Estes Saturn V #1969 Build - Let's share ideas and experiences...

Discussion in 'Mid Power Rocketry (MPR)' started by EeebeeE, Feb 8, 2019.

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  1. Feb 8, 2019 #1

    EeebeeE

    EeebeeE

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    THis is intended NOT to be a build thread. Many of us have ordered and are now receiving our Saturn V's for the 7/20 launch. Some of us have started, including me. Why don't we share experiences and ideas so that we can make our builds go smoother and avoid potential disasters.

    Here are some of the things I have noticed so far.

    The main airframe is THIN... Real thin and before you start marking the tube or filling the spirals I strongly suggest building your motor tube first. Once it is done, install it and make sure all the glue is dry. That way the airframe is supported and is less likely to be damaged.

    The motor clip tube fits very snugly onto the clip. I used yellow glue and it grabbed its position before I could slide it down all the way. I suggest using 2-part 5-minute epoxy instead because for the first couple minutes before it starts to set, you can move the tube fairly easily. Instead of having 3-4 seconds, you have about 90.

    The instructions do not call for gluing in the forward CR. Poppycock!. It needs to be glued but you have to do it after the motor tube assembly is installed. See next paragraph.

    The CR's fit loosely. I used 5-minute epoxy after the issue I had with the motor clip retainer. After the glue sets when you glue the assembly in place, you should go around the CRs with 5-min. epoxy where they meet the airframe both on the forward CR and the aft CR.

    Once the motor assembly is in place and additional glue has been added to the CR's, it is a lot easier to mark the airframe.

    Finally, I used masking tape to hold the area around the tab that glues the ends of the 3rd stage cone together. I flattened out the connection so the tab got a firm flat position. Here's a photo. Once the glue dries, I should have a pretty good bond.
    Saturn V 02.jpg

    Looking forward to reading other experiences.
     
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  2. Feb 8, 2019 #2

    James Harechmak

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    The body wraps are fairly robust, I used the Tim Van Milligan approach for attaching them and had no issues with cracking. The fin halves seem to be ABS like the LJII so plastic weld glue like Plastruct is probably gonna be the best bet for them.
     
  3. Feb 8, 2019 #3

    captbk

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    Subscribed.
     
  4. Feb 8, 2019 #4

    EeebeeE

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    It is hard to sand card stock, but the best thing to do with the 3rd stage cone is to test fit and sand often. This will most likely be one of the tougher challenges. You want to get it right. Also I noticed that the ring intended for the 3rd Stage+ shoulder has a VERY tight fit into the airframe. That might need some sanding as well.
     
  5. Feb 8, 2019 #5

    EeebeeE

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    I intend to use Loctite Epoxy for plastics. I have found this to be a much better alternative than plastic cement in rockets in that it bonds plastic together rather than melts it. I abused a Maxi Alpha III, flying it on high impulse F motors after having glued the plastic fincan together with this stuff. When I finally shredded it, it was because of fin flutter...not the glue joints giving way.
     
  6. Feb 9, 2019 #6

    EeebeeE

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    I have created a RockSim and an Open Rocket file based on the components in this latest kit.
     

    Attached Files:

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  7. Feb 9, 2019 #7

    James Harechmak

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    One gotcha I found....... If your wife is chatting you up about some crazy cat evolution game make sure your wraps are on the proper side of the location marks before you glue them down. Estes doesn't have Saturn V spares at this point. I'm just gonna go with it and fly this one to pieces since I've got 2 more fresh kits. IMG_20190209_094439764.jpeg
     
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  8. Feb 9, 2019 #8

    afadeev

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    I haven't heard of anyone complaining of cracking the wraps. I don't believe it's a "thing".
    One could melt the wraps by over-applying certain glues (some formulations of CA, epoxy, etc), so using the right glue for the job is extremely helpful. I've tried both Plastruct and Beacon Fabri-Tac.
    I like the latter a bit more because it's less messy, and though it instantly "grabs" and holds the wrap to the body tube, yet the wrap can still be peeled off to fix a major alignment mistake, or remove an air pocket, or be "pushed" to fine-tune the alignment.

    TVM advocates using double-sided 3M tape #463, but that guarantees that the wrap will be too short (needs to go over the longer circumference buffered with tape), so now you would have to mitigate that gap. Also, this would leave you with raised ridges between the wrap and the body tube. So those will also need to be filled and sanded. This seams like an unnecessary PITA approach.


    Agree completely - Plastruct, or thick CA for plastic fins.
    I've used one of each on one set of fins, and could not pull apart the halves with either.

    Two areas I am not happy with are:
    1). 3rd stage transition cone - mine came out as a less than perfect cone. More visible after painting. I'm not sure what I will do differently on the second kit, except, impregnate the surface with thin CA and sand it.
    2). I over-fillet-ed the fairing to body and fairing to protruding fin areas with thick CA, and it looks less than perfectly uniform. I may need to go back and sand those areas. However, then end result are much stronger and nearly solid fairing surfaces.

    SatV pieces.jpg

    YMMV,
    a
     
    Last edited: Feb 9, 2019
  9. Feb 9, 2019 #9

    mikec

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    afadeev, are you sure you have the #1969 version? Your pictures look like 2157s to me, I think the #1969 has different wraps and a molded transition for the S-IVB.
     
  10. Feb 9, 2019 #10

    Crawf56

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  11. Feb 9, 2019 #11

    EeebeeE

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    I have found, by accident that the JBWeld Plastic epoxy is awesome. I glued together my nosecone and rocket tower with it... then about 20 minutes, accidentally knocked it off my workbench. It fell 3 feet onto a cement floor. No damage. This does not melt plastic at all, and the bond is very strong. Also had no trouble with the wraps except the 3rd stage vertical. The smaller tube created more flex so it didn't want to completely stick at the seam. I used the plastic epoxy and the seam then used masking tape to hold it down while it cured.
     
  12. Feb 10, 2019 #12

    OC-Patrick

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    So I'm just about to slide the motor mount into the main body tube. Instructions say to slide it 3-3/8" up. Why so high up? Krushnik effect?
     
  13. Feb 10, 2019 #13

    JJSR

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    And why is mmt so long?? 16 inches,,
     
  14. Feb 10, 2019 #14

    James Harechmak

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    As far as I can tell the MMT is do far in to push the CG forward to reduce the nose weight and it's long so the ejection charge can push out all 3 chutes consistently.
     
  15. Feb 10, 2019 #15

    SecondRow

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    +1 to both of these answers (+2?). The stuffer tube is long to reduce the volume inside where the parachutes lie. And the Krushnic effect shouldn't come into play with the location of the MMT. As long as the motor is not recessed more than 1 BT diameter, Krushnic won't occur. With the CR at 3 3/8" and the motor aft of the CR, it will be less than the 4" threshold.

    This is probably also a good time to note that the instructions call for the rocket to be 8" above the blast deflector when launching. Otherwise, you might get Bernoulli lock and have a bad day.
     
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  16. Feb 10, 2019 #16

    JJSR

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    Very interesting secondrow, I had never heard of this before.
    Thinking back at some of the mishaps at the pads of out club this could apply.
    Thanks for enlightening us.
     
  17. Feb 10, 2019 #17

    hcmbanjo

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    Or, slide the motor clip onto the engine mount tube DRY (no glue) up to the pencil marks. Then glue fillet both sides of the rings.
    I do this on all engine mount centering rings and never have to worry about the glue starting to set up before the rings are slid on.
     
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  18. Feb 14, 2019 #18

    captbk

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    Anyone have any tips or pictures of attaching fins and fairings? The way the instructions look the fairings hang over the bottom of the tube and the fin is flush with it?
     
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  19. Feb 14, 2019 #19

    JJSR

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    Well, that's kind of tricky,,, you're saposta cut the bt around them..
    However on mine it didn't seem to work out, if I pushed them up on the lower wrap they would over cover the flutes, and stick above the wrap. So I figure I'll add a piece of bt to the bottom.

    20190214_124755.jpg
     
  20. Feb 14, 2019 #20

    James Harechmak

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    Swiped this pic from accur8. The fairings on the actual SV hang above the rib structures. A little epoxy clay on the inside lip of the fairing will help with gluing surface. MSC103-05_sm.JPG
     
  21. Feb 14, 2019 #21

    Bat-mite

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    Just bought mine. I believe MDRA is joining in on the 7/20 fun with a drag race. AC Supply has them for about $65 after shipping, BTW. Other places want $90.

    I'm sure I will be checking this thread often.
     
  22. Feb 14, 2019 #22

    SecondRow

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    image.jpg image.jpg image.jpg
    The fairings should be flush with the tube, not the fins. And yes, the top of the fairing will extend past the top of the wrap. They are supposed to. Later, you will cut out sections of the body tube between the fairings.
     
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  23. Feb 14, 2019 #23

    BBowmaster

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    Not quite on topic but...

    Do you guys think the #1969 is significantly better than the #2157?
     
  24. Feb 14, 2019 #24

    SecondRow

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    The build is mostly the same, but slightly easier. The main build differences are that you have to roll one less paper transition (because of the plastic LM shroud) and the tower is constructed differently (I haven’t tried it, though). It will probably fly the same.

    The #1969 wraps are more accurate than the #2157. I think it looks better. Significantly better? Idk, yet.
     
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  25. Feb 16, 2019 #25

    jmuck78

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    Did you attach the fins to the body tube as well as the fin fairings? There was a bit of a trade off there - if i push the fins all the way through the fin fairing so that they attach to the body tube, the joint is stronger, but there is less fin area for stability.
     
  26. Feb 16, 2019 #26

    James Harechmak

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    The fins need attached to the body tube. If you get the CG right there will be plenty of fin for the recommended motors.
     
  27. Feb 16, 2019 #27

    JJSR

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    jmuck I was talking about the fairings, the fins only go so far, till they are against the bt
     
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  28. Feb 16, 2019 #28

    James Harechmak

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    I'll run a small bead if epoxy clay on the inside edge of the fairing for a larger surface to glue down. IMG_20190216_130825039.jpeg
     
  29. Feb 16, 2019 #29

    afadeev

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    Absolutely YES.
    If you think about landing scenarios, the heavy bottom of the main airframe is likely to touchdown first. Thus you really want to give the fins a chance to stay attached to the body, to minimize future repair work.
    1). Glue the fins to the body (make sure you 4x measure the spot first, so that the fairing then fit exactly where it needs to go.
    2). Fillet the fins (epoxy, or thick CA).
    3). Glue the shroud over the fins: shroud to body, and shroud to the fins.
    4). Fillet shroud attachment points.

    When you are done, the previously fragile shroud will be almost rock solid, and serve as a mid-point reinforcement for the fins.

    The fin is supposed to go all the way down to the body.
    Fairings also act as an aerodynamic element/conical fin.

    Please take it easy on (TVM's) epoxy clay - it's super heavy, and doesn't bind plastic as well as CA, Plastruct, or regular epoxy.

    a

    P.S.: I made the mistake of buying TVM's epoxy clay a while ago. Nightmare product. Anyone who wants it can have it for free (you pay shipping). Else, I'm throwing it away during spring cleaning.
     
  30. Feb 16, 2019 #30

    James Harechmak

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    I like PC-11 or JB water weld, they seem to be lighter than other epoxy clays and take CA as well as Milliput at a fraction of the cost.
     

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