Scale Staged Black Brant XI 1:7.5

Discussion in 'High Power Rocketry (HPR)' started by micro, Sep 16, 2019.

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  1. Sep 16, 2019 #1

    micro

    micro

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    I've had the parts for this project for a year and a half I think, time to finally get to it! Pretty sure I will need my L2 to fly this full stack.

    This will be all paper/wood construction. I am a low/slow guy. Not going for any records here, I just love staging.

    Black_Brant_XI_launch_from_Wallops_Island.jpg
     
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  2. Sep 16, 2019 #2

    Dustin Lobner

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    I was looking through the Wikipedia article on the Black Brant series, neat rocket with a great history. Good luck! Good excuse for an L2 too, lol. :cool::)
     
  3. Sep 16, 2019 #3

    micro

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    I started with the sustainer fins. I've been planning how to do these for some time. The foil is hard to get right as the leading angle is less than 1 degree. I've had really good luck in the past making ply fins with veneer birch and balsa so I figured a way to create the fins from built up thin layers with a skin layer. The skin is scored at the edges between planes.

    IMG_20190904_221957577_resize_35.jpg
    IMG_20190904_223632759_resize_68.jpg
     
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  4. Sep 16, 2019 #4

    Nytrunner

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    Nice project! The real thing has a great Flame-to-rocket ratio

    Good luck getting the staging to work out. As they say, high-power staging isn't twice as hard, it's 10x as hard (and keep adding zeroes for subsequent stages)
     
  5. Sep 18, 2019 #5

    micro

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    Some pics of the fins, though hard to see the angles in the pics.

    BTW thanks to @Bruiser for the measurements.

    IMG_20190911_203518760_resize_70.jpg

    IMG_20190912_204157250_resize_37.jpg

    IMG_20190912_204406621_resize_68.jpg

    Here's the underside of the trailing edge where you can see the layers before I filled them.

    IMG_20190911_203147838~2_resize_10.jpg

    After gluing the joints and a cursory fill and sand.

    IMG_20190912_204000645_resize_38~2.jpg
     
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  6. Sep 18, 2019 #6

    micro

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    The sustainer is LOC 2.14" tube. The fin can/nozzle area is almost exactly the diameter of the coupler tube.

    I got started on the fin can setting a CR to the leading edge of the fin tabs, using a coupler to make sure it's square to the airframe. Then glued in a motor tube using a temporary rear CR to center it.
    IMG_20190915_190644806_resize_74.jpg

    IMG_20190915_202302704_resize_66.jpg

    Angled fin slots are marked and cut. I'll glue in each fin before cutting the next one in order to keep the tube from getting out of round since the cut will extend to the end of the tube.
    IMG_20190915_193419347_resize_3.jpg

    IMG_20190918_075958719~2_resize_12.jpg

    Also got started on the tailcone. It's 1/32 birch ply, will need plenty of filling and sanding.
    IMG_20190917_214317136_resize_45.jpg
     
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  7. Sep 20, 2019 #7

    micro

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    4 fins in place. Next is the slotted fin can which will need internal fillets for strength since it will support the interstage coupler. Then I'll start building out the tailcone/interstage.

    IMG_20190918_224144539_resize_84.jpg
     
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  8. Sep 20, 2019 #8

    Nytrunner

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    Are the 3rd stage fins canted?
     
  9. Sep 20, 2019 #9

    micro

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    No, sorry, I just meant the slots are wedge shaped to accept the foiled leading edge of the fins.
     
  10. Sep 20, 2019 #10

    Nytrunner

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    Ah, reading comprehension error on my part
     
  11. Sep 20, 2019 #11

    ECayemberg

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    AWESOME project!!! Following with interest!!!:D
     
  12. Sep 20, 2019 #12

    watheyak

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    I agree. You had me at the angled fins.
     
  13. Sep 20, 2019 #13

    JCRL

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    Best of luck! This build looks incredibly technical and I'm excited to see the finished rocket!
     
  14. Sep 22, 2019 #14

    micro

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    Glad you guys are following along, I'll carry on then!

    Added a centering ring down inside the fin can coupler material, up against the aft ends of the fin tabs for strength. Used screws as temporary handles to dry fit and eventually glue it in place.

    IMG_20190921_230834686_resize_57.jpg

    Worked on the tailcone. Here I have some scrap airframe and coupler that I'll dry fit the cone onto to glue the centering into the back of the cone. I've sanded the edge of the CR to match the cone angle.

    IMG_20190921_225710812~2_resize_53.jpg

    And the CR glued in place. Starting to look like a cone type thing!

    IMG_20190921_230656406~2_resize_21.jpg
     
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  15. Sep 24, 2019 #15

    micro

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    A third CR went on the end of the coupler for strength where the airframe extension will go. The cone will go on followed by the airframe extension. Another temporary CR will keep it straight.

    IMG_20190923_215525278_resize_86.jpg

    So far the Cg is well ahead of the Cp so I will be moving the location of the electronics bay further aft to reduce overstability. I'll have it just far enough forward to accommodate a 6GXL motor.

    Capture.JPG
     
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  16. Sep 26, 2019 #16

    micro

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    The tail cone should meet flush with the fin can so it needs some filler to smooth out the joint. I marked the edge where they should meet with masking tape and filled. After drying I sanded up to the edge and cleaned up some more after removing the tape. After the pics I filled the gaps behind the fins using the angles I'd already sanded as guides.

    IMG_20190925_201606271_resize_26.jpg
    IMG_20190925_201725449_resize_59.jpg
     
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  17. Sep 26, 2019 #17

    mbeels

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    Wow, looking really good. Following with interest.
     
  18. Sep 26, 2019 #18

    micro

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    Thanks!

    The electronics bay is pretty standard design. For a rocket this size I use #6 threaded rod. Will have a rotary switch for power and a slide switch to shunt the igniter.

    IMG_20190925_213611530_resize_14.jpg
     
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  19. Sep 26, 2019 #19

    Bruiser

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    Great work on this. I'll be following your build.

    -Bob
     
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  20. Sep 28, 2019 #20

    Ez2cDave

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    Black_Brant_XI_launch_from_Wallops_Island - larger.jpg

    Black_Brant_XI_1 - larger.jpg
     

    Attached Files:

  21. Sep 28, 2019 #21

    micro

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    Thanks Bob!

    Thanks Dave, the first pic is the flight I'll be modeling. It was a test flight with a shorter sustainer than flights loaded up with instrumentation.

    Got a first coat of primer on the business end of the sustainer. I love how the first coat of primer unifies the look of all the various materials. Looking good so far, plenty of sanding, filling, and priming from here.

    IMG_20190926_204435031_resize_52.jpg

    IMG_20190928_001431678_resize_54.jpg

    IMG_20190928_004640085_resize_28.jpg
     
  22. Sep 30, 2019 #22

    micro

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    Sanded down the first coat of primer with 220 and filled some low spots.

    Extended the motor tube about 3/4 inch and glued on the Estes retainer. I had made the interstage extension a bit longer than anticipated, and I like the motor retainer sticking out a bit so I can easily tape the igniter lead to it.

    Then got the connectors on the leads. I like to use these PC board header type connectors here. I have a batch of ematches soldered to PC header pins ready to go in my launch box so at the field I just plug and tape.

    IMG_20190929_225422010_resize_18.jpg

    The connection to the ebay is similar but the molex equivalent. A harness can be made up and keyed with male and female contacts. The connection isn't locking but the contacts have a pretty strong tension so it won't disconnect until the airframe separates and pulls them apart. The connectors are carefully soldered in addition to crimped because they will take some abuse.

    IMG_20190929_225333840_resize_89.jpg
     
    Last edited: Sep 30, 2019
  23. Oct 4, 2019 #23

    micro

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    The LOC nose cone is a bit long, and actually doesn't really start to taper for a couple inches past the base. I was able to cut a couple inches out for a more scale shaped nose.

    IMG_20191003_183124376~2_resize_50.jpg

    Above shows where I made the cut. Then I cut off the shoulder. A few minutes with the dremel and I epoxied it back together.

    IMG_20191003_194641139_resize_20.jpg

    IMG_20191003_202619803_resize_98.jpg

    Pic with new nose cone. Bottom section has second coats of filler, primer, and sanded to 220.

    IMG_20191003_202805420_resize_0.jpg
     
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  24. Oct 5, 2019 #24

    Tyler P

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    Watching with great interest! I love sounding rockets and have a small collection of different Black Brants. My next big scale build will probably be another BB.
     
  25. Oct 5, 2019 #25

    802high

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    Wow those fins a a work of art.
     
  26. Oct 7, 2019 #26

    micro

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    Thanks!

    Third coat of primer.

    IMG_20191006_140223799_HDR_resize_11.jpg

    Installed a centering ring about 10" below the nose cone. I like to do this as an anchor point as well as holding the chute up by the nose cone so it doesn't slide to the bottom during boost.

    IMG_20191006_220745958_resize_83.jpg
     
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  27. Oct 8, 2019 #27

    micro

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    Alright got the black on yesterday. The black brant should be flat black but I went with a satin sheen because it will be a lot tougher. Flat will show every scuff and scrape. I plan on flying this a lot. Don't tell anyone.

    IMG_20191007_221717033_HDR_resize_4.jpg

    It's hard to get the fin angles with the camera but here's the best I could do with the lamp at a good angle.

    IMG_20191007_221355925_resize_52.jpg

    While the paint dried I sewed an octagonal parasheet with spill hole.

    IMG_20191007_222947901_resize_56.jpg

    This evening I drilled a couple holes in the switch ring for the rotary switches. Upper stages will have a power switch and an igniter disconnect switch.

    IMG_20191007_221836092_resize_61.jpg

    They do kind of stick out like a sore thumb but at least they'll be rotated toward the back (either side of the rail). Safety is paramount so I find a really dummy-proof system at the pad is important for the safety of a complex rocket. There's always someone who needs to offer "assistance" which can lead to distraction. I hate monkeying with tape, wires, etc. out at the pad.
     
    Last edited: Oct 8, 2019
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  28. Oct 10, 2019 #28

    micro

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    Painted the red stripe and the gray fin can. So much masking!

    IMG_20191009_211610298_resize_33.jpg

    Hopefully I can paint the tailcone tomorrow and get to work on the detail bits.
     
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  29. Oct 13, 2019 #29

    micro

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    I'm hoping to fly the sustainer in the next couple of weeks. First flight will have main ejection at apogee, I was able to do some testing today.

     
  30. Oct 14, 2019 #30

    micro

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    Getting some paint on it. Starting to look like a black brant.

    IMG_20191010_222040970_HDR_resize_61.jpg

    Wiring up the electronics bay. Decided to go with a second rotary switch instead of a slide switch for the motor igniter. Soldered leads to the switches, will mount them in the band, then make the connections.

    IMG_20191013_220701161_resize_91.jpg
     
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