Lunch time Bullpup

Discussion in 'Low Power Rocketry (LPR)' started by Brian Kirksey, Oct 3, 2018.

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  1. Oct 3, 2018 #1

    Brian Kirksey

    Brian Kirksey

    Brian Kirksey

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    This is my first rocket in over 30 years and thought it would be a fun lunch time project at work. When I started this kit , I built it a little out of order (per instructions) as I was still waiting on several orders I placed for rocket building tools, supplies, glues, etc.
     
  2. Oct 3, 2018 #2

    Brian Kirksey

    Brian Kirksey

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    I filled in the spiral tube voids.
    IMG_1165.jpg

    I removed the Laser tabs from the fins with a guide.
    IMG_1166.jpg

    I added a radius to the fins. I used a small piece of Delrin/ Acetal with a little sandpaper wrap.
    IMG_1167.jpg
     
  3. Oct 3, 2018 #3

    Brian Kirksey

    Brian Kirksey

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    I tried my best to fill in the natural Balsa grain with a light coat of filer to be sanded later.
    IMG_1168.jpg


    I got a little carried away with sanding. I was reminded its better to go light and keep checking.. I ruined a fin by going to thin. I was trying to take material off the front and I was removing material of the rear. Oops. So I went to the local store and bought a piece of .093 Balsa and remade a fin.
    IMG_1170.jpg

    IMG_1171.jpg

    I added a radius to the minor fins as well.
    IMG_1172.jpg
     
  4. Oct 3, 2018 #4

    Brian Kirksey

    Brian Kirksey

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    I know the Bullpup is a friction motor mount kit. I talked myself into a modification. Might have been better off waiting till I had a few kits under my belt. I ordered a few mini clips but they were too small. So one day during my lunch I sheared off a small piece .019 half-hard type 301 spring steel. I used a a vice and made my own Engine hook. IMG_1351.jpg IMG_1352.jpg
     
  5. Oct 3, 2018 #5

    Brian Kirksey

    Brian Kirksey

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    Part of my rocket supplies came and I was able to add the Kevlar thread to the mount for an improved parachute tether.
    I glued the motor mount rings with wood glue.
    IMG_1353.jpg
    I drilled a small pass-through hole through the engine spacer.
    IMG_1354.jpg
    Once the wood glue cured, I held onto the engine hook to let the epoxy set over the kevlar thread.
    IMG_1355.jpg
     
  6. Oct 3, 2018 #6

    Brian Kirksey

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    I purchased an estes plastic molded Alignment jig. Due to the molding process I noticed the center hole was not 90 degrees square so I reamed it out with a reamer. I custom made a plug that the engine mount would slide over. Then I had to machine a relief for the engine mount hook other wise it would be under tension and make the rocket tube list to one side..
    302231_main-400x400-200x200.jpg
    One of the details i did not catch after gluing the motor mount in the rocket tube and gluing the rear engine cone was how high the rocket now sat in the alignment jig. Now the fins would have almost no contact with the alignment blades. I even tried to machine a longer guide to remedy this..still was not optimum.


    This morning I came into work and tried a different approach. I machine a different kind of fin alignment guide out of .093 Lexan. Made three layers to add precision to the rocket body and the fin alignment. Took a little longer and i made this in the morning before work vs and lunchtime.
    IMG_1358.jpg IMG_1360.jpg
     

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    Last edited: Oct 3, 2018
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  7. Oct 3, 2018 #7

    kuririn

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    For your first rocket in 30 years, you are exhibiting some impressive and advanced building techniques. Making your own engine hooks? Love it. Just my opinion, but epoxy is not necessary for porous materials and low power. The bond strength of wood glue is greater than the materials it bonds. So if there is a failure, it will be in the material itself, not the glue joint.
    And filling in body tube spirals? Mark of a true craftsman. I usually don't bother.:rolleyes:

    EDIT: Just saw your latest post. Custom fabricated fin jigs? Out of Lexan? Get OUTTA here! So that explains your skills, I guess you work in some kind of machine shop?
     
    Last edited: Oct 3, 2018
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  8. Oct 3, 2018 #8

    Brian Kirksey

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    kuririn,

    Thanks for compliments and the tips regarding wood glue and the epoxies. That makes total sense now that you mention it.
    This last week while waiting for stuff to land in my mailbox I have been reading a lot here and have been following some of the past rocket builds from this forum. I am super thankful for this place and I owe any success in rockets to you guys. If I had not discovered this forum I would have built this kit using only the instructions that came with the kit.

    :) Thank you for the jig kudos too. Yes, my family owns a small fabrication shop and I run one of the CNC machines.
     
  9. Oct 3, 2018 #9

    Tyler P

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    Nice build!
     
  10. Oct 4, 2018 #10

    Normzilla

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    I was thinking the same thing.

    Go high power man. Do it.
     
  11. Oct 4, 2018 #11

    rharshberger

    rharshberger

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    Where are you located?
     
  12. Oct 4, 2018 #12

    neil_w

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    Ditto what others have said, that's some impressive technique for a first time back (or any time). You are going to inspire some jealousy around here for having access to your own CNC.

    I could be wrong, but it looks like in post #3 that you attempted to apply the wood filler to the fins straight out of the tube. That's pretty difficult; the stuff is not really made to spread out like that. Normally you would thin it out a bit with water, approximately to thick mustard consistency, and then you can brush on a thin layer with a normal paintbrush.
     
  13. Oct 4, 2018 #13

    Brian Kirksey

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    Neil,
    Thank you for the wood filler tip. Yes I struggled with that a bit. I added a dab of wood filler and then like one drop of water. I think in the future I will be making a slightly bigger patch of filler and definitely make it a little more like mustard consistency, like you mentioned. That day did not really go as good as I hoped.
     
  14. Oct 4, 2018 #14

    Brian Kirksey

    Brian Kirksey

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    Where are you located?
     
  15. Oct 4, 2018 #15

    Brian Kirksey

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    Scribing guidelines.
    IMG_1361.jpg

    Bent up a sheet-metal line scribe guide half the diameter of the rocket tube.
    IMG_1362.jpg

    Even though a little care was taken to scribe the lines, the jig verified I was off a tad on one line and corrected the error.
    IMG_1363.jpg

    After fins dried, jig was removed and one round of fillets for strength were added. I assume one pass of fillets is plenty.
     
    Last edited: Oct 4, 2018
  16. Oct 4, 2018 #16

    rharshberger

    rharshberger

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    Southeastern Washington near Richland.
     
  17. Oct 5, 2018 #17

    Andrew_ASC

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    Brian, I think you would enjoy high power rocketry because of your background in machining. There are many high power projects with custom machine work. After you have fun with the low power bull pup, just imagine it larger and busting past 2,500 ft on your first H motor at about 3 pounds mass and yardstick length where it fills the palms of your hands.

    Consider joining NAR or Tripoli as a member and you too can attempt a high power certification. They also have insurance at sanctioned launches.
     
  18. Oct 5, 2018 #18

    Brian Kirksey

    Brian Kirksey

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    Mid power and high power sound extremely exciting. I bought the bullpup, and then, I picked up a Red Nova, and a few other Estes small kits. Now I have my eyes set on the Madcow mini Black Brant II and the 1.6" Mini AGM-33 Pike.
    I most likely will join and support the rocketry clubs local and national if I continue down this glorious rabbit hole of fun building and launching rockets.
    I assume mid power and high power rocketry could be issues where I live in the ever changing bay area landscape (google, apple, facebook). I will have to look into the local launch allowances. I believe currently launches are allowed once a month at a local airbase Moffett Field and it definitely has a limited ceiling.
     
  19. Oct 5, 2018 #19

    Brian Kirksey

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    Well today lightning struck and I knew better for this to happen. I loaded my rocket tool box in my Tundra this morning along with my rocket. I should have boxed my WIP work in progress. Long story short my pet poodle took out a fin on my Bullpup. This tragedy definitely effected my whole day that I allowed this to happen. Tonight I repaired the fin by cleaning the foot of the fin up and re-using the fin alignment jig I made and re-glued the fin back on in its proper location.
    After a few hours I removed the jig and it looks good again, could have been much worse.

    I just added the fillets with Wood Glue. For low power rockets I assume CWG is fine for small radius fillet work. I this a sound assumption? Thanks in advance.
     
  20. Oct 5, 2018 #20

    Andrew_ASC

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    Tripoli and NAR should have prefectures or clubs listed in your regional area or if real lucky same state that will have FAA waivers for high power rocketry.

    Now as far as buying mid power motors go from buyrocketmotors.com they wanted a L0 NAR or Tripoli membership. Meanwhile Apogee rockets only wanted an ID of 18+.

    Once your with NAR or Tripoli they let you buy a high power motor limit one per certification attempt until you certify. The thing about Tripoli is they let you build Aluminum airframes and launch those on research days. NAR doesn’t do research days or research motors. NAR is more for sport flying.

    After certification flight is complete and paperwork is signed you send that to a motor vendor and can order as many high power motors with your rated level as you want and even attempt the next level with a limit of one per certification attempt.

    Anyways nice bullpup build.
     
  21. Oct 5, 2018 #21

    rharshberger

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    Carpenters Wood Glue (any brand, my preferred is TiteBond II aka TBII) will work, but the best wood glue for filleting is TiteBond No Run No Drip wood glue or TiteBond Quick and Thick (there may be a few bottles on shelves of Titebond Trim and Molding Glue, they are all three the same product just different iterations, TB QT is the newest version). The TB QT is a thick version that wont run making fillets easy to make, I usually apply it to the fin root, then wait a few minutes for it to gel even more and using a dampened finger (water) smooth the fillet to the way I want it to look.
     
  22. Oct 5, 2018 #22

    Andrew_ASC

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    Wood glue is fine for low power rockets.
     
  23. Oct 5, 2018 #23

    Mustang67

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    Thought I would help you down the rabbit hole. https://bayarearocketry.com/ One of many vendors to choose from, however these guys may be fairly close to you.

    I was once in your shoes as well, been out for some time. Then my 16-year old son said about two years ago now, "hey dad, are you ever going to launch that rocket sitting in the basement that you built in 98" I said how do you know I built it in 98, you were not even born yet. He said you wrote 6/98 on the bottom of the plate where the motor must go in. Do you think it would even fly? I then searched for a forum to see what I would need to fly it, found this community, and well........now I happily have about 30 of them in the basement, 15% of the pile is completed:) And so the story goes:D:D:D
     
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  24. Oct 5, 2018 #24

    Brian Kirksey

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    Great story!!!
     
  25. Oct 5, 2018 #25

    Brian Kirksey

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    Tomorrows task: add clay to the nose and attach launch alignment lug. I also want to start learning how to use open rocket for weight ratio simulations.
     
  26. Oct 5, 2018 #26

    snrkl

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    Great build.. super jealous of the tools at your disposal!

    My only suggestion with the jig is to leave room at the root/body tube connection point for glue - you don't want to accidentally glue the jig to the fin/bt... I use foamcore for fin guides normally, and when I do, for a 4fin rocket, I cut the square that contains the circle (or a little smaller for BT60 tubes) with the corners centered on the fin locations..
     
  27. Oct 5, 2018 #27

    scott johnson

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  28. Oct 5, 2018 #28

    scott johnson

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    Here is my custom launch pad, it is convertible from 1/8" through 1/4" launch rods. I need to find some 1" aluminum rail so I can fabricate an adjustable mount for it. My next versions will have adjustable legs for better leveling. Currently I shim the feet to get it level.
     
  29. Oct 5, 2018 #29

    scott johnson

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    The simplest jigs I have made are pieces of 1x1 aluminum angle that I have slotted down the middle. I have them in 3/32", 1/8", 3/16" and 1/4". They collapse a little as some stress is relieved when I mill the slot so I always mill them .010" larger. They align the fins perfectly with the body tube and have plenty of room so they don't get glued to the fin or body tube.
     
  30. Oct 5, 2018 #30

    Brian Kirksey

    Brian Kirksey

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    Yes, great idea..Thank you for the insight. Yes, there is no reason to have the soft balsa fins rubbing and getting hung up on the fin guides.. I want to avoid dents and rubs. Great point about the clearance too. My next jig, for the next build, will have reliefs where the glue to body tube will be to avoid any possible glue to jig contact. Luckily I did not have an issue with this one.
     

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