Estes Pershing 1A Clone

Discussion in 'Scale' started by Leo, Feb 3, 2019.

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  1. Feb 25, 2019 #31

    Ez2cDave

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    MARTIN-MARIETTA DRAWING -1.JPG


    ASSEMBLIES.JPG
     
    Last edited: Feb 25, 2019
  2. Feb 25, 2019 #32

    cwbullet

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    Great diagram.
     
  3. Feb 25, 2019 #33

    neil_w

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    Where's the CP on that thing?
     
  4. Feb 25, 2019 #34

    Leo

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    Find the missing dimension in the diagram...
     
  5. Feb 25, 2019 #35

    Ez2cDave

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    Hmm . . . Diameter of the airframe ?

    Every source I have seen either lists it as 40 inches or 1.02 meters.

    https://www.alternatewars.com/BBOW/Space_Engines/Thiokol_ATK_Engines.htm

    Thiokol TX-174 (Pershing Stage I Motor)
    Motor Casing: D6AC Steel
    Overall Length: 102.61 inches
    Outside Diameter: 40 inches
    Propellant: 4,451 lbs of solid propellant, web burn time of 38.3 seconds
    Average Thrust: 26,290 lbf
    Total Impulse: 1,017,200 lb-seconds.

    References:
    Jane’s All the World’s Aircraft 1981-82

    Thiokol TX-175 (Pershing Stage II Motor)
    Motor Casing: D6AC Steel
    Overall Length: 96.72 inches
    Outside Diameter: 40 inches
    Propellant: 2785 lbs of solid propellant, web burn time of 39 seconds
    Average Thrust (vac): 19,220 lbf
    Total Impulse: 757,200 lb-seconds.

    Notes: The forward dome of the motor casing has three ports for impulse control.

    References:
    Jane’s All the World’s Aircraft 1981-82

    Dave F.
     
    Last edited: Feb 25, 2019
  6. Feb 26, 2019 #36

    Leo

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    Nope, try again :)
     
  7. Feb 26, 2019 #37

    Ez2cDave

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    You missed that the airframe diameter was not shown . . . So, what else is missing ?
     
  8. Feb 26, 2019 #38

    Leo

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    The air frame diameter is actually shown 3 times in the diagram.
     
  9. Feb 26, 2019 #39

    Ez2cDave

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    Okay . . . So, what's missing ?
     
  10. Feb 27, 2019 #40

    Mugs914

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    Second stage vane shaft centerline relative to vane pad...
     
  11. Feb 27, 2019 #41

    Leo

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    That's the one......
     
  12. Feb 27, 2019 #42

    Ez2cDave

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    I believe it can be calculated from the main diagram and this side portion.

    VANE SHAFT.JPG
     
  13. Feb 27, 2019 #43

    Leo

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    It would still be an estiment but at least you'd have a good reference....
     
  14. Mar 19, 2019 #44

    tenspeed

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    How's this project going?
     
  15. Mar 20, 2019 #45

    Leo

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    I had to make a break. I'm completely remodeling my rocket room :)

    I'm also complimenting in turning this model into a 2 stage version. Not sure though....
     
  16. Mar 20, 2019 #46

    PhlAsh

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    "All dimensions are in inches"
    that thing's only 13" tall?
     
  17. Mar 20, 2019 #47

    PhlAsh

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    Four. It's given as "1.25" on the base extension line (straight up from the word "dimension" in "All dimensions are..."
     
  18. Mar 20, 2019 #48

    Leo

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    Well, not really but close -> 0.62 + 0.62 = 1.24 :)
     
  19. Mar 21, 2019 #49

    PhlAsh

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    ...so their dimensioning *and* their rounding sucks. 1.25/2 = 0.625
     
  20. Mar 22, 2019 #50

    Mugs914

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    But close enough for the Martin-Marietta model shop to produce desk ornaments for the various execs/generals/politicians...
     
  21. Mar 22, 2019 #51

    Leo

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    Exactly. Who knows what other dimensions are off. When I look at pictures of the actual missile I questions some of the dimensions so I need to take the data with a grain of salt. But hey, it's better than having no reference at all.
     
  22. Apr 1, 2019 #52

    visualtrek

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    Thank you sooooo much for the 3D work & printable files. This is why I purchased a 3d printer in the first place: to rebuild this rocket!!! I had this rocket when I was a teenager, and got rid of my rockets after college........what a huge mistake. I bought the big Creality CR-10 S5 printer so I could print big files.
     
  23. May 8, 2019 #53

    timorley

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    Leo,

    Thank you very much for creating these! I'm relatively new to 3D printing, and this type of project is one of the main reasons I got into it. I was more than thrilled when I stumbled into this thread. I printed your nose cone files out and they fit my BT-101 perfectly and they look terrific. I did print mine with PETG (Gray color), which is the filament I've been mostly working with. It has its challenges, but it can be super strong and as you mentioned handles hot weather/sun better. I couldn't get spiral/vase mode to be the 0.8mm, was always too thin. So I printed mine double wall in Standard mode, combined with slower printing speed for PETG, my print time was about 30 hours! So yeah, I won't be printing these for anyone either. The results turned out great! My caliper measures my wall thickness as 0.80mm, and the combined weight of the nose cone dry fitted it 113 grams in total. I'll start my own build thread, but wanted to report back to you that your files are terrific. On to printing your fins now. Thinking like you, print the upper fins scale and the lower oversized, will see how it looks. Here are some pictures of my nose cone, nothing is glued yet. And one more thank you! Pershing1ANoseParts.jpg Pershing1ANose.jpg
     
  24. May 8, 2019 #54

    Leo

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    That's fantastic Tim! The parts turned out great.
    I love to see people print/build the designs I put on Thingiverse.
    My nose cone is single walled but because PLA is heavier it comes in at 115.65g.
    Looking very much forward to your build thread.

    Leo
     
  25. May 8, 2019 #55

    timorley

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    Leo likes this.
  26. May 8, 2019 #56

    Leo

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    I'm undecided if I should just make centering rings out of card board like the original Estes version or design some to 3D print... :confused:
     
  27. May 9, 2019 #57

    Trident

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    Leo, I just saw a link to this post, from someone on “the other forum”. Your parts look great. I’ll be anxious to hear reports on flight testing, someday. :)
     
  28. May 9, 2019 #58

    timorley

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    I'm going to stick with cardboard. No particular reason other than I know it works. :)
     
  29. May 13, 2019 #59

    timorley

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    Leo, What is your intention for where the shock cord plate goes? I noticed it fits nicely between the transition of the base and the mid section of the nose cone, and would add some rigidity at that joint. In case that is not what you had in mind, I actually printed an extra one out and cut a very small amount off the outside ends of the cross members of the piece, which when flipped downward helps center it in the top of the base to be glued. Hope that makes sense.
     
  30. May 13, 2019 #60

    Leo

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    Tim,

    Here is what I intended for the shock cord plate.

    Shock_Cord_Plate.png
    The idea is to epoxy it to the base of the nose cone. This should strengthen the thin walled base. It is my intention to drill a hole and epoxy a piece of Kevlar as loop to hook up the shock cord and parachute.
    Let me know if you prefer a different approach! I can easily redesign the plate or any other idea you might have.
     

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