L3 attempt: "Let's Try This Again"

Discussion in 'High Power Rocketry (HPR)' started by Cl(VII), Mar 28, 2019.

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  1. Apr 3, 2019 #31

    Cl(VII)

    Cl(VII)

    Cl(VII)

    Chris Bender, Lab Rat TRF Sponsor

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    OK, attaching the fins. The kit comes with a nice set of CNC cut fiberglass fin guides, and unlike some models from the Loco-Bovine I've gotten (Go Devil 38 for instance) these actually match, and the slots are correct. The only "issue" is that they are very slightly loose on the fins, so you can't just stand the whole rocket up and let friction hold everything just right. To sure these up I clamped them together and drilled 4 matched sets of holes. I used these holes to align and support the jigs using 1/4-threaded rod and a lot of wing nuts.

    The body tube was prepped by marking off the fin areas, sanding with 60 grit, and wiping down with hexanes, acetone and ethanol. All bonding on the fins was done with the recommended Scotch-Weld DP420 (I used black in case I decided not to do t2t). The fins were attached one at a time with the root edge spaced 3 inches from the aft end of the bt. A motor case was used to balance the whole setup.

    IMG_5196.jpg
     
    Zertyme likes this.
  2. Apr 4, 2019 #32

    Cl(VII)

    Cl(VII)

    Cl(VII)

    Chris Bender, Lab Rat TRF Sponsor

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    Obviously, I like 3D printing as my design "skills" go far beyond my ability to make things by traditional techniques. As such, 3D printing has been the answer to my electronics mounting problems. Both of the below designs are approaching, may be at, their final forms.

    Altimeter bay: This bay is only 2.5" long, and will hold a Raven3 with Simple Circuit to make the wiring setup easier, and a SLCF. Both will work off magnetic switches. I can;t use my pull-pin switches as the entire bay is full removable with no vent band, instead it slides into the tube and is held in place with four M4 setscrews...no (safe) way to use pull-pins in my estimation. The correct tool for the job by my estimation was the magnetic switch, and I have a lot of experience with them. Because I had the room I've decided to go with the time tested 9V battery for both altimeters. These will be safe for the altimeters even in a dead short situation.

    alt1.JPG alt2.JPG

    Tracking Bay: All tracking will be in the NC as it is fiberglass instead of CF. There is a lot of room in there, so I designed a sled that will let me use any combination of Missileworks T3, TeleGPS and Featherweight tracker. There is even a post to lash the Featherweight antenna too (when bridged with a cable from the tracker) to keep it away from the T3 antenna should I fly all 3. The cap hovering above is to go on the end of a dowel rod that fits in the top of the sled. This cap will line up with a post in the NC tip to provide lateral support to the rod the antenna will be zip tied to for support. The sled itself attaches to the bulkplate through a nut capture in the base, as all my sleds do.

    track1.JPG track2.JPG
     
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  3. Apr 5, 2019 #33

    jpoehlman

    jpoehlman

    jpoehlman

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    Chris,
    Looks like another amazing project you are off to a great start on. Your attention to detail and documentation of the process is always a good read for me. If you need another interested (be it less skilled) hand at some point, let me know.

    Also, At this point, it looks like I’m headed to the Rocket pasture this year finally. So if you need any ground support, count me in on your team. I’ll probably head up Thursday and return Sunday, but open to input for sure.

    Looking great as always!
     
  4. Apr 5, 2019 #34

    Cl(VII)

    Cl(VII)

    Cl(VII)

    Chris Bender, Lab Rat TRF Sponsor

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    Fillets. With the fins all tacked on it was fillet time. The fillet area was marked off (11 mm from joint on fin and bt), sanded rough with 60 grit, and wiped down with hexanes, acteone and ethanol. Again, Scotch-Weld DP420 black was used. I can't say enough how glad I am I got the 3M epoxy gun and disposable mixing tips...awesome kit. The area was taped off, and the fillets shaped with a piece of 1" schedule 40 PVC dipped in ethanol and lightly shaken off so a little residual ethanol remains (the dip helps get a smooth surface on the fillet). After about 15 min the tape was removed. These will need some sanding, particularly along the edges as they have a squarish edge in some places, before the t2t goes on...yes, I'm going to do it, can't help myself.

    IMG_5199.jpg IMG_5201.jpg IMG_5202.jpg IMG_5203.jpg
     
  5. Apr 5, 2019 #35

    Cl(VII)

    Cl(VII)

    Cl(VII)

    Chris Bender, Lab Rat TRF Sponsor

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    Thanks, and glad you are making the trip, it will be well worth it. I will keep your (and Jeff's) offers of help in mind. I will at least need a second when I setup the tower, and Dad isn't HP certified, so he can't help unless we do it when the range is closed at the end of the day.
     
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