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  1. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    My last post brings the build process current to the finished model. The next posts, which are likely to be spaced due to personal time constraints, will largely focus on an upcoming "hop" attempt. More aimed at the novelty of controlling a severely under powered model, and probably outside the...
  2. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    The joys of finishing. You sand, you prime, you repeat. On top of the task of traditional priming and painting was the effort to give the model a scale appearance based on its polished stainless steel panels. I actually counted the panels on the real test article, scaled them down to size, then...
  3. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    I knew nose weight would play a factor in this design. My approach here was to create a base for the foam to sit on, and on top of the "base plate", I would epoxy the weight. Weight of choice was BB's in 3 small BT50 "cups." The cups each hold 2oz of weight, are glued to each other, then glued...
  4. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    Fun with foam - not. This was probably my least favorite part of the build, so much so that I probably needed to shave the thing down a bit more to bring it closer to scale. Foam of this type is probably just messy and not very satisfying to work with since I know it needs a lot of help. Quite...
  5. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    The next task I tackled was adding a launch lug and designing a "removable" Raptor engine bell housing. Of all the methods to custom make a bell housing, I settled on chopping the tip off of a BT60 from an Estes US ARMY Patriot. (I think I noted the part # in the initial build thread message.)...
  6. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    The leg-fins were a bit of a challenge overall. Between rolling my own tubing, then later figuring out what geometry makes them sit correctly and what cuts to make, I finally got everything situation. Happy with the appearance, I glued them all into place. You can see in one of the photos where...
  7. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    On a much smaller rocket, I might consider a swing test to validate stability, but I could see my attempt to get it moving go badly and damaging the model from testing. At this point, if/when I decide to make a flight attempt, I'm going all in. I'll snap many photos before and then "send it."...
  8. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    I'll add a personal anecdote to this build thread, that hopefully you can relate to or have yourself experienced. At this step of the build, as I was admiring the model sitting awkwardly on my build desk with its twiggy dowels, I had a nostalgic flashback to 1990 - the first year I got into...
  9. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    In an earlier post I showed a photo of the internal foam disc skeletal structure. In this series of images, I've already wrapped the skeletal frame with poster board and glued the discs in place. I printed out a fin marking template to align the 3-leg-finned rocket, made marks, and inserted the...
  10. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    See attached. Thanks for offering to check it out!
  11. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    Sounds like a good reason to get into CTI hardware. :) I've honestly not launched a rocket in about 3 years and haven't looked at the availability of commercial hardware or motors. The F30 you referenced does appear to fit the bill. If I can at all solve for the thrust/weight issue with this...
  12. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    @neil_w - I don't fully trust my OR skills, but this sim was intended to try and get a ballpark figure. The "fin" design for this model is awkward as is being that the top of the legs is effectively a BT20 tube. I guess that would make the fin thickness .74-ish with a rounded leading & trailing...
  13. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    The next main task in developing the model was figuring out what materials would stand up to hard landings. Being that the fins were also a part of the legs, I figured I'd frame the fin-legs with dowels, and instead of balsa, more 1/4" foam core. Of course, I needed some rudimentary angles to...
  14. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    I definitely have not looked at the rest of the available 24mm engines nor their performance characteristics. My biggest concern on high thrust and short duration is that this isn’t the most aerodynamic design. I’ll run more sims later. I also don’t know at what point the internal 1/4” foam ring...
  15. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    Like many scratchbuild projects, this one started last month while roaming the aisles at Michael's Arts/Crafts. With the upcoming SpaceX test looming on the horizon, inspiration struck. (All model rocketeers have this in common. LOL...junk finds, craft stores, thrift stores, yard sales, toy...
  16. eugenefl

    1/47th Semi-Scale SpaceX Starhopper, aka "Deskhopper" Scratchbuild

    Ahead of the attempt by SpaceX to test their Raptor engine on the Starhopper test article on 8/26/19, I released an image on various platforms of my scratch build of the Starhopper that I am very proud of and excited to share with you here. Brief background: I've be a TRF member since late...
  17. eugenefl

    How often does everybody get to launch?

    As far as the club launches go, we're fortunate to have a local club with access to a range that permits high power rocketry. Our attendance is irregular. We go maybe once a year or every other year and I typically only go to spectate which means I have someone new to the hobby with me. This is...
  18. eugenefl

    Falcon Heavy! BT60-based with separating boosters

    I'd go the extra long shock cord route if you want some additional insurance against a chute shredding. The weight on those side boosters will be so light and without any passive guidance or boost will go unstable and into a tumble as soon as it separates from the main booster. That velocity...
  19. eugenefl

    Falcon Heavy! BT60-based with separating boosters

    Ahh...I couldn't figure out parallel boosters in OR. Nice to see it's a feature that's coming in a future release. Anyhow, I too started a build about a week ago. Custom turned parts (via makeshift lathe) using shipping tubes. I'll start another thread as to not detract and cross pollinate build...
  20. eugenefl

    3d Sphere to 2d Paper "Slices" Template Tool? (Round Nosecones)

    Yes, thank you for that link/reference. I didn't know what the technical term was for what I was looking to accomplish. I had also come across a research paper that went into this far more in depth. I am actually looking to fiberglass a round foam core and wanted to transfer the paper pattern to...
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