Chapter 19:  Wings                                                                                  Next  Previous  Home


    I didn't take too many pics of the core cutting process, but there really is nothing new here. The only tip to pass on is well known but here it is anyway. Make little bridges across the spar cap trough with mixing sticks, cut across them and then cut the troughs separately .  Makes a nicer cut, just like on the canard. 


    The first pics is the inboard core with John Epplin's templates installed and ready to cut, second pic is one of the cores being assembled with micro. I stood it on the trailing edge, lined everything up as near perfect as possible, placed finish nails to hold it secure and weighted it down for cure. One trick to pass along here, when placing the micro, don't let it get near the edges, you don't want that stuff to get to the wing surface or else you will be grinding it away later with a dremel. You will need to  LIGHTLY sand the wing surface to remove any minor mis-match or defects, the micro will play havoc with this process. If you can keep it off the wing surface you will be way ahead of the game.
    Also read the note, chapter 19 page 3 second paragraph. Nat has you cut  a wedge of wing core off using a band saw  AFTER he tells you to micro it back together.  If you cut it first you can use the hot wire saw. I fooled him though and used the hot wire saw anyway! Yes it will cut micro! One the second wing I had my education and knew what to do.
                      

Here's  a shot of the shear web lay-ups.

Next the leading edge cores are bonded into position with micro, this is a big step with lots of checking, rechecking and finally a "leap of faith" .
The spar cap troughs must be lined up perfectly to insure the spar cap is the proper thickness all along the wing, the level lines must be absolutely plumb and the cores must also match up to each other nicely and finally the trailing edge must be straight and lined up with each core.   There are plenty of places to screw things up in this step.  Note also the little blocks glued to the jigs. The jigs are generally a lousy fit as anyone who has done this knows. I took this tip from Jay Hegeman's web site  and recommend it.  What it does is guarantee that both wings will fit the jigs the same way. Good Idea! Also preserve all those level lines as long as possible! Transfer them onto the leading edge and shear web whenever you can.  After assembling the cores some of them will be invisible to you, if you transfer them onto the LE and shear web you can still use them to check alignment.


Next the wing core is jigged to the bench. I spent some quality time
with string lines and shims to get the core as straight as possible,
It ended up straight within 1/16" over the length of the core.
Better than any Cessna I bet, well maybe not a Citation X.
Spar cap layups, nothing new here from the main spar or canard, just make sure you have enough to finish when you start the last one.

    My wife Paula & I hard at work on one of the wing layups. These typically took about 8 - 10 hours to complete.
I'm very fortunate to have her support on this project, although I'm not sure she believes it will ever fly!

These shots show part of the aileron installation.  I ran into trouble here, in center pic you can see the glass to glass bond is not at the minimum .5" called for in the plans. I had to make a repair on this one. Also seen is the straight edge I used to keep the hinges in line with each other. This worked very well and my ailerons move easy with no binding at all. Also seen here are the Click Bond studs I used to mount the hinges to the wings. I received a few emails from people very concerned that I should just follow the plans and use screws.  I'm not the first guy to do this,  also I  don't think they know how the click bond stud is used and are under the impression that the aileron hinges are glued or bonded to the wing! This is not true, in fact the click bonds are installed just as if they were a screw. That is they go thru the skin with the head above the wing skin, the head bonds to the top wing skin and all the adhesive (flox) does is keep them from turning. The head of the CB's is only .020" thick. This allows them to be filled over with micro or in my case I recessed the foam locally  before glassing the wing, mine are completely flush. Wayne Hicks  suggest using a small rivet to insure the stud does not turn. I did this but now think it unnecessary, if anything just grind a few notches along the perimeter and this is probably over kill, the Flox really grips these tight. Also you should put a layer of BID over them to keep them  secure and prevent any paint issues later.

 Here you can see the spherical bearing  I used for the Aileron torque tube . The plans phenolic block is subject to early wear, the supplied Triangle bearing is made from Delrin or Nylon and works fine except at this location  it is subject to flame impingement in the event of an engine fire. Also, it is a self aligning bearing  not spherical, and not designed to swivel in use. Most people use it anyway and it works. The spherical bearings Infinity sells cost $50.00 each and I'm sure they are very nice. These were $3.00 ea.  Stamped  plated steel housing with a machined steel insert and oil impregnated bronze "ball".  I did need to machine little bushings to fit over my -3  click bond studs as the holes are 5/16".


Here you can see the aileron torque tube, bell-cranks and  push rods.  If you study it closely and compare it to the plans you will note all of my
hardware is installed  in accordance with standard practice, ie all of the bolts are pointing down  and thru the rod ends, the rod ends are on top of the bell cranks.  I don't know why the plans don't show it this way, and there may be something I'm missing, but it works. I have all the  required travel, clearance etc. All I needed to do to allow this is flip the CS-128 bellcrank over. If you see a problem with this, I'm all ears! In the photo it looks like I don't have 90 degrees between the push rod and bellcrank, but it is perpendicular.

    Next and last step is match drilling the wings to the main spar. I managed to get the whole enchilada in the garage from corner to corner.  I started out using my auto-level-laser. About half  way thru I decided to do a reality check with a water level to make sure  before I drilled any holes, good thing I did! The laser was off by  about .5" over 100'. I didn't want to wait to have it fixed so I just went with the water level like most others have done.  The water levels are not fool proof either!  Make sure all the air is out of the tubing or it can be off., also let things settle for a bout a minute as sometimes it takes a moment for the columns to equalize
    I also tried to use the hole saw method and after about one hole decided to buy a reamer instead. To me this seems like the only way to go for this step. Just drill it up to 39/64", then run the .625" reamer thru it, couldn't be easier! The bushing  will fit perfect this way.  My holes all came out center except both outboard lower hard-points were off  center by about 1/8" high.  This is no problem, the hole is well inside the hard point, but it makes me wonder how I made the same measuring error on both wings!  It also forced me to enlarge one of the pockets as I could not get a socket over the bolt.
    One more thing, You will note that I have installed 2 level boards on the wings. The plans call for 1 on each wing but I was concerned that one might get knocked off so I went with  a backup.  Both were perfectly level when installed, however weeks later when I needed  them  the  boards out of agreement on the RH wing by .1 degrees.  Now I had to decide which one was wrong! Luckily I still had the level line on the outboard core to use.  The outboard level board agreed with the level line. Afterwards I investigated a little further and found the inboard board was no longer flat. I had been when installed so it warped somehow.  So my tip of the day for this step is to cut your level boards so that only the ends will touch your level, in other words cut a relief along the top center 80% or so of the board so the level only touches near the ends.  This makes for a more repeatable surface to measure against.


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