Level 2 project: "Long Tom" LOC Cruiser -> stretched Tomahawk CM

Discussion in 'High Power Rocketry (HPR)' started by Nytrunner, May 5, 2018.

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  1. May 5, 2018 #1

    Nytrunner

    Nytrunner

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    I've been collecting and preparing parts off and on for about a year now, and it's time to get building!
    Last year I was challenged to fly for L2 at NARAM 60 in Pueblo which is 3 months away.

    Started with finding the LOC Cruiser before it was discontinued. It looked like a cool straightforward build.
    Then I found a big 5.5" elliptical nosecone in Madcow's Rocketry Warehouse acquisition stash.
    Since I have a knack for coming up with great terrible ideas, I thought I'd turn it into a long Tomahawk looking thing and do L2 in style. I swapped the long nosecone for a short one from LOC, and bagan designing a boattail.
    After reading Eric Cayemburg's threads, I'll be doubling the walls using couplers. That'll be easier than fiberglassing, keep the weight down, and allow for stronger motors in the future.
    listing.PNG IMG_20170412_203026688_HDR.jpg Decisions.png 3d finished.jpg
    View attachment Long Tom.ork


    Since I enjoy making things more complicated than they need to be, I decided I'm going to try and get all certifications on Red Lightning motors (started with a Cesaroni H120 a year and a half ago), and this build is targeting the CTI J355. Fortunately, this is a big cardboard airframe, and it should turn out fairly lightweight. And if I fail to meet the weight mark for the J355,.....there's always the K515!

    20180425_003450.jpg

    Read on over the next few months to watch the adventure, and at the very least learn from my mistakes! :cool:
     
    Last edited: May 17, 2018
  2. May 5, 2018 #2

    Nytrunner

    Nytrunner

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    Boattail

    This portion of the initial design took most of my thought. Working out how to slot the cone accurately, get a good bond to the polypropylene nosecone, orient the tail unit properly, etc...

    I started by chopping the ends off the cone with a hacksaw and cleaning up the cuts with an exacto and sandpaper. A club member who can make jigs in his sleep set me up with an indexable jig for routing the slots which came out perfectly.
    1754_1517703046284.jpeg

    I fixed a slimline retainer on the first motor tube with JB weld butted up against a custom tapered centering ring for the end of the tailcone.
    I then learned that I hugely overestimated the amount of mixed rocketpoxy I'd need. First time with the stuff, so I'm confident I'll get a feel for it. It sure is messy, but alcohol athand made cleanup pretty easy.
    20180503_221301.jpg 20180504_233405.jpg 20180504_233948.jpg

    To make sure I had the motor tube centered properly, I jammed a kit centering ring into the switchband and made a little centering cap for the end of the tailcone. Reminds me of the motor makers with their mandrel holding caps.
    20180504_185802.jpg 20180504_235143.jpg 20180504_185954.jpg

    That was the last couple days' activities, I'll be making fin jigs and beveling next. It spent the night aft end down in a "holding device" to cure.

    20180504_235335.jpg

    Update:

    I had some spare uncured rocketpoxy, so I experimented with blending the tailcone and the slimline retainer.
    One side is better than the other do to sagging (and I not having a real solid gameplan for this effort)
    You can also see the masking tape laid down for fillets. They'll get cleaned up when it's time to pour (although the idea of pouring fillets on a curved substrate is giving me major hesitations)

    20180512_133139.jpg
     
    Last edited: May 16, 2018
  3. May 5, 2018 #3

    Nytrunner

    Nytrunner

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    Fins

    The main fins protrude into the end of the body tube slightly, so I made an 8 slot guide to lay out the cuts as well as a 4" 4 slot guide for the tailcone.
    20180505_151821.jpg 20180506_231109.jpg 20180506_231154.jpg

    The tab roots were spread with TBII, set, removed, and dried for 1 minute twice before being coated a third time held in place by the guide. When fully set, I removed the tail assembly and flowed some tab root fillets with TBII.

    Next I began preparing for the external rocketpoxy fillets on the plastic tailcone. Since I don't have a stash of pvc scraps lying around my apartment, I painted the old tip of the nose (now tail) cone with a sharpie and laid out lines for the tape dams that will follow.
    20180511_182935.jpg 20180511_182647.jpg

    With the leading tips extending into the body tube, I'll have to do some booster work before laying the final fillets.

    To be continued....
     
    Last edited: May 12, 2018
  4. May 5, 2018 #4

    Nytrunner

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    Nosecone (er...dome)

    Using a payloadbay.com guide, I drilled boltholes in the nose bulkhead/lid and an embedded centering ring.
    Turns out I'm basically making my own version of Loc's noseweight system for this elliptical cone.

    The ring is fixed with rocketpoxy, and a 3" PSII tube is mounted to the inside front of the cone with 30m epoxy. The tube will help hold my lead shot weight discs when the time comes for balancing.
    20180511_185537.jpg 20180512_000554.jpg 20180514_191129.jpg

    Still to come: shear pin accommodations.
     
    Last edited: May 16, 2018
  5. May 5, 2018 #5

    Nytrunner

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    Booster business Part 1

    Since the fins protrude into the booster tube, I had to do some prepwork on the tube and it's internal components prior to adhering the tail assembly on permanently for fillets.
    And I'm going to need a 2nd booster post because I will run out of picture attachments....

    The original cruiser had the wings inline with two of the fins, but I decided it'd look better if they were rotated 45 degrees. Thus, an 8 slot guide was made to transfer cuts for the fin protrusion. In the 2nd picture you can see the marking for where the rear centering ring meets the tailcone shoulder.

    20180505_151821.jpg 20180511_215744.jpg

    I wanted to use threaded inserts in the centering rings to mount the 1515 rail buttons, so I added some 1/4" plywood to the rear and middle centering ring so the insert has more to bite into. Also, this insert necessitated a cutout in the rearmost reinforcing coupler.
    Remember the horror stories of positioning Bt-60 couplers while using Titebond II? Try it with a 5.5"x 11" coupler and all its associated boding area. Luckily, I kept the chopped bottom of the tailcone shoulder which turned out to be a perfect Coupler Emplacement Tool. (and the stock tube slots actually make a pretty good alignment gauge)

    20180511_214354.jpg 20180511_222754.jpg 20180512_131859.jpg 20180511_224633.jpg

    With the internals all set in place, I mixed more rocketpoxy, spread it all up in the booster tube's aft, and set the tail assembly to cure overnight. Again, the slots make alignment check easy.
    Now LOC only sent a 20" motor tube, and I wanted to extend that all the way to the forward wings in order to reduce the free volume that had to be pressurized by the drogue charge. I ordered a 17" tube for this purpose and sliced part of a reclaimed 2.5" PSII body tube to make an external motor mount coupler. Careful application of TBII and long arms got everything aligned properly (with a Pro54 6G case lending a hand as well.....No the case didn't get glued in the tube)

    20180512_231749.jpg 20180514_201847.jpg 20180514_212359.jpg

    Stay tuned for Booster Business Part 2 for wing mounting and railbuttons!
     
    Last edited: May 16, 2018
  6. May 5, 2018 #6

    Nytrunner

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    Ebay

    Got some components laid out and charge wells fixed to the bulkheads.
    20180615_214934.jpg
    The charge wells are 1/2" copper fittings. I'm looking at 1-1.5 grams for the drogue and 2.25-2.75 for the main.

    I got a 10 pack of these switches on amazon since I have the real estate on that massive board. More on that as it develops
     
    Last edited: Jun 16, 2018
  7. May 5, 2018 #7

    Nytrunner

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    Recovery!

    Made a couple burritos. I'll unpack those more later.
     

    Attached Files:

    Last edited: Jun 16, 2018
  8. May 5, 2018 #8

    grouch

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    Cool man. I flew a J355 for my L2 cert. Cool motor for sure. Best of luck with the build.
     
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  9. May 5, 2018 #9

    A-N-D-R-E-W

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    Really cool build you have going on, thanks for the pictures and detailed write up, now let’s see it fly!
     
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  10. May 5, 2018 #10

    Nytrunner

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    Rocket's red glare!

    Lol, if I had a time machine to travel to August, I'd post footage now. We'll see how things play out!
     
  11. May 5, 2018 #11

    Handeman

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    The AT K695R is a cool red motor for a L2 cert! Kicked my 4 inch 10 lbs. to just over 6800 ft.
     
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  12. May 6, 2018 #12

    rharshberger

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    And if a K695R isn't enough there is alway the K1275R! Love the Red motors.
     
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  13. May 6, 2018 #13

    Nytrunner

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    As long as the motor doesn't push it over 15 lbs, t should work out in the J355.

    Nothing wrong with a little design constrain to keep me on my toes.
     
  14. May 6, 2018 #14

    neil_w

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    Nice. Glad to see the infamous red chair make it into one of the pictures at least. ;)
     
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  15. May 6, 2018 #15

    Nytrunner

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    When the rocket's done, it'll be lying on that chaIr for a picture just like Big SAM. It just makes a convenient holding fixture
     
  16. May 7, 2018 #16

    MikeyDSlagle

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    Awesome. Looks good. And might I say, it's about time! You've been working on that PSII trainer fleet for ages. LOL

    I'm joking with ya of course. Enjoy the build and good luck on the flight.

    I like the look of the Cruiser. With the boat tail it comes off looking like a torpedo to me, not a bad thing.
     
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  17. May 7, 2018 #17

    Nytrunner

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    All things in the fullness of time :cool:

    I've learned a ton working out electronics, tracking, and deployment kinks on those things.

    I'll update when the fins are fully affixed
     
  18. May 7, 2018 #18

    Andrew_ASC

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    How long is your fin span? On forward fins I am worry for you about Flutter. I just Fin Simmed a Wildman Sandhawk, and AeroFinSim hates Loki 38-1200 motors on the 4.04" fin span G10 material and 0.0984" thickness. The L-2 sized airframe takes a 38-1200 casing but the fin geometry especially span does not like any more than an I motor. Granted it's all theoretical... But the Mach on a K motor predicted nearly double the flutter Mach. I'm kinda shocked it only liked Mach 0.76, but the fin span is high. Perhaps my fin CG is slightly off. Mines in pieces on the floor.
     
  19. May 7, 2018 #19

    Flyfalcons

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    Didn't want to call it a Tom Cruiser?
     
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  20. May 7, 2018 #20

    Nytrunner

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    The ork is attached in the 1st post. They're somewhere around 6-7" out, but I don't recall.

    Just looking at the nose should tell you this rocket isn't built to break airspeed records. If that was my aim for Level 2, I wouldn't have put a 54mm tube in a 5.5" body.
    (bonus objective is recording how many times a suburban with a cruise missile strapped to the top can get pulled over between Colorado and Alabama)

    Ooh, that would've had potential if I cared about actors (My favorite of his movies is the one where I got to see him die 20 times)

    I had an Estes Patriot called SAM, my L1 was called Big SAM
    I picked Long Tom since I had a Quest Tomahawk called Tom, and it fit the pattern.
    (Tom later became OpTom when my girlfriend at the time, an optometry student, drew the Optic Trac on it when I gave it to her to paint. Barely got it back before we broke up too :cool:)
     
    Last edited: May 7, 2018
  21. May 7, 2018 #21

    boatgeek

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    Cool project! I like the shorter nose cone you chose. Why stop at the K500? There's a delightful L1030 that still fits a 54mm motor mount. It probably wouldn't shred... [Slides back to the enabler cave]
     
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  22. May 7, 2018 #22

    Nytrunner

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    It's no hand built square cone, but it is pretty cool

    Shredding is not on the menu with the full length couplers :dark:
    For perspective, a 37" motor tube ends at the front of the wings. I'm thinking that leaves enough room for that Doomsday 54-M from Loki, but I must agree with Andrew for once, too much speed will make those wings take flight.
     
  23. May 7, 2018 #23

    Andrew_ASC

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    Shaving 1.04" off the Sandhawk span really helps with flutter mach it went to M1.29 in theory world. I'm still eager to stuff a J1000 or K1127 into it. It might need a touch more tweaks. This Mark L-3 dude was all finsim it bro. I was in the enabled boat and jumped into the sharky waters below.
     
  24. May 8, 2018 #24

    Nytrunner

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    These wings are already short compared to a tomahawk, so they'll be staying as is.

    Speaking of fins/wings: sneak peak

    20180505_210517.jpg 20180506_231455.jpg
     
  25. May 8, 2018 #25

    Andrew_ASC

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    Well that's good that they are real thick. I'll worry less now.
     
  26. May 8, 2018 #26

    neil_w

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    Nice airfoils, you ain’t messin’ around.
     
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  27. May 8, 2018 #27

    boatgeek

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    I think the Doomsday 54-M is 44" long. It might still fit if you don't have a big drogue or recovery harness. On the plus side, it's a red motor, so it would fit the theme.

    If I every build an L3 project, it may need to be named Doomsday M. :)
     
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  28. May 8, 2018 #28

    Nytrunner

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    All my plans get foiled in the end

    Oh dear....this is not how this was supposed to go. The M1378 fits with an inch to spare, and only kicks Long Tom to ~1250 ft/s....That's right around transonic, but lower than I recall the divergence speed. I'm going to have to recheck finsim......
    See, this is sounding more like a terrible great idea, and those are bad. I strictly do great terrible ideas.

    If you do build that, you should get a decal like "dooMsday" with the horns from Loki's helmet on the M
     
  29. May 8, 2018 #29

    Andrew_ASC

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    No. A terrible idea would be trying the first M class radio control rocket glider as a L-3 cert flight. It could have little pneumatic gear like an R/C plane with fins so wide. You could land it X-15 style, but I don't think any TAP would approve.
     
  30. May 8, 2018 #30

    Steve Shannon

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    The process doesn’t allow gliders for L3 certification.
     

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