Hangar Door

Discussion in 'Workshop Tips and Secrets / Tools' started by bmcj, Aug 30, 2015.

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  1. Sep 2, 2015 #21

    mcrae0104

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    I think the wind loads being discussed are in the closed position, not open. But when open, a door such as the one you describe would have a wind advantage. Not sure what the water exposure advantage would be over a bi-fold door--can you explain? Probably one reason bi-fold doors are commonplace is that the (motorized) opening mechanism can be so simple.
     
  2. Sep 2, 2015 #22

    rv7charlie

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    Like this?

    ultimate

    There are a couple of them on my home field. That particular design is pretty Rube Goldberg. Lots of cables and pulleys and garage door tracks and rot-prone 1x4 lumber (treated is too heavy for this design). Unfortunately, to keep the door light, it takes lots of garage door tracks about 4-5 feet apart. I've seen a blurb for an all-steel, very heavy looking version of this (without all the cables, pulleys etc) in a few of the aviation mags. Not light; I'm confident, not cheap. But it's free-standing (no loads on the hangar roof).

    Charlie
     
  3. Sep 2, 2015 #23

    rv7charlie

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    If you build it like a regular bifold door, with hinges across the top and hinges along the fold line, and cables along the bottom edge to lift it, then there's no reason it won't work just as well as steel doors, assuming you design & execute the sandwich construction properly. Typical 42' bifolds are constructed of 1 1/2" mild steel tubing, and are very flimsy without the effective truss that forms as they fold, and the multiple support points (cables). But as others have said, it will be expensive.

    A much less expensive & possibly lighter option would be surplus aluminum irrigation tubing. I wanted a 'taxi out' door for the shop side of my hangar, so I built a 10' x 30' rigid counterweighted door using 6" tubing with Suntuff, & IIRC, it weighs less than 500 lbs. Worst thing would be implementing the hinge mechanisms & joints on round tubing. Something like Suntuff, fiberglass, etc also allows light into the hangar, something that's lost with metal or a foam/fiberglass sandwich skin.

    Charlie
     
  4. Sep 2, 2015 #24

    autoreply

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    Mostly thinking about our climate. With the door sliding in and up, it's always only the outside that gets exposed to water. With our salty air doing otherwise can be an issue.

    That one indeed Charlie, albeit "broken" in a few sections horizontally. I've seen a few big ones, probably made from sandwich panels. Should be pretty light and simple with a bit of glass on both sides, say 5 kg/m2?
     
  5. Sep 2, 2015 #25

    StarJar

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    Yaeh I like that "broken horizontally in the middle". That would be fun. Some cables winched around a long pipe, maybe to pull it up.
    Maybe a sandwich of 1/8" ply from big box, on 1 x 2's. All the wood would be about $300. Maybe replace a few with translucent.
    Have I gotten off track? Am I nuts?
    And besides it's Bruce's hanger, so I'll settle down.
    Added: A post could come down with it, in the middle, and plant in the ground.
     
    Last edited: Sep 2, 2015
  6. Sep 2, 2015 #26

    bmcj

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    And now I offer the 'twist' I promised you. The opening is vaulted in the middle (imagine a squatty pentagram), plus it is not overly tall. To place a beam across would cut it down to an unusable height in the middle. I have been trying to figure out how to put up a door that leaves the center-vaulted height open for taller tails or props (one of my props is 8' long). So far, solutions I have come up with are:

    1. Barn door style, each half swings outward with a wheel on each end to support the cantilever. Can be a problem in the wind.

    2. Split bi-fold door style (split vertically down the middle into left and right doors) with cable draws on each end, drawing more on the taller portion (the bi-fold fold line would incline upward toward the center).

    3. Stack door that stacks completely in front of the frame so that the taller sections don't jam under the low corners.

    4. A one piece hydrolift that swings outward/upward (like an upward tilting garage door but stays completely on the outside). This would be difficult due to moment arms and wind loads, so not really realistic given the typical house structure.
     
  7. Sep 2, 2015 #27

    Hot Wings

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    Could you place poles at either end to support a standard bi-fold but just "trim" the ends of the upper half to match the roof line? You would still have 2 poles sticking up when closed to break the outline. Maybe turn them into decorative flag poles to satisfy the homeowners association?
     
  8. Sep 2, 2015 #28

    bmcj

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    You lost me, but whatever it is you're suggesting, it sounds good. ;)

    EDIT: OK, I think I understand now... ground-mounted poles in front of the hangar (one on each side) that completely supports a full span bi-fold door?
     
  9. Sep 2, 2015 #29

    rv7charlie

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    First, why is it cute to intentionally withhold needed data, when you're asking us for help?

    If you're saying that the door must effectively be the entire wall under a gable roof line, then it's very unlikely you could use *any* type of door that 'hangs' in the building, due to structural limitations of the vaulted gable roof line. Unless, of course, you've also withheld info like having a load bearing truss built into the walls and roof.

    1 will work, with limits you describe. Also requires a horizontal surface for the castors to run on, to support the cantilever weight.
    2 would likely impose vertical loads that would cause structural failure of the roof and/or the wall-roof intersection and/or the wall-foundation intersection.
    3 I can't see any geometry that keeps the taller sections of the 'stack' outside the roof line.
    4 sounds structurally unsound, with a single point attachment at the roof peak, and a lot of vertical load on the peak (see #2)

    Just build a rectangular hydroswing style door as tall as the roof peak, with a horizontal truss along the top line and hinged to two posts, as Hot Wings describes. or add counterweights & swing it manually.
     
  10. Sep 2, 2015 #30

    Hot Wings

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    Not exactly what I was thinking, but it's actually a slight improvement with regard to visual integration - if the existing building can take the inward load from top half of the door when open.
     
  11. Sep 2, 2015 #31

    Hot Wings

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    Not exactly what I was thinking, but it's actually a slight improvement with regard to visual integration - if the existing building can take the outward load from top half of the door when open.

    Edit: Upon reflection we are not thinking the same thing. No truss needed at the top hinge line which would be attached to the existing vault top horizontal. The added poles are only needed to let the rollers go far enough up for the bottom to rise for adequate head room. A truss of sorts (depending on materials and thickness) would be needed at the bottom edge unless multiple lift wires were used. The rollers for the lower edge could be off set to put the door flush with the existing structure when closed.

    The bi-fold door I designed for my shop has the upper hinge line 30 inches or so above the top of the door. When open it provides full vertical clearance, unlike most hangar doors that cut off a bit of height to maintain the "V".
     
    Last edited: Sep 2, 2015
  12. Sep 2, 2015 #32

    bmcj

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    Sorry, withholding information wasn't meant to handicap any suggestions... it was intended to avoid clouding the original point (first part) of my question, which was can a door be built light and inexpensively using a foam and fiberglass sandwich panel.

    As for the rest of your well made points:

    1 will work, with limits you describe. Also requires a horizontal surface for the castors to run on, to support the cantilever weight.
    I was actually speaking about a side-hinged panel that swings out horizontally just like a common door does.

    2 would likely impose vertical loads that would cause structural failure of the roof and/or the wall-roof intersection and/or the wall-foundation intersection.
    This is my favorite idea, but you are correct about the vertical loads. That is why the first part of my question included "light-weight" as a goal.

    3 I can't see any geometry that keeps the taller sections of the 'stack' outside the roof line.
    Yes, I think you are correct and that my thinking was faulty.

    4 sounds structurally unsound, with a single point attachment at the roof peak, and a lot of vertical load on the peak (see #2)I agree that it is a "load-monster", though my thought was three hinges... one at peak, and a couple of "extender hinges" at the two corners. Again, though, it is probably a loading nightmare, especially in the wind. This idea was also highly dependent on a light build

    Just build a rectangular hydroswing style door as tall as the roof peak, with a horizontal truss along the top line and hinged to two posts, as Hot Wings describes. or add counterweights & swing it manually.
    I'm still not sure if I follow this (sorry, my brain is stuck in first gear).
     
  13. Sep 2, 2015 #33

    rv7charlie

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    1 A 21' wide panel (1/2 the opening) will impose tremendous loads on the 'barn door' hinges on the vertical side post. The horizontal surface would be the 'apron' in front of the hangar; the castor would be on the bottom of the swinging portion of the door (at the centerline of the opening when closed). Note that it's pretty difficult to get that apron perfectly flat and horizontal, so it always carries 1/2 the weight of the door panel. And if you do manage it, rain water will be just as prone to flow in to the hangar as away from the hangar.

    2 run the numbers on weight, but I'd have my doubts....

    3---

    4 Google 'hydroswing' & see the truss that's actually part of the door. The web of the truss is usually about a foot tall (wide, when the door is shut). This provides strength in bending when the door is open (~horizontal), and the reinforcing truss is vertical.

    My description would have the door supported on two bearings; one at the top of each post. If built as a one piece 'hydroswing' style and using hydraulic rams to open the door, you'd need to be sure that the vertical supporting posts can withstand the considerable side loads imposed as the rams start pushing the door out and up. This can be assisted by 'guying' the posts back alongside the building. If the door itself is built as a truss (meaning that it can be hung from the top corners without sagging in the middle, and with vertical members that can self-support when the door is horizontal, then you could go with a single horizontal 1' deep truss at mid point, where the rams push the door. edit: The above assumes floor mounted rams, pushing at the vertical center point of the door. If the rams are mounted to the support posts and push on the bottom edge of the door, then you'd need a 1' truss on the top and the bottom of the door itself. And the bending loads on the support posts are different.

    If built as a bifold instead of one-piece hydroswing, you'd need those 1' trusses built onto the door at both the top (probably outside, for clearance) and the bottom (inside, to avoid losing vertical clear height when open). With a bifold, something has to carry the load of the cables (and likely, the winch, as well), and the only thing available is the door itself.

    Note that one piece doors make tremendous sails when open and the wind is howling. Bifolds much less so, because they present only half the area, and tend to break up airflow. But the one piece doors make great shade in the summer, even with translucent white Suntuff covering.

    To Hot Wings: if I'm understanding his requirements, the door must open all the way up to the peak of the roof, so there is no horizontal surface available to attach the top hinge line. The truss I was describing would be part of the door itself; all loads are carried by the two vertical support posts.

    The door I'm trying to describe would look like an old school 'store front' that presents a rectangle to the viewer on the street, even though the roof line hidden behind it is a gable roof.

    Charlie
     
  14. Sep 2, 2015 #34

    bmcj

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    Thanks Charlie. For the swinging door, I envisioned a spring loaded wheel that stays in contact with the ground and has a springforce capable of supporting the cantilevered weight of the door so that the hinges don't have to.
     
  15. Sep 2, 2015 #35

    rv7charlie

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    How much range (height variation), and how much weight? A spring strong enough to support the weight when extended, will load the hinges in the other direction by that weight when compressed, no?
     
  16. Sep 2, 2015 #36

    Hot Wings

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    Just to be clear - Is this what we are looking at?
     

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  17. Sep 2, 2015 #37

    bmcj

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    Not quite. More like this:

    Hangar Truss.jpg


    And I was thinking of a trapezoidal bi-fold doors (a left door and a right door) with the hinge line running mid height:

    Hangar Truss Door.jpg
     
  18. Sep 3, 2015 #38

    Hot Wings

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    So more like this?
     

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  19. Sep 3, 2015 #39

    rv7charlie

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    If you lift as shown, the apex will destroy the roof truss with side load. If you cantilever the lift points forward so the cables pull out and up, ending with a vertical pull at fully open, you might get away with it, with attention to detail (tracks for rollers on the sides of the bottom edge). Lift attach points would need to be at the vertical center of the lower panel, or the bottom edge won't want to come all the way up. Pulling at the hinge line would put tremendous side (bending) loads on both the support posts and the roof.

    If you lift at the bottom (like a normal bifold), it will again destroy the roof truss with side load (this time out, instead of inward force). It would also require the bottom edge to rise as high as the apex hinge. Even if it was stable, with either lift point as soon as the bottom edge approaches the same height as the apex the assembly will go 'over center' and if you're lucky enough that it stays on the posts, you won't be able to lower it without a forklift or a few floor jacks and 4x4 posts. (That's one of the downsides of any conventional bifold design; I've seen over-centers happen and it isn't fun to fix.)

    The split bifold (yellow doors) could probably be made to work, but I'd be very surprised if a door can be built light enough to avoid over stressing the roof truss & roof/wall, wall/foundation intersections. And the gearing to make it work smoothly would be pretty convoluted.
    edit: Don't forget also, that the 'inside' edges (center split edges) won't have anything to push against as you lift. There's a lot of side force out at the top hinge, and inward at the bottom edge of the door when it's up. The top hinge will heavily side load the roof truss when the door is up (in addition to the vertical load), and the bottom-center corner of each door will swing inward, twisting each door.

    Additionally, I do think you need to count the cost of the foam, fiberglass, and resin it would take to build a door that's going to be close to 500 square feet. I doubt that the door will be light enough to work, but you might be able to fly, hanging from your wallet after building it.....

    edit: insert ;-) here...
     
    Last edited: Sep 3, 2015
  20. Sep 3, 2015 #40

    Hot Wings

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    As drawn 100% correct. But his was just a quick sketch for concept. The end posts would have to be additional structure and the door off set to swing into the hangar opening.

    as soon as the bottom edge approaches the same height as the apex the assembly will go 'over center'

    Don't let it ever get to over center. If the hinge point on the posts is high enough the bottom of the door will clear the apex of the roof truss and still have a nice stable "V".
     

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