Building an Estes Mini “A” Heli

Discussion in 'Low Power Rocketry (LPR)' started by Amsterdam, Dec 5, 2018.

Help Support The Rocketry Forum by donating:

  1. Dec 5, 2018 #1

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    i swung into a local RC hobby shop today just to see what they had, and to my surprise they had a whole corner of NEW Estes kits. My usual HS as well as hobby lobby had no new shipments since Hobbico went south.

    The first I’m making is the Mini “A” Heli
    [​IMG]

    It was the only one they had and unfortunately the tube was crushed

    [​IMG]

    It wasn’t a big issue, I have plenty of bt-5s around.
     
  2. Dec 5, 2018 #2

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    Following the instructions the first thing I did was mark the body tube at twelve and four inches, and cut the remainder off. Estes supplied a bt-5 cutting guide, a real bonus!

    [​IMG]

    Next I shaped the fins. Since this model is a contest design I sanded a shallow airfoil (probably could have been more aggressive), and lightly tapered the fins.

    [​IMG]
    I’m not the best photographer.
    [​IMG]
     
  3. Dec 5, 2018 #3

    jlabrasca

    jlabrasca

    jlabrasca

    Well-Known Member

    Joined:
    Oct 31, 2016
    Messages:
    744
    Likes Received:
    135
    I'll be interested to see how you do with laser-cut the airfoil formers. I finally gave up and steamed the rotors to twist them into shape. I have another copy still in the bag, and want to try the formers again.

    One suggested modification

    #19036 -

    edit: didn't meant to drop a big image into your build thread. sorry.
     
    Last edited: Dec 5, 2018
  4. Dec 5, 2018 #4

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    I took my 80 grit sanding block and roughed up the area where the fins will be glued on.
    I used a three fin guide I got from apogee. It’s a very snug fit, even after running a warding file in the slots.

    I ran a thin bead of wood glue on the root edge, and struggled to slide them in the mounting guide smearing wood glue all over the body tube.

    So I wiped that off, and tried again, after hitting the slots with a file. (Warding files are one of my favorite tools, seriously buy a set.)

    Wood Glue had gotten on the fin guide and I figured it wouldn’t be wise to wait for the fins to dry.

    So I tracked them on with medium CA. I used to hate working with CA till I discovered accelerant. Makes a world of difference.

    [​IMG]
     
    Last edited: Dec 5, 2018
  5. Dec 5, 2018 #5

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    We’ll see! I haven’t looked that far ahead.

    I like your mod, the huge slots seem like over kill anyways.
     
  6. Dec 5, 2018 #6

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    I added wood glue fillets, only a thin set, really just to make sure there’s a wood glue to paper bond. The smeared glue from wrestling with the fin guide looks terrible but I’ve never been as (skilled) meticulous and clean as a lot of the builders on TRF.

    [​IMG]



    I also added a little CA to the cut end of the body tube, and smoothed it over with a file.

    [​IMG]
     
  7. Dec 5, 2018 #7

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    I was thankful for the tip! Honest though I’m on mobile which basically auto fits everything, I have no clue how large my pics are. Probably killing everyone’s margins

    You probably know about it but I’ve always used elastic thread for burn strings, never had one fail to snap. Just go to JoAnns and ask some one for elastic thread. They should have some with the specialty threads. usually just one kind.
     
    Last edited: Dec 5, 2018
  8. Dec 6, 2018 #8

    GlenP

    GlenP

    GlenP

    Well-Known Member

    Joined:
    Oct 4, 2014
    Messages:
    1,127
    Likes Received:
    31
    That looks like a good idea. I have one of these kits in the bag. I wonder if you could stagger those holes around the tube to spread out the weak spots, rather than having them in a straight line?
     
  9. Dec 6, 2018 #9

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    Man I already cut mine.. I’m definitely going to try a spiral patteren of holes on a new 4” piece.

    Went for the lower case i

    [​IMG]
     
  10. Dec 6, 2018 #10

    GlenP

    GlenP

    GlenP

    Well-Known Member

    Joined:
    Oct 4, 2014
    Messages:
    1,127
    Likes Received:
    31
    or the letter A, or N, depending on the direction you read it, in Morse code.
     
  11. Dec 6, 2018 #11

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    Hey! “A” Lol works for me.

    Blades are made I just need to sand them. I used the guides. But didn’t follow the instructions.

    I did not glue the hinge to the blade before warping it.

    [​IMG]
    I ran an xacto knife lightly a few times in the crease, then ran a mechanical pencil through the cut, and slowly bent it till I heard creaking and cracking.

    Then I slid the number 2 guide down to the middle from the slotted end, slid 1 on the same side, and finally three slid on from the opposite side.

    Then filled the crease with medium CA.

    It would have been very difficult to push guides 1&2 all the way down the blade after gluing


    [​IMG]
     
    Last edited: Dec 6, 2018
  12. Dec 6, 2018 #12

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    Forgot to take a picture of the paper board hinge pieces, but now that’s all put together and the nose cone is prepped for gluing. I prefer epoxy when gluing plastics.

    [​IMG]

    Now the whole top section will be hit with thin CA, and sanded. Figure this Dremel bit will work nice for the holes, stuck it in a razor saw handle so it’s easier to use.

    [​IMG]
     
  13. Dec 6, 2018 #13

    tlainhart

    tlainhart

    tlainhart

    New Member

    Joined:
    May 29, 2009
    Messages:
    4
    Likes Received:
    0
    I enjoyed building this kit. The blades didn't come out as curved as I thought they should, but the second flight was successful (having never flown a heli, I didn't position the rubber bands correctly for the first, such that the blades locked in the "down" position. After retrieving my lawn dart, I replaced the crinkled top.)

    Re using CA for tacking - someone here or on Facebook posted that they use a product called "Rapid Fuse" by DAP, which is mostly CA as far as I can tell. Thick-ish, and sets in around 30 seconds. I've been using it for tacking, and love it. And as an overall adhesive, it's great.
     
  14. Dec 7, 2018 #14

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    I didn’t think the blades had enough curve either, sanding them made them look better.
    Here’s untouched, and sanded side by side

    [​IMG]
     
  15. Dec 7, 2018 #15

    jlabrasca

    jlabrasca

    jlabrasca

    Well-Known Member

    Joined:
    Oct 31, 2016
    Messages:
    744
    Likes Received:
    135
    Much better than my attempt. Thanks for posting.
     
  16. Dec 10, 2018 at 10:00 PM #16

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    The rocket is fully assembled!

    I glued the supports to blades with wood glue, I’m not sure what these where made from exactly.

    [​IMG]

    Poked two holes for the burnstring to thread through.

    [​IMG]

    Glued the top piece on with 5 minute epoxy, epoxy doesn’t grab instantly like wood glue will, so it allowed plenty of time to line it up correctly

    [​IMG]

    And test fit the blades

    [​IMG]

    Last thing to do is paint it.
     
  17. Dec 11, 2018 at 1:52 AM #17

    GlenP

    GlenP

    GlenP

    Well-Known Member

    Joined:
    Oct 4, 2014
    Messages:
    1,127
    Likes Received:
    31
    Nice job, looks like a fun build, this is inspiring me to get started on mine. I built the FlisKits Tiddlywink, and also have the Rose-A-Roc in the bag, So I will have MMX, 13mm, and 18mm helicopter rockets in my collection, when I get around to building them.

    I wonder if you could put little flow directors on those vents at the top so that the ejection charge will initiate a spin, then when the rotors pop, it will ascend... momentarily, if it is still coasting upright.
     
    Last edited: Dec 11, 2018 at 1:58 AM
  18. Dec 11, 2018 at 2:24 AM #18

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    Thanks,

    Would be fun to try the deflectors if they could be made light enough,
    I think getting the bottom fins to rotate 90* (parallel with the blades) would fun on designs like this and the rose-a-roc,where the rotor is attached to the airframe.
    Might’ve get’em spinning at a higher rpm
     
  19. Dec 11, 2018 at 5:11 PM #19

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    Done!. Rusto 2x ink blue, flat white, flourecent pink. Light coats. If I had performance in mind I would have sealed the wood with aerogloss or spar varnish, and skiped the paint.

    left to right. Scratch, Estes Mini A, Apogee Texas twister. All use mini engines.

    [​IMG]

    Deployed

    [​IMG]

    Thanks for reading!
     
  20. Dec 12, 2018 at 2:30 AM #20

    GlenP

    GlenP

    GlenP

    Well-Known Member

    Joined:
    Oct 4, 2014
    Messages:
    1,127
    Likes Received:
    31
  21. Dec 12, 2018 at 9:26 PM #21

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    I do like! My minds been on scratch designs, especially because Santa’s bring me a lathe and drill press this year.

    This ideas not fully thought out but I’ll post anyways

    [​IMG]

    the OD is 15.55 mm, not pictured is the internal plunger assembly that pushes the center rod up along with the attached rotor assembly and nosecone. Freeing the 1/32 blades from the not pictured music wire hooks attached to the bt.
    All of these small parts would have to be hand made and I’m probably not up to the task lol.
     
  22. Dec 13, 2018 at 1:09 AM #22

    BABAR

    BABAR

    BABAR

    Builds Rockets for NASA TRF Supporter TRF Lifetime Supporter

    Joined:
    Aug 27, 2011
    Messages:
    3,145
    Likes Received:
    87
    Those look great. Looking forward to flight report
     
  23. Dec 13, 2018 at 3:58 PM #23

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    I’m curious how well the blade shape performs.

    The scratch build has an aggressive airfoil, and the blades are angled downwards at 8*, with a little more dihedral than it needs. Makes it spins very fast. It won’t go very high but it takes its time coming down, tends to wobble and stall though. I blame the swinging motor mount.

    The Texas twister comes down like one of those plastic whirly bird things, you know the two blades on a stick that you spin between your hands?

    Both recover reliably, I wish I could say the same for some of the hastily packed chutes I’ve launched.
     
  24. Dec 13, 2018 at 6:06 PM #24

    Rktman

    Rktman

    Rktman

    Eric Noguchi

    Joined:
    Mar 5, 2017
    Messages:
    550
    Likes Received:
    6
    That's an impressively well thought-out design. Will the rotors be free spinning or will the whole rocket spin? Those hinges look very intricate, will you be 3D printing it or carving it from something like plastic sheet?
     
  25. Dec 13, 2018 at 7:57 PM #25

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    As of right now, the whole rocket spins. I haven’t given much thought to that end.
    Plywood. 1/64, or 1/32. The CR that the hinges mount in should probably be two glued together to add strength. Doesn’t look like fun to cut by hand

    The hinge pin would be brass or aluminum tube, 1/16? I forget the sizes.

    This is a quick drawing of where the CRs would be slotted. Top and bottom respectively
    I should play with the angles for the hinge CR to leave a little more meat at the center.

    The center holes on the bottom one are for the rubber bands to thread through.

    [​IMG]

    3D printing would be cool, I get stuck thinking in materials I’ve used. I don’t have access to any solid works to draw something up
     
    Last edited: Dec 13, 2018 at 8:04 PM
  26. Dec 13, 2018 at 9:42 PM #26

    Rktman

    Rktman

    Rktman

    Eric Noguchi

    Joined:
    Mar 5, 2017
    Messages:
    550
    Likes Received:
    6
    If you know a place that does laser cutting, I could draw the hinges and the CR with those holes cut out in Illustrator and export the images as DXF files, which is what I think they use to control the laser for cutting.
     
  27. Dec 13, 2018 at 9:57 PM #27

    Amsterdam

    Amsterdam

    Amsterdam

    __________

    Joined:
    May 30, 2015
    Messages:
    205
    Likes Received:
    3
    That’s very kind of you! I don’t, lmao however If you feel like drawing them up when your bored in the future I would appreciate the generosity.

    I flew the A heli today. Winds were light and it was warm enough.
    Surpassed all expectations. This rocket is a hell of a performer. Loaded with an A10. Laser straight boost. The A10 is always a fun engine, it’s like being shot from a cannon.
    The rocket slowed down tremendously, almost looked like ejection happened right at apogee.
    With the blades out it began spinning with no pause or stall, and continued to spin with no swaying for almost a minute, and almost 300 yards down range.

    Anyone holding off on building there’s should get started ASAP.

    Sorry there’s no video, I’m terrible a filming anyways.
     
  28. Dec 13, 2018 at 10:25 PM #28

    Rktman

    Rktman

    Rktman

    Eric Noguchi

    Joined:
    Mar 5, 2017
    Messages:
    550
    Likes Received:
    6
    Booked up next week but free the week after if you'd like to send me your full scale drawings. I can trace them in Illustrator, making it so much easier to modify things like hole sizes and hinge pin cutouts. Good practice as I'd like to get some things laser cut myself and I'm anxious to know what's involved. Let me know.
     

Share This Page