't think loki would even survive. Personally I think this project is a little ridiculous but I was entertaining the idea in the sims. Thanks for all this info! If anyone has additional input id appreciate it.
     
  29. Nov 8, 2019 #29

    MClark

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    I see the chance of success to be extremely low.
    They need to reassess, if they want to continue find new friends.
    M
     
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