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Narfi's Life after EU: Chapter Five - CH750-SD 3 Place Aircraft

Discussion in 'Life, the Universe and Everything' started by narfi, Sep 5, 2020.

  1. Wistrel

    Wistrel Kick Ass Elf


    (Sorry... I don't think I'll ever grow up ^_^))
  2. narfi

    narfi Lost

    hehe, do we ever?
    • Friendly Friendly x 1
  3. Jamira

    Jamira Samurai Girl

    Yes, we do. Takes a while but will happen ;-)
  4. Jamira

    Jamira Samurai Girl

    What might that be after building your own airplane?
    • Winner Winner x 1
  5. Wistrel

    Wistrel Kick Ass Elf

    I think he said building a catamaran or something?
  6. Wistrel

    Wistrel Kick Ass Elf

    but... maybee......

  7. narfi

    narfi Lost

    • Like Like x 1
  8. narfi

    narfi Lost

    I think I was asking too much of the little circle cutter attachment for the dremel. The plastic threads started giving and I ended up with wobbley holes with steps in them.........

    Made myself up a redneck circle cutter for my little handheld router (bigger router showed up and is mounted in the table now) and used a broken 1/8" bit as a pin. Worked really well and made some nice clean circles inside and out.

    Epoxied the matching peices together in our mudroom entrance to the house since its too cold out in the tent. Frosting nightly and termination dust in the mountains is getting pretty low here.

    Cleaned up the holes with the largest flap wheels that would fit chucked up in the drill press and the outside of the circles carefully by hand on the belt sander.

    Routed the inside 45° on the table mounted router, fun to use it for the first time.

    It all looks good but I am worried about the size..... they might be to bulky and ill have to cut them down smaller once I start using them inside the ribs..... Will have to see how much clearance I have inside the flanges. Its currently quite a bit bigger than the zenith specifications for steel manufactured ones.

    I did a test peice and it worked but I got it a little cocked in the hole hitting it and the male die split separated between plys (not my epoxy joint) so ill need to epoxy it back together and be super careful not to hit them crooked.

    Perhaps I should back the female side with another solid peice and drill a center hole to use a bold to squeeze them together instead of "wacking" them with a mallet. I dont have a press......








    Roughly 3 more hours.

    Total time spent building: 10 hours
    Total Cost: $8276
    Airplane + consumables + project specific costs: $5340
    Tools, etc.. I will keep for future projects: $2936
  9. Jamira

    Jamira Samurai Girl

    Well, it's probably time to think about a 3D printer my friend! Such parts are easy to design:

    Design such parts in CAD will be done within a few minutes and printing takes depending size and filling rate a few hours. But you can go to sleep meanwhile ;-) A cheap printer costs $200 and 1 kg of ABS or PLA $20-25. So what?

    You may also think about a holding down clamp to avoid warpings:
    upload_2020-10-21_1-1-31. upload_2020-10-21_1-2-32.
    Last edited: Oct 21, 2020
  10. Jamira

    Jamira Samurai Girl

    Tbh we really thought about printing all the bulkheads of the Do X body and stabilize them with some 8 or 10 mm steel wire or so. Since she won't fly this would be enough. Buy 20 or 30 cheap printers and print 24/7 would take 1-2 years to get this:
    58 bulkheads and the keel, nearly 40 meters long, 10 meters wide, 6 meters high. Costs were dramatically low compared to traditional manufactoring. Something around 50000 Euro only including all the printers instead of the estimated 5 million Euro. That would be 1%! In words: ONE PERCENT! But our boss decided: No, it must be riveted true aluminium, not painted plastic!

    But it would be possible. And you should really start thinking about using new technologies!
    Last edited: Oct 21, 2020
  11. narfi

    narfi Lost

    Epoxied the separated peice back together as well as solid backing plates for the female peices. Cut them down to within a few mm of the specified OD so there shouldn't be any issue fitting inside any rib flanges now. My fear of strength seems unfounded, even cut down they seem pretty stout. Used my new drill press to drill center holes through each peice to use a bolt and washers for clamping pressure. Fun using the new tools, but they are cheaper versions than I am used to from work, there isn't much travel on the drill and I couldn't go through the full stack, but did get far enough to mark the bottom of the F peice through the male plug then drilled it separately.

    More clecos and pneumatic rivet puller with zenith machined heads showed up yesterday so hopefully my aluminum starts trickling in and I can start making visible progress.




    Roughly 1 more hour over 2 days.

    Total time spent building: 11 hours
    Total Cost: $8276
    Airplane + consumables + project specific costs: $5340
    Tools, etc.. I will keep for future projects: $2936
  12. narfi

    narfi Lost

    Yes, but my budget is blown for this winter :)
    If these do not work, I may look into finding someplace that I can send the files to for printing, but I am still hopeful.
    You are right though, they are simple to design (even I could probably do it) and print (I would still need to learn all the ins and outs of that).

    5 million euro?????? Something doesn't add up there for me.
    If that includes professional labor at union prices then yes, but there is no way there is 5 million euro of aluminum there, and I thought this was a non profit/university type volunteer project?

    If you went the route of making a non realistic model that was just the right size and dimensions and not worrying about being 100% accurate with materials and methods, I would think CNC plywood would be much cheaper and quicker than plastic printing. I assume the tooling would be significantly cheaper as well.....
  13. narfi

    narfi Lost

    hmm.... thinking about this more.....
    for a museum static display, you want to show the realistic materials and methods but it doesn't need to fly and as with everything cost and time is a factor.
    Lets be honest with ourselves, dinosaurs in the museum do not have real flesh or claws visible, even their bones are not real, but they look real and show what the guests of the museaum want and need to see. They do also display real bones and claws when they can afford them?

    Why not a hybrid approach with the DO X?

    2 methods,
    Have true aluminum bulkheads and rivets in all visible and cut away sections visible to the public.
    Have all covered areas cnc cut from plywood and skinned with real aluminum screwed to the plywood with false round (rivet) caps glued over the screwheads when finished. When painted and viewed or touched from the outside it appears as a pure aluminum aircraft, the cut always are pure aluminum and show what the structure and skeleton should look like, but your cost and time is dramatically decreased.
    You can do the same with the wings and any other structures as well. Use the best method for each section based on how it will be viewed and the cost and time required.
    • Like Like x 1
  14. Jamira

    Jamira Samurai Girl

    LOL! Yeah, exactly this is the plan. All visible and probably touchable structures are made from original material and all hidden structures from what ever fits best to do the job. Regarding 5 million ... I too think it's a bit overestimated. I will visit Sophia Bobley in Hungaria next year. She designed the model of Amundson's Dornier Wal for the Dornier Museum and her company built it. Probably we will see another picture of estimated costs. Especially if we are allowed to build it within the Dornier Museum. We plan kinda vitreous workshop wich is open for visitors during the building process. For the moment we have shitty Corona at the neck ...

    But I don't want to hitchhike your thread!

    I love the job you did with that plywood. Looks pretty solid. After your own airplane you can start immediately with series production using such solid tools or sell them to other freaks like you who want to do each damn part by themself ;-)
    Last edited: Oct 24, 2020
  15. Wistrel

    Wistrel Kick Ass Elf

    I think you are already making visual progress. People don't appreciate the effort that goes into even making this template or tool things you are making there. All takes time. Heck I have so many smaller jobs that would take less time and I never get to.

    I suck so much at life haha.
  16. narfi

    narfi Lost

    Made the cutting templates and form blocks for the rest of the horizontal and elevator parts this weekend. Still waiting on the .016 :(

    Sent an email to Roger asking for more parts to make.

    Roughly 6hrs


    Total time spent building: 17 hours
    Total Cost: $8276
    Airplane + consumables + project specific costs: $5340
    Tools, etc.. I will keep for future projects: $2936
  17. narfi

    narfi Lost

    Thanks, and don't be hard on yourself. Life is an adventure and we all approach it differently and get different things back out of it. I have a very addictive personality and it shows in what I do. I spent ~15 years reading a novel per day, I spent over 5 years playing Entropia hard core, now I am putting that same focus into building things. Not right or wrong, just different. A more balanced approach to life may be more healthy, but I can't seem to balance well.
    • Like Like x 2
  18. Wistrel

    Wistrel Kick Ass Elf

    A novel a day... I couldn't do that even if I didn't sleep. And then I'd go literally mad.
  19. narfi

    narfi Lost

    Getting colder, but at least with this project I can put on a coat and gloves and still do something. When working on the boat I had to close up in September till spring because it was too cold for epoxy.

    Got a lab coat I've been wearing its a little snug over the winter gear but still fits until I add another layer. Has worked well at keeping my cloths less dusty with sanding and routing the aluminum.

    Talked to Roger yesterday, he still doesn't have a big list of parts for me yet but said I could do the flaperon, slats, and rear wing ribs.

    Took me about 2 hours last night to make the cutting templates and form blocks for the slats ribs. In my head thats a 20min project..... but in reality im not as efficient as I imagine :p


    Total time spent building: 19 hours
    Total Cost: $8276
    Airplane + consumables + project specific costs: $5340
    Tools, etc.. I will keep for future projects: $2936
  20. narfi

    narfi Lost

    It was suggested on the homebuiltaircraft forum that the skins will fit tighter if temperatures stay the same when drilling and riviting so the aluminum isn't expanding and contracting.
    I'll try to do my drilling and assembly at steady temperatures, but should be ok making the parts in the cold.

    3 more hours got me the cutting templates and bending forms for the flaperons.


    Total time spent building: 22 hours
    Total Cost: $8276
    Airplane + consumables + project specific costs: $5340
    Tools, etc.. I will keep for future projects: $2936

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