First try at cowling

Discussion in 'Pitts Miscellaneous' started by garyg, Jan 12, 2018.

  1. Jan 12, 2018 #1

    garyg

    garyg

    garyg

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    S1-11B. Cowling seems to look and fit good. Camlocks are used on the side panels. I made a couple of small correctable mistakes. I should have paid attention and made the first set holes on the side panel nearer to the nose bowl. I think. I should have paid closer attention to the drawings but I wanted to keep the spacing even between the top/bottom panels screws and the side panel camlocks, so I just placed them in the middle of the upper and lower panel screws not thinking about the front edge being 3 inches from the first camlock. In the wind. The drawings show an irregular pattern between upper and lower panels screws and side panel camlocks. I am going to stick another camlock in front of the first one so it will make the first 2 about 2 inches apart and the rest 3.8 inches apart. Wheel pants/leg fairings are not mounted but are ready for attachment. (I just notice that the second picture is missing a cleco on left upper, I just didnt put it in before I took the picture.)

    The bottom panel has a hole for the per plans air intake. Since I have a cold air induction, I need to build a rather large intake housing with a big hole in the nose bowl. So I might make a new bottom panel without the hole or just patch it with a plate or maybe the cold air induction housing will cover the existing hole. The opening needs to exist and be larger at the front due to the throttle body it just may not need to extend as far back. I am thinking just a small extension would completely cover the opening.

    Not much room for an exhaust but it looks possible. I used some pipe insulation the size of the exhaust for experimentation (a piece is sticking out the bottom). Whatever exhaust it is it will need to head directly to the opening. Plenty of room in frt of the left bank of cylinders for an oil cooler if I didnt have to run the prop governor cable there. If it was placed there do they work well?

    be gentle.....

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    Last edited: Jan 12, 2018
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  2. Jan 12, 2018 #2

    Lotahp1

    Lotahp1

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    Looking great!
     
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  3. Jan 12, 2018 #3

    Dave Baxter

    Dave Baxter

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    Looks good to me Gary,trying to juggle all the variables, where to place the channel brackets spinner and nose bowl carb / fuel injection inlet, oil cooler and exhaust are all a challenge even with basic drawings is difficult enough, but with no real drawings different engine and accessory combinations really lets the fun begin?

    I used the Summit racing type sheet metal fasteners similar to the skybolt ones, as I do not like cam locks yuk! I also shortened the lower full span ailerons and built uppers trying to replicate the lower ones, and there are no drawings!

    Besides if it was easy everyone would do it! Your work looks really good to me and the fastener spacing will only give your airplane character, right? Dave

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    Last edited: Jan 12, 2018
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  4. Jan 12, 2018 #4

    DanSalcedo

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    Looks good so far Gary. I had to make a few little blister bumps in my cowl where the exhaust pipes hit/ stuck thru the cowl. Just the way it is with a simple curve alum cowl.

    Dan
     
  5. Jan 12, 2018 #5

    garyg

    garyg

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    Dave,

    Thanks!

    Yeah the drawings are sometimes barely acceptable. Other times incomplete. And then there are the other changes that are self inflicted. And then there are the ones where I should have paid more attention.

    The channels per drawings were supposed to be 0.063 but were made (by someone else) out of 0.050. We dont think that will hurt anything but the camlocks studs I bought per drawing are now too long by 0.13 as there were right on the border. The drawings say use 36 camlocks but then I can only find spots for 34, so I just made 4 rows, one less in number of screws on opposing panels. This made for a fairly symmetrical look but then left me a long end. The firewall nut plates encroached on where you might really want the channels but the drawings are none to exact about the placement of the channels and the nut plates so that is another free for all. The nose bowl lip wasn't shaped the way it needs to be so I had to cut it in about 50 places and heat gun the tabs down. Now I will have to glue the slices together and add some layers.


    The cold air induction really screws up the available space below the engine and creates a new issue with trying to get the air into the intake.

    And it looks to me like the cowling is really close to the engine. At narrow front end there is only about a 1/2 to 3/4 of and inch from the last valve cover to the cowling. The Van's baffle I kit I bought is going be reduced to a mere inch or so, with enough left to hopefully attach the seal to it.

    The oil cooler is also going to be a magic act as well as the throttle/mixture cables running near the exhaust exit. and then the inverted system and hose.

    Like I joked in another thread, I need a Tardis bowl.
     
    Last edited: Jan 12, 2018
  6. Jan 12, 2018 #6

    garyg

    garyg

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    Thanks!

    I think my next move is going to be getting the throttle/mixture cables on and then going for an exhaust to see if I need some blister/bumps for the exhaust. You have the wider engine and so you might have had more room than I will have right now. I am not sure how much clearance there needs to be to anything else. I doubt there is more than 1/2 to 3/4 around a couple of the pipes in some places.
     
  7. Jan 12, 2018 #7

    cwilliamrose

    cwilliamrose

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    Just curious Dave, why the Camloc hate?
     
  8. Jan 12, 2018 #8

    garyg

    garyg

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    at 7 bucks a piece for stud and receptacles and needing 40 of them plus a 25 dollar off brand dimpler and (if you buy Camlocs and not go it alone on the big hole) 300-400 dollar hole saw, I know why I hate them......
     
  9. Jan 12, 2018 #9

    Jerry

    Jerry

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    Beautiful first try ! I’m making a faceted windshield for my ‘bolt and I’m on my second final one. That’s after making two or three test pieces for bending, etc.
     
  10. Jan 12, 2018 #10

    Jerry

    Jerry

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    Deleted... looks like either me or the system double posted. I’m thinking it was the system. :)
     
    Last edited: Jan 12, 2018
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  11. Jan 12, 2018 #11

    cwilliamrose

    cwilliamrose

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    Wow Gary! That's a lot of Camlocs!! I made my own Camloc dimpler way back when and I don't use the retainer rings for the grommet (if that saves a few bucks??). I didn't know I needed a fancy hole saw, I just use a drill. I might have ten Camlocs in my airplane when it's done.
     
  12. Jan 12, 2018 #12

    DanSalcedo

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    My Southco studs are about 6 inches apart. 7 in each row to attach the removable cowl sides. 250mph hasn't ripped them off yet

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  13. Jan 13, 2018 #13

    garyg

    garyg

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    Dan,

    My drawings have a couple or errors here. The channels drawings says the upper has 9 receptacles, the lower 8. The side panel drawing says/shows 8 top, 8 bottom. the quantity listing says 36, which would be 9 top and bottom. Who's to say here? My Aztec has 2 close together (about 2 inches apart) at the windy side bowl, so I won't be the only one.

    The panels, per drawings, butt each other, not overlapping at the channels. This seems to be somewhat different than a lot of them. Not sure why the decision to butt them. It is easy to verify the plans because the metal sheets cut to drawings just barely cover the circumference.

    Another drawing oddity, is the oil fill/check door. The drawings have the door made out of 0.063, yet the panel itself is only 0.032. I think this will have the door sticking out 0.032 above the surface. I think you said you used a Cessna door for yours (my long ago recollection), so I have been watching ebay for a decent one that is not overpriced before I try to make my own from scratch, which wouldn't be that hard but the Cessna would probably be thinner with it's own re-enforcement braces.

    One other oddity is there doesn't seem to be an adjustment between overlapped panels and non-overlapping adjacent panels/bowl/firewall attach points. it is semi-obvious (the mismatch) but not prohibitively so.
     
    Last edited: Jan 13, 2018
  14. Jan 13, 2018 #14

    Steve H

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  15. Jan 13, 2018 #15

    DanSalcedo

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    When I originally built my cowl it had a piano hinge along the bottom side cowl and studs ant the top and swung down to open. I thought that's what the plans said. I worked good until I installed the wings and the flying wires and to my surprise the cowl would hit the wires and only open 1/2 way.
    So I had to make new side cowls that overlapped the top and bottom to allow for the studs on both edges
    The pic below is from after my first flight and shows where the cowl hit the wires and the piano hinge. I had to cut the aft edge of the side cowl to allow it to open fully.

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  16. Jan 13, 2018 #16

    Neil

    Neil

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    If you want to do a hidden hinge you can do that with an .032 door and a flange on the inside of the skin. Part of the hinge effectively doubles the door thickness inside of the flange. The last photo is the oil door, but you get the idea. You could use an .063 door and place an .032 shim between the skin and the flange. Also a sort of fuzzy shot of the sheet metal at the nose bowl.

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    Last edited: Jan 13, 2018
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  17. Jan 13, 2018 #17

    JeremyHolt

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    Gary was is the thread for the rest of the build?
     
  18. Jan 15, 2018 #18

    garyg

    garyg

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    Jeremy,

    A build thread seems like a lot of work...although I definitely like to follow them (including yours!). I was just kind of happy the way the cowling was looking even if I have a long way to go yet. I will post some pictures of some other pieces. As soon as the composites in the hanger quit spreading dust clouds around (next couple of months or so) I am going to take the wings out and hopefully try my hand rigging. Until then I have quite a bit to do FWF and complete the wiring to the engine.
     
  19. Jan 16, 2018 #19

    Lotahp1

    Lotahp1

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    Just use a .016 shim under your .050 channels (assuming you don’t want to remake the channels). That way your cam lock studs will work.

    What hole saw did you need? I like using a Rotobroach for cutting the hole. (About $250 for a pretty decent set of rotobroachs. They are one of my favorite tools. They are THE tool to use to make a perfect hole in stainless , 4130, Aluminum etc. just use some good cutting fluid and they last a long time even cutting stainless firewall holes.
     
  20. Jan 16, 2018 #20

    garyg

    garyg

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    Have not drilled the holes yet for the receptacles. I just saw the very expensive tool CamLoc wants to sell you. haven't seen an equivalent to it but I am not sure why such a fancy tool is required for a hole that does not influence how they look or operate.

    I may place a 0.016 layer on top (like chafe tape) as this will help cover space the panel closer to the bowl and rear panel level and keep the panels from direct contact.
     

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