Can we save this Estes Pershing 1A?

Discussion in 'Mid Power Rocketry (MPR)' started by James Duffy, Jan 29, 2019.

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  1. Jan 29, 2019 #1

    James Duffy

    James Duffy

    James Duffy

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    The Estes Pershing 1A has long been a 'holy grail" kit of mine, the one Estes Maxi Brute release that has always been just out of reach. While Estes has rereleased their big V-2 and Honest John kits a number of times, the Pershing has never reappeared since its original appearance back in the '70s. Occasionally one would pop up on eBay, but the prices would get stupid and I would wave off. The dream of an Estes Pershing seemed destined to remain just that, a dream...

    Until one just appeared on my doorstep one day. I'm not kidding.

    Apparently, while beerlofting with my rocket buddies after a day of flying on some godforsaken field, I happened to mention that I really wanted to build one of these beasties. One of our group quietly stored this tidbit for later action.

    So, this showed up over the holidays:

    IMG_3826.JPG

    Damn! Let's open the box...

    IMG_3827.JPG

    Yep, it's a partially-built kit, and a bit of a mess, but do I care? Not one damn bit!

    IMG_3829.JPG

    Critically, the most important part of the kit, the nose cone, is intact and in good condition.

    This is going to be fun. I have the best friends, no?

    James
     
  2. Jan 29, 2019 #2

    Buzzard

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    Excellent news, James!!! Will be following with interest.

    Chas
     
  3. Jan 29, 2019 #3

    James Duffy

    James Duffy

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    So, let's begin with a survey of the rest of the box contents and put together a plan.

    The main body tube has been assembled, but years of storage have inflicted a toll. No problem, we can order a new BT101 from Randy at eRockets, along with a stuffer tube and centering rings.

    IMG_3830.JPG

    The vacuform bits had been assembled with some degree of competence, but again, time has eliminated any chance of rehabilitating these bits. No problem, though. We'll just draw some new parts in Illustrator and laser cut some new fins and mounting pads.

    IMG_3831.JPG IMG_3832.JPG IMG_3833.JPG

    More later,
    James
     
  4. Jan 29, 2019 #4

    James Duffy

    James Duffy

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    So, here's the plan for this Pershing 1A project:

    * This will not be a scale obsessive, competition focused build. Adhering to the funky '70s vibe of the kit is paramount.

    * We will not be "beefing up" the build for some stupid application of too much motor. Having said that, it is clear that the D12 is really not appropriate for this particular task, so the project will proceed with the AeroTech E15-4 in mind.

    * The vacuform bits are shot. Laser-cut alternatives will be drawn and built up.

    * The decals est muerte. Rather than replace them with new laser- or inkjet-printed decals, we will endeavor to paint the markings where possible.

    * The tiny white stencils will be too small to paint and can't be printed anyway, so they will be replicated with dry transfers.

    More later,
    James
     
    Last edited: Jan 29, 2019
  5. Jan 29, 2019 #5

    James Duffy

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    Construction begins with the engine mount. This component is completed just like the instructions call for, just with new parts. The rubber shock cord was replaced with a Kevlar shock cord anchor. Titebond III was used for assembly here, and a drop of thin CA was dropped on the Kevlar knot to make sure that it does not unravel.

    engine-mount-smaller.jpg

    After allowing it to dry, this assembly was glued into the main airframe tube using five minute epoxy. I prefer epoxy for that particular task as it does not produce the telltale "pucker" effect on the outside of the airframe tube as is cures. (no photo, boring, self-explanatory step)

    More later,
    James
     
  6. Jan 29, 2019 #6

    James Duffy

    James Duffy

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    As noted earlier, the decals have turned to merde. Rather than replace the originals with printed decals, we're going to paint the markings where reasonable. The large orange bits will be the easiest to mask and paint, but some of the others may be trickier.

    IMG_3835.JPG

    We'll start with the red "31" and white "US ARMY" markings. A sheet of frisket material will be laser cut to produce a sheet of stencils. These stencils will be applied to the model where needed, and the markings airbrushed with the appropriate color. Frisket material is available in the paint section of your local Hobby Lobby, and a pack can be purchased with one of their 40%-off coupons. Importantly, the frisket film cuts beautifully in the laser cutter. I've used this technique before on an earlier project. The critical thing is to use this with acrylic paint only, as enamels and lacquers will melt the material. A PDF of the stencils is attached below.

    Next, we'll turn to the tiny white stencils and the large "US ARMY" marking. As these are white, they can't be produced using traditional laser- or inkjet-printing techniques. Also, the frisket process will not yield the fine detail contained in these tiny markings, so we're going to commission a sheet of dry transfers. This is a photographic process that creates markings that can be positioned and pressed onto the surface of a model. (Again,I've used this process before.) Regardless of the color of the finished transfer, the artwork needs to be produced in black to create the film negative. A copy of the artwork is attached below.

    If you're interested in creating dry transfer markings, visit the AllOut Graphics website. Warning: the process is not cheap, but the results are fantastic.

    Observant readers will note that the large "US ARMY" marking appears on both the stencil sheet and the dry transfer master. That's because I have not yet decided which process to use for this marking, and want a couple of options from which to choose.

    More later,
    James
     

    Attached Files:

  7. Jan 30, 2019 #7

    Nytrunner

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    Nice restoration project! Too bad you can't bring it down to Student Launch with you in a few months
    (That is a large nosecone!)

    Is it really too heavy for the D12?
     
  8. Jan 30, 2019 #8

    James Duffy

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    Well, there's no reason I couldn't bring it to SLI, although there really won't be an opportunity to fly the rocket.

    Yes, the nose cone is a whopper! I'm cleaning it up for painting now, and there is a lot of real estate on this thing.

    Clearly. I saw a couple fly years ago when I was a kid, and both of them really labored into the air. Only one of them survived the flight, IIRC.

    James
     
  9. Jan 30, 2019 #9

    Nytrunner

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    Wow, how heavy is it? I thought it was on the lines of the 3" School rocket by BMS (unless it requires much ballast for the stubby fins)

    Just need a field and a launch pad :)
     
  10. Jan 30, 2019 #10

    James Duffy

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    The nose cone with installed weight is 5.3 ounces all by itself. The 1977 Estes catalog lists the flying weight for a finished model at 11.5 ounces, which means that it will be 13+ish ounces in the real world. With a motor installed it will be close to a pound, I'm willing to bet.

    James
     
  11. Jan 30, 2019 #11

    Nytrunner

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    Dang, my beefed up School('d) Rocket is ~9-10 without motor (or T3 and chute release, but that's only for Pro24 6grain flights :D )

    A pound on the pad's still ~6.5 thr/wgt, but I understand your caution with such a select kit
     
  12. Jan 30, 2019 #12

    burkefj

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    I'm glad you found one I finally gave up and just built a 5" one from scratch using depron 1mm and 5mm as the structure that weighs 20 oz ready to fly with an f 32. Came out naturally nose heavy, did not need to add nose weight. Looking forward to how you finish yours.
     
  13. Jan 30, 2019 #13

    James Duffy

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    The pictures of your Pershing are one of the reasons that I'm so motivated to build one, Frank!

    James
     
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  14. Jan 30, 2019 #14

    rharshberger

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    What format does Illustrator save its files as? Would you be willing to share said files and a Rocksim file for this rocket? With proper dimensions I can turn a basswood nosecone to clone the rocket for myself.
     
  15. Jan 30, 2019 #15

    James Duffy

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    Adobe Illustrator produces files with an .ai or .eps extension, and I am happy to share them. Unfortunately, neither of these are allowable file types for attachments to this forum which is why I post the PDF files. The PDF files can be used by some vector graphics programs (such as Illustrator) to create output that can be used by laser cutters.

    I'd be happy to pull the dimensions off of the nose cone and post a simple drawing here, if that would help. May take a couple of days, though.

    James
     
  16. Jan 30, 2019 #16

    James Duffy

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    I was able to do the nose cone drawing pretty quickly, and it is attached below.

    James
     

    Attached Files:

  17. Jan 30, 2019 #17

    linville86

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    Great project. Have you thought about trying to save the decals? I know putting them in a baggie and hanging them in a sunny window for a few days will de-yellow them. I tried it with an old wizard decal, took about 4 days. Worked wonders on them.
     
  18. Jan 30, 2019 #18

    James Duffy

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    I might try that as an academic exercise, but I really prefer the look of the painted and dry transfer markings.

    James
     
  19. Jan 30, 2019 #19

    James Duffy

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    This next step actually happened several weeks ago, but I'll recap it here. With the vacuform bits unsalvageable, we'll need to create some balsa and ply replacements. The first step is to measure the archeological remains of the vacuform fossils.

    IMG_3837.JPG

    Next, we'll use those measurements as we dive into Illustrator to draw the replacements. (PDF files attached below.)

    The final parts will have fin mount pads made from 1/16" thick balsa. The lower fins will have a 1/16" thick plywood core with faceted balsa cladding, and the upper fins will feature a built-up balsa structure to capture the unique wedge shape. Both the upper and lower fins will feature tabs to facilitate mounting through both the pad structure and the airframe tube.

    With the parts drawn up, the drawings have been emailed to Mike and Nick Nowak, who are starting a custom laser cutting service, Galactic Manufacturing. You can contact them via their page on Facebook if you'd like to order your own Pershing fin parts.

    More later,
    James
     

    Attached Files:

  20. Jan 31, 2019 #20

    jd2cylman

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    Just an FYI, Boyce Aerospace offers 3D printed fins scaled to this rocket. I built the Maxi Brute V2 as a kid in the late '70's. Flew the crap out of it with D12-3's. Got about 75 feet each time. Finally crashed it. I always wanted the Pershing, but somehow never got one. Boyce has the Pershing fins, but no cone. I'm not a fabricator. I might show the PDF of the cone to my buddy who is a master wood worker and see what he thinks. The shoulder on the cone seems awfully short, although I see you don't actually have a length for that listed. What is it, 1 inch?
     
  21. Jan 31, 2019 #21

    James Duffy

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    The shoulder on the cone is indeed very short, roughly 3/4"/18mm long.

    James
     
  22. Jan 31, 2019 #22

    jd2cylman

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    Would it hurt to make it longer? If one is turning their own... I seem to recall the V2 NC shoulder was a couple inches long. Weight up front wouldn't be bad, right?
     
  23. Jan 31, 2019 #23

    rharshberger

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    Depends on how far back that weight goes, the nosecone iirc is about 1/3 the length of the rocket and most of that mass would be at about 1/4 of the distance between the tip and the tail, a turned nosecone would need to be balsa most likely or basswood (hollowed significantly).
     
  24. Jan 31, 2019 #24

    jd2cylman

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    That's what I was thinking, might not be enough forward.
     
  25. Jan 31, 2019 #25

    James Duffy

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    The nosecone on this model is very long, ~19.5" of the total 41" on the rocket! Adding mass at the shoulder would place it in the wrong location.

    James
     
  26. Jan 31, 2019 #26

    Tobor

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    Although Illustrator can only "save" a file in a few formats, it can "export" to quite a few others including jpeg, bmp, tiff and png.

    Unless your version of illustrator is very old, the following should apply.
    Adobe Illustrator Supported file formats (Link)
     
  27. Jan 31, 2019 #27

    James Duffy

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    I post the PDF exports from Illustrator here because 1) they are supported by this forum, and 2) unlike the files listed above, allow for editing appropriate to the end need, which is usually laser-cut output.

    If this archaic forum allowed it I would post the .ai files, which would be best for all concerned.

    James
     
  28. Jan 31, 2019 #28

    Leo

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    Thanks for the nose cones dimensions. Do you also have drawings with dimensions of the other parts?

    I'm looking at 3D printing the plastic parts. I have a spare BT-101 from the early 80's lying around. Bout time I put it to good use :)
     
  29. Jan 31, 2019 #29

    burkefj

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    Oh if somebody could do a blow molded cone this size at a somewhat reasonable price they'd sell a ton, the rest of the fins are trivial to do in fiberglass, plywood or balsa or even the 3D printed parts. I would imagine that 3D printed cone would be pretty expensive at this size and fiberglass is pretty heavy. I've done one this size using a 4 inch fiberglass cone but it's so heavy that you really need to fly the model on g75 s, you really want something light weight at this size.
     
  30. Jan 31, 2019 #30

    Tobor

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    Ah ha. Well then, how about a Zip file?
     

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