My quest for an O motor launch.

Discussion in 'High Power Rocketry (HPR)' started by Bat-mite, Apr 17, 2019.

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  1. Apr 17, 2019 #1

    Bat-mite

    Bat-mite

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    I decided to start a new thread, coming on the heels of Help Me Decide What to Do.

    I am on a quest to launch my first O motor. I don't have a rocket (yet) that can handle that, but one is on its way.

    The rocket will be a Performance Hobbies Performer 200. You may already be familiar with Handeman's and Nathan's Performer 150s. This is the 8" version of that kit. Length will exceed 14' when built.

    I have attached the OR file. The kit was rapidly cut and assembled by Curtis and shipped yesterday. Scheduled to arrive tomorrow.

    I will do my best to document the build in this thread.

    The motor will be a 98mm X 72" bolted case, manufactured by DeeRoc29 and Scott S. Scott will formulate the propellant, and he and I will mix the motor together.

    In order to accommodate the extreme length of the motor, I had Ken/Curtis cut 28" off of the booster and slot it so that it can serve as a detachable fin can. Thus, the booster and fin can combo will be 88" long. Subtracting the intrusion of the AV bay will leave about 3" for the drogue package. I'll be working on how to manage that.

    Target date for launch will be Red Glare 21 in April, 2020; however, if the opportunity comes sooner, I'd prefer to do it in a less crowded environment.

    So maybe this thread will drag on for a year! In any case, feel free to comment, question, criticize, etc.

    See you soon!
     
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  2. Apr 17, 2019 #2

    Nytrunner

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    With a 4" motor in an 8" body, you've got lots of room for harness in the cylinder around the top of the motor. Will you be fastening the shock cord to the forward closure? (assuming it's tapped?)
     
  3. Apr 17, 2019 #3

    THarrison

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    You should put a 6" mount in it and adapt down for the 98mm flight. This configuration would let you fly a lot of different O motors.
     
  4. Apr 17, 2019 #4

    Bat-mite

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    That's the plan as of now.

    No room for an eyebolt. Will likely employ a long Y harness from the top CR. With the detachable fin can, it will be easily installable/removable.
     
  5. Apr 17, 2019 #5

    Bat-mite

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    See the other referenced thread. Thanks.
     
  6. Apr 17, 2019 #6

    Bat-mite

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    And, of course, I forgot the attachment.
     

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  7. Apr 17, 2019 #7

    jsdemar

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    The motor casing can be longer than the booster's fin can. I have done that several times. Put the coupler in the top of the fin can. Standard Curtis Turner length of 60" airframe plus 12" of his standard 24" coupler sticking out. That is 72" for the casing. The thrust ring with bolted closures will stick out about 2". Therefore the top of the motor casing will be recessed about 2". This is enough for the eyebolt and the motor retainer. You can use two kevlar loops/straps slayed out and epoxied inside the coupler for addition shockcord retention backup. They'll also keep it from spinning and unscrewing the eyebolt.

    I've flown my 8" rocket made from Curtis' parts on 98mm N's and O's. It has a 6" motor mount. Here is a picture of it launching at Spaceport America carrying a stack of student payloads in 2015.

    image001.jpg IMG_20150425_101407359.jpg
     
  8. Apr 17, 2019 #8

    Bat-mite

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    Thanks, John. I will learn a lot as I go. And I absolutely, positively will not start bonding parts together until I am perfectly sure I know what I'm doing!

    (Oh, no. I think that means the rocket will never get built.)
     
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  9. Apr 17, 2019 #9

    Bat-mite

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    A little miscommunication. DeeRoc29 is making something for another Scott, which is not for my rocket. Couldn't edit the OP.
     
  10. Apr 17, 2019 #10

    Theory

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    love watching these "big build" threads. while I may never execute one myself, they are inspirational to be sure

    wishing you the very best my friend!!!
     
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  11. Apr 17, 2019 #11

    G_T

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    I recessed the lower bulkhead up inside the coupler for my O project to allow for a few inches longer motor. I double walled the coupler for the electronics bay portion and step jointed the thick lower bulkhead. I used bolts for assembly and deployed everything out the top. It was quite solid. You can see the details in the rocksim file I provided if interested https://www.rocketryforum.com/threads/sprite-6-and-a-baby-o.37382/

    Word of warning which is probably obvious anyway - watch the CG when putting in a large motor, particularly if you ever use a 6" motor. They are heavy motors and can seriously mess with your stability margin. You don't want a landshark! When moving up to N and larger motors one needs to be more diligent as the motor tends to be a larger percentage of the total pad weight. Longer skinnier versions of O are less likely to cause issues as the mass is distributed around the CP rather than mostly behind.

    I also recommend considering rings not tubes for the larger motors. They are going to have a lot more heat soak than little 75mm motors. You can use a replacable assembly held on by bolts. Then you can plug in what you need, including accomodation for a cluster if you are so inclined. But of course you'll have to get slightly more clever with the fins.

    I made my nosecone contain an electronics bay, and made it quite solid. The 6" nosecone weighed 9# empty IIRC, so balance was never an issue with any motor the rocket could carry. The extra bay came in handy first flight as there was a person needing to send up a payload (experimental tracker) so we just needed to mount it to the nosecone's ebay board. It was independent of the rocket's ebay, and separated enough to not worry all that much about interference between the two sets of transmitters on that flight. It worked well.

    Good luck with your project!

    Gerald
     
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  12. Apr 17, 2019 #12

    ActingLikeAKid

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    Following. This project sounds amazing!
     
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  13. Apr 17, 2019 #13

    Tim51

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    +1. An inspiration to us all. Will be following from afar in watch 'n' learn mode.
     
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  14. Apr 18, 2019 #14

    Rail Dawg

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    O motors are cool!

    Good luck with the project!

    Chuck C.
     
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  15. Apr 18, 2019 #15

    Tobor

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    Ooooooooooooooo. Subscribed!
     
  16. Apr 18, 2019 #16

    jsdemar

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    And 98mm O motors are the bleeding edge of cool. :)
     
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  17. Apr 18, 2019 #17

    pondman

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    Yes they are!
     
  18. Apr 18, 2019 #18

    Nick@JET

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    That’s Awesome Bat! I flew an O3400 in my big QCC (ultimate Darkstar 6”x13’ with Madcow FW 5:1 NC - heavy NC!) and approx 5” between top of motor and the AV Bay. I built with Y harness and everything stuffed beside the motor with out issue. Luckily as I never dry fit with O motor and really never planned to fly on that motor prior to the build.

    I threw a bunch of big quicklinks in the NC for extra weight + tracker but didn’t need it. On pad Was close to 90lbs - Boost was arrow straight approx 950mph - 15,800”.
    You will thoroughly love a motor that big, I had someone else video it so I could just watch and enjoy.

    Will be watching - go gettem! View attachment 380310
     
  19. Apr 18, 2019 #19

    Bat-mite

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    I need to do that, too!

    Thanks, all, for the encouragement and kind words.
     
  20. Apr 20, 2019 #20

    Bat-mite

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    Wow. Curtis shipped me the kit in practically no time. I mean, I said to Ken, "I'm ready," and it was t my door 1.5 days later.

    Only one glitch: he slotted the booster instead of the cut-off piece of payload. So ... I redesigned it to have the extension forward of the booster to keep life simple. The updated OR file is attached.

    Here are the boxes:

    upload_2019-4-20_11-8-51.png

    And here are the parts stacked, before I got the pieces apart and couplers out:

    upload_2019-4-20_11-9-18.png
     
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  21. Apr 20, 2019 #21

    Bat-mite

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    Hmm, two minutes later and I can't edit. Here's the OR file.
     

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  22. Apr 20, 2019 #22

    Theory

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    YEA BUDDY!!! those are some serious components
     
  23. Apr 22, 2019 #23

    Bat-mite

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    Orders just placed with Binder, Aerocon, and Madcow for adhesives and odds and ends.
     
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  24. Apr 23, 2019 #24

    Nick@JET

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    Nice NC!
     
  25. Apr 23, 2019 #25

    cbrarick

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    you could come to urrf and watch me fly the same motor (98 mm O). this is the last of the series of 98's. everything longer is significantly diminishing returns...just glue them together well...

    One of my tricks is to use bolts to hold together short fin-cans. I did that with my gizmo xl dd - added another body tube for bigger motors so I could avoid the doughnut ebay. You've seen it fly at Red Glare - search "Agent P" it held together under the N10000
     
  26. Apr 23, 2019 #26

    Bat-mite

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    I was going to bolt on a short fin can, but now I am using the 60" booster as designed, and a bolt-on forward extension.

    Will look up your Agent P. Thanks.
     
  27. Apr 23, 2019 #27

    Bat-mite

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    As many of you know, I don't care much about the finish of my rockets. I do not have the patience or the time to attempt high gloss, fancy paint jobs. I generally use Rustoleum paint-and-primer-in-one rattle cans. So my choice of colors is limited.

    That being said, any thoughts on this color scheme? The grayish would be aluminum, the red would be Colonial Red, and then gloss black.

    upload_2019-4-23_10-25-54.png

    I sort of loosely based it on the MAC Performance Radial Flyer idea.

    upload_2019-4-23_10-27-40.jpeg
     
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  28. Apr 23, 2019 #28

    Nytrunner

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    Finish is your preference.

    Interesting fin shape there, have you expounded on the choice for that?
     
  29. Apr 23, 2019 #29

    Bat-mite

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    That's not the fin shape. You can see that in the OR file. I was just using MS Paint to look at colors.
     
  30. Apr 23, 2019 #30

    Nytrunner

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    Ah, gotcha. That makes sense

    Can't at work :rolleyes:
     

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