Quick build wooden wing

Discussion in 'Member Project Logs' started by FritzW, Oct 22, 2014.

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  1. Oct 22, 2014 #1

    FritzW

    FritzW

    FritzW

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    This is version #1 of a wing I made for an "all CNC cut, tab and slot, jig-less" HiMax I was thinking about building. I came up with so many ideas for an improved version #2 wing that I only built this one wing panel. I also wanted a more generic fuselage to test different wings and tail feathers on so the HiMax went to the back burner for now. I'll have pictures of the version #2 wing on my Neirrh XXL build log soon.


    First, the ribs:

    IMG_2716.jpg The ribs are 1/8" Birch aircraft ply with 1/8" ply doubler "sticks" that glue to slots on each side of the truss diagonals. They get a 1/8" x 1/2" ply capstrip later on.

    2013-01-21 17.11.02.jpg Here's what the sticks and slots look like.

    IMG_2718.jpg I glued the sticks in with TightBond III. I was looking for a easy, one part, adhesive that was locally available. I didn't make that decision lightly, I did a bunch of testing before I went with TightBond.

    IMG_2717.jpg Tabs on the nose ribs fit into slots on the main ribs. The gap between the two is for the spar web. The two little holes in the nose rib are for the static and pitot lines. The larger hole is for wing tip light wiring.

    2013-01-21 16.35.36.jpg All of the support structure for the aileron hinges and bell crank are pre-drilled and are indexed by temporary bolts while the glue dries.

    2013-01-13 15.19.55.jpg All of the ribs, sticks, spar webs, cap strips etc... are cut in one operation. It took about an hour per 4'x8' sheet and it took two and a half sheets for both wing panels.

    ...Next the spars
     

    Attached Files:

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  2. Oct 22, 2014 #2

    FritzW

    FritzW

    FritzW

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    The Spars Part 1: (edit, the images aren't showing up, if it doesn't fix itself in a few minutes I'll re-post them)

    The spars are 3/4"x3/4" Spruce with 1/16" ply webs. That sounded awful thin for a spar web but that's what the HiMax plans called for and the math backs it up. I ordered 8' pieces for the spar caps so they could be shipped UPS. Splicing them was probably more trouble than it was worth to save a little money on shipping.

    IMG_2783.jpg IMG_2782.jpg IMG_2784.jpg This isn't the right build sequence (no spar caps yet) it just shows how the main ribs use the nose ribs to "trap the spar web

    IMG_2856.jpg I needed to splice sections of ply together to get the full 12' length. I used a butt joint and doubler, same as the fuselage on a VP-1. Also the surface grain is running span wise instead of vertical. I have so many web stiffeners it didn't matter which way the surface grain ran.

    IMG_2822.jpg I also had to splice the spar caps, cutting the splice on the caps was easy enough on the CNC machine...

    IMG_2825s.JPG ...but gluing them together (T-88) in a cold garage was a tedious chore.

    IMG_2858.jpg I kept the finished splices away from the highly stressed areas

    IMG_2802.jpg These temporary spacers plug into the rib slots...

    IMG_2803.JPG ...and are held in place with the wedges.
     

    Attached Files:

    Last edited: Oct 22, 2014
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  3. Oct 22, 2014 #3

    FritzW

    FritzW

    FritzW

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    The Spars Part 2:


    IMG_2804.jpg IMG_2806.jpg IMG_2808.jpg The spacers are the same size as the ribs and hold the spar caps in the correct position while the glue dries. I used T-88 to glue the spar caps in. TightBond III would have worked but I wasn't ready to make that leap just yet.

    IMG_2904.jpg The front spar doublers were pretty standard. The rear spar doubler was made in one piece except for the strut attach block.

    IMG_2906.jpg The strut attach block was made separate to keep the bolt loading parallel to the grain.

    Having slots in the spar webs looks pretty scary but they get completely filled and doublers get glued in on both sides of the ribs so the slots are completely "trapped"


    Next: putting the wing together
     
    Last edited: Oct 22, 2014
  4. Oct 22, 2014 #4

    FritzW

    FritzW

    FritzW

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    Assembling the wing:

    IMG_2779.jpg Once the ribs were done (it only took an afternoon to assemble all the ribs) I plugged them into the spars just to see what it would look like.

    IMG_2931.jpg With the ribs and spars done it was just a matter of putting "tab A in slot A and tab B in slot B"

    IMG_2956.jpg IMG_2927.jpg One mistake I made was not assembling the "root set" off the wing then just gluing the assemble to the wing.

    IMG_2955.jpg ...it led to a real hassle trying to get everything clamped together and clamped to the wing. If I'd built root set separately it would have been dead simple.

    IMG_2941.jpg IMG_2971.jpg One of the compression struts. This will be much simpler on the version #2 wing. I'm also going to do away with wooden drag/anti-drag members and use a much simpler method that will use custom motorcycle spokes (if I can get them made the way I want)

    IMG_2969.jpg This shows how the cap strips will go on the ribs. It also shows the index tab to align the ribs to the rear spar. You can see the front spar intercostels, the rear spar has the same thing.

    Next: leading edge skins
     
    Last edited: Oct 22, 2014
  5. Oct 22, 2014 #5

    FritzW

    FritzW

    FritzW

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    Leading edge skins:

    Leading Edge with arcs.jpg The plan was to make one piece LE skins with scallops. That didn't work out so I made the scallops as a separate piece.

    IMG_2980.jpg IMG_2982s.jpg The LE skins are only 1/16" Birch ply but it can be a pain to get a nice bend in them. I made a little steam box and hooked it up to a wall paper steamer. After about 10 minutes in the steam box they were bent around the LE like a dream.

    IMG_2987.jpg Using straps like this was fine for letting the skins cool, dry and take a permanent set but they didn't really hold the skins in complete close contact with the ribs.

    IMG_0388.jpg IMG_0389.jpg These clamp blocks held the skins in complete contact with the ribs (they were cut with the nose rib profile +1/32". I used these to form the rest of the skins and to when I glued the skins on, they worked like a charm. I think I've come up with a simpler "all in one" steam box/skin former that will allow me to make LE skins with the scallops in one piece.

    IMG_3024.jpg I added the scallops as separate pieces after I had the LE skins glued on.

    IMG_3025.jpg A few more pieces to finish the tank deck and tank hatch area and the wing was pretty much done. I didn't finish the ailerons because those will be a major change on the version #2 wing.
     
    Last edited: Oct 22, 2014
  6. Oct 22, 2014 #6

    FritzW

    FritzW

    FritzW

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    IMG_0370.jpg I used the large size MiniMax tanks in this wing (they're for sale by the way:)) The V2 wing will have either a welded aluminum or "pop rivet and ProSeal" tank. I think I can make a lighter/better tank without that much extra work.

    IMG_0386.jpg IMG_0368.jpg I used the machine to make the spar and strut fittings, it worked great once I had it set up right. You can see from the burnt fixture I had the feeds and speeds set wrong on my first attempt.

    RM spar attach.jpg A quick note on those fittings: with everything (spar web, doublers etc.) pre-drilled with the same files used to cut the fittings, the bushings pressed right into place and the fittings fit just right.

    IMG_2974.jpg I don't know how much the wing weighed at this point but if a skinny, young, handsome dude like this can hold it, it's pretty darn light. You can see one of my many unfinished projects stuck to the ceiling. It's sort of a single seat Tailwind. ...so many airplanes, so little time.
     
    Last edited: Oct 22, 2014
  7. Oct 22, 2014 #7

    FritzW

    FritzW

    FritzW

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    P.S.

    The natural progression of this "jig-less, tab and slot" method is to come up with a completely "snap together" airplane. ...maybe a wooden Ercoupe:)

    The idea I've been messing with is the "Router Lark", a sort of a parasol wing Volksplane. I know I've posted these before, but just to keep all of this in one basket I'll post them here.

    L1 Fuse Start3.jpg Here it is without the rear fuselage diagonals etc.

    L1 CM3.jpg Some "see through" detail

    L1 CM2.jpg L1 CM3b.jpg The idea is most of the airplane is made up of easy to build modules that can be built on a kitchen table. You only need a garage when it comes time to put the modules together. All of the parts are made on a CNC machine, even the longerons. Any parts that don't have "tabs and slots" will have index pins, either 1/8" dowels that get glued in or 1/8" Nylon bolts that get taken out when the glue dries.

    L1 CM3a.jpg There are some steel parts that I'll have to have cut on a waterjet (my machine doesn't have flood cooling ...yet)

    Working out the geometry of the anti-servo tab...

    Router Lark Cutaway 7.jpg Router Lark Cockpit Module.jpg ...or maybe this one, same idea, different layout.
     
    Last edited by a moderator: Mar 20, 2019

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