Sonex 1362

Author: Tim

  • Spar Mating holes layout

    The left and right front spars overlap as can be seen in W08 Detail K.  In the overlap region there are 5 accurate holes that line up.  If you look later in the plans only the outside two bolt the two spars together.  The middle three are used as alignment holes when you drill the outside ones to each other and the fuselage.  When making the main spar webs, W10-01 the plans note to layout and drill these hole accurately.

    So given the accuracy of marking and then drilling what is the likelihood that all 5 sets of holes will line up exactly.  Well Dan and I discussed this at length and this is what we came up with.  Any two sets of holes will define the two spar webs and the rest of the holes will just over constrain the parts.  Think of it this way, you overlap the two spars as shown in the plans, you put a pin in one set of the 5 holes that line up.  Now you cannot move the two spars in X and Y directions the only degree of freedom left is rotational.  So now you can rotate the spars until another set of the 4 holes (that are left) are aligned.  Put a pin in those two aligned holes.  Now the two spars are fully constrained to each other and if the final 3 sets of holes line up GREAT, but if they don’t there is nothing you can do about it.  Given the accuracy of marking and drilling it is easy to be off by a 1/64 of an inch, which is .015″.  Now on a #40 hole (.098″ dia) that 64th of an inch  is 15% and will be noticeable by eye.  But that is in just one direction (X) you could be off in the other (Y) also.

    Now I know that these holes will be up drilled at a later date so maybe it doesn’t matter.  But here is what we did.  We drilled the two outside holes of the 5 “wing attach” on each spar web as accurately as we could.  We then flipped one spar round and clecoed them together as they are layed out in the final assembly using the outside holes.  Now we match drilled the 3 middle holes  through the two webs.  Now all 5 sets of hole will line up since the middle 3 were “aligned” by the outside 2.

    Are we over thinking this?  Probably.  Are we engineers? Yup.

    Here are the two spar webs aligned by the two outside clecos

     

    Here we are checking the angle:

     

    Checking the overlap on the bottom:

     

    Return to Wing – Main Spar

  • Shaping Spar Parts

    August  – Finishing the spar andgle parts

    Spar Parts In Progress

     

    Marking the holes in W10-01. This took a while, wanted it to be accurate since it is the template for the other webs

    Some progress on the spar parts:

    Fiinshed up the Spar Parts

    Return To Wings – Main Spar

  • Cutting spar webs A

    Well we started on the spar.  Now W10-01 is 7 1/16″ wide by 141″ long and is .032 thick.  So how does one make a good cut 141″ long?  Well Dan did the work on this one and I think he used the edge of sheet for one side and used the Malco shears for teh other.  He gave a little extra on the width so we could file down to it.  Dan was careful with the shears to avoid getting a wavy edge, a little is inevitiable but he did a great job.

    Picture of cutting web with shears

    Dan set up a table for the bandsaw to help with cutting out W10-03 (.125″ thick), W10-05 (.090″ thick) and W10-02 (0.032″ thick).

    Band Saw Set Up

    Band Saw Table

    Spar pieces rough cut from the band saw table

    Shaped Spar Parts

    We had to clean them up with the vixen file down to the line.  Dan stacked some of the similar parts together to get a consistant edge.

    Here is Dan working on a part from W-11 getting cleaned up

    Spar Angle Part Cleaned Up

    Return To Wing Page – Main Spar

  • Completed Horiz Stab

    August 6, 2011  The horizontal stabilizer is hung on the wall

    Horizontal Stab On The Wall
    Horizontal Stab On The Wall

    Looks beautiful to me.

    Return To Empennage

  • Vertical Stab Tip Splice Install

    After finishing the horizontal stabilizer we decided to install the custom “splice strip” for the fiberglass tip.  The sheetmetal strip slipped easily between the top rib and the skin.  The dimples aligned it right in place.  Here are the rivets inserted:

    Vertical Staibilizer Custom Sheetmetal Strip To Attach the Fiberglass Tip

    Return To Empennage

  • Horizontal Stabilizer Rivet

    Dan finished riveting the frame together.  He put the skins on with clecos:

     

    Horizontal Stab Frame Riveted Together Test Skin Fit

    Here is a close up of the leading edge, looks really nice.  I am glad our tech councilor suggested to get a good bend on the leading edge.

    Here is the leading edge looking from the outboard side:

    Here is the training edge with the hinge:

     

    Horizontal Stab Trailing edge before riveting skins

    Just before staring to rivet

    One skin side flush riveted:

    Here is the completed Horizintal Stabilizer:

    Dan noted that you have to really have the rivet gun square/flat with the skin or the rivet might become tipped a little in the dimple.   Only a couple had to be drilled out.

    After admiring our work and gloating for a minute we hung it on the wall.

    Return to Empenage – Horizontal Stailizer

  • Horizontal Stabilizer Spars Assembly

    We assembled the complete horizontal stabilizer frame and skins one last time to make sure all the parts were in the right place.

    One more assembly check
    Ready To Start Riveting

    We started with the (rear) main spar assembly (SNX-T3-01).  The inner rivets are fine, but the outer ones are closer to the flange so you cannot get the rivet gun in there without deflecting the flange

    Rivet Gun Interferes With Flange

    Dan had previously made some spacers to put between the rivet head and the rivet gun.  We decided to make a new spacer with a smaller bore to fit the rivet stem better.  We had some 3/8 rod and we cut off a piece and drilled a hole.  The first two attempts had the hole off center and it looked really bad.  The next one was too tall and the gun could not grip the stem.  The fourth one finally worked.

    Rivet Stem Spacer

    It’s amazing how much time these little side exercises take up.  We finished riveting the main spar.

    We started on the front spar (SNZ-T03-05).

    However we decided t rivet SNX-T04-01 (the inner ribs) to SNX-T03-05, forward root clip.  The plans show to rivet this later with assembling the whole frame, but it looks more cramped and awkward to get a rivet puller in there.

    On the front spar we were careful of the orientation of the inner most rivets, the first rows (on each side) are flipped from the rest.

    Return To Empennage – Horizontal Stabilizer

  • Compressor Disassembly

    I bought a 60 gallon Craftsman air compressor off of craigslist last fall.  It has great specs, 11.5 cfm at 90 psi.  It is a 220v model.

    The Beast

    When we went to check it out we ran it and it was loud lout loud.  A real clack clack clak…  You can’t talk to someone next to you.  I thought this was the normal sound for large compressor and I bought it and we brought it back to the workshop.  A friend who is building a Harmon Rocket has a new compressor and Dan mentioned it is really quiet compared to the beast I bought.  Well I finally tore is apart and after consulting with Dan and some engine guys at work, the crankshaft bearings are scored and beat up.  So I ordered a new set and we will see if that solves the problem.  In the meantime I am cleaning it up from all the paint residue inside and out from the previous owner.

    Interesting side note on the bearings.  I could move the connecting rod back and forth on the crankshaft and wrist pin and clack against the shoulders on the crankshaft.  The bearings are narrower than the width of the connecting rod and cap.  But there does not seem to be any wear on the sides of the connecting rod and end cap, I assume the crankshaft would be harder than the others.  I guess you would call this side play on the connecting rod.

    Return to Workshop – Tools

  • Prime Horizontal Stabilizer Parts

    Dan primed the horizintal stabilizer parts and skins.  We had gotten a gallon of 3M Mar Hyde Self Etch Primer.  Dan used his compressed air paint spray gun.  He has a lot more control over the spray width and delivery than with the spray cans we’ve used so far.  He put a really nice light and consistant coat on, great job.  Safety notes: Dan used a respirator with cartriges and had the workspace venting with a fan pulling air out a window.

    Horiz Stab Frame Parts PrimedA Horiz Stab Skin PrimedA Horiz Stab Skin Primed

    Return to Empennage

    A Horiz Stab Skin Primed

    Return To Empennage – Horizontal Stabilizer

  • Horiz Stab Dimple and Prep

    Dan dimpled the hoizintal stab frame and skins and I finished preparing the frame parts for priming.

    We found a used DRDT-2 dimpler for sale on the Vans Air Force website last fall and used it with a 120 degree pop rivet dimple die from Avery (We also evaluated the Cleveland die and the results are the same.)  The DRDT-2 made the dimpling go really fast, but there are a few places that cannot fit (notice just below the die on the bottom beam in the picture).

    DRDT-2 Dimpler

    Dan had modified a pair of large vice lock pliers.  A freind welded on some smal channel to the jaws.  The top channel has a hole for the male die half.  The lower channel has a 120 degree counter sink hole with a through hole for the male die pin, essentially Dan replicated the female side of the dimple die in the lower channel.   We’ll post a picture.  It works really well, fits in all the tight corners on flanges.

    I prepped the frame parts for priming by roughing them up with 240 grit sandpaper to take the shine off and get some swirls.  I would finish up with maroon Scotchbite pad.  Lots of surfaces to cover.

     

    Return To Empennage – Horizontal Stabilizer

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