Mega Rebel from Arkansas [Rocketarium] - Phase 1

Discussion in 'Oddrocs' started by Crawf56, Dec 21, 2019.

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  1. Jan 15, 2020 #61

    Crawf56

    Crawf56

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    Here is the Estes D12-3 motor from the launch, with a D12-5 for comparison.

    Note that chunks of the nozzle are gone. Not sure if that happened on impact with the ground.

    m_IMG_0699small.jpg

    m_IMG_0701small.jpg
     
  2. Jan 15, 2020 #62

    Crawf56

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    Looking at the ejection charge end of the motor.

    m_IMG_0700small.jpg

    m_IMG_0703small.jpg
     
  3. Jan 15, 2020 #63

    Crawf56

    Crawf56

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    I still am not sure if this was a motor failure, or a construction failure. :confused: (I am leaning toward construction.)

    Will be ordering another engine mount from Apogee. The rebuild begins....;)
     
  4. Jan 19, 2020 #64

    Tobor

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    I have flown enough "D" motors since the 70's to know that your CATO event was due to the motor. I "think" what happened is the nozzle of the D12-3 had one or more fractures. When the motor ignited the thrust forced the fracture(s) to expand and then fragment. With a portion of the nozzle gone, all the characteristics of the motor burn changed, causing accelerated rate of burn and a much larger then normal exhaust plume.

    Alternatively, the fracture(s) could have been in the BP rather then the clay nozzle. But a fracture in the BP usually results in the motor case splitting open upon ignition.
     
  5. Feb 9, 2020 #65

    Crawf56

    Crawf56

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    Here is the motor mount from Apogee that I am using. Except I am using an E motor hook.

    m_IMG_0774small.jpg
     
  6. Feb 9, 2020 #66

    Crawf56

    Crawf56

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    A tale of two glues....

    For the plywood body, I used CA (per the instructions).

    For the motor mount, I initially used Titebond II. Then, I went to Elmer's Glue-All. I did this because I have had problems (sometimes) with Titebond 'softening' cardboard tubes. And small amounts of Titebond actually drying rapidly, making it difficult to fit items in a tube.

    The Glue-All is a little easier to work with, but it does not form a fillet like the Titebond. I also fear that the Glue-All does not hold as well as the Titebond.

    So, I am going back to Titebond for the motor re-installation. Though I am also considering 30 minute epoxy.


    m_IMG_0777small.jpg
     
  7. Feb 9, 2020 #67

    Crawf56

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    Motor mount assembled. Drilled a small hole in the front ring to hold the shock chord (again).

    m_IMG_0775small.jpg


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  8. Feb 9, 2020 #68

    58pan

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    Built the Rebel John last year, get lots of comments at launches.
    Mine flew great. I think i tacked it together with ca than tite bond fillets
     
    Last edited: Feb 9, 2020
  9. Feb 10, 2020 #69

    Crawf56

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    Thanks 58pan. Got the motor mount glued with Titebond. I appear to have a viable rocket again!

    m_IMG_E0777small.jpg
     

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