L3 Build

Discussion in 'High Power Rocketry (HPR)' started by mperegrinefalcon, Apr 16, 2019.

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  1. May 3, 2019 #31

    BF Rockets

    BF Rockets

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    They fit a little looser but they aren't coming out of the channel. Go test fit one and see. I think I saw where CJ Hendrickson recommended this once so it must be legit. I flew my L3 that way (M1500 in a 4 inch rocket). I think 1515s look too big on a 4 inch rocket.
     
  2. May 3, 2019 #32

    blackjack2564

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    Just be sure and check the fit when using 1010 buttons in 1515 rails.
    There are 3 sizes 1010 that I know of, standard-aero- small.
    Only the standard I have used fit, the others will fall out when wiggled!
    Also after several high thrust flights, there can be substantial wear on buttons. I either flip them over or replace as the 2 edges inside rail get worn flat. Especially with dirty rails!
     
  3. May 21, 2019 #33

    mperegrinefalcon

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    Time for a update:
    The fins have arrived, the rest of the rocket has not even shipped from Madcow. I am a bit disappointed because I ordered it about a month ago. Hopefully I can get it in time to build for High Skies in July. and launch it there. I picked up some 1515 airfoil rail buttons from Apogee Components, and they look massive. I just sent an email to the club asking what the longest 1010 rail they have is. I will be picking up the motor and casing at MHM in June and launching a minimum diameter 38mm rocket on a J530 as well as the VTS-6 I am working on painting at the moment.
     
  4. Jun 23, 2019 #34

    mperegrinefalcon

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    Okay peeps, update time.

    I wrote a sternly worded email to Michael from Madcow about the lateness of my rocket and he told me that there was an issue with the slotting file again. They seem to be having countless problems with slotting for these fins, so I told him to just make six slots at 10" long. I will use my dremel and a cutting wheel to extend the slots and I will use a piece of aluminium angle to make sure that the slots are straight. The slots for the main fins will be in two part so the tube doesn't collapse on itself. At the halfway mark I will leave a 2" section un-slotted to support it during construction. Once complete the structure of the motor mount will help a lot with rigidity. I have purchased the motor, casing, harnesses and parachute protectors. I got two 30 foot long, 3 loop 7/16" Kevlar harnesses from OneBadHawk for the recovery.

    Hopefully I actually get my kit this time. I am getting really annoyed with Madcow not telling me when there is an issue and instead just waiting for me to call and find out what the issue is.
     
    Last edited: Jun 23, 2019
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  5. Jun 23, 2019 #35

    crossfire

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    What kit is it?
     
  6. Jun 23, 2019 #36

    mperegrinefalcon

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    It's not a kit they sell or manufacture it's my design for my L3 rocket I am naming Viper. I ordered the components from Madcow. Look to the first post to see the design.
     
    Last edited: Jun 23, 2019
  7. Jun 23, 2019 #37

    crossfire

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    Your design looks very nice. Kind of reminds me of a Dynacom kit from the past. Don't understand what would be the hold up on it. Like you said you can always extend fin slots if that is the hold up. Good luck on the flight.
     
  8. Jun 23, 2019 #38

    mperegrinefalcon

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    Thanks man! A Crossfire was my 3rd rocket. Got it with the Estes launch pad when I was 7. Good times.
     
  9. Jun 24, 2019 #39

    jqavins

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    More than a lot. Restoring the integrity of the tube would be accomplished just by having the slots filled by plywood glued in place. Not that the MMT and fillets won't stiffen it even more.

    One can hardly blame you for being annoyed. If I find myself in your position, i.e. ordering a custom kit, I'll think twice about using Madcow.
     
  10. Jun 24, 2019 #40

    mperegrinefalcon

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    Just make sure your slotting isn't too long and minimun .5" from the base and you should be okay ordering components from the website. I have ordered custom things before and they have been great and arrived in a timely manner. Custom work does take longer to fulfill than shipping out a kit. When the design needs more than 4 slots or has abnormally long long slots it tends to cause problems for them. I understand the issues they are having, I am just annoyed about the lack of communication to me about issues.
     
  11. Jun 26, 2019 #41

    mperegrinefalcon

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    I just go the tracking info for this rocket and Michael Klet just called me to let me know it will ship today or tomorrow.
     
  12. Jun 28, 2019 #42

    mperegrinefalcon

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    The components have arrived, no time today to post pictures or work on it at all sadly.
     
  13. Jul 21, 2019 #43

    mperegrinefalcon

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    Time for the first build update.

    I slotted the tube for everything first. I used a dremel with a carbide cutting wheel to cut the slots out. I used a piece of angled aluminum for my straight edge to mark everything.
    slotting 2.jpg
    Slotting.jpg

    The tube seems to be holding up to these long slots very well. There was no need to worry about the length of the slots.

    Nosecone coupler is epoxied inside. The metal tip is off until I paint and finish the nosecone.
    Nosecone.jpg

    The first two centering rings are on the motor mount.
    Centering rings.jpg

    The fillets here have been sanded and are not absolutely perfectly smooth, but they will certainly be strong enough. The underside of the lower centering ring does not have a fillet to facilitate the fin tabs. The fillets on the underside of the upper centering sagged more than I would have liked, but it is not really an issue. I should have waited a little longer for the epoxy to firm up.

    I have a decision to make here. I can either use a 1/4" forged eyebolt that will fit through a hole I drilled in the upper centering ring, or I can wrap some kevlar around the motor tube and epoxy it in place. For the eyebolt I will have to find a nut that will either fit against the airframe as the ones I have do not, or just embed the eyebolts threads in epoxy to hold it in place. I have some 1/2" kevlar I can wrap around the body of the motor mount and epoxy to the eyebolt to reinforce it's mounting if it needs it. I know epoxying kevlar directly to the motor mount works, I just have heard that epoxy makes kevlar brittle. I have used epoxying shock cord to the motor mount on my 2.6" Madcow Screech, but that is only a 5 lb rocket, not 30-35 lb rocket. The eyebolt also gives me the option to change out the shock cord.
    Centering ring drilled.jpg Centering ring with eyebolt.jpg
     
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  14. Jul 22, 2019 #44

    Nytrunner

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    Does that Eyebolt fit in the tube? It's a bit bulky
     
  15. Jul 22, 2019 #45

    jqavins

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    Assuming it fits, does it fit with enough space to let you change out the shock cord?
     
  16. Jul 22, 2019 #46

    numbo

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    Drill a hole on the other side, smooth the edges, and run kevlar in one and out the other. Put eyes on the kevlar as a harness. If you ever need to replace it tape the new piece to the old and pull it through the two holes for a new harness.
     
  17. Jul 22, 2019 #47

    mperegrinefalcon

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    I got the eye bolt to fit with ground down nuts. It fit in the airframe, but it is too close to allow for kevlar to be attached to it. I realized this after I had epoxied the nuts on sadly, but having the eyebolt in the rocket changes nothing. I will cut the loop on it off, but that is it.
    20190721_213415.jpg
    20190721_221251.jpg

    I am going to change gears here and not mount the shock cord to the motor mount. It is too far down in the 57" tube for me to reach to change out anyway, and I don't like epoxying kevlar to the mount. Instead I will epoxy a bulkhead into a length of coupler, similar to a piston, and epoxy that inside the body tube as my attachment point. This way I can get really good fillets on the bulkhead, and have the surface area of the 4" long coupler epoxied into the airframe, this will eliminate having to worry about getting fillets inside the AF and make getting the bulkhead level much easier. I am leaving enough room in the airframe below the bulkhead for a Loki 76/8000 case so I can use bigger motors in this rocket. This will also serve to reduce the amount of volume I need to pressurize for ejection so I don't have to use as much black powder, and allow me to reach in and easily swap out my shock cord.

    This is just a sport rocket, so I am not concerned about the extra mass of this component and the permanently attached eye bolt. This was a learning
    experience, ie be patient and think things through more. :mad:
     
    Last edited: Jul 22, 2019
  18. Jul 22, 2019 #48

    blackjack2564

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    Possibly glue a coupler nut to side of tube.
    1. If it does not clear dremel [grind] off the high side & encapsulate it with epoxy.

    2.Drill a second hole opposite the first to make a "Y" harness for recovery attachment. The Y should be just long enough to barely stick out top of airframe for shock cord attachment.
    Having this Y harness will also make the fincan drop straight and centered rather than lop sided which happens when only one cord is on one side. This prevents the same side of fincan from smacking the ground every flight.
    Glue the Y harness such that no glue is on it above the hole. No worries about chaffing because there can be no side movement that low in fincan.

    Edit: looks like you solved your issues while I was typing.
     
  19. Jul 22, 2019 #49

    mperegrinefalcon

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    Yes it does fit in the tube.

    No, it doesn't. The knot would block the motor from going all the way in. There is basically no room for anything other than directly attaching to the motor mount.

    I could do a Y harness, and that was my first thought, but I want to be able to easily replace the shock cord, so I think the bulkhead epoxied to a coupler, then use that to make positioning in the air frame easier and give more surface area for the epoxy. The tube is 57.5" long and my fat arms won't fit down far enough to reach the motor mount.
     
  20. Jul 22, 2019 #50

    numbo

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    Or just put an eye in the top of the motor. Air-popped popcorn is a great filler for extra space; biodegradable and keeps chutes from moving around during acceleration when using shorter motors, etc.
     
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  21. Jul 22, 2019 #51

    Ez2cDave

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    Is your Airframe Tube 4" diameter, SCH 20 PVC and the Motor Mount is Fiberglass ?

    Dave F.

    [​IMG]

    [​IMG]
     
  22. Jul 22, 2019 #52

    mperegrinefalcon

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    Nope, just white Madcow Fiberglass.
     
  23. Jul 22, 2019 #53

    Ez2cDave

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    Glad to hear that . . . Looks like SCH 20 PVC !

    Dave F.
     
  24. Jul 22, 2019 #54

    mperegrinefalcon

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    Yeah would not want a PVC rocket, that would end bad.
     
  25. Jul 22, 2019 #55

    Wallace

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    Sorry for being late to the party but I feel the need to throw in my 2 cents as far as slotting FWFG tubes goes. The nature of the beast means they are under some serious tension/compression as manufactured so the less you cut, the better off you are as far as relieving said, not even taking into account the fact that you are, like it or not, cutting structural fibers. Just look at the tube shape you end up with after slotting. Obviously you can regain some of that strength when installing fins but good luck regaining shape. For long fin spans I'd suggest multiple smaller slots with corresponding notches in the fins. Just my opinion...
     
  26. Jul 22, 2019 #56

    mperegrinefalcon

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    Yeah, I agree. I wouldn't do any longer than this. After the fins are in and the internal fillets done I will foam the fincan. This should help with tube rigidity.
     
    Last edited: Jul 22, 2019
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  27. Jul 23, 2019 #57

    Wallace

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  28. Jul 23, 2019 #58

    mperegrinefalcon

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  29. Jul 23, 2019 #59

    mperegrinefalcon

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    Just thinking out loud, I have some 1" kevlar strap. I might just use that to create a Y harness. I will probably retire this rocket before it wears out, or I can just add that bulkhead in later. I epoxied kevlar for my 4" madcow frenzy and it is incredibly strong, though it is still an unfinished project and not launched yet.
     
  30. Jul 23, 2019 #60

    AHansom

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    High quality eye bolt in the top of the motor!!! Easy to inspect, install and change the shock cord. Interesting idea, Using shorter motors;)
     
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