Zach's Pitts Project

Discussion in 'Pitts' started by wzm, Apr 23, 2017.

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  1. Apr 23, 2017 #1

    wzm

    wzm

    wzm

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    Back in late December, I started building a Pitts S1. I began with Aviat plans, and originally planned on building a completely plans based S1S, before jmorgan put up a Wolf wing rib kit in the classifieds here, which I bought from him and began work on earlier this month. I'm now leaning towards a Wolf tail to go with the wings, but keeping an upright seat back and plans style gear.

    The fuselage tubing came from VR3, which has been a huge time saver. I actually built a set of S1S ribs before moving over the the Wolf ribs, which you can see in the photos below.

    Anyhow, here's a progression of how things have gone for the last few months, this might be interesting, or it might be a lot like looking at someone else's vacation slides:

    Cutting gussets for the -S wing ribs:
    [​IMG]
    [​IMG]
    [​IMG]

    Routing nose blocks for the -S ribs:
    [​IMG]
    [​IMG]

    Gluing up -S ribs on a nail based jig:
    [​IMG]

    A jig for the center ribs, these were tricky because they have an inner lip glued to one side of the rib:
    [​IMG]

    And the fun part, building the fuselage:
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
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    [​IMG]
    (this is the first "sitting in it" photo)
    [​IMG]
    [​IMG]
    Jigging the tail:
    [​IMG]
    and the cabane struts, VR3 doesn't cope the cabane struts, they just saw cut to length. The jigging and coping is taking a lot of work. This is the moment when I really realized how much time ordering coped tubing has saved.
    [​IMG]


    What's next? The main fuselage structure is mostly finish welded, but the tail, rear diagonals, seat, and cabane struts are all just tacked right now. I need to finish the cabane construction, finish weld what's left, put in the horizontal tail bracing, build landing gear, and about one million other fuselage steps. Luckily, the measurements from the tailpost to the firewall corners only differ by 3/64", or something like that, so everything is pretty straight

    The Wolf rib kit is nearing completion (I'm at 39 out of 40 ribs, and am about to begin on aileron ribs), and Chris Murley should have some spars for it soon.

    This is about 300 hours worth of work, although I've had help for a lot of it, and there are two different full sets of wing ribs in there, so I don't think my hour count is useful to anyone else. I did an EAA inspection around 150 hours, and should really do another one soon.
     
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  2. Apr 23, 2017 #2

    ndlakesdreamer

    ndlakesdreamer

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    You sir have made great progress. I'm impressed with what you've accomplished in 300 hours.
     
  3. Apr 23, 2017 #3

    jmorgan

    jmorgan

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    Thank you for posting this. Awesome progress! I'm very glad to see someone making use of those ribs. Please keep us updated when you can.
     
  4. Apr 23, 2017 #4

    smizo

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    Great job Zack, looking forward to following along! Great progress since we last spoke!
     
  5. Apr 24, 2017 #5

    dimcuesta

    dimcuesta

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    Nice! Keep calm and build-on!
     
  6. Apr 24, 2017 #6

    jstreat

    jstreat

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    Looks great. Did you lay the seat down some? Now is the time if you have not.

    JST
     
  7. Apr 25, 2017 #7

    acropilotbret

    acropilotbret

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    awesome keep it coming!!!!:)
     
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  8. Apr 25, 2017 #8

    Hova

    Hova

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    Was going to give you a call last weekend but got called into work. Maybe Sunday if you're around we can play show and tell with Pitts projects?
     
  9. Apr 25, 2017 #9

    wzm

    wzm

    wzm

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    jstreat: I didn't. In the end, I just didn't feel up for redesigning the canopy, rails, turtledeck, and tube cluster at the back of the seat. I fly a Citabria now, so this will be far more plane then I'm used to. If I ever exceed the capabilities of this, I'll think about a S1-11b or a Laser. I really appreciate your advice though, as well as the offer to show me how it's done! I am still thinking about going with no electrical, and only a starter + a battery plug. It would save a fortune on instruments, cut a decent amount of weight, and for my local area, it wouldn't be a burden.

    Hova: I should be around, I'll drop you a line, and maybe I can fly up to LMO.

    Do either of you have any advice on a good place on the Front Range to do transition training with? I saw that Greg Baker is in the Colorado Springs area, and I'm not sure if John Blum is still working up here.
     
  10. Apr 25, 2017 #10

    raymoeller

    raymoeller

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    It's good to see that proper refreshments are present!
     
  11. Apr 25, 2017 #11

    Hova

    Hova

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    I would go with Greg Baker. Good guy. Looks like youve got a long way to go before you really need to worry about the training though! John lost his medical a year or so ago and had to step down unfortunately.
     
  12. May 8, 2017 #12

    wzm

    wzm

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    I might as well add an update, I finally finished my aileron ribs roughly a week after the first post in this thread. All of the wing ribs are now finished, which has been a ton of work. 76 wing ribs and 24 aileron ribs was probably more then anyone ever wants to do in a few months.

    The cabane struts are now fully jigged and tacked, although I have not finish welded them yet. I had real problems getting good beads on thin wall 4130 coupons, so I got help from a more experienced friend with the finish welding up until now. I finally sat down this week, made a ton of coupons, and tweaked things until I was able to get better results. What changed? ER70S-2 was replaced by ER80S-D2, which made a surprisingly big difference (the ER80S-D2 seems to contaminate less easily), and I then tried 1/16" 80S-D2 filler instead of .045". The 1/16" seems to cool the pool a little more, which means that I have more room between forming a pool, and blowing out the metal. This post showed me the way forward on this problem, and the coupons I've put together are looking good after destructive testing.

    Finally, landing gear jigging is well under way. I didn't expect these to be such a complicated structure, but none of the angles or datum points are simple. Once again, I've had a ton of help in setting these up. I don't have a lathe, so coming up with a fixture to hold the different inner diameter mounting pins in place was a difficult problem to solve. I'll let the picture speak for itself on this one.

    Cabanes:
    [​IMG]

    Who needs real tools?
    [​IMG]

    And the final landing gear jig coming together:
    [​IMG]

    I'm now at 337 hours, which feels like an auspicious number.
     
    Last edited: May 8, 2017
  13. May 8, 2017 #13

    cwilliamrose

    cwilliamrose

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    Make sure you don't weld in the right cabane diagonal. That one needs to be removable so that the fuel tank can be installed. See Sht 1-210.3 of the Aviat plans for details.
     
    Last edited: May 8, 2017
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  14. May 8, 2017 #14

    wzm

    wzm

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    I'd missed that in cross referencing the sheet ~200 plans and the VR3 plans. Thank you for catching it when I had things tacked, that will save me some heartburn.
     
  15. May 9, 2017 #15

    cwilliamrose

    cwilliamrose

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    I figured it wasn't supposed to be in a photo of a tacked together fuselage so I thought I'd mention it.
     
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  16. May 9, 2017 #16

    IanJ

    IanJ

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    Saving heartburn, one build at a time...
     
  17. May 10, 2017 #17

    cwilliamrose

    cwilliamrose

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    It goes the other way too, here's one with (apparently) two removable diagonals;

    TEMP.jpg
    Of course other liberties were taken in this build. Now available on BS if anyone wants something a bit different than those boring old drawings. :rolleyes:
     
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  18. Jun 30, 2017 #18

    wzm

    wzm

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    Things are moving along, but most of the work isn't very visible. I'm currently at 415 hours.

    The main fuselage structure is all welded up, but I've left the cabane struts and firewall pins partially welded, so that I have a little more movement if things don't quite line up. The right hand side cabane diagonal came out easily after I popped the tacks, and I filed it to fit into the assembled structure easily. I have not welded in the tabs for the removable diagonal yet though. When I was nearly finished with the structural welding, I called in a local aerospace welder for an hour to close up some of the difficult clusters, like the inside of the tail post.

    I've also started drafting and cutting fuselage fittings, and I found a local water cutter who charges about $4 per fitting, but this is slow work. The fuselage belly formers were cut by a friend with a CNC router table, because they don't need to be water cut. The torque tube blocks are drawn, and I've sent them out to a machine shop. I ordered extras, so if I didn't get them wrong, there should be spare parts. Finally, my spouse has been stitching practice seat covers. She has a sewing background, but hasn't done upholstery before. I hand cut some foam for cushions with an electric carving knife, but the local water jet guy says he can CNC cut foam, so I might redo the cushions that way for fit and finish reasons.

    I bought a set of wing and landing gear fittings from Steen, as well as a fuel tank. In the end, I felt I couldn't beat their workmanship for the price. I have not yet decided on whether or not to polish the fuel tank, but it would look nice.

    Bill, I actually saw that fuselage last month. The fuselage itself shows a lot of creativity, but it sounds like it was a great buy for the new owner: they got a ton of (non-fuselage) parts out of the deal.

    Now, on to the interesting part, pictures!

    [​IMG]

    [​IMG]
    This shows how I ended up preventing weld blowout. I'd thought I could get away with putting a hole into the weld crotch, but I still had out gassing problems. Unfortunately, I hadn't drilled between tubes when I was tacking things up, so I ended up needing to back off and drill my ventilation hole. These will get plugged later, it's just less pretty then doing it inside the cluster.

    [​IMG]

    [​IMG]
     
    Last edited: Jun 30, 2017
  19. Jun 30, 2017 #19

    Hova

    Hova

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    looking like good progress!
     
  20. Jun 30, 2017 #20

    smizo

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    keep up the great work!
     

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