What did you screw up on your Airplane project today?

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Foundationer, Jun 26, 2019.

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  1. Jun 26, 2019 #1

    Foundationer

    Foundationer

    Foundationer

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    As I was making about the 10th potentially expensive, slow motion screw up on this project I thought "what we need is an 'inspirational' thread that shows that everyone does it...".

    Here's a picture of the foam cutter starting at the bottom so the cut above is displaced rendering the whole thing garbage. And a big pile of flap cores after I made it go the other way round the line.
     

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  2. Jun 26, 2019 #2

    BJC

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    You are gaining experience every day.


    BJC
     
  3. Jun 26, 2019 #3

    proppastie

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    1: is that a CNC hot wire.....did I miss a post for that?
    2: top one is still good?
     
  4. Jun 26, 2019 #4

    Foundationer

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  5. Jun 26, 2019 #5

    cdlwingnut

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    love the idea of this thread, one of my latest bigger mess ups was putting my false rib in the wrong spot on my first wing and had to cut it off build a new one and glue it to the right spot.
     
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  6. Jun 26, 2019 #6

    Hephaestus

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    Couldn't sleep was wide awake at 4, so I was playing with some of the wing calculations in raymers.

    2 pages later I notice the numbers really don't make sense... I'm still not sure where the wing area # came from, sqmm*25.4 maybe? Definitely not sqft ...

    Let's just say the number may be right but I have no idea what screwed up uncaffeinated measurement system it's result is in - so it's pretty useless. :mad:

    I think this is why you're supposed to do math with tequila in hand - so by the time you screw up the units you're so far past the point of operating a calculator it no longer matters :p
     
  7. Jun 27, 2019 #7

    bifft

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    Well, the big mistake was a week and a half ago instead of tonight. My vapor return line was leaking enough to leave a blue stain on the hose. So I made a new fitting (the leaking one was also custom), and instead of leaking just a little it leaked a lot. Tried to put the old one back on, cross threaded it and then broke it (don't wrench when tired and angry). So now grounded.

    Made another replacement fitting, tried that tonight. Also completely fails to seal against the hose.

    Will see if I can get with a retired machinist I talked to at the last EAA chapter meeting instead of trying to teach myself online.
     
  8. Jun 27, 2019 #8

    BJC

    BJC

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    Not done today, but I will observe that it is entirely possible to follow the instruction manual and end up trimming the kit-supplied upper cowling too short, requiring that an extension be spliced onto the part.


    BJC
     
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  9. Jun 29, 2019 #9

    cdlwingnut

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    I measured and measured again the length my plywood piece had to be then cut it, somehow I misread the tape because it was about 2 inches too short. Oops
     
  10. Jun 29, 2019 #10

    Foundationer

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    Measure twice, cut once, throw it in the bin and do it right next time. That's my motto.
     
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  11. Jun 29, 2019 #11

    pictsidhe

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    That isn't screwing up!
     
  12. Jun 29, 2019 #12

    Hot Wings

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    That is my "favorite" mistake. Do it often. Try to measure out 31 inch. Think "It's 1 inch more than 30" then neatly mark 1 inch less than 30. Result? A perfectly cut part..............2 inches short.

    This method works with smaller units as well. :(
     
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  13. Jun 29, 2019 #13

    deskpilot

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    Easy to do if you're reading the rule upside down.
     
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  14. Jun 29, 2019 #14

    TFF

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    I did not work on mine, so I’m good.
     
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  15. Jun 30, 2019 #15

    Doggzilla

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    Had ice in a regulator because a drier filter was clogged with oil and water couldn't get out of the lines. Hit with hammer to try and dislodge the ice and instead it warped the brass fitting that connects it to the housing. Had to replace the entire assembly for $1500.
     
  16. Jun 30, 2019 #16

    Pops

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    Thought I had a ground problem because both the wing tip light and strobe did not work on the left wing. Didn't have the plug at the wing root plugged in together all the way. If you plug it together until the little latch engages it will work, if you don't, it don't :)
     
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  17. Jul 8, 2019 #17

    Foundationer

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    Today I discovered that I'd completely screwed up my upper wing skins! I had some old hotwire templates from before I had the CNC hotwire idea and I though 'let's make sure they match up with what I've built' thinking that would be a nice little 'yay! It's all great! sort of moment'. So I did this just before I went to work. ARGH! Day spent moping around depressed.
    IMG_20190708_191246.jpg

    Got home & spied a pile of templates in the corner still wrapped in cellophane... Wait a minute!
    IMG_20190708_191629.jpg
    I was using one from the original tapered tips idea that's about a foot shorter. Of course it's not the right shape. So basically they're fine. No problems. But for a whole afternoon I thought I was going to have to start again.

    It's really important for me to constantly remind myself how dumb I am.
     
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  18. Jul 8, 2019 #18

    Kyle Boatright

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    A while back, I cut/damaged the cord on my Lightspeeds so I sent them to the factory for repair. The repair charge was $100. They were returned (repaired) a few days ago and I unboxed them Saturday evening. New cord, and the battery pack even had fresh batteries. I was a happy camper.

    First thing Sunday, I went for some RV-10 transition training and managed to pinch/cut the new cord in the seat track before the first flight. So I'm back exactly where I started, except I'm down $100. I got zero use from my repaired cord.
     
    Last edited: Jul 9, 2019
  19. Jul 9, 2019 #19

    Toobuilder

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    ...on the plus side, you have new batteries!
     
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  20. Jul 9, 2019 #20

    Toobuilder

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    Worried about an overvoltage event with my electrically dependant airplane, I followed the somewhat vague guidance in the March issue of Kitplanes and "modified" my ND alternator to accept an external regulator.

    It doesn't work anymore.
     

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